LM78S40

ACTIVE

1.5A Adjustable Step Up, Step Down or Inverting Regulator

Product details

Rating Catalog Operating temperature range (°C) 0 to 70 Topology Boost, Buck, Flyback, Forward, Inverting, SEPIC Type Converter Vin (min) (V) 2.5 Vin (max) (V) 40 Switching frequency (min) (kHz) 0.1 Switching frequency (max) (kHz) 100 Features Adjustable current limit, Nonsynchronous Vout (min) (V) 1.245 Vout (max) (V) 40 Iq (typ) (µA) 1800
Rating Catalog Operating temperature range (°C) 0 to 70 Topology Boost, Buck, Flyback, Forward, Inverting, SEPIC Type Converter Vin (min) (V) 2.5 Vin (max) (V) 40 Switching frequency (min) (kHz) 0.1 Switching frequency (max) (kHz) 100 Features Adjustable current limit, Nonsynchronous Vout (min) (V) 1.245 Vout (max) (V) 40 Iq (typ) (µA) 1800
PDIP (NFG) 16 52.451 mm² 6.35 x 8.26
  • Step-up, step-down or inverting switching regulators
  • Output adjustable from 1.25V to 40V
  • Peak currents to 1.5A without external transistors
  • Operation from 2.5V to 40V input
  • Low standby current drain
  • 80 dB line and load regulation
  • High gain, high current, independent op amp
  • Pulse width modulation with no double pulsing

  • Step-up, step-down or inverting switching regulators
  • Output adjustable from 1.25V to 40V
  • Peak currents to 1.5A without external transistors
  • Operation from 2.5V to 40V input
  • Low standby current drain
  • 80 dB line and load regulation
  • High gain, high current, independent op amp
  • Pulse width modulation with no double pulsing

The LM78S40 is a monolithic regulator subsystem consisting of all the active building blocks necessary for switching regulator systems. The device consists of a temperature compensated voltage reference, a duty-cycle controllable oscillator with an active current limit circuit, an error amplifier, high current, high voltage output switch, a power diode and an uncommitted operational amplifier. The device can drive external NPN or PNP transistors when currents in excess of 1.5A or voltages in excess of 40V are required. The device can be used for step-down, step-up or inverting switching regulators as well as for series pass regulators. It features wide supply voltage range, low standby power dissipation, high efficiency and low drift. It is useful for any stand-alone, low part count switching system and works extremely well in battery operated systems.


The LM78S40 is a monolithic regulator subsystem consisting of all the active building blocks necessary for switching regulator systems. The device consists of a temperature compensated voltage reference, a duty-cycle controllable oscillator with an active current limit circuit, an error amplifier, high current, high voltage output switch, a power diode and an uncommitted operational amplifier. The device can drive external NPN or PNP transistors when currents in excess of 1.5A or voltages in excess of 40V are required. The device can be used for step-down, step-up or inverting switching regulators as well as for series pass regulators. It features wide supply voltage range, low standby power dissipation, high efficiency and low drift. It is useful for any stand-alone, low part count switching system and works extremely well in battery operated systems.


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Technical documentation

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Type Title Date
* Data sheet LM78S40 Universal Switching Regulator Subsystem datasheet 10 May 2004
Application note AN-711 LM78S40 Switching Voltage Regulator Applications (Rev. B) 07 May 2013

Design & development

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Supported products & hardware

Supported products & hardware

Products
AC/DC & DC/DC controllers (external FET)
LM3017 High Efficiency Low-Side Controller with True Shutdown LM3478 2.97~40V Wide Input Range Boost/SEPIC/Flyback DC-DC Controller LM3478Q-Q1 40-V wide VIN low-side N-channel controller for switching regulators with 10-µA shutdown current LM3481 2.97V to 48V High-Efficiency Controller for Boost, SEPIC and Flyback LM3481-Q1 2.97-V to 48-V high-efficiency controller for boost, SEPIC and flyback, AEC-Q100 qualified LM3488 2.97V to 40V Wide Vin Low-Side N-Channel Controller for Switching Regulators LM3488Q-Q1 40-V wide VIN low-side N-channel controller for switching regulators with 5-µA shutdown current LM3524D 40V, 0.2A 350KHz PWM controller LM3578A 2-V to 40-VIN switching regulators in buck, boost, terminal, depending upon the application LM5020 13-100V Wide Vin, Current Mode PWM Boost, Flyback, Sepic Controller LM5022 6-60V Wide Vin, current mode boost, SEPIC and Flyback controller TL1451 Dual Pulse-Width-Modulation Control Circuit TL1451A 3.6V to 50V dual channel controller with Wide input voltage range TL1451A-EP Enhanced Product Dual Pulse-Width-Modulation Control Circuits TL1451A-Q1 3.6-V to 50-V dual-channel PWM controller, AEC-Q100 qualified TL5001 PWM Controller with wide input range, with ±5% tolerance on reference, operation –20°C to 85°C TL5001A PWM Controller with wide input range, with ±3% tolerance on reference, operation –20°C to 85°C TL5001A-Q1 PWM Controller with wide input range, with ±3% tolerance on reference, operation –20°C to 85°C TL5001M PWM Controller with wide input range, with ±5% tolerance on reference, operation –55°C to 125°C TPS40210-Q1 4.5-V to 52-V wide input range current mode boost controller with 700-mV reference voltage TPS40211-Q1 4.5-V to 52-V wide input range current mode boost controller with 260-mV reference voltage TPS43000 Multi-Topology (buck, boost, sepic) High Frequency DC/DC Controller TPS55010 2.95V To 6V Input, 2W, Isolated DC/DC Converter with Integrated FETS UC2572 Negative output Flyback pulse width modulator
AC/DC & DC/DC converters (integrated FET)
LM25017 7.5-48V Wide Vin, 650mA Constant On-Time Synchronous Buck Regulator LM25018 7.5-48V Wide Vin, 300mA Constant On-Time Synchronous Buck Regulator LM25019 7.5-48V Wide Vin, 100mA Constant On-Time Synchronous Buck Regulator LM2577 3.5-V to 40-V, 3-A low component count step-up regulator LM2585 4-V to 40-V, 3-A step-up wide VIN flyback regulator LM2586 4-V to 40-V, 3-A step-up wide VIN flyback regulator with frequency synchronization LM2587 4V to 40V, 5A Step-Up Wide Vin Flyback Regulator LM2588 4-V to 40-V, 5-A step-up wide VIN flyback regulator with frequency synchronization LM2621 1.2V to 14V input voltage, 1A load current, step-up DC-DC LM2623 0.8V to 14V input voltage, 2A load current, step-up DC-DC LM2623-Q1 0.8-V to 14-V input voltage, 2-A load current, step-up DC/DC, AEC-Q100 qualified LM2735 520kHz/1.6MHz space efficient boost and SEPIC DC-DC regulator LM2735-Q1 520-kHz, 1.6-MHz space efficient boost and SEPIC DC/DC regulator, AEC-Q100 qualified LM34925 7.5-100V Wide Vin, 100mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters LM34926 7.5-100V Wide Vin, 300mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters LM34927 7.5-100V Wide Vin, 600mA Integrated Secondary Bias Regulator for Isolated DC/DC Converters LM5000 3.1-40V Wide Vin, 2A Current Mode Non-Synchronous Boost Regulator LM5001 3.1-75V Wide Vin, 1A Current Mode Non-Synchronous Switch Mode Regulator LM5001-Q1 3.1-V to 75-V wide VIN, 1-A current mode non-synchronous switch mode regulator LM5002 3.1-75V Wide Vin, 0.5A Current Mode Boost, Flyback, Sepic Converter LM5015 4.25-75V, Monolithic Two-Switch Forward DC-DC Regulator LM5017 7.5-100V Wide Vin, 600mA Constant On-Time Synchronous Buck Regulator LM5018 7.5-100V Wide Vin, 300mA Constant On-Time Synchronous Buck Regulator LM5019 7.5-100V Wide Vin, 100mA Constant On-Time Synchronous Buck Regulator LM5160 LM5160 wide input 65V, 2A synchronous buck/Fly-Buck™ converter LM5160-Q1 Wide Input 65V, 2A Synchronous Buck / Fly-Buck™ Converter LM5160A LM5160A Wide Input 65V, 2A Synchronous Buck / Fly-Buck™ Converter LM5161 Wide Input 4.5-V to 100-V, 1-A Synchronous Buck / Fly-Buck Converter LM78S40 1.5A Adjustable Step Up, Step Down or Inverting Regulator TPS55340 5-A, 40-V, wide VIN boost, flyback, & SEPIC converter TPS55340-EP Enhanced integrated, 5-A, 40-V wide input range boost/SEPIC/flyback DC/DC regulator TPS55340-Q1 Integrated, 5-A 40-V wide input range boost/SEPIC/flyback DC/DC regulator, AEC-Q100 qualified TPS61175 3-A ,40V High Voltage Boost Converter with Soft-start and Programmable Switching Frequency TPS61175-Q1 3-A, 40-V high voltage boost converter with soft-start and programmable switching frequency
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PDIP (NFG) 16 Ultra Librarian

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