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L4971

May 2005

1

FEATURES

55V

REFERENCE VOLTAGE

3.3V TO 50V

TO 300KHz

BYPULSE AND HICCUP MODE)

CONSUMPTION

DISCONNECTION

2

DESCRIPTION

The L4971 is a step down monolithic power

switching regulator delivering 1.5A at a voltage be-

tween 3.3V and 50V (selected by a simple external

divider). Realized in BCD mixed technology, the

device uses an internal power D-MOS transistor

(with a typical Rdson of 0.25

Ω) to obtain very high

efficency and high switching speed.

A switching frequency up to 300KHz is achievable

(the maximum power dissipation of the packages

must be observed).

A wide input voltage range between 8V to 55V and

output voltages regulated from 3.3V to 50V 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, soft-start, protection against feed-

back loop disconnection, inhibit for zero current

consumption and thermal shutdown.

The device is available in plastic dual in line, DIP8

for standard assembly, and SO16W for SMD as-

sembly.

1.5A STEP DOWN SWITCHING REGULATOR

Rev. 11

Figure 1. Package

Table 1. Order Codes

Part Number

Package

L4971

DIP8

L4971D

SO16W

L4971D013TR

SO16 in Tape & Reel

SO16W

DIP8

Figure 1. Block Diagram

D97IN748A

5

2

8

4

1

L4971

220

µF

63V

330

µF

Vi=8V to 55V

20K

2.7nF

9.1K

22nF

3

7

L1

126

µH

(77120)

6

D1

STPS

3L60U

100nF

220nF

100nF