UP TO 1A STEP DOWN CONVERTER

OPERATING INPUT VOLTAGE FROM 8V TO

55V

PRECISE 5.1V REFERENCE VOLTAGE

OUTPUT VOLTAGE ADJUSTABLE FROM

3.3V TO 50V

SWITCHING FREQUENCY ADJUSTABLE UP

TO 500KHz

VOLTAGE FEEDFORWARD

ZERO LOAD CURRENT OPERATION

INTERNAL CURRENT LIMITING (PULSE-BY-

PULSE AND HICCUP MODE)

PROTECTION AGAINST FEEDBACK DIS-

CONNECTION

THERMAL SHUTDOWN

DESCRIPTION

The L4976 is a step down monolithic power

switching regulator delivering 1A at a voltage be-

tween 3.3V and 50V (selected by a simple exter-

nal divider). Realized in BCD mixed technology,

the device uses an internal power D-MOS transis-

tor (with a typical Rdson of 0.25

Ω) to obtain very

high efficency and high switching speed.

A switching frequency up to 250KHz is achiev-

able (the maximum power dissipation of the pack-

ages must be observed).

A wide input voltage range between 8V to 55V

and output voltages regulated from 3.3V to 40V

cover the majority of today’s applications.

Features of this new generations of DC-DC con-

verter include pulse-by-pulse current limit, hiccup

mode for short circuit protection, voltage feedfor-

ward regulation, protection against feedback loop

disconnection and thermal shutdown.

The device is available in plastic dual in line,

MINIDIP 8 for standard assembly, and SO16W

for SMD assembly.

May 2000

®

ORDERING NUMBERS: L4976 (Minidip)

L4976D (SO16)

L4976

1A STEP DOWN SWITCHING REGULATOR

Minidip

SO16W

5

2

8

4

1

L4976

220

µF

63V

330

µF

Vi=8V to 55V

20K

2.7nF

9.1K

22nF

3

7

L1

260

µH

(77120)

6

D1

GI

SB360

220nF

100nF

TYPICAL APPLICATION CIRCUIT

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