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LM2596

www.ti.com

SNVS124C –NOVEMBER 1999–REVISED APRIL 2013

LM2596 SIMPLE SWITCHER

Power Converter 150 kHz

3A Step-Down Voltage Regulator

Check for Samples: LM2596

FEATURES

DESCRIPTION

The LM2596 series of regulators are monolithic

• 3.3V, 5V, 12V, and Adjustable Output Versions

integrated circuits that provide all the active functions

• Adjustable Version Output Voltage Range,

for a step-down (buck) switching regulator, capable of

1.2V to 37V ±4% Max Over Line and Load

driving a 3A load with excellent line and load

Conditions

regulation. These devices are available in fixed output

voltages of 3.3V, 5V, 12V, and an adjustable output

• Available in TO-220 and TO-263 Packages

version.

• Ensured 3A Output Load Current

Requiring a minimum number of external

• Input Voltage Range Up to 40V

components, these regulators are simple to use and

• Requires Only 4 External Components

include internal frequency compensation , and a

• Excellent Line and Load Regulation

fixed-frequency oscillator.

Specifications

The LM2596 series operates at a switching frequency

• 150 kHz Fixed Frequency Internal Oscillator

of 150 kHz thus allowing smaller sized filter

• TTL Shutdown Capability

components than what would be needed with lower

frequency switching regulators. Available in a

• Low Power Standby Mode, I

Typically 80 μA

standard 5-lead TO-220 package with several

• High Efficiency

different lead bend options, and a 5-lead TO-263

• Uses Readily Available Standard Inductors

surface mount package.

• Thermal Shutdown and Current Limit

A standard series of inductors are available from

Protection

several different manufacturers optimized for use with

the LM2596 series. This feature greatly simplifies the

APPLICATIONS

design of switch-mode power supplies.

• Simple High-Efficiency Step-Down (Buck)

Other features include a ensured ±4% tolerance on

Regulator

output voltage under specified input voltage and

output load conditions, and ±15% on the oscillator

• On-Card Switching Regulators

frequency. External shutdown is included, featuring

• Positive to Negative Converter

typically 80 μA standby current. Self protection

features include a two stage frequency reducing

current limit for the output switch and an over

temperature shutdown for complete protection under

fault conditions.

(1)

(1) † Patent Number 5,382,918.

Typical Application

(Fixed Output Voltage Versions)

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2SIMPLE SWITCHER is a registered trademark of Texas Instruments.

3All other trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (42 pages)

PAGE 1
LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 LM2596 SIMPLE SWITCHER® Power Converter 150 kHz 3A Step-Down Voltage Regulator Check for Samples: LM2596 FEATURES DESCRIPTION • • The LM2596 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 3A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Connection Diagrams Figure 1. 5-Lead Bent and Staggered Leads, Through Hole TO-220 (T) Package See Package Number NDH0005D Figure 2. 5-Lead DDPAK/TO-263 (S) Package See Package Number KTT0005B These devices have limited built-in 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.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 LM2596-3.3 Electrical Characteristics Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range LM2596-3.3 Symbol Parameter Conditions Typ (1) SYSTEM PARAMETERS VOUT η (1) (2) (3) (3) Limit (2) Units (Limits) 3.168/3.135 V(min) 3.432/3.465 V(max) Test Circuit Figure 20 Output Voltage Efficiency 4.75V ≤ VIN ≤ 40V, 0.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com LM2596-ADJ Electrical Characteristics Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range LM2596-ADJ Symbol Parameter Conditions Typ (1) SYSTEM PARAMETERS VFB (3) 4.5V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A Efficiency (3) Units (Limits) 1.193/1.180 V(min) 1.267/1.280 V(max) 1.230 V VOUT programmed for 3V.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 All Output Voltage Versions Electrical Characteristics (continued) Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V version.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (Circuit of Figure 20) 6 Normalized Output Voltage Line Regulation Figure 3. Figure 4. Efficiency Switch Saturation Voltage Figure 5. Figure 6. Switch Current Limit Dropout Voltage Figure 7. Figure 8.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 Typical Performance Characteristics (continued) (Circuit of Figure 20) Operating Quiescent Current Shutdown Quiescent Current Figure 9. Figure 10. Minimum Operating Supply Voltage ON /OFF Threshold Voltage Figure 11. Figure 12. ON /OFF Pin Current (Sinking) Switching Frequency Figure 13. Figure 14.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) (Circuit of Figure 20) Continuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 2A L = 32 μH, COUT = 220 μF, COUT ESR = 50 mΩ Feedback Pin Bias Current A: Output Pin Voltage, 10V/div. B: Inductor Current 1A/div. C: Output Ripple Voltage, 50 mV/div. Figure 16. Horizontal Time Base: 2 μs/div. Figure 15.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 Test Circuit and Layout Guidelines Fixed Output Voltage Versions CIN —470 μF, 50V, Aluminum Electrolytic Nichicon “PL Series” COUT —220 μF, 25V Aluminum Electrolytic, Nichicon “PL Series” D1 —5A, 40V Schottky Rectifier, 1N5825 L1 —68 μH, L38 Adjustable Output Voltage Versions where VREF = 1.23V Select R1 to be approximately 1 kΩ, use a 1% resistor for best stability.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com LM2596 Series Buck Regulator Design Procedure (Fixed Output) PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) Given: VOUT = Regulated Output Voltage (3.3V, 5V or 12V) VIN(max) = Maximum DC Input Voltage ILOAD(max) = Maximum Load Current Given: VOUT = 5V VIN(max) = 12V ILOAD(max) = 3A 1. Inductor Selection (L1) A.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) 3. Catch Diode Selection (D1) A. The catch diode current rating must be at least 1.3 times greater than the maximum load current. Also, if the power supply design must withstand a continuous output short, the diode should have a current rating equal to the maximum current limit of the LM2596.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Table 1.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) 2. Inductor Selection (L1) 2. Inductor Selection (L1) A. Calculate the inductor Volt • microsecond constant E • T (V • μs), A. Calculate the inductor Volt • microsecond constant from the following formula: (E • T), where • • (5) VSAT = internal switch saturation voltage = B. E • T = 34.2 (V • μs) 1.16V C.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) 5. Catch Diode Selection (D1) A. The catch diode current rating must be at least 1.3 times greater than the maximum load current. Also, if the power supply design must withstand a continuous output short, the diode should have a current rating equal to the maximum current limit of the LM2596.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 Table 2. Output Capacitor and Feedforward Capacitor Selection Table (continued) Output Voltage (V) Through Hole Output Capacitor Panasonic HFQ Series (μF/V) Nichicon PL Series (μF/V) 9 330/25 330/25 12 330/25 15 220/35 24 28 Surface Mount Output Capacitor Feedforward Capacitor AVX TPS Series (μF/V) Sprague 595D Series (μF/V) Feedforward Capacitor 1.5 nF 100/16 180/16 1.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Table 3. Inductor Manufacturers Part Numbers Inductance (μH) Current (A) Schott Renco Through Hole Surface Mount Through Hole Pulse Engineering Surface Mount Through Hole Surface Mount Coilcraft Surface Mount L15 22 0.99 67148350 67148460 RL-1284-22-43 RL1500-22 PE-53815 PE-53815-S DO3308-223 L21 68 0.99 67144070 67144450 RL-5471-5 RL1500-68 PE-53821 PE-53821-S DO3316-683 L22 47 1.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 Table 5. Capacitor Manufacturers Phone Numbers (continued) AVX Corp. Sprague/Vishay Phone (803) 448-9411 FAX (803) 448-1943 Phone (207) 324-4140 FAX (207) 324-7223 Table 6. Diode Selection Table VR 3A Diodes Surface Mount Schottky Ultra Fast 4A–6A Diodes Through Hole Schottky Recovery 20V SK32 30V 30WQ03 SK33 40V or More 1N5820 SR302 MBR320 1N5821 MBR330 Recovery All of these diodes are rated to at least 50V.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com APPLICATION INFORMATION Table 7. PIN DESCRIPTIONS Name +VIN Description 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 needed by the regulator. Ground Circuit ground. Output Internal switch. The voltage at this pin switches between (+VIN − VSAT) and approximately −0.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 Because of their small size and excellent performance, surface mount 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 turn on when the input voltage is suddenly applied, and of course, higher input voltages produce higher inrush currents.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Solid tantalum capacitors have a much better ESR spec for cold temperatures and are recommended for temperatures below −25°C. Figure 26. Capacitor ESR vs Capacitor Voltage Rating (Typical Low ESR Electrolytic Capacitor) CATCH DIODE Buck regulators require a diode to provide a return path for the inductor current when the switch turns off.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 In many cases the preferred mode of operation is the continuous mode. It offers greater output power, lower peak switch, inductor and diode currents, and can have lower output ripple voltage. But it does require larger inductor values to keep the inductor current flowing continuously, especially at low output load currents and/or high input voltages.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com DISCONTINUOUS MODE OPERATION The selection guide chooses inductor values suitable for continuous mode operation, but for low current applications and/or high input voltages, a discontinuous mode design may be a better choice. It would use an inductor that would be physically smaller, and would need only one half to one third the inductance value needed for a continuous mode design.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 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, preferable at the output capacitor.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com The selection guide in Figure 22 shows that the vertical line for a 2.5A load current, and the horizontal line for the 12V input voltage intersect approximately midway between the upper and lower borders of the 33 μH inductance region. A 33 μH inductor will allow a peak-to-peak inductor current (ΔIIND) to flow that will be a percentage of the maximum load current. Referring to Figure 30, follow the 2.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 THERMAL CONSIDERATIONS The LM2596 is available in two packages, a 5-pin TO-220 (T) and a 5-pin surface mount TO-263 (S). The TO-220 package needs a heat sink under most conditions. The size of the heatsink depends on the input voltage, the output voltage, the load current and the ambient temperature.
PAGE 26
LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Circuit Data for Temperature Rise Curve TO-220 Package (T) Capacitors Through hole electrolytic Inductor Through hole, Renco Diode Through hole, 5A 40V, Schottky PC board 3 square inches single sided 2 oz. copper (0.0028″) Figure 31.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 Figure 33. Delayed Startup Figure 34. Undervoltage Lockout for Buck Regulator DELAYED STARTUP The circuit in Figure 33 uses the the ON /OFF 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 start up is shown). As the input voltage rises, the charging of capacitor C1 pulls the ON /OFF pin high, keeping the regulator off.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com This circuit has an ON/OFF threshold of approximately 13V. Figure 35. Undervoltage Lockout for Inverting Regulator This example uses the LM2596-5.0 to generate a −5V output, but other output voltages are possible by selecting other output voltage versions, including the adjustable version.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 CIN —68 μF/25V Tant. Sprague 595D 470 μF/50V Elec. Panasonic HFQ COUT —47 μF/20V Tant. Sprague 595D 220 μF/25V Elec. Panasonic HFQ Figure 37. Inverting −5V Regulator with Delayed Startup Figure 38. 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 33 μH, 3.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com Figure 39. Inverting Regulator Ground Referenced Shutdown Figure 40.
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LM2596 www.ti.com SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 TYPICAL THROUGH HOLE PC BOARD LAYOUT, ADJUSTABLE OUTPUT (1X SIZE), DOUBLE SIDED CIN—470 μF, 50V, Aluminum Electrolytic Panasonic, “HFQ Series” COUT—220 μF, 35V Aluminum Electrolytic Panasonic, “HFQ Series” D1—5A, 40V Schottky Rectifier, 1N5825 L1—47 μH, L39, Renco, Through Hole R1—1 kΩ, 1% R2—Use formula in Design Procedure CFF—See Table 2. Thermalloy Heat Sink #7020 Figure 41.
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LM2596 SNVS124C – NOVEMBER 1999 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision B (April 2013) to Revision C • 32 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM2596S-12/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR LM2596S -12 P+ LM2596S-3.3 NRND DDPAK/ TO-263 KTT 5 45 TBD Call TI Call TI LM2596S -3.3 P+ LM2596S-3.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM2596T-3.3/NOPB ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2596T -3.3 P+ LM2596T-5.0 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2596T -5.0 P+ LM2596T-5.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 (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) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2596SX-12/NOPB DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2596SX-3.3 DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2596SX-3.3/NOPB DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.
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PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2596SX-12/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2596SX-3.3 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2596SX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2596SX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2596SX-ADJ DDPAK/TO-263 KTT 5 500 367.0 367.0 45.
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MECHANICAL DATA NDH0005D www.ti.
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MECHANICAL DATA KTT0005B TS5B (Rev D) BOTTOM SIDE OF PACKAGE www.ti.
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MECHANICAL DATA NEB0005B www.ti.
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MECHANICAL DATA NEB0005E www.ti.
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IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.