LM2596 SIMPLE SWITCHER® Power Converter 150-kHz

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An IMPORTANT NOTICE at the end of this data sheet addresses availability warranty changes use in safetycritical applications
intellectual property matters and other important disclaimers PRODUCTION DATA
LM2596
SNVS124D –NOVEMBER 1999–REVISED MAY 2016
LM2596 SIMPLE SWITCHER® Power Converter 150kHz
3A StepDown Voltage Regulator
1
1 Features
1• 33V 5V 12V and Adjustable Output Versions
• Adjustable Version Output Voltage Range 12V
to 37V ± 4 Maximum Over Line and Load
Conditions
• Available in TO220 and TO263 Packages
• 3A Output Load Current
• Input Voltage Range Up to 40 V
• Requires Only 4 External Components
• Excellent Line and Load Regulation Specifications
• 150kHz FixedFrequency Internal Oscillator
• TTL Shutdown Capability
• Low Power Standby Mode IQ Typically 80 μA
• High Efficiency
• Uses Readily Available Standard Inductors
• Thermal Shutdown and CurrentLimit Protection
• Create a Custom Design Using the LM2596 with
the WEBENCH Power Designer
2 Applications
• Simple HighEfficiency StepDown (Buck)
Regulator
• OnCard Switching Regulators
• Positive to Negative Converter
3 Description
The LM2596 series of regulators are monolithic
integrated circuits that provide all the active functions
for a stepdown (buck) switching regulator capable of
driving a 3A load with excellent line and load
regulation These devices are available in fixed output
voltages of 33 V 5 V 12 V and an adjustable output
version
Requiring a minimum number of external
components these regulators are simple to use and
include internal frequency compensation and a fixed
frequency oscillator
The LM2596 series operates at a switching frequency
of 150 kHz thus allowing smaller sized filter
components than what would be required with lower
frequency switching regulators Available in a
standard 7pin TO220 package with several different
lead bend options and a 7pin TO263 surface mount
package
Device Information(1)
PART NUMBER PACKAGE BODY SIZE (NOM)
LM2596
TO220 (7) 14986 mm × 1016 mm
TO263 (7) 1010 mm × 889 mm
(1) For all available packages see the orderable addendum at
the end of the data sheet
Typical Application
(Fixed Output Voltage Versions)
2
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Table of Contents
1 Features 1
2 Applications 1
3 Description 1
4 Revision History 2
5 Description (continued) 3
6 Pin Configuration and Functions 3
7 Specifications 4
71 Absolute Maximum Ratings 4
72 ESD Ratings 4
73 Operating Conditions 4
74 Thermal Information 4
75 Electrical Characteristics – 33V Version 5
76 Electrical Characteristics – 5V Version 5
77 Electrical Characteristics – 12V Version 5
78 Electrical Characteristics – Adjustable Voltage
Version 5
79 Electrical Characteristics – All Output Voltage
Versions 6
710 Typical Characteristics 7
8 Detailed Description 10
81 Overview 10
82 Functional Block Diagram 10
83 Feature Description 10
84 Device Functional Modes 14
9 Application and Implementation 15
91 Application Information 15
92 Typical Applications 22
10 Power Supply Recommendations 31
11 Layout 31
111 Layout Guidelines 31
112 Layout Examples 31
113 Thermal Considerations 33
12 Device and Documentation Support 35
121 Custom Design with WEBENCH Tools 35
122 Receiving Notification of Documentation Updates 35
123 Community Resources 35
124 Trademarks 35
125 Electrostatic Discharge Caution 35
126 Glossary 35
13 Mechanical Packaging and Orderable
Information 35
4 Revision History
NOTE Page numbers for previous revisions may differ from page numbers in the current version
Changes from Revision C (April 2013) to Revision D Page
• Added ESD Ratings table Feature Description section Device Functional Modes Application and Implementation
section Power Supply Recommendations section Layout section Device and Documentation Support section and
Mechanical Packaging and Orderable Information section 1
• Removed all references to design software Switchers Made Simple 1
Changes from Revision B (April 2013) to Revision C Page
• Changed layout of National Semiconductor Data Sheet to TI format 10
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5 Description (continued)
A standard series of inductors are available from several different manufacturers optimized for use with the
LM2596 series This feature greatly simplifies the design of switchmode power supplies
Other features include a ±4 tolerance on output voltage under specified input voltage and output load
conditions and ±15 on the oscillator frequency External shutdown is included featuring typically 80 μA
standby current Selfprotection features include a two stage frequency reducing current limit for the output
switch and an overtemperature shutdown for complete protection under fault conditions
6 Pin Configuration and Functions
NDH Package
7Pin TO220
Top View
KTT Package
7Pin TO263
Top View
Pin Functions
PIN
IO DESCRIPTION
NO NAME
1 VIN I
This is the positive input supply for the IC switching regulator A suitable input bypass
capacitor must be present at this pin to minimize voltage transients and to supply the
switching currents required by the regulator
2 Output O
Internal switch The voltage at this pin switches between approximately (+VIN − VSAT) and
approximately −05 V with a duty cycle of VOUT VIN To minimize coupling to sensitive
circuitry the PCB copper area connected to this pin must be kept to a minimum
3 Ground — Circuit ground
4 Feedback I Senses the regulated output voltage to complete the feedback loop
5 ONOFF I
Allows the switching regulator circuit to be shut down using logic signals thus dropping the
total input supply current to approximately 80 µA Pulling this pin below a threshold voltage
of approximately 13 V turns the regulator on and pulling this pin above 13 V (up to a
maximum of 25 V) shuts the regulator down If this shutdown feature is not required the
ONOFF pin can be wired to the ground pin or it can be left open In either case the
regulator will be in the ON condition
4
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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device These are stress ratings
only which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions Exposure to absolutemaximumrated conditions for extended periods may affect device reliability
(2) If MilitaryAerospace specified devices are required please contact the Texas Instruments Sales Office Distributors for availability and
specifications
(3) Voltage internally clamped If clamp voltage is exceeded limit current to a maximum of 1 mA
7 Specifications
71 Absolute Maximum Ratings
over operating freeair temperature range (unless otherwise noted)(1)(2)
MIN MAX UNIT
Maximum supply voltage (VIN) 45 V
SDSS pin input voltage(3) 6 V
Delay pin voltage(3) 15 V
Flag pin voltage –03 45 V
Feedback pin voltage –03 25 V
Output voltage to ground steadystate –1 V
Power dissipation Internally limited
Lead temperature
KTW package
Vapor phase (60 s) 215
°CInfrared (10 s) 245
NDZ package soldering (10 s) 260
Maximum junction temperature 150 °C
Storage temperature Tstg –65 150 °C
(1) JEDEC document JEP155 states that 500V HBM allows safe manufacturing with a standard ESD control process
72 ESD Ratings
VALUE UNIT
V(ESD) Electrostatic discharge Humanbody model (HBM) per ANSIESDAJEDEC JS001(1) ±2000 V
73 Operating Conditions
MIN MAX UNIT
Supply voltage 45 40 V
Temperature –40 125 °C
(1) For more information about traditional and new thermal metrics see the Semiconductor and IC Package Thermal Metrics application
report SPRA953
(2) The package thermal impedance is calculated in accordance to JESD 517
(3) Thermal Resistances were simulated on a 4layer JEDEC board
(4) Junction to ambient thermal resistance (no external heat sink) for the package mounted TO220 package mounted vertically with the
leads soldered to a printed circuit board with (1 oz) copper area of approximately 1 in2
(5) Junction to ambient thermal resistance with the TO263 package tab soldered to a single sided printed circuit board with 05 in2 of 1oz
copper area
(6) Junction to ambient thermal resistance with the TO263 package tab soldered to a single sided printed circuit board with 25 in2 of 1oz
copper area
(7) Junction to ambient thermal resistance with the TO263 package tab soldered to a double sided printed circuit board with 3 in2 of 1oz
copper area on the LM2596S side of the board and approximately 16 in2 of copper on the other side of the PCB
74 Thermal Information
THERMAL METRIC(1)
LM2596
UNITKTW (TO263) NDZ (TO220)
7 PINS 7 PINS
RθJA Junctiontoambient thermal resistance(2)(3)
See(4) — 50
°CW
See(5) 50 —
See(6) 30 —
See(7) 20 —
RθJC(top) Junctiontocase (top) thermal resistance 2 2 °CW
5
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(1) All room temperature limits are 100 production tested All limits at temperature extremes are specified via correlation using standard
Statistical Quality Control (SQC) methods All limits are used to calculate Average Outgoing Quality Level (AOQL)
(2) Typical numbers are at 25°C and represent the most likely norm
(3) External components such as the catch diode inductor input and output capacitors can affect switching regulator system performance
When the LM2596 is used as shown in Figure 35 system performance is shown in the test conditions column
75 Electrical Characteristics – 33V Version
Specifications are for TJ 25°C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT
SYSTEM PARAMETERS(3) (see Figure 35 for test circuit)
VOUT Output voltage 475 V ≤ VIN ≤ 40 V
02 A ≤ ILOAD ≤ 3 A
TJ 25°C 3168 33 3432
V
–40°C ≤ TJ ≤ 125°C 3135 3465
η Efficiency VIN 12 V ILOAD 3 A 73
(1) All room temperature limits are 100 production tested All limits at temperature extremes are specified via correlation using standard
Statistical Quality Control (SQC) methods All limits are used to calculate Average Outgoing Quality Level (AOQL)
(2) Typical numbers are at 25°C and represent the most likely norm
(3) External components such as the catch diode inductor input and output capacitors can affect switching regulator system performance
When the LM2596 is used as shown in Figure 35 system performance is shown in the test conditions column
76 Electrical Characteristics – 5V Version
Specifications are for TJ 25°C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT
SYSTEM PARAMETERS(3) (see Figure 35 for test circuit)
VOUT Output voltage 7 V ≤ VIN ≤ 40 V
02 A ≤ ILOAD ≤ 3 A
TJ 25°C 48 5 52
V
–40°C ≤ TJ ≤ 125°C 475 525
η Efficiency VIN 12 V ILOAD 3 A 80
(1) All room temperature limits are 100 production tested All limits at temperature extremes are specified via correlation using standard
Statistical Quality Control (SQC) methods All limits are used to calculate Average Outgoing Quality Level (AOQL)
(2) Typical numbers are at 25°C and represent the most likely norm
(3) External components such as the catch diode inductor input and output capacitors can affect switching regulator system performance
When the LM2596 is used as shown in Figure 35 system performance is shown in the test conditions column
77 Electrical Characteristics – 12V Version
Specifications are for TJ 25°C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT
SYSTEM PARAMETERS(3) (see Figure 35 for test circuit)
VOUT Output voltage 15 V ≤ VIN ≤ 40 V
02 A ≤ ILOAD ≤ 3 A
TJ 25°C 1152 12 1248
V
–40°C ≤ TJ ≤ 125°C 114 126
η Efficiency VIN 25 V ILOAD 3 A 90
(1) All room temperature limits are 100 production tested All limits at temperature extremes are specified via correlation using standard
Statistical Quality Control (SQC) methods All limits are used to calculate Average Outgoing Quality Level (AOQL)
(2) Typical numbers are at 25°C and represent the most likely norm
(3) External components such as the catch diode inductor input and output capacitors can affect switching regulator system performance
When the LM2596 is used as shown in Figure 35 system performance is shown in the test conditions column
78 Electrical Characteristics – Adjustable Voltage Version
Specifications are for TJ 25°C (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT
SYSTEM PARAMETERS(3) (see Figure 35 for test circuit)
VFB Feedback voltage
45 V ≤ VIN ≤ 40 V 02 A ≤ ILOAD ≤ 3 A 123
VVOUT programmed for 3 V
(see Figure 35 for test circuit)
TJ 25°C 1193 1267
–40°C ≤ TJ ≤ 125°C 118 128
η Efficiency VIN 12 V VOUT 3 V ILOAD 3 A 73
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(1) All room temperature limits are 100 production tested All limits at temperature extremes are specified via correlation using standard
Statistical Quality Control (SQC) methods All limits are used to calculate Average Outgoing Quality Level (AOQL)
(2) Typical numbers are at 25°C and represent the most likely norm
(3) The switching frequency is reduced when the second stage current limit is activated The amount of reduction is determined by the
severity of current overload
(4) No diode inductor or capacitor connected to output pin
(5) Feedback pin removed from output and connected to 0 V to force the output transistor switch ON
(6) Feedback pin removed from output and connected to 12 V for the 33V 5V and the adjustable versions and 15 V for the 12V
version to force the output transistor switch OFF
(7) VIN 40 V
79 Electrical Characteristics – All Output Voltage Versions
Specifications are for TJ 25°C ILOAD 500 mA VIN 12 V for the 33V 5V and adjustable version and VIN 24 V for the
12V version (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT
DEVICE PARAMETERS
Ib Feedback bias current Adjustable version only
VFB 13 V
TJ 25°C 10 50
nA
–40°C ≤ TJ ≤ 125°C 100
fO Oscillator frequency(3) TJ 25°C 127 150 173
kHz
–40°C ≤ TJ ≤ 125°C 110 173
VSAT Saturation voltage(4) (5) IOUT 3 A
TJ 25°C 116 14
V
–40°C ≤ TJ ≤ 125°C 15
DC
Max duty cycle (ON)(5) 100
Min duty cycle (OFF)(6) 0
ICL Current limit(4) (5) Peak current
TJ 25°C 36 45 69
A
–40°C ≤ TJ ≤ 125°C 34 75
IL
Output leakage
current(4) (6)
Output 0 V VIN 40 V 50 μA
Output –1 V 2 30 mA
IQ
Operating quiescent
current(6) See (6) 5 10 mA
ISTBY
Current standby
quiescent ONOFF pin 5 V (OFF)(7) TJ 25°C 80 200 μA
–40°C ≤ TJ ≤ 125°C 250 μA
SHUTDOWNSOFTSTART CONTROL (see Figure 35 for test circuit)
VIH
ONOFF pin logic input
threshold voltage
Low (regulator ON)
TJ 25°C 13
V
–40°C ≤ TJ ≤ 125°C 06
VIL High (regulator OFF)
TJ 25°C 13
V
–40°C ≤ TJ ≤ 125°C 2
IH ONOFF pin input
current
VLOGIC 25 V (regulator OFF) 5 15 μA
IL VLOGIC 05 V (regulator ON) 002 5 μA
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710 Typical Characteristics
See Figure 35 for test circuit
Figure 1 Normalized Output Voltage Figure 2 Line Regulation
Figure 3 Efficiency Figure 4 Switch Saturation Voltage
Figure 5 Switch Current Limit Figure 6 Dropout Voltage
8
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Typical Characteristics (continued)
See Figure 35 for test circuit
Figure 7 Operating Quiescent Current Figure 8 Shutdown Quiescent Current
Figure 9 Minimum Operating Supply Voltage Figure 10 ONOFF Threshold Voltage
Figure 11 ONOFF Pin Current (Sinking) Figure 12 Switching Frequency
9
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Typical Characteristics (continued)
See Figure 35 for test circuit
Figure 13 Feedback Pin Bias Current
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8 Detailed Description
81 Overview
The LM2596 SIMPLE SWITCHER® regulator is an easytouse nonsynchronous stepdown DCDC converter
with a wide input voltage range up to 40 V The regulator is capable of delivering up to 3A DC load current with
excellent line and load regulation These devices are available in fixed output voltages of 33V 5V 12V and an
adjustable output version The family requires few external components and the pin arrangement was designed
for simple optimum PCB layout
82 Functional Block Diagram
83 Feature Description
831 Delayed StartUp
The circuit in Figure 14 uses the ONOFF pin to provide a time delay between the time the input voltage is
applied and the time the output voltage comes up (only the circuitry pertaining to the delayed startup is shown)
As the input voltage rises the charging of capacitor C1 pulls the ONOFF pin high keeping the regulator OFF
Once the input voltage reaches its final value and the capacitor stops charging resistor R2 pulls the ONOFF pin
low thus allowing the circuit to start switching Resistor R1 is included to limit the maximum voltage applied to the
ONOFF pin (maximum of 25 V) reduces power supply noise sensitivity and also limits the capacitor C1
discharge current When high input ripple voltage exists avoid long delay time because this ripple can be
coupled into the ONOFF pin and cause problems
This delayed startup feature is useful in situations where the input power source is limited in the amount of
current it can deliver It allows the input voltage to rise to a higher voltage before the regulator starts operating
Buck regulators require less input current at higher input voltages
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Feature Description (continued)
Figure 14 Delayed StartUp
832 Undervoltage Lockout
Some applications require the regulator to remain off until the input voltage reaches a predetermined voltage
Figure 15 shows an undervoltage lockout feature applied to a buck regulator while Figure 16 and Figure 17
apply the same feature to an inverting circuit The circuit in Figure 16 features a constant threshold voltage for
turnon and turnoff (Zener voltage plus approximately one volt) If hysteresis is required the circuit in Figure 17
has a turnon voltage which is different than the turnoff voltage The amount of hysteresis is approximately equal
to the value of the output voltage If Zener voltages greater than 25 V are used an additional 47kΩ resistor is
required from the ONOFF pin to the ground pin to stay within the 25 V maximum limit of the ONOFF pin
Figure 15 Undervoltage Lockout
for Buck Regulator
833 Inverting Regulator
The circuit in Figure 18 converts a positive input voltage to a negative output voltage with a common ground The
circuit operates by bootstrapping the ground pin of the regulator to the negative output voltage then grounding
the feedback pin the regulator senses the inverted output voltage and regulates it
This circuit has an ONOFF threshold of approximately 13 V
Figure 16 Undervoltage Lockout
for Inverting Regulator
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Feature Description (continued)
This example uses the LM259650 to generate a −5V output but other output voltages are possible by
selecting other output voltage versions including the adjustable version Because this regulator topology can
produce an output voltage that is either greater than or less than the input voltage the maximum output current
greatly depends on both the input and output voltage Figure 19 provides a guide as to the amount of output load
current possible for the different input and output voltage conditions
The maximum voltage appearing across the regulator is the absolute sum of the input and output voltage and
this must be limited to a maximum of 40 V For example when converting +20 V to −12 V the regulator would
see 32 V between the input pin and ground pin The LM2596 has a maximum input voltage spec of 40 V
Additional diodes are required in this regulator configuration Diode D1 is used to isolate input voltage ripple or
noise from coupling through the CIN capacitor to the output under light or no load conditions Also this diode
isolation changes the topology to closely resemble a buck configuration thus providing good closedloop stability
TI recommends using a Schottky diode for low input voltages (because of its lower voltage drop) but for higher
input voltages a fast recovery diode could be used
Without diode D3 when the input voltage is first applied the charging current of CIN can pull the output positive
by several volts for a short period of time Adding D3 prevents the output from going positive by more than a
diode voltage
This circuit has hysteresis
Regulator starts switching at VIN 13 V
Regulator stops switching at VIN 8 V
Figure 17 Undervoltage Lockout With Hysteresis for Inverting Regulator
CIN — 68μF 25V Tant Sprague 595D
470 μF 50V Elec Panasonic HFQ
COUT — 47μF 20V Tant Sprague 595D
220μF 25V Elec Panasonic HFQ
Figure 18 Inverting −5V Regulator With Delayed StartUp
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Feature Description (continued)
Figure 19 Inverting Regulator Typical Load Current
Because of differences in the operation of the inverting regulator the standard design procedure is not used to
select the inductor value In the majority of designs a 33μH 35A inductor is the best choice Capacitor
selection can also be narrowed down to just a few values Using the values shown in Figure 18 will provide good
results in the majority of inverting designs
This type of inverting regulator can require relatively large amounts of input current when starting up even with
light loads Input currents as high as the LM2596 current limit (approximately 45 A) are required for at least 2 ms
or more until the output reaches its nominal output voltage The actual time depends on the output voltage and
the size of the output capacitor Input power sources that are current limited or sources that can not deliver these
currents without getting loaded down may not work correctly Because of the relatively high startup currents
required by the inverting topology the delayed startup feature (C1 R1 and R2) shown in Figure 18 is
recommended By delaying the regulator startup the input capacitor is allowed to charge up to a higher voltage
before the switcher begins operating A portion of the high input current required for startup is now supplied by
the input capacitor (CIN) For severe startup conditions the input capacitor can be made much larger than
normal
834 Inverting Regulator Shutdown Methods
Using the ONOFF pin in a standard buck configuration is simple To turn the regulator ON pull the ONOFF pin
below 13 V (at 25°C referenced to ground) To turn the regulator OFF pull the ONOFF pin above 13 V With
the inverting configuration some level shifting is required because the ground pin of the regulator is no longer at
ground but is now setting at the negative output voltage level Two different shutdown methods for inverting
regulators are shown in Figure 20 and Figure 21
Figure 20 Inverting Regulator Ground Referenced Shutdown
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Feature Description (continued)
Figure 21 Inverting Regulator Ground Referenced Shutdown Using Opto Device
84 Device Functional Modes
841 Discontinuous Mode Operation
The selection guide chooses inductor values suitable for continuous mode operation but for low current
applications or high input voltages a discontinuous mode design may be a better choice A discontinuous mode
design would use an inductor that would be physically smaller and would require only one half to one third the
inductance value required for a continuous mode design The peak switch and inductor currents will be higher in
a discontinuous design but at these low load currents (1 A and below) the maximum switch current will still be
less than the switch current limit
Discontinuous operation can have voltage waveforms that are considerably different than a continuous design
The output pin (switch) waveform can have some damped sinusoidal ringing present (see Figure 36) This
ringing is normal for discontinuous operation and is not caused by feedback loop instabilities In discontinuous
operation there is a period of time where neither the switch nor the diode are conducting and the inductor
current has dropped to zero During this time a small amount of energy can circulate between the inductor and
the switchdiode parasitic capacitance causing this characteristic ringing Normally this ringing is not a problem
unless the amplitude becomes great enough to exceed the input voltage and even then there is very little
energy present to cause damage
Different inductor types or core materials produce different amounts of this characteristic ringing Ferrite core
inductors have very little core loss and therefore produce the most ringing The higher core loss of powdered iron
inductors produce less ringing If desired a series RC could be placed in parallel with the inductor to dampen the
ringing
Figure 22 Post Ripple Filter Waveform
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9 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification and TI does not warrant its accuracy or completeness TI’s customers are
responsible for determining suitability of components for their purposes Customers should
validate and test their design implementation to confirm system functionality
91 Application Information
911 Input Capacitor (CIN)
A low ESR aluminum or tantalum bypass capacitor is required between the input pin and ground pin It must be
placed near the regulator using short leads This capacitor prevents large voltage transients from occuring at the
input and provides the instantaneous current required each time the switch turns ON
The important parameters for the Input capacitor are the voltage rating and the RMS current rating Because of
the relatively high RMS currents flowing in a buck regulator's input capacitor this capacitor must be chosen for
its RMS current rating rather than its capacitance or voltage ratings although the capacitance value and voltage
rating are directly related to the RMS current rating
The RMS current rating of a capacitor could be viewed as a capacitor's power rating The RMS current flowing
through the capacitors internal ESR produces power which causes the internal temperature of the capacitor to
rise The RMS current rating of a capacitor is determined by the amount of current required to raise the internal
temperature approximately 10°C above an ambient temperature of 105°C The ability of the capacitor to dissipate
this heat to the surrounding air will determine the amount of current the capacitor can safely sustain For a given
capacitor value a higher voltage electrolytic capacitor will be physically larger than a lower voltage capacitor and
thus be able to dissipate more heat to the surrounding air and therefore will have a higher RMS current rating
The consequences of operating an electrolytic capacitor above the RMS current rating is a shortened operating
life The higher temperature speeds up the evaporation of the capacitor's electrolyte resulting in eventual failure
Selecting an input capacitor requires consulting the manufacturers data sheet for maximum allowable RMS ripple
current For a maximum ambient temperature of 40°C a general guideline would be to select a capacitor with a
ripple current rating of approximately 50 of the DC load current For ambient temperatures up to 70°C a
current rating of 75 of the DC load current would be a good choice for a conservative design The capacitor
voltage rating must be at least 125 times greater than the maximum input voltage and often a much higher
voltage capacitor is required to satisfy the RMS current requirements
Figure 23 shows the relationship between an electrolytic capacitor value its voltage rating and the RMS current
it is rated for These curves were obtained from the Nichicon PL series of lowESR highreliability electrolytic
capacitors designed for switching regulator applications Other capacitor manufacturers offer similar types of
capacitors but always check the capacitor data sheet
Standard electrolytic capacitors typically have much higher ESR numbers lower RMS current ratings and
typically have a shorter operating lifetime
Because of their small size and excellent performance surfacemount solid tantalum capacitors are often used
for input bypassing but several precautions must be observed A small percentage of solid tantalum capacitors
can short if the inrush current rating is exceeded This can happen at turnon when the input voltage is suddenly
applied and of course higher input voltages produce higher inrush currents Several capacitor manufacturers do
a 100 surge current testing on their products to minimize this potential problem If high turnon currents are
expected it may be necessary to limit this current by adding either some resistance or inductance before the
tantalum capacitor or select a higher voltage capacitor As with aluminum electrolytic capacitors the RMS ripple
current rating must be sized to the load current
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Application Information (continued)
912 Feedforward Capacitor (CFF)
NOTE
For adjustable output voltage version only
A feedforward capacitor shown across R2 in Table 6 is used when the output voltage is greater than 10 V or
when COUT has a very low ESR This capacitor adds lead compensation to the feedback loop and increases the
phase margin for better loop stability For CFF selection see the Detailed Design Procedure section
Figure 23 RMS Current Ratings for Low ESR Electrolytic Capacitors (Typical)
913 Output Capacitor (COUT)
An output capacitor is required to filter the output and provide regulator loop stability Low impedance or lowESR
electrolytic or solid tantalum capacitors designed for switching regulator applications must be used When
selecting an output capacitor the important capacitor parameters are the 100kHz ESR the RMS ripple current
rating voltage rating and capacitance value For the output capacitor the ESR value is the most important
parameter
The output capacitor requires an ESR value that has an upper and lower limit For low output ripple voltage a
low ESR value is required This value is determined by the maximum allowable output ripple voltage typically 1
to 2 of the output voltage But if the selected capacitor's ESR is extremely low there is a possibility of an
unstable feedback loop resulting in an oscillation at the output Using the capacitors listed in the tables or
similar types will provide design solutions under all conditions
If very low output ripple voltage (less than 15 mV) is required see Output Voltage Ripple and Transients for a
post ripple filter
An aluminum electrolytic capacitor's ESR value is related to the capacitance value and its voltage rating In most
cases higher voltage electrolytic capacitors have lower ESR values (see Figure 24) Often capacitors with much
higher voltage ratings may be required to provide the low ESR values required for low output ripple voltage
The output capacitor for many different switcher designs often can be satisfied with only three or four different
capacitor values and several different voltage ratings See Table 3 and Table 4 for typical capacitor values
voltage ratings and manufacturers capacitor types
Electrolytic capacitors are not recommended for temperatures below −25°C The ESR rises dramatically at cold
temperatures and is typically 3 times as large at −25°C and as much as 10 times as large at −40°C See
Figure 25
Solid tantalum capacitors have a much better ESR specifications for cold temperatures and are recommended
for temperatures below −25°C
17
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Application Information (continued)
Figure 24 Capacitor ESR vs Capacitor Voltage Rating (Typical LowESR Electrolytic Capacitor)
914 Catch Diode
Buck regulators require a diode to provide a return path for the inductor current when the switch turns off This
must be a fast diode and must be placed close to the LM2596 using short leads and short printedcircuit traces
Because of their very fast switching speed and low forward voltage drop Schottky diodes provide the best
performance especially in low output voltage applications (5 V and lower) Ultrafast recovery or highefficiency
rectifiers are also a good choice but some types with an abrupt turnoff characteristic may cause instability or
EMI problems Ultrafast recovery diodes typically have reverse recovery times of 50 ns or less Rectifiers such
as the 1N5400 series are much too slow and should not be used
Figure 25 Capacitor ESR Change vs Temperature
915 Inductor Selection
All switching regulators have two basic modes of operation continuous and discontinuous The difference
between the two types relates to the inductor current whether it is flowing continuously or if it drops to zero for a
period of time in the normal switching cycle Each mode has distinctively different operating characteristics
which can affect the regulators performance and requirements Most switcher designs will operate in the
discontinuous mode when the load current is low
The LM2596 (or any of the SIMPLE SWITCHER™ family) can be used for both continuous or discontinuous
modes of operation
In many cases the preferred mode of operation is the continuous mode which offers greater output power lower
peak switch lower inductor and diode currents and can have lower output ripple voltage However the
continuous mode does require larger inductor values to keep the inductor current flowing continuously especially
at low output load currents or high input voltages
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Application Information (continued)
To simplify the inductor selection process an inductor selection guide (nomograph) was designed (see Figure 27
through Figure 30) This guide assumes that the regulator is operating in the continuous mode and selects an
inductor that will allow a peaktopeak inductor ripple current to be a certain percentage of the maximum design
load current This peaktopeak inductor ripple current percentage is not fixed but is allowed to change as
different design load currents are selected (see Figure 26)
Figure 26 (ΔIIND) PeaktoPeak Inductor
Ripple Current (as a Percentage of the Load Current)
vs Load Current
By allowing the percentage of inductor ripple current to increase for low load currents the inductor value and size
can be kept relatively low
When operating in the continuous mode the inductor current waveform ranges from a triangular to a sawtooth
type of waveform (depending on the input voltage) with the average value of this current waveform equal to the
DC output load current
Inductors are available in different styles such as pot core toroid Ecore bobbin core and so forth as well as
different core materials such as ferrites and powdered iron The least expensive the bobbin rod or stick core
consists of wire wound on a ferrite bobbin This type of construction makes for an inexpensive inductor but
because the magnetic flux is not completely contained within the core it generates more ElectroMagnetic
Interference (EMl) This magnetic flux can induce voltages into nearby printedcircuit traces thus causing
problems with both the switching regulator operation and nearby sensitive circuitry and can give incorrect scope
readings because of induced voltages in the scope probe (see OpenCore Inductors)
When multiple switching regulators are located on the same PCB opencore magnetics can cause interference
between two or more of the regulator circuits especially at high currents A torroid or Ecore inductor (closed
magnetic structure) should be used in these situations
The inductors listed in the selection chart include ferrite Ecore construction for Schottky ferrite bobbin core for
Renco and Coilcraft and powdered iron toroid for Pulse Engineering
Exceeding an inductor's maximum current rating may cause the inductor to overheat because of the copper wire
losses or the core may saturate If the inductor begins to saturate the inductance decreases rapidly and the
inductor begins to look mainly resistive (the DC resistance of the winding) This can cause the switch current to
rise very rapidly and force the switch into a cyclebycycle current limit thus reducing the DC output load current
This can also result in overheating of the inductor or the LM2596 Different inductor types have different
saturation characteristics so consider this when selecting an inductor
The inductor manufacturer's data sheets include current and energy limits to avoid inductor saturation
For continuous mode operation see the inductor selection graphs in Figure 27 through Figure 30
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Application Information (continued)
Figure 27 LM259633 Figure 28 LM259650
Figure 29 LM259612 Figure 30 LM2596ADJ
Table 1 Inductor Manufacturers Part Numbers
INDUCTANCE
(μH)
CURRENT
(A)
SCHOTTKY RENCO PULSE ENGINEERING COILCRAFT
THROUGH
HOLE
SURFACE
MOUNT
THROUGH
HOLE
SURFACE
MOUNT
THROUGH
HOLE
SURFACE
MOUNT
SURFACE
MOUNT
L15 22 099 67148350 67148460 RL128422
43 RL150022 PE53815 PE53815S DO3308223
L21 68 099 67144070 67144450 RL54715 RL150068 PE53821 PE53821S DO3316683
L22 47 117 67144080 67144460 RL54716 — PE53822 PE53822S DO3316473
L23 33 140 67144090 67144470 RL54717 — PE53823 PE53823S DO3316333
L24 22 170 67148370 67148480 RL128322
43 — PE53824 PE53825S DO3316223
L25 15 210 67148380 67148490 RL128315
43 — PE53825 PE53824S DO3316153
L26 330 080 67144100 67144480 RL54711 — PE53826 PE53826S DO5022P334
L27 220 100 67144110 67144490 RL54712 — PE53827 PE53827S DO5022P224
L28 150 120 67144120 67144500 RL54713 — PE53828 PE53828S DO5022P154
L29 100 147 67144130 67144510 RL54714 — PE53829 PE53829S DO5022P104
L30 68 178 67144140 67144520 RL54715 — PE53830 PE53830S DO5022P683
L31 47 220 67144150 67144530 RL54716 — PE53831 PE53831S DO5022P473
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Application Information (continued)
Table 1 Inductor Manufacturers Part Numbers (continued)
INDUCTANCE
(μH)
CURRENT
(A)
SCHOTTKY RENCO PULSE ENGINEERING COILCRAFT
THROUGH
HOLE
SURFACE
MOUNT
THROUGH
HOLE
SURFACE
MOUNT
THROUGH
HOLE
SURFACE
MOUNT
SURFACE
MOUNT
L32 33 250 67144160 67144540 RL54717 — PE53932 PE53932S DO5022P333
L33 22 310 67148390 67148500 RL128322
43 — PE53933 PE53933S DO5022P223
L34 15 340 67148400 67148790 RL128315
43 — PE53934 PE53934S DO5022P153
L35 220 170 67144170 — RL54731 — PE53935 PE53935S —
L36 150 210 67144180 — RL54734 — PE54036 PE54036S —
L37 100 250 67144190 — RL54721 — PE54037 PE54037S —
L38 68 310 67144200 — RL54722 — PE54038 PE54038S —
L39 47 350 67144210 — RL54723 — PE54039 PE54039S —
L40 33 350 67144220 67148290 RL54724 — PE54040 PE54040S —
L41 22 350 67144230 67148300 RL54725 — PE54041 PE54041S —
L42 150 270 67148410 — RL54734 — PE54042 PE54042S —
L43 100 340 67144240 — RL54732 — PE54043 —
L44 68 340 67144250 — RL54733 — PE54044 —
916 Output Voltage Ripple and Transients
The output voltage of a switching power supply operating in the continuous mode will contain a sawtooth ripple
voltage at the switcher frequency and may also contain short voltage spikes at the peaks of the sawtooth
waveform
The output ripple voltage is a function of the inductor sawtooth ripple current and the ESR of the output
capacitor A typical output ripple voltage can range from approximately 05 to 3 of the output voltage To
obtain low ripple voltage the ESR of the output capacitor must be low however exercise caution when using
extremely low ESR capacitors because they can affect the loop stability resulting in oscillation problems TI
recommends a post ripple filter if very low output ripple voltage is required (less than 20 mV) (see Figure 32)
The inductance required is typically between 1 μH and 5 μH with low DC resistance to maintain good load
regulation A low ESR output filter capacitor is also required to assure good dynamic load response and ripple
reduction The ESR of this capacitor may be as low as desired because it is out of the regulator feedback loop
Figure 22 shows a typical output ripple voltage with and without a post ripple filter
When observing output ripple with a scope it is essential that a short low inductance scope probe ground
connection be used Most scope probe manufacturers provide a special probe terminator which is soldered onto
the regulator board preferably at the output capacitor This provides a very short scope ground thus eliminating
the problems associated with the 3inch ground lead normally provided with the probe and provides a much
cleaner and more accurate picture of the ripple voltage waveform
The voltage spikes are caused by the fast switching action of the output switch and the diode the parasitic
inductance of the output filter capacitor and its associated wiring To minimize these voltage spikes the output
capacitor should be designed for switching regulator applications and the lead lengths must be kept very short
Wiring inductance stray capacitance as well as the scope probe used to evaluate these transients all contribute
to the amplitude of these spikes
When a switching regulator is operating in the continuous mode the inductor current waveform ranges from a
triangular to a sawtooth type of waveform (depending on the input voltage) For a given input and output voltage
the peaktopeak amplitude of this inductor current waveform remains constant As the load current increases or
decreases the entire sawtooth current waveform also rises and falls The average value (or the center) of this
current waveform is equal to the DC load current
If the load current drops to a low enough level the bottom of the sawtooth current waveform reaches zero and
the switcher smoothly changes from a continuous to a discontinuous mode of operation Most switcher designs
(regardless of how large the inductor value is) is forced to run discontinuous if the output is lightly loaded This is
a perfectly acceptable mode of operation
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Figure 31 PeaktoPeak Inductor
Ripple Current vs Load Current
In a switching regulator design knowing the value of the peaktopeak inductor ripple current (ΔIIND) can be
useful for determining a number of other circuit parameters Parameters such as peak inductor or peak switch
current minimum load current before the circuit becomes discontinuous output ripple voltage and output
capacitor ESR can all be calculated from the peaktopeak ΔIIND When the inductor nomographs in Figure 27
through Figure 30 are used to select an inductor value the peaktopeak inductor ripple current can immediately
be determined Figure 31 shows the range of (ΔIIND) that can be expected for different load currents Figure 31
also shows how the peaktopeak inductor ripple current (ΔIIND) changes as you go from the lower border to the
upper border (for a given load current) within an inductance region The upper border represents a higher input
voltage while the lower border represents a lower input voltage
These curves are only correct for continuous mode operation and only if the inductor selection guides are used
to select the inductor value
Consider the following example
VOUT 5 V maximum load current of 25 A
VIN 12 V nominal varying between 10 V and 16 V
The selection guide in Figure 28 shows that the vertical line for a 25A load current and the horizontal line for the
12V input voltage intersect approximately midway between the upper and lower borders of the 33μH inductance
region A 33μH inductor allows a peaktopeak inductor current (ΔIIND) which is a percentage of the maximum
load current to flow In Figure 31 follow the 25A line approximately midway into the inductance region and
read the peaktopeak inductor ripple current (ΔIIND) on the left hand axis (approximately 620 mApp)
As the input voltage increases to 16 V approaching the upper border of the inductance region the inductor ripple
current increases Figure 31shows that for a load current of 25 A the peaktopeak inductor ripple current (ΔIIND)
is 620 mA with 12 VIN and can range from 740 mA at the upper border (16 VIN) to 500 mA at the lower border
(10 VIN)
Once the ΔIIND value is known use these equations to calculate additional information about the switching
regulator circuit
1 Peak Inductor or peak switch current
2 Minimum load current before the circuit becomes discontinuous
3 Output Ripple Voltage (ΔIIND) × (ESR of COUT) 062 A × 01 Ω 62 mVpp
4 added for line break
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917 OpenCore Inductors
Another possible source of increased output ripple voltage or unstable operation is from an opencore inductor
Ferrite bobbin or stick inductors have magnetic lines of flux flowing through the air from one end of the bobbin to
the other end These magnetic lines of flux will induce a voltage into any wire or PCB copper trace that comes
within the inductor's magnetic field The strength of the magnetic field the orientation and location of the PC
copper trace to the magnetic field and the distance between the copper trace and the inductor determine the
amount of voltage generated in the copper trace Another way of looking at this inductive coupling is to consider
the PCB copper trace as one turn of a transformer (secondary) with the inductor winding as the primary Many
millivolts can be generated in a copper trace located near an opencore inductor which can cause stability
problems or high output ripple voltage problems
If unstable operation is seen and an opencore inductor is used it is possible that the location of the inductor
with respect to other PC traces may be the problem To determine if this is the problem temporarily raise the
inductor away from the board by several inches and then check circuit operation If the circuit now operates
correctly then the magnetic flux from the open core inductor is causing the problem Substituting a closed core
inductor such as a torroid or Ecore will correct the problem or rearranging the PC layout may be necessary
Magnetic flux cutting the IC device ground trace feedback trace or the positive or negative traces of the output
capacitor should be minimized
Sometimes placing a trace directly beneath a bobbin inductor will provide good results provided it is exactly in
the center of the inductor (because the induced voltages cancel themselves out) However problems could arise
if the trace is off center one direction or the other If flux problems are present even the direction of the inductor
winding can make a difference in some circuits
This discussion on open core inductors is not to frighten users but to alert users on what kind of problems to
watch out for Opencore bobbin or stick inductors are an inexpensive simple way of making a compact efficient
inductor and they are used by the millions in many different applications
92 Typical Applications
921 LM2596 Fixed Output Series Buck Regulator
CIN — 470μF 50V Aluminum Electrolytic Nichicon PL Series
COUT — 220μF 25V Aluminum Electrolytic Nichicon PL Series
D1 — 5A 40V Schottky Rectifier 1N5825
L1 — 68 μH L38
Figure 32 Fixed Output Voltage Version
9211 Design Requirements
Table 2 lists the design parameters for this example
Table 2 Design Parameters
PARAMETER EXAMPLE VALUE
Regulated Output Voltage (33 V 5 V or 12 V)
VOUT
5 V
Maximum DC Input Voltage VIN(max) 12 V
Maximum Load Current ILOAD(max) 3 A
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9212 Detailed Design Procedure
92121 Inductor Selection (L1)
1 Select the correct inductor value selection guide from Figure 27 Figure 28 or Figure 29 (output voltages of
33V 5V or 12V respectively) Use the inductor selection guide for the 5V version shown in Figure 28
2 From the inductor value selection guide identify the inductance region intersected by the maximum input
voltage line and the maximum load current line Each region is identified by an inductance value and an
inductor code (LXX) From the inductor value selection guide shown in Figure 28 the inductance region
intersected by the 12V horizontal line and the 3A vertical line is 33 μH and the inductor code is L40
3 Select an appropriate inductor from the four manufacturer's part numbers listed in Table 1 The inductance
value required is 33 μH See row L40 of Table 1 and choose an inductor part number from any of the
manufacturers shown In most instances both throughhole and surfacemount inductors are available
92122 Output Capacitor Selection (COUT)
1 In the majority of applications low ESR (Equivalent Series Resistance) electrolytic capacitors between 82 μF
and 820 μF and low ESR solid tantalum capacitors between 10 μF and 470 μF provide the best results This
capacitor must be placed close to the IC using short capacitor leads and short copper traces Do not use
capacitors larger than 820 μF
NOTE
For additional information see section on output capacitors in Table 3
2 To simplify the capacitor selection procedure see Table 3 for quick design component selection This table
contains different input voltages output voltages and load currents and lists various inductors and output
capacitors that will provide the best design solutions
From Table 3 locate the 5V output voltage section In the load current column choose the load current line
that is closest to the current required for the application for this example use the 3A line In the maximum
input voltage column select the line that covers the input voltage required for the application in this
example use the 15V line The rest of the line shows recommended inductors and capacitors that will
provide the best overall performance
Table 3 LM2596 Fixed Voltage Quick Design Component Selection Table
CONDITIONS INDUCTOR
OUTPUT CAPACITOR
THROUGHHOLE ELECTROLYTIC SURFACEMOUNT TANTALUM
OUTPUT
VOLTAGE
(V)
LOAD
CURRENT
(A)
MAX INPUT
VOLTAGE
(V)
INDUCTANCE
(μH)
INDUCTOR
(#)
PANASONIC
HFQ SERIES
(μFV)
NICHICON
PL SERIES
(μFV)
AVX TPS
SERIES
(μFV)
SPRAGUE
595D SERIES
(μFV)
33
3
5 22 L41 47025 56016 33063 39063
7 22 L41 56035 56035 33063 39063
10 22 L41 68035 68035 33063 39063
40 33 L40 56035 47035 33063 39063
6 22 L33 47025 47035 33063 39063
2 10 33 L32 33035 33035 33063 39063
40 47 L39 33035 27050 22010 33010
5
3
8 22 L41 47025 56016 22010 33010
10 22 L41 56025 56025 22010 33010
15 33 L40 33035 33035 22010 33010
40 47 L39 33035 27035 22010 33010
9 22 L33 47025 56016 22010 33010
2 20 68 L38 18035 18035 10010 27010
40 68 L38 18035 18035 10010 27010
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Table 3 LM2596 Fixed Voltage Quick Design Component Selection Table (continued)
CONDITIONS INDUCTOR
OUTPUT CAPACITOR
THROUGHHOLE ELECTROLYTIC SURFACEMOUNT TANTALUM
OUTPUT
VOLTAGE
(V)
LOAD
CURRENT
(A)
MAX INPUT
VOLTAGE
(V)
INDUCTANCE
(μH)
INDUCTOR
(#)
PANASONIC
HFQ SERIES
(μFV)
NICHICON
PL SERIES
(μFV)
AVX TPS
SERIES
(μFV)
SPRAGUE
595D SERIES
(μFV)
12
3
15 22 L41 47025 47025 10016 18016
18 33 L40 33025 33025 10016 18016
30 68 L44 18025 18025 10016 12020
40 68 L44 18035 18035 10016 12020
15 33 L32 33025 33025 10016 18016
2 20 68 L38 18025 18025 10016 12020
40 150 L42 8225 8225 6820 6825
The capacitor list contains both throughhole electrolytic and surfacemount tantalum capacitors from four
different capacitor manufacturers TI recommends that both the manufacturers and the manufacturer's series
that are listed in Table 3
In this example aluminum electrolytic capacitors from several different manufacturers are available with the
range of ESR numbers required
– 330μF 35V Panasonic HFQ Series
– 330μF 35V Nichicon PL Series
3 The capacitor voltage rating for electrolytic capacitors should be at least 15 times greater than the output
voltage and often require much higher voltage ratings to satisfy the low ESR requirements for low output
ripple voltage
For a 5V output a capacitor voltage rating of at least 75 V is required But even a low ESR switching
grade 220μF 10V aluminum electrolytic capacitor would exhibit approximately 225 mΩ of ESR (see
Figure 24 for the ESR vs voltage rating) This amount of ESR would result in relatively high output ripple
voltage To reduce the ripple to 1 or less of the output voltage a capacitor with a higher value or with a
higher voltage rating (lower ESR) must be selected A 16V or 25V capacitor will reduce the ripple voltage
by approximately half
92123 Catch Diode Selection (D1)
1 The catch diode current rating must be at least 13 times greater than the maximum load current Also if the
power supply design must withstand a continuous output short the diode must have a current rating equal to
the maximum current limit of the LM2596 The most stressful condition for this diode is an overload or
shorted output condition See Table 4 In this example a 5A 20V 1N5823 Schottky diode will provide the
best performance and will not be overstressed even for a shorted output
Table 4 Diode Selection Table
VR
3A DIODES 4A TO 6A DIODES
SURFACEMOUNT THROUGHHOLE SURFACEMOUNT THROUGHHOLE
SCHOTTKY ULTRA FAST
RECOVERY SCHOTTKY ULTRA FAST
RECOVERY SCHOTTKY ULTRA FAST
RECOVERY SCHOTTKY ULTRA FAST
RECOVERY
20 V
All of
these
diodes
are
rated to
at least
50V
1N5820 All of
these
diodes
are
rated to
at least
50V
All of
these
diodes
are
rated to
at least
50V
SR502 All of
these
diodes
are
rated to
at least
50V
SK32 SR302 1N5823
MBR320 SB520
30 V
30WQ03 1N5821
SK33 MBR330 50WQ03 SR503
31DQ03 1N5824
1N5822 SB530
40 V SK34 SR304 50WQ04 SR504
MBRS340 MBR340 1N5825
30WQ04 MURS320 31DQ04 MUR320 MURS620 SB540 MUR620
50 V SK35 30WF10 SR305 50WF10 HER601
or MBRS360 MBR350 50WQ05 SB550
More 30WQ05 31DQ05 50SQ080
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2 The reverse voltage rating of the diode must be at least 125 times the maximum input voltage
3 This diode must be fast (short reverse recovery time) and must be placed close to the LM2596 using short
leads and shortprinted circuit traces Because of their fast switching speed and low forward voltage drop
Schottky diodes provide the best performance and efficiency and must be the first choice especially in low
output voltage applications Ultrafast recovery or highefficiency rectifiers also provide good results Ultra
fast recovery diodes typically have reverse recovery times of 50 ns or less Rectifiers such as the 1N5400
series must not be used because they are too slow
92124 Input Capacitor (CIN)
A low ESR aluminum or tantalum bypass capacitor is required between the input pin and ground pin to prevent
large voltage transients from appearing at the input This capacitor must be placed close to the IC using short
leads In addition the RMS current rating of the input capacitor should be selected to be at least ½ the DC load
current The capacitor manufacturers data sheet must be checked to assure that this current rating is not
exceeded Figure 23 shows typical RMS current ratings for several different aluminum electrolytic capacitor
values
For an aluminum electrolytic the capacitor voltage rating must be approximately 15 times the maximum input
voltage Exercise caution if solid tantalum capacitors are used (see Input Capacitor (CIN)) The tantalum capacitor
voltage rating should be 2 times the maximum input voltage and TI recommends that they be surge current
tested by the manufacturer
Use caution when using ceramic capacitors for input bypassing because it may cause severe ringing at the VIN
pin
The important parameters for the Input capacitor are the input voltage rating and the RMS current rating With a
nominal input voltage of 12 V an aluminum electrolytic capacitor with a voltage rating greater than 18 V
(15 × VIN) is necessary The next higher capacitor voltage rating is 25 V
The RMS current rating requirement for the input capacitor in a buck regulator is approximately ½ the DC load
current In this example with a 3A load a capacitor with a RMS current rating of at least 15 A is required
Figure 23 can be used to select an appropriate input capacitor From the curves locate the 35V line and note
which capacitor values have RMS current ratings greater than 15 A A 680μF 35V capacitor could be used
For a throughhole design a 680μF 35V electrolytic capacitor (Panasonic HFQ series or Nichicon PL series or
equivalent) would be adequate Other types or other manufacturers' capacitors can be used provided the RMS
ripple current ratings are adequate
For surfacemount designs solid tantalum capacitors can be used but exercise caution with regard to the
capacitor surge current rating (see Input Capacitor (CIN) in this data sheet) The TPS series available from AVX
and the 593D series from Sprague are both surge current tested
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9213 Application Curves
Continuous Mode Switching Waveforms VIN 20 V VOUT 5 V
ILOAD 2 A L 32 μH COUT 220 μF COUT ESR 50 mΩ
A Output Pin Voltage 10 Vdiv
B Inductor Current 1 Adiv
C Output Ripple Voltage 50 mVdiv
Figure 33 Horizontal Time Base 2 μsdiv
Load Transient Response for Continuous Mode VIN 20 V VOUT
5 V ILOAD 500 mA to 2 A L 32 μH COUT 220 μF COUT ESR
50 mΩ
A Output Voltage 100 mVdiv (AC)
B 500mA to 2A Load Pulse
Figure 34 Horizontal Time Base 100 μsdiv
922 LM2596 Adjustable Output Series Buck Regulator
where VREF 123 V
Select R1 to be approximately 1 kΩ use a 1 resistor for best stability
CIN — 470μF 50V Aluminum Electrolytic Nichicon PL Series
COUT — 220μF 35V Aluminum Electrolytic Nichicon PL Series
D1 — 5A 40V Schottky Rectifier 1N5825
L1 — 68 μH L38
R1 — 1 kΩ 1
CFF — See Feedforward Capacitor (CFF)
Figure 35 Adjustable Output Voltage Version
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9221 Design Requirements
Table 5 lists the design parameters for this example
Table 5 Design Parameters
PARAMETER EXAMPLE VALUE
Regulated output voltage (33V 5V or 12V) VOUT 20 V
Maximum DC input voltage VIN(max) 28 V
Maximum load current ILOAD(max) 3 A
Switching frequency F Fixed at a nominal 150 kHz
9222 Detailed Design Procedure
92221 Custom Design with WEBENCH Tools
Click here to create a custom design using the LM2596 device with the WEBENCH® Power Designer
1 Start by entering your VIN VOUT and IOUT requirements
2 Optimize your design for key parameters like efficiency footprint and cost using the optimizer dial and
compare this design with other possible solutions from Texas Instruments
3 WEBENCH Power Designer provides you with a customized schematic along with a list of materials with real
time pricing and component availability
4 In most cases you will also be able to
– Run electrical simulations to see important waveforms and circuit performance
– Run thermal simulations to understand the thermal performance of your board
– Export your customized schematic and layout into popular CAD formats
– Print PDF reports for the design and share your design with colleagues
5 Get more information about WEBENCH tools at wwwticomwebench
92222 Programming Output Voltage
Select R1 and R2 as shown in Table 6
Use Equation 1 to select the appropriate resistor values
(1)
Select a value for R1 between 240 Ω and 15 kΩ The lower resistor values minimize noise pickup in the sensitive
feedback pin (For the lowest temperature coefficient and the best stability with time use 1 metal film
resistors) Calculate R2 with Equation 2
(2)
Select R1 to be 1 kΩ 1 Solve for R2 in Equation 3
(3)
R2 1k (1626 − 1) 1526k closest 1 value is 154 kΩ
R2 154 kΩ
92223 Inductor Selection (L1)
1 Calculate the inductor Volt • microsecond constant E × T (V × μs) with Equation 4
where
• VSAT internal switch saturation voltage 116 V
• VD diode forward voltage drop 05 V (4)
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Calculate the inductor Volt • microsecond constant
(E × T)
(5)
2 Use the E × T value from the previous formula and match it with the E × T number on the vertical axis of the
Inductor Value Selection Guide shown in Figure 30
E × T 342 (V × μs)
3 On the horizontal axis select the maximum load current
ILOAD(max) 3 A
4 Identify the inductance region intersected by the E × T value and the maximum load current value Each
region is identified by an inductance value and an inductor code (LXX) From the inductor value selection
guide shown in Figure 30 the inductance region intersected by the 34 (V • μs) horizontal line and the 3A
vertical line is 47 μH and the inductor code is L39
5 Select an appropriate inductor from the manufacturers' part numbers listed in Table 1 From the table in
Table 1 locate line L39 and select an inductor part number from the list of manufacturers part numbers
92224 Output Capacitor Selection (COUT)
1 In the majority of applications low ESR electrolytic or solid tantalum capacitors between 82 μF and 820 μF
provide the best results This capacitor must be placed close to the IC using short capacitor leads and short
copper traces Do not use capacitors larger than 820 μF
NOTE
For additional information see section on output capacitors in Output Capacitor (COUT)
section
2 To simplify the capacitor selection procedure see Table 6 for a quick design guide This table contains
different output voltages and lists various output capacitors that will provide the best design solutions
From Table 6 locate the output voltage column From that column locate the output voltage closest to the
output voltage in your application In this example select the 24V line Under the Output Capacitor (COUT)
section select a capacitor from the list of throughhole electrolytic or surfacemount tantalum types from four
different capacitor manufacturers TI recommends that both the manufacturers and the manufacturers' series
that are listed in Table 6 be used
In this example through hole aluminum electrolytic capacitors from several different manufacturers are
available
– 220μF 35V Panasonic HFQ Series
– 150μF 35V Nichicon PL Series
3 The capacitor voltage rating must be at least 15 times greater than the output voltage and often much
higher voltage ratings are required to satisfy the low ESR requirements required for low output ripple voltage
For a 20V output a capacitor rating of at least 30 V is required In this example either a 35V or 50V
capacitor would work A 35V rating was chosen although a 50V rating could also be used if a lower output
ripple voltage is required
Other manufacturers or other types of capacitors may also be used provided the capacitor specifications
(especially the 100kHz ESR) closely match the types listed in Table 6 Refer to the capacitor manufacturers
data sheet for this information
92225 Feedforward Capacitor (CFF)
See Table 6
For output voltages greater than approximately 10 V an additional capacitor is required The compensation
capacitor is typically between 100 pF and 33 nF and is wired in parallel with the output voltage setting resistor
R2 It provides additional stability for high output voltages low input or output voltages or very low ESR output
capacitors such as solid tantalum capacitors Calculate the value for CFF with Equation 6
29
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(6)
This capacitor type can be ceramic plastic silver mica and so forth Because of the unstable characteristics of
ceramic capacitors made with Z5U material they are not recommended
Table 6 contains feedforward capacitor values for various output voltages In this example a 560pF capacitor is
required
Table 6 Output Capacitor and Feedforward Capacitor Selection Table
OUTPUT
VOLTAGE
(V)
THROUGHHOLE OUTPUT CAPACITOR SURFACEMOUNT OUTPUT CAPACITOR
PANASONIC
HFQ SERIES
(μFV)
NICHICON PL
SERIES
(μFV)
FEEDFORWARD
CAPACITOR
AVX TPS
SERIES
(μFV)
SPRAGUE
595D SERIES
(μFV)
FEEDFORWARD
CAPACITOR
2 82035 82035 33 nF 33063 4704 33 nF
4 56035 47035 10 nF 33063 39063 10 nF
6 47025 47025 33 nF 22010 33010 33 nF
9 33025 33025 15 nF 10016 18016 15 nF
1 2 33025 33025 1 nF 10016 18016 1 nF
1 5 22035 22035 680 pF 6820 12020 680 pF
2 4 22035 15035 560 pF 3325 3325 220 pF
2 8 10050 10050 390 pF 1035 1550 220 pF
92226 Catch Diode Selection (D1)
1 The catch diode current rating must be at least 13 times greater than the maximum load current Also if the
power supply design must withstand a continuous output short the diode must have a current rating equal to
the maximum current limit of the LM2596 The most stressful condition for this diode is an overload or
shorted output condition See Table 4 Schottky diodes provide the best performance and in this example a
5A 40V 1N5825 Schottky diode would be a good choice The 5A diode rating is more than adequate and
will not be overstressed even for a shorted output
2 The reverse voltage rating of the diode must be at least 125 times the maximum input voltage
3 This diode must be fast (short reverse recovery time) and must be placed close to the LM2596 using short
leads and shortprinted circuit traces Because of their fast switching speed and low forward voltage drop
Schottky diodes provide the best performance and efficiency and must be the first choice especially in low
output voltage applications Ultrafast recovery or highefficiency rectifiers are also good choices but some
types with an abrupt turnoff characteristic may cause instability or EMl problems Ultrafast recovery diodes
typically have reverse recovery times of 50 ns or less Rectifiers such as the 1N4001 series must not be
used because they are too slow
92227 Input Capacitor (CIN)
A low ESR aluminum or tantalum bypass capacitor is required between the input pin and ground to prevent large
voltage transients from appearing at the input In addition the RMS current rating of the input capacitor should
be selected to be at least ½ the DC load current The capacitor manufacturers data sheet must be checked to
assure that this current rating is not exceeded Figure 23 shows typical RMS current ratings for several different
aluminum electrolytic capacitor values
This capacitor must be placed close to the IC using short leads and the voltage rating must be approximately 15
times the maximum input voltage
If solid tantalum input capacitors are used TI recommends that they be surge current tested by the
manufacturer
Use caution when using a high dielectric constant ceramic capacitor for input bypassing because it may cause
severe ringing at the VIN pin
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The important parameters for the input capacitor are the input voltage rating and the RMS current rating With a
nominal input voltage of 28 V an aluminum electrolytic aluminum electrolytic capacitor with a voltage rating
greater than 42 V (15 × VIN) is required Because the the next higher capacitor voltage rating is 50 V a 50V
capacitor must be used The capacitor voltage rating of (15 × VIN) is a conservative guideline and can be
modified somewhat if desired
The RMS current rating requirement for the input capacitor of a buck regulator is approximately ½ the DC load
current In this example with a 3A load a capacitor with a RMS current rating of at least 15 A is required
Figure 23 can be used to select an appropriate input capacitor From the curves locate the 50V line and note
which capacitor values have RMS current ratings greater than 15 A Either a 470 μF or 680 μF 50V capacitor
could be used
For a through hole design a 680μF 50V electrolytic capacitor (Panasonic HFQ series or Nichicon PL series or
equivalent) would be adequate Other types or other manufacturers' capacitors can be used provided the RMS
ripple current ratings are adequate
For surface mount designs solid tantalum capacitors can be used but exercise caution with regard to the
capacitor surge current rating (see Input Capacitor (CIN) in this data sheet) The TPS series available from AVX
and the 593D series from Sprague are both surge current tested
9223 Application Curves
Discontinuous Mode Switching Waveforms VIN 20 V VOUT 5
V ILOAD 500 mA L 10 μH COUT 330 μF COUT ESR 45
mΩ
A Output Pin Voltage 10 Vdiv
B Inductor Current 05 Adiv
C Output Ripple Voltage 100 mVdiv
Figure 36 Horizontal Time Base 2 μsdiv
Load Transient Response for Discontinuous Mode VIN 20 V
VOUT 5V ILOAD 500 mA to 2 A L 10 μH COUT 330 μF
COUT ESR 45 mΩ
A Output Voltage 100 mVdiv (AC)
B 500mA to 2A Load Pulse
Figure 37 Horizontal Time Base 200 μsdiv
31
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10 Power Supply Recommendations
The LM2596 is designed to operate from an input voltage supply up to 40 V This input supply must be well
regulated and able to withstand maximum input current and maintain a stable voltage
11 Layout
111 Layout Guidelines
As in any switching regulator layout is very important Rapidly switching currents associated with wiring
inductance can generate voltage transients which can cause problems For minimal inductance and ground
loops the wires indicated by heavy lines must be wide printedcircuit traces and must be kept as short as
possible For best results external components must be placed as close to the switcher lC as possible using
ground plane construction or single point grounding
If open core inductors are used take special care selecting the location and positioning of this type of inductor
Allowing the inductor flux to intersect sensitive feedback lC groundpath and COUT wiring can cause problems
When using the adjustable version take special care selecting the location of the feedback resistors and the
associated wiring Physically place both resistors near the IC and route the wiring away from the inductor
especially an opencore type of inductor (see OpenCore Inductors for more information)
112 Layout Examples
CIN — 470μF 50V Aluminum Electrolytic Panasonic HFQ Series
COUT — 330μF 35V Aluminum Electrolytic Panasonic HFQ Series
D1 — 5A 40V Schottky Rectifier 1N5825
L1 — 47μH L39 Renco Through Hole
Thermalloy Heat Sink #7020
Figure 38 Typical ThroughHole PCB Layout Fixed Output (1x Size) DoubleSided
32
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Layout Examples (continued)
CIN— 470μF 50V Aluminum Electrolytic Panasonic HFQ Series
COUT—220μF 35V Aluminum Electrolytic Panasonic HFQ Series
D1—5A 40V Schottky Rectifier 1N5825
L1—47μH L39 Renco Through Hole
R1—1 kΩ 1
R2—Use formula in Design Procedure
CFF—See Table 6
Thermalloy Heat Sink #7020
Figure 39 Typical ThroughHole PCB Layout Adjustable Output (1x Size) DoubleSided
33
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113 Thermal Considerations
The LM2596 is available in two packages a 7pin TO220 (T) and a 7pin surface mount TO263 (S)
The TO220 package requires a heat sink under most conditions The size of the heat sink depends on the input
voltage the output voltage the load current and the ambient temperature Figure 40 shows the LM2596T
junction temperature rises above ambient temperature for a 3A load and different input and output voltages The
data for these curves was taken with the LM2596T (TO220 package) operating as a buck switching regulator in
an ambient temperature of 25°C (still air) These temperature rise numbers are all approximate and there are
many factors that can affect these temperatures Higher ambient temperatures require more heat sinking
The TO263 surface mount package tab is designed to be soldered to the copper on a printedcircuit board
(PCB) The copper and the board are the heat sink for this package and the other heat producing components
such as the catch diode and inductor The PCB copper area that the package is soldered to must be at least 04
in2 and ideally must have 2 or more square inches of 2oz (00028 in) copper Additional copper area improves
the thermal characteristics but with copper areas greater than approximately 6 in2 only small improvements in
heat dissipation are realized If further thermal improvements are required TI recommends doublesided
multilayer PCB with large copper areas and airflow
Figure 41 shows the LM2596S (TO263 package) junction temperature rise above ambient temperature with a 2
A load for various input and output voltages This data was taken with the circuit operating as a buck switching
regulator with all components mounted on a PCB to simulate the junction temperature under actual operating
conditions This curve can be used for a quick check for the approximate junction temperature for various
conditions but be aware that there are many factors that can affect the junction temperature When load currents
higher than 2 A are used doublesided or multilayer PCB with large copper areas or airflow might be required
especially for high ambient temperatures and high output voltages
For the best thermal performance wide copper traces and generous amounts of PCB copper must be used in
the board layout (One exception to this is the output (switch) pin which should not have large areas of copper)
Large areas of copper provide the best transfer of heat (lower thermal resistance) to the surrounding air and
moving air lowers the thermal resistance even further
Package thermal resistance and junction temperature rise numbers are all approximate and there are many
factors that will affect these numbers Some of these factors include board size shape thickness position
location and even board temperature Other factors are trace width total printedcircuit copper area copper
thickness single or doublesided multilayer board and the amount of solder on the board The effectiveness of
the PCB to dissipate heat also depends on the size quantity and spacing of other components on the board as
well as whether the surrounding air is still or moving Furthermore some of these components such as the catch
diode will add heat to the PCB and the heat can vary as the input voltage changes For the inductor depending
on the physical size type of core material and the DC resistance it could either act as a heat sink taking heat
away from the board or it could add heat to the board
34
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Thermal Considerations (continued)
CIRCUIT DATA FOR TEMPERATURE RISE CURVE TO220 PACKAGE (T)
Capacitors Throughhole electrolytic
Inductor Throughhole Renco
Diode Throughhole 5A 40V Schottky
PCB 3square inch singlesided 2oz copper (00028″)
Figure 40 Junction Temperature Rise TO220
CIRCUIT DATA FOR TEMPERATURE RISE CURVE TO263 PACKAGE (S)
Capacitors Surfacemount tantalum molded D size
Inductor Surfacemount Pulse Engineering 68 μH
Diode Surfacemount 5A 40V Schottky
PCB 9square inch singlesided 2oz copper (00028″)
Figure 41 Junction Temperature Rise TO263
35
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12 Device and Documentation Support
121 Custom Design with WEBENCH Tools
Click here to create a custom design using the LM2596 device with the WEBENCH® Power Designer
1 Start by entering your VIN VOUT and IOUT requirements
2 Optimize your design for key parameters like efficiency footprint and cost using the optimizer dial and
compare this design with other possible solutions from Texas Instruments
3 WEBENCH Power Designer provides you with a customized schematic along with a list of materials with real
time pricing and component availability
4 In most cases you will also be able to
– Run electrical simulations to see important waveforms and circuit performance
– Run thermal simulations to understand the thermal performance of your board
– Export your customized schematic and layout into popular CAD formats
– Print PDF reports for the design and share your design with colleagues
5 Get more information about WEBENCH tools at wwwticomwebench
122 Receiving Notification of Documentation Updates
To receive notification of documentation updates navigate to the device product folder on ticom In the upper
right corner click on Alert me to register and receive a weekly digest of any product information that has
changed For change details review the revision history included in any revised document
123 Community Resources
The following links connect to TI community resources Linked contents are provided AS IS by the respective
contributors They do not constitute TI specifications and do not necessarily reflect TI's views see TI's Terms of
Use
TI E2E™ Online Community TI's EngineertoEngineer (E2E) Community Created to foster collaboration
among engineers At e2eticom you can ask questions share knowledge explore ideas and help
solve problems with fellow engineers
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support
124 Trademarks
E2E is a trademark of Texas Instruments
SIMPLE SWITCHER WEBENCH are registered trademarks of Texas Instruments
All other trademarks are the property of their respective owners
125 Electrostatic Discharge Caution
These devices have limited builtin ESD protection The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates
126 Glossary
SLYZ022 — TI Glossary
This glossary lists and explains terms acronyms and definitions
13 Mechanical Packaging and Orderable Information
The following pages include mechanical packaging and orderable information This information is the most
current data available for the designated devices This data is subject to change without notice and revision of
this document For browserbased versions of this data sheet refer to the lefthand navigation
PACKAGE OPTION ADDENDUM
wwwticom 3Oct2018
AddendumPage 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing
Pins Package
Qty
Eco Plan
(2)
LeadBall Finish
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(45)
Samples
LM2596S12NOPB ACTIVE DDPAK
TO263
KTT 5 45 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR LM2596S
12 P+
LM2596S33 NRND DDPAK
TO263
KTT 5 45 TBD Call TI Call TI LM2596S
33 P+
LM2596S33NOPB ACTIVE DDPAK
TO263
KTT 5 45 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR LM2596S
33 P+
LM2596S50 NRND DDPAK
TO263
KTT 5 45 TBD Call TI Call TI LM2596S
50 P+
LM2596S50NOPB ACTIVE DDPAK
TO263
KTT 5 45 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR LM2596S
50 P+
LM2596SADJNOPB ACTIVE DDPAK
TO263
KTT 5 45 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR 40 to 125 LM2596S
ADJ P+
LM2596SX12NOPB ACTIVE DDPAK
TO263
KTT 5 500 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR LM2596S
12 P+
LM2596SX33NOPB ACTIVE DDPAK
TO263
KTT 5 500 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR LM2596S
33 P+
LM2596SX50NOPB ACTIVE DDPAK
TO263
KTT 5 500 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR LM2596S
50 P+
LM2596SXADJ NRND DDPAK
TO263
KTT 5 500 TBD Call TI Call TI 40 to 125 LM2596S
ADJ P+
LM2596SXADJNOPB ACTIVE DDPAK
TO263
KTT 5 500 PbFree (RoHS
Exempt)
CU SN Level3245C168 HR 40 to 125 LM2596S
ADJ P+
LM2596T12LF03 ACTIVE TO220 NDH 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM LM2596T
12 P+
LM2596T12NOPB ACTIVE TO220 NDH 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM LM2596T
12 P+
LM2596T33LF03 ACTIVE TO220 NDH 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM LM2596T
33 P+
LM2596T33NOPB ACTIVE TO220 NDH 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM LM2596T
33 P+
LM2596T50 NRND TO220 NDH 5 45 TBD Call TI Call TI LM2596T
50 P+
LM2596T50LF03 ACTIVE TO220 NDH 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM LM2596T
50 P+
PACKAGE OPTION ADDENDUM
wwwticom 3Oct2018
AddendumPage 2
Orderable Device Status
(1)
Package Type Package
Drawing
Pins Package
Qty
Eco Plan
(2)
LeadBall Finish
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(45)
Samples
LM2596T50NOPB ACTIVE TO220 NDH 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM LM2596T
50 P+
LM2596TADJ NRND TO220 NDH 5 45 TBD Call TI Call TI 40 to 125 LM2596T
ADJ P+
LM2596TADJLF02 ACTIVE TO220 NEB 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM LM2596T
ADJ P+
LM2596TADJNOPB ACTIVE TO220 NDH 5 45 Green (RoHS
& no SbBr)
CU SN Level1NAUNLIM 40 to 125 LM2596T
ADJ P+

(1) The marketing status values are defined as follows
ACTIVE Product device recommended for new designs
LIFEBUY TI has announced that the device will be discontinued and a lifetimebuy period is in effect
NRND Not recommended for new designs Device is in production to support existing customers but TI does not recommend using this part in a new design
PREVIEW Device has been announced but is not in production Samples may or may not be available
OBSOLETE TI has discontinued the production of the device

(2) RoHS TI defines RoHS to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances including the requirement that RoHS substance
do not exceed 01 by weight in homogeneous materials Where designed to be soldered at high temperatures RoHS products are suitable for use in specified leadfree processes TI may
reference these types of products as PbFree
RoHS Exempt TI defines RoHS Exempt to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption
Green TI defines Green to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <1000ppm threshold Antimony trioxide based
flame retardants must also meet the <1000ppm threshold requirement

(3) MSL Peak Temp The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications and peak solder temperature

(4) There may be additional marking which relates to the logo the lot trace code information or the environmental category on the device

(5) Multiple Device Markings will be inside parentheses Only one Device Marking contained in parentheses and separated by a ~ will appear on a device If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device

(6) LeadBall Finish Orderable Devices may have multiple material finish options Finish options are separated by a vertical ruled line LeadBall Finish values may wrap to two lines if the finish
value exceeds the maximum column width

Important Information and DisclaimerThe information provided on this page represents TI's knowledge and belief as of the date that it is provided TI bases its knowledge and belief on information
provided by third parties and makes no representation or warranty as to the accuracy of such information Efforts are underway to better integrate information from third parties TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals
TI and TI suppliers consider certain information to be proprietary and thus CAS numbers and other limited information may not be available for release
PACKAGE OPTION ADDENDUM
wwwticom 3Oct2018
AddendumPage 3

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis

TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type
Package
Drawing
Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm)
B0
(mm)
K0
(mm)
P1
(mm)
W
(mm)
Pin1
Quadrant
LM2596SX12NOPB DDPAK
TO263
KTT 5 500 3300 244 1075 1485 50 160 240 Q2
LM2596SX33NOPB DDPAK
TO263
KTT 5 500 3300 244 1075 1485 50 160 240 Q2
LM2596SX50NOPB DDPAK
TO263
KTT 5 500 3300 244 1075 1485 50 160 240 Q2
LM2596SXADJ DDPAK
TO263
KTT 5 500 3300 244 1075 1485 50 160 240 Q2
LM2596SXADJNOPB DDPAK
TO263
KTT 5 500 3300 244 1075 1485 50 160 240 Q2
PACKAGE MATERIALS INFORMATION
wwwticom 15Sep2018
Pack MaterialsPage 1
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
LM2596SX12NOPB DDPAKTO263 KTT 5 500 3670 3670 450
LM2596SX33NOPB DDPAKTO263 KTT 5 500 3670 3670 450
LM2596SX50NOPB DDPAKTO263 KTT 5 500 3670 3670 450
LM2596SXADJ DDPAKTO263 KTT 5 500 3670 3670 450
LM2596SXADJNOPB DDPAKTO263 KTT 5 500 3670 3670 450
PACKAGE MATERIALS INFORMATION
wwwticom 15Sep2018
Pack MaterialsPage 2
MECHANICAL DATA
NDH0005D
wwwticom
MECHANICAL DATA
KTT0005B
wwwticom
BOTTOM SIDE OF PACKAGE
TS5B (Rev D)
MECHANICAL DATA
NEB0005B
wwwticom
MECHANICAL DATA
NEB0005E
wwwticom
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