LM2578A/LM3578A

Switching Regulator

General Description

The LM2578A is a switching regulator which can easily be

set up for such DC-to-DC voltage conversion circuits as the

buck, boost, and inverting configurations. The LM2578A fea-

tures a unique comparator input stage which not only has

separate pins for both the inverting and non-inverting inputs,

but also provides an internal 1.0V reference to each input,

thereby simplifying circuit design and p.c. board layout. The

output can switch up to 750 mA and has output pins for its

collector and emitter to promote design flexibility. An external

current limit terminal may be referenced to either the ground

or the V

tion, the LM2578A has an on board oscillator, which sets the

Hz to 100 kHz (typical).

The LM2578A is an improved version of the LM2578, offer-

ing higher maximum ratings for the total supply voltage and

output transistor emitter and collector voltages.

Features

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Inverting and non-inverting feedback inputs

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1.0V reference at inputs

n

Operates from supply voltages of 2V to 40V

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Output current up to 750 mA, saturation less than 0.9V

n

Current limit and thermal shut down

n

Duty cycle up to 90%

Applications

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Switching regulators in buck, boost, inverting, and

single-ended transformer configurations

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Motor speed control

n

Lamp flasher

Connection Diagram and Ordering Information

Dual-In-Line Package

00871129

Order Number LM3578AM, LM2578AN or LM3578AN

See NS Package Number M08A or N08E

February 2005

© 2005 National Semiconductor Corporation

DS008711

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