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LM2595

www.ti.com

SNVS122B –MAY 1999–REVISED APRIL 2013

LM2595 SIMPLE SWITCHER

Power Converter 150 kHz 1A Step-Down Voltage Regulator

Check for Samples: LM2595

FEATURES

DESCRIPTION

The LM2595 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 1A 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 (Surface

version.

Mount) Packages

• Ensured 1A Output Load Current

Requiring a minimum number of external

components, these regulators are simple to use and

• Input Voltage Range Up to 40V

include internal frequency compensation†, and a

• Requires Only 4 External Components

fixed-frequency oscillator.

• Excellent Line and Load Regulation

The LM2595 series operates at a switching frequency

Specifications

of 150 kHz thus allowing smaller sized filter

• 150 kHz Fixed Frequency Internal Oscillator

components than what would be needed with lower

• TTL Shutdown Capability frequency switching regulators. Available in a

standard 5-lead TO-220 package with several

• Low Power Standby Mode, I

Typically 85 μA

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

• High Efficiency

surface mount package. Typically, for output voltages

• Uses Readily Available Standard Inductors

less than 12V, and ambient temperatures less than

50°C, no heat sink is required.

• Thermal Shutdown and Current Limit

Protection

A standard series of inductors are available from

several different manufacturers optimized for use with

APPLICATIONS

the LM2595 series. This feature greatly simplifies the

design of switch-mode power supplies.

• Simple High-Efficiency Step-Down (Buck)

Regulator

Other features include an ensured ±4% tolerance on

output voltage under specified input voltage and

• Efficient Pre-Regulator for Linear Regulators

output load conditions, and ±15% on the oscillator

• On-Card Switching Regulators

frequency. External shutdown is included, featuring

• Positive to Negative Converter

typically 85 μA stand-by 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.

† Patent Number 5,382,918.

Typical Application

(Fixed Output Voltage Versions)

Connection Diagrams

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, Switchers Made Simple are registered trademarks 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 (41 pages)

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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 LM2595 SIMPLE SWITCHER® Power Converter 150 kHz 1A Step-Down Voltage Regulator Check for Samples: LM2595 FEATURES DESCRIPTION • • The LM2595 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving a 1A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com Figure 1. Bent and Staggered Leads, Through Hole Package 5–Lead TO-220 (NDH) Figure 3. 16-Lead Ceramic Dual-in-Line Package (NFE) Figure 2. Surface Mount Package 5-Lead TO-263 (KTT) 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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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 LM2595-3.3 Electrical Characteristics Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range. Symbol Parameter Conditions LM2595-3.3 Typ Limit (1) SYSTEM PARAMETERS VOUT η (3) (3) (2) Test Circuit Figure 21 4.75V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 1A Output Voltage Efficiency (1) (2) Units (Limits) VIN = 12V, ILOAD = 1A 3.3 V 3.168/3.135 V(min) 3.432/3.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com LM2595-12 Electrical Characteristics (continued) Specifications with standard type face are for TJ = 25°C, and those with boldface type apply over full Operating Temperature Range.
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LM2595 www.ti.com SNVS122B – MAY 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. ILOAD = 200 mA.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (Circuit of Figure 21) 6 Normalized Output Voltage Line Regulation Figure 4. Figure 5. Efficiency Switch Saturation Voltage Figure 6. Figure 7. Switch Current Limit Dropout Voltage Figure 8. Figure 9.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 Typical Performance Characteristics (continued) (Circuit of Figure 21) Operating Quiescent Current Shutdown Quiescent Current Figure 10. Figure 11. Minimum Operating Supply Voltage ON /OFF Threshold Voltage Figure 12. Figure 13. ON /OFF Pin Current (Sinking) Switching Frequency Figure 14. Figure 15.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) (Circuit of Figure 21) Continuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 1A L = 68 μH, COUT = 120 μF, COUT ESR = 100 mΩ Feedback Pin Bias Current Discontinuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 600 mA L = 22 μH, COUT = 220 μF, COUT ESR = 50 mΩ 8 B 1A 0.5A 0A C 50 mV AC/ div. A: Output Pin Voltage, 10V/div. B: Inductor Current 0.5A/div.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 Typical Performance Characteristics (continued) (Circuit of Figure 21) Load Transient Response for Discontinuous Mode VIN = 20V, VOUT = 5V, ILOAD = 250 mA to 750 mA L = 22 μH, COUT = 220 μF, COUT ESR = 50 mΩ A 100 mV AC/div. B 1A 0.5A 0A A: Output Voltage, 100 mV/div. (AC) B: 250 mA to 750 mA Load Pulse Horizontal Time Base: 200 µs/div. Figure 20.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 If open core inductors are used, special care must be taken as to 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, special care must be taken as to the location of the feedback resistors and the associated wiring.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com Table 1. LM2595 Series Buck Regulator Design Procedure (Fixed Output) (continued) 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.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 Table 2. LM2595 Fixed Voltage Quick Design Component Selection Table (continued) Conditions Inductor Output Capacitor Through Hole Electrolytic Surface Mount Tantalum Output Load Max Input Inductance Inductor Panasonic Nichicon AVX TPS Sprague Voltage Current Voltage (μH) (#) HFQ Series PL Series Series 595D Series (V) (A) (V) (μF/V) (μF/V) (μF/V) (μF/V) 1 5 0.5 1 12 0.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com Table 3. LM2595 Series Buck Regulator Design Procedure (Adjustable Output) (continued) 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.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 Table 3. LM2595 Series Buck Regulator Design Procedure (Adjustable Output) (continued) 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.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com Table 4. Output Capacitor and Feedforward Capacitor Selection Table (continued) Output Voltage (V) Through Hole Electrolytic Output Capacitor Surface Mount Tantalum Output Capacitor Panasonic Nichicon PL Feedforward AVX TPS Sprague Feedforward HFQ Series Series Capacitor Series 595D Series Capacitor (μF/V) (μF/V) (μF/V) (μF/V) 9 180/25 180/25 1.5 nF 100/16 180/16 1.5 nF 12 120/25 120/25 1.5 nF 68/20 120/20 1.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 Table 5. Inductor Manufacturers Part Numbers Inductance (μH) Current (A) Renco L4 68 0.32 RL-1284-68-43 RL1500-68 PE-53804 PE-53804-S DO1608-68 L5 47 0.37 RL-1284-47-43 RL1500-47 PE-53805 PE-53805-S DO1608-473 L6 33 0.44 RL-1284-33-43 RL1500-33 PE-53806 PE-53806-S DO1608-333 L9 220 0.32 RL-5470-3 RL1500-220 PE-53809 PE-53809-S DO3308-224 L10 150 0.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com Table 7. Capacitor Manufacturers Phone Numbers (continued) Sprague/Vishay Phone (207) 324-4140 FAX (207) 324-7223 Table 8. Diode Selection Table VR 1A Diodes Surface Mount Schottky Ultra Fast 3A Diodes Through Hole Schottky Recovery SK12 20V SK13 30V MBRS130 All of these diodes are rated to at least 50V.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 APPLICATION INFORMATION PIN FUNCTIONS +VIN 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 −0.5V, with a duty cycle of approximately VOUT/VIN.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com 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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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 Solid tantalum capacitors have a much better ESR spec for cold temperatures and are recommended for temperatures below −25°C. Figure 27. 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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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com 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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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 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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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com The voltage spikes are caused by the fast switching action of the output switch and the diode, and 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.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 As the input voltage increases to 14V, it approaches the upper border of the inductance region, and the inductor ripple current increases. Referring to the curve in Figure 31, it can be seen that for a load current of 0.8A, the peak-to-peak inductor ripple current (ΔIIND) is 300 mA with 12V in, and can range from 340 mA at the upper border (14V in) to 225 mA at the lower border (10V in).
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com The TO-263 surface mount package tab is designed to be soldered to the copper on a printed circuit board. 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 PC board copper area that the package is soldered to should be at least 0.4 in2, and ideally should have 2 or more square inches of 2 oz. (0.0028 in) copper.
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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 Circuit Data for Temperature Rise Curve TO-263 Package (KTT) Capacitors Surface mount tantalum, molded “D” size Inductor Surface mount, Schott, 68 μH Diode Surface mount, 3A 40V, Schottky PC board 3 square inches single sided 2 oz. copper (0.0028″) Figure 33. Junction Temperature Rise, TO-263 Figure 34. Delayed Startup Figure 35.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com DELAYED STARTUP The circuit in Figure 34 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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LM2595 www.ti.com SNVS122B – MAY 1999 – REVISED APRIL 2013 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 = 13V Regulator stops switching at VIN = 8V Figure 37. Undervoltage Lockout with Hysteresis for Inverting Regulator CIN: — 220 μF/25V Tant.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com 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 LM2595 current limit (approx 1.5A) are needed 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.
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LM2595 www.ti.
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LM2595 SNVS122B – MAY 1999 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision A (April 2013) to Revision B • 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) LM2595S-12 NRND DDPAK/ TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2595S -12 P+ LM2595S-12/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2595S -12 P+ LM2595S-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) LM2595T-3.3/NOPB ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2595T -3.3 P+ LM2595T-5.0 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2595T -5.0 P+ LM2595T-5.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-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 LM2595SX-12 DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2595SX-12/NOPB DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2595SX-3.3 DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2595SX-12 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2595SX-12/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2595SX-3.3 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2595SX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2595SX-5.0 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2595SX-5.
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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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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.