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