LM2596S-5.0

LM2596 SIMPLE SWITCHER® Power Converter 150 kHz 3A Step-Down Voltage Regulator General 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 avail- able in fixed output voltages of 3.3V, 5V, 12V, and an adjust- able 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 needed with lower frequency switching regu- lators. Available in a standard 5-lead TO-220 package with several different lead bend options, and a 5-lead TO-263 surface mount package. 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 switch-mode power supplies. Other features include a guaranteed ±4% tolerance on out- put voltage under specified input voltage and output load conditions, and ±15% on the oscillator frequency. External shutdown is included, featuring typically 80 µA standby cur- rent. 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. Features n 3.3V, 5V, 12V, and adjustable output versions n Adjustable version output voltage range, 1.2V to 37V ±4% max over line and load conditions n Available in TO-220 and TO-263 packages n Guaranteed 3A output load current n Input voltage range up to 40V n Requires only 4 external components n Excellent line and load regulation specifications n 150 kHz fixed frequency internal oscillator n TTL shutdown capability n Low power standby mode, IQ typically 80 µA n High efficiency n Uses readily available standard inductors n Thermal shutdown and current limit protection Applications n Simple high-efficiency step-down (buck) regulator n On-card switching regulators n Positive to negative converter Note: †Patent Number 5,382,918. Typical Application (Fixed Output Voltage Versions) 01258301 SIMPLE SWITCHER® and Switchers Made Simple® are registered trademarks of National Semiconductor Corporation. May 2002 LM 2596 SIM PLE SW ITCHER Pow erConverter150 kHz 3A Step-Down V oltage Regulator © 2002 National Semiconductor Corporation DS012583 www.national.com Connection Diagrams and Ordering Information Bent and Staggered Leads, Through Hole Package 5-Lead TO-220 (T) Surface Mount Package 5-Lead TO-263 (S) 01258302 Order Number LM2596T-3.3, LM2596T-5.0, LM2596T-12 or LM2596T-ADJ See NS Package Number T05D 01258303 Order Number LM2596S-3.3, LM2596S-5.0, LM2596S-12 or LM2596S-ADJ See NS Package Number TS5B LM 25 96 www.national.com 2 Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Maximum Supply Voltage 45V ON /OFF Pin Input Voltage −0.3 ≤ V ≤ +25V Feedback Pin Voltage −0.3 ≤ V ≤+25V Output Voltage to Ground (Steady State) −1V Power Dissipation Internally limited Storage Temperature Range −65˚C to +150˚C ESD Susceptibility Human Body Model (Note 2) 2 kV Lead Temperature S Package Vapor Phase (60 sec.) +215˚C Infrared (10 sec.) +245˚C T Package (Soldering, 10 sec.) +260˚C Maximum Junction Temperature +150˚C Operating Conditions Temperature Range −40˚C ≤ TJ ≤ +125˚C Supply Voltage 4.5V to 40V LM2596-3.3 Electrical Characteristics Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera- ture Range Symbol Parameter Conditions LM2596-3.3 Units (Limits)Typ(Note 3) Limit (Note 4) SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 VOUT Output Voltage 4.75V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A 3.3 V 3.168/3.135 V(min) 3.432/3.465 V(max) η Efficiency VIN = 12V, ILOAD = 3A 73 % LM2596-5.0 Electrical Characteristics Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera- ture Range Symbol Parameter Conditions LM2596-5.0 Units (Limits)Typ(Note 3) Limit (Note 4) SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 VOUT Output Voltage 7V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A 5.0 V 4.800/4.750 V(min) 5.200/5.250 V(max) η Efficiency VIN = 12V, ILOAD = 3A 80 % LM2596-12 Electrical Characteristics Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera- ture Range Symbol Parameter Conditions LM2596-12 Units (Limits)Typ(Note 3) Limit (Note 4) SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 VOUT Output Voltage 15V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A 12.0 V 11.52/11.40 V(min) 12.48/12.60 V(max) η Efficiency VIN = 25V, ILOAD = 3A 90 % LM 2596 www.national.com3 LM2596-ADJ Electrical Characteristics Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera- ture Range Symbol Parameter Conditions LM2596-ADJ Units (Limits)Typ(Note 3) Limit (Note 4) SYSTEM PARAMETERS (Note 5) Test Circuit Figure 1 VFB Feedback Voltage 4.5V ≤ VIN ≤ 40V, 0.2A ≤ ILOAD ≤ 3A 1.230 V VOUT programmed for 3V. Circuit of Figure 1 1.193/1.180 V(min) 1.267/1.280 V(max) η Efficiency VIN = 12V, VOUT = 3V, ILOAD = 3A 73 % All Output Voltage Versions Electrical Characteristics Specifications with standard type face are for TJ = 25˚C, and those with boldface type apply over full Operating Tempera- ture Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V ver- sion. ILOAD = 500 mA Symbol Parameter Conditions LM2596-XX Units (Limits)Typ(Note 3) Limit (Note 4) DEVICE PARAMETERS Ib Feedback Bias Current Adjustable Version Only, VFB = 1.3V 10 nA 50/100 nA (max) fO Oscillator Frequency (Note 6) 150 kHz 127/110 kHz(min) 173/173 kHz(max) VSAT Saturation Voltage IOUT = 3A (Notes 7, 8) 1.16 V 1.4/1.5 V(max) DC Max Duty Cycle (ON) (Note 8) 100 % Min Duty Cycle (OFF) (Note 9) 0 ICL Current Limit Peak Current (Notes 7, 8) 4.5 A 3.6/3.4 A(min) 6.9/7.5 A(max) IL Output Leakage Current Output = 0V (Notes 7, 9) 50 µA(max) Output = −1V (Note 10) 2 mA 30 mA(max) IQ Quiescent Current (Note 9) 5 mA 10 mA(max) ISTBY Standby Quiescent Current ON/OFF pin = 5V (OFF) (Note 10) 80 µA 200/250 µA(max) θJC Thermal Resistance TO-220 or TO-263 Package, Junction to Case 2 ˚C/W θJA TO-220 Package, Junction to Ambient (Note 11) 50 ˚C/W θJA TO-263 Package, Junction to Ambient (Note 12) 50 ˚C/W θJA TO-263 Package, Junction to Ambient (Note 13) 30 ˚C/W θJA TO-263 Package, Junction to Ambient (Note 14) 20 ˚C/W ON/OFF CONTROL Test Circuit Figure 1 ON /OFF Pin Logic Input 1.3 V VIH Threshold Voltage Low (Regulator ON) 0.6 V(max) VIL High (Regulator OFF) 2.0 V(min) LM 25 96 www.national.com 4 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 Tempera- ture Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable version and VIN = 24V for the 12V ver- sion. ILOAD = 500 mA Symbol Parameter Conditions LM2596-XX Units (Limits)Typ(Note 3) Limit (Note 4) IH ON /OFF Pin Input Current VLOGIC = 2.5V (Regulator OFF) 5 µA 15 µA(max) IL VLOGIC = 0.5V (Regulator ON) 0.02 µA 5 µA(max) Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: The human body model is a 100 pF capacitor discharged through a 1.5k resistor into each pin. Note 3: Typical numbers are at 25˚C and represent the most likely norm. Note 4: All limits guaranteed at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). Note 5: External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator system performance. When the LM2596 is used as shown in the Figure 1 test circuit, system performance will be as shown in system parameters section of Electrical Characteristics. Note 6: The switching frequency is reduced when the second stage current limit is activated. Note 7: No diode, inductor or capacitor connected to output pin. Note 8: Feedback pin removed from output and connected to 0V to force the output transistor switch ON. Note 9: Feedback pin removed from output and connected to 12V for the 3.3V, 5V, and the ADJ. version, and 15V for the 12V version, to force the output transistor switch OFF. Note 10: VIN = 40V. Note 11: Junction to ambient thermal resistance (no external heat sink) for the TO-220 package mounted vertically, with the leads soldered to a printed circuit board with (1 oz.) copper area of approximately 1 in2. Note 12: Junction to ambient thermal resistance with the TO-263 package tab soldered to a single printed circuit board with 0.5 in2 of (1 oz.) copper area. Note 13: Junction to ambient thermal resistance with the TO-263 package tab soldered to a single sided printed circuit board with 2.5 in2 of (1 oz.) copper area. Note 14: Junction to ambient thermal resistance with the TO-263 package tab soldered to a double sided printed circuit board with 3 in2 of (1 oz.) copper area on the LM2596S side of the board, and approximately 16 in2 of copper on the other side of the p-c board. See Application Information in this data sheet and the thermal model in Switchers Made Simple™ version 4.3 software. Typical Performance Characteristics (Circuit of Figure 1) Normalized Output Voltage Line Regulation Efficiency 01258304 01258305 01258306 LM 2596 www.national.com5 Typical Performance Characteristics (Circuit of Figure 1) (Continued) Switch Saturation Voltage Switch Current Limit Dropout Voltage 01258307 01258308 01258309 Operating Quiescent Current Shutdown Quiescent Current Minimum Operating Supply Voltage 01258310 01258311 01258312 ON /OFF Threshold Voltage ON /OFF Pin Current (Sinking) Switching Frequency 01258313 01258314 01258315 LM 25 96 www.national.com 6 Typical Performance Characteristics (Circuit of Figure 1) (Continued) Feedback Pin Bias Current 01258316 LM 2596 www.national.com7 Typical Performance Characteristics Continuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 2A L = 32 µH, COUT = 220 µF, COUT ESR = 50 mΩ Discontinuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 500 mA L = 10 µH, COUT = 330 µF, COUT ESR = 45 mΩ 01258317 Horizontal Time Base: 2 µs/div. A: Output Pin Voltage, 10V/div. B: Inductor Current 1A/div. C: Output Ripple Voltage, 50 mV/div. 01258318 Horizontal Time Base: 2 µs/div. A: Output Pin Voltage, 10V/div. B: Inductor Current 0.5A/div. C: Output Ripple Voltage, 100 mV/div. Load Transient Response for Continuous Mode VIN = 20V, VOUT = 5V, ILOAD = 500 mA to 2A L = 32 µH, COUT = 220 µF, COUT ESR = 50 mΩ Load Transient Response for Discontinuous Mode VIN = 20V, VOUT = 5V, ILOAD = 500 mA to 2A L = 10 µH, COUT = 330 µF, COUT ESR = 45 mΩ 01258319 Horizontal Time Base: 100 µs/div. A: Output Voltage, 100 mV/div. (AC) B: 500 mA to 2A Load Pulse 01258320 Horizontal Time Base: 200 µs/div. A: Output Voltage, 100 mV/div. (AC) B: 500 mA to 2A Load Pulse Test Circuit and Layout Guidelines Fixed Output Voltage Versions 01258322 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 LM 25 96 www.national.com 8 Test Circuit and Layout Guidelines (Continued) As in any switching regulator, layout is very important. Rap- idly 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 should be wide printed circuit traces and should be kept as short as possible. For best results, external components should be located as close to the switcher lC as possible using ground plane construction or single point grounding. If open core inductors are used, special care must be taken as to the location and positioning of this type of induc- tor. 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. Physically locate both resistors near the IC, and route the wiring away from the inductor, especially an open core type of inductor. (See application section for more information.) Adjustable Output Voltage Versions 01258323 where VREF = 1.23V Select R1 to be approximately 1 kΩ, use a 1% resistor for best stability. CIN — 470 µF, 50V, Aluminum Electrolytic Nichicon “PL Series” COUT — 220 µF, 35V Aluminum Electrolytic, Nichicon “PL Series” D1 — 5A, 40V Schottky Rectifier, 1N5825 L1 — 68 µH, L38 R1 — 1 kΩ, 1% CFF — See Application Information Section FIGURE 1. Standard Test Circuits and Layout Guides LM 2596 www.national.com9 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. Select the correct inductor value selection guide from Fig- ures Figure 4, Figure 5, or Figure 6. (Output voltages of 3.3V, 5V, or 12V respectively.) For all other voltages, see the design procedure for the adjustable version. B. From the inductor value selection guide, identify the induc- tance 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). C. Select an appropriate inductor from the four manufacturer’s part numbers listed in Figure 8. 1. Inductor Selection (L1) A. Use the inductor selection guide for the 5V version shown in Figure 5. B. From the inductor value selection guide shown in Figure 5, the inductance region intersected by the 12V horizontal line and the 3A vertical line is 33 µH, and the inductor code is L40. C. The inductance value required is 33 µH. From the table in Figure 8, go to the L40 line and choose an inductor part number from any of the four manufacturers shown. (In most instance, both through hole and surface mount inductors are available.) 2. Output Capacitor Selection (COUT) A. 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 should be located close to the IC using short capacitor leads and short copper traces. Do not use capacitors larger than 820 µF . For additional information, see section on output capaci- tors in application information section. B. To simplify the capacitor selection procedure, refer to the quick design component selection table shown in Figure 2. This table contains different input voltages, output voltages, and load currents, and lists various inductors and output ca- pacitors that will provide the best design solutions. C. The capacitor voltage rating for electrolytic capacitors should be at least 1.5 times greater than the output voltage, and often much higher voltage ratings are needed to satisfy the low ESR requirements for low output ripple voltage. D. For computer aided design software, see Switchers Made Simple™ version 4.3 or later. 2. Output Capacitor Selection (COUT) A. See section on output capacitors in application infor- mation section. B. From the quick design component selection table shown in Figure 2, locate the 5V output voltage section. In the load current column, choose the load current line that is closest to the current needed in your application, for this example, use the 3A line. In the maximum input voltage column, select the line that covers the input voltage needed in your application, in this example, use the 15V line. Continuing on this line are recommended inductors and capacitors that will provide the best overall performance. The capacitor list contains both through hole electrolytic and surface mount tantalum capacitors from four different capaci- tor manufacturers. It is recommended that both the manufac- turers and the manufacturer’s series that are listed in the table be used. In this example aluminum electrolytic capacitors from several different manufacturers are available with the range of ESR numbers needed. 330 µF 35V Panasonic HFQ Series 330 µF 35V Nichicon PL Series C. For a 5V output, a capacitor voltage rating at least 7.5V or more is needed. But even a low ESR, switching grade, 220 µF 10V aluminum electrolytic capacitor would exhibit approxi- mately 225 mΩ of ESR (see the curve in Figure 14 for the ESR vs voltage rating). This amount of ESR would result in rela- tively high output ripple voltage. To reduce the ripple to 1% of the output voltage, or less, a capacitor with a higher value or with a higher voltage rating (lower ESR) should be selected. A 16V or 25V capacitor will reduce the ripple voltage by approxi- mately half. LM 25 96 www.national.com 10 LM2596 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. 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. The most stressful condition for this diode is an overload or shorted output condition. B. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. C. This diode must be fast (short reverse recovery time) and must be located close to the LM2596 using short leads and short printed circuit traces. Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best performance and efficiency, and should be the first choice, especially in low output voltage applications. Ultra-fast recovery, or High-Efficiency rectifiers also provide good re- sults. Ultra-fast recovery diodes typically have reverse recov- ery times of 50 ns or less. Rectifiers such as the 1N5400 series are much too slow and should not be used. 3. Catch Diode Selection (D1) A. Refer to the table shown in Figure 11. In this example, a 5A, 20V, 1N5823 Schottky diode will provide the best perfor- mance, and will not be overstressed even for a shorted output. 4. Input Capacitor (CIN) A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground pin to prevent large voltage transients from appearing at the input. This capacitor should be located close to the IC using short leads. In addition, the RMS current rating of the input capacitor should be selected to be at least 1⁄2 the DC load current. The capacitor manufactur- ers data sheet must be checked to ass