General Description

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.

Features

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