78S40

LM78S40 NSC | Alldatasheet

Document overview

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Technical content

Features

n Step-up, step-down or inverting switching regulators n Output adjustable from 1.25V to 40V n Peak currents to 1.5A without external transistors n Operation from 2.5V to 40V input n Low standby current drain n 80 dB line and load regulation n High gain, high current, independent op amp n Pulse width modulation with no double pulsing Block and Connection Diagrams DS010057-2 16-Lead DIP DS010057-1 Top View April 1998 LM78S40 Universal Switching Regulator Subsystem © 1998 National Semiconductor Corporation DS010057 www.national.com

Ordering Information

Part Number NS Package Temperature Range LM78S40J/883 J16A Ceramic DIP −55˚C to +125˚C LM78S40N N16E Molded DIP −40˚C to +125˚C LM78S40CN N16E Molded DIP 0˚C to +70˚C 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. Storage Temperature Range Ceramic DIP −65˚C to +175˚C Molded DIP −65˚C to +150˚C Operating Temperature Range Extended (LM78S40J) −55˚C to +125˚C Industrial (LM78S40N) −40˚C to +125˚C Commercial (LM78S40CN) 0˚C to +70˚C Lead Temperature Ceramic DIP (Soldering, 60 sec.) 300˚C Molded DIP (Soldering, 10 sec.) 265˚C Internal Power Dissipation (Note 2) (Note 3) 16L-Ceramic DIP 1.50W 16L-Molded DIP 1.04W Input Voltage from V IN to GND 40V Input Voltage from V+ (Op Amp) to GND 40V Common Mode Input Range (Comparator and Op Amp) −0.3 to V+ Differential Input Voltage (Note 4) ±30V Output Short Circuit Duration (Op Amp) Continuous Current from VREF 10 mA Voltage from Switch Collectors to GND 40V Voltage from Switch Emitters to GND 40V Voltage from Switch Collectors to Emitter 40V Voltage from Power Diode to GND 40V Reverse Power Diode Voltage 40V Current through Power Switch 1.5A Current through Power Diode 1.5A ESD Susceptibility (to be determined) LM78S40 Electrical Characteristics(Note 5) TA = Operating temperature range, VIN = 5.0V, V+(Op Amp) = 5.0V, unless otherwise specified. Symbol Parameter Conditions Min Typ Max Units GENERAL CHARACTERISTICS I CC Supply Current V IN = 5.0V 1.8 3.5 mA (Op Amp Disconnected) V IN = 40V 2.3 5.0 mA ICC Supply Current V IN = 5.0V 4.0 mA (Op Amp Connected) V IN = 40V 5.5 mA REFERENCE SECTION V REF Reference Voltage I REF = 1.0 mA Extend −55˚C < TA < +125˚C, Comm 0 < TA < +70˚C, 1.180 1.245 1.310 V VR LINE Reference Voltage V IN = 3.0V to VIN = 40V, 0.04 0.2 mV/V Line Regulation I REF = 1.0 mA, TA = 25˚C VR LOAD Reference Voltage I REF = 1.0 mA to IREF = 10 mA, 0.2 0.5 mV/mA Load Regulation T A = 25˚C OSCILLATOR SECTION I CHG Charging Current V IN = 5.0V, TA = 25˚C 20 50 µA ICHG Charging Current V IN = 40V, TA = 25˚C 20 70 µA IDISCHG Discharge Current V IN = 5.0V, TA = 25˚C 150 250 µA IDISCHG Discharge Current V IN = 40V, TA = 25˚C 150 350 µA VOSC Oscillator Voltage Swing VIN = 5.0V, TA = 25˚C 0.5 V ton/toff Ratio of Charge/ 6.0 µs/µs Discharge Time CURRENT LIMIT SECTION V CLS Current Limit Sense Voltage TA = 25˚C 250 350 mV OUTPUT SWITCH SECTION VSAT 1 Output Saturation Voltage 1 ISW = 1.0A (Figure 1) 1.1 1.3 V VSAT 2 Output Saturation Voltage 2 ISW = 1.0A (Figure 2) 0.45 0.7 V 3 www.national.com

Electrical Characteristics(Note 5) (Continued) TA = Operating temperature range, VIN = 5.0V, V+(Op Amp) = 5.0V, unless otherwise specified. Symbol Parameter Conditions Min Typ Max Units OUTPUT SWITCH SECTION h FE Output Transistor Current Gain IC = 1.0A, VCE = 5.0V, TA = 25˚C 70 IL Output Leakage Current V O = 40V, TA = 25˚C 10 nA POWER DIODE V FD Forward Voltage Drop I D = 1.0A 1.25 1.5 V IDR Diode Leakage Current V D = 40V, TA = 25˚C 10 nA COMPARATOR V IO Input Offset Voltage V CM = VREF 1.5 15 mV IIB Input Bias Current V CM = VREF 35 200 nA IIO Input Offset Current V CM = VREF 5.0 75 nA VCM Common Mode Voltage Range TA = 25˚C 0 V IN–2 V PSRR Power Supply Rejection Ratio VIN = 3.0V to 40V, TA = 25˚C 70 96 dB OPERATIONAL AMPLIFIER VIO Input Offset Voltage V CM = 2.5V 4.0 15 mV IIB Input Bias Current V CM = 2.5V 30 200 nA IIO Input Offset Current V CM = 2.5V 5.0 75 nA AVS + Voltage Gain+ R L = 2.0 kΩ to GND; 25 250 V/mV VO = 1.0V to 2.5V, TA = 25˚C AVS − Voltage Gain− R L = 2.0 kΩ to V+ (Op Amp) 25 250 V/mV VO = 1.0V to 2.5V, TA = 25˚C VCM Common Mode Voltage Range TA = 25˚C 0 V CC −2 V CMR Common Mode Rejection V CM = 0V to 3.0V, TA = 25˚C 76 100 dB PSRR Power Supply Rejection Ratio V+ (Op Amp) = 3.0V to 40V, TA = 25˚C 76 100 dB IO + Output Source Current T A = 25˚C 75 150 mA IO − Output Sink Current T A = 25˚C 10 35 mA SR Slew Rate T A = 25˚C 0.6 V/µs VOL Output Voltage LOW I L = −5.0 mA, TA = 25˚C 1.0 V VOH Output Voltage High I L = 50 mA, TA = 25˚C V + (Op V Amp) − Note 1:Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when ordering the device beyond its rated operating conditions. Note 2:TJ Max = 150˚C for the Molded DIP, and 175˚C for the Ceramic DIP. Note 3:Ratings apply to ambient temperature at 25˚C. Above this temperature, derate the 16L-Ceramic DIP at 10 mW/˚C, and the 16L-Molded DIP at 8.3 mW/˚C. Note 4:For supply voltages less than 30V, the absolute maximum voltage is equal to the supply voltage. Note 5:A military RETS specification is available on request. At the time of printing, the LM78S40 RETS specification complied with the Min and Max limits in this table. The LM78S40J may also be procured as a Standard Military Drawing. www.national.com 4

Typical Performance Characteristics Design Formulas Characteristic Step-Down Step-Up Inverting Units (ton +toff) Max µs C T 4x1 0−5 ton 4x1 0−5 ton 4x1 0−5 ton µF Ipk 2IO Max A LMin µH R SC 0.33/Ipk 0.33/Ipk 0.33/Ipk Ω C O µF Note 6:VSAT = Saturation voltage of the switching element. VD = Forward voltage of the flyback diode. C T vs OFF Time DS010057-6 Reference Voltage vs Junction Temperature DS010057-7 Discharge Current vs Input Voltage DS010057-8 Current Limit Sense Voltage vs Input Voltage DS010057-9 5 www.national.com

FIGURE 4. Pulse Width Modulated Step-Down Regulator (fOSC = 20 kHz)

Physical Dimensionsinches (millimeters) unless otherwise noted 16-Lead Ceramic Dual-In-Line Package (J) Order Number LM78S40J/883 16-Lead Molded Dual-In-Line Package (N) Order Number LM78S40N or LM78S40CN 9 www.national.com

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DE- VICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL SEMI- CONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or sys- tems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose fail- ure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. A critical component in any component of a life support device or system whose failure to perform can be rea- sonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: support@nsc.com www.national.com National Semiconductor Europe Fax: +49 (0) 1 80-530 85 86 Email: europe.support@nsc.com Deutsch Tel: +49 (0) 1 80-530 85 85 English Tel: +49 (0) 1 80-532 78 32 Français Tel: +49 (0) 1 80-532 93 58 Italiano Tel: +49 (0) 1 80-534 16 80 National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: sea.support@nsc.com National Semiconductor Japan Ltd. Tel: 81-3-5620-6175 Fax: 81-3-5620-6179 LM78S40 Universal Switching Regulator Subsystem National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.