January 2008

Rev 4

1/30

AN1518

Application note

Designing with the 2.5 A DC-DC converter L5973D

Introduction

The L5973D is a step-down monolithic power switching regulator capable of delivering up to

2.5 A at output voltages from 1.235 V to 35 V. The operating input voltage ranges from 4.4 V

to 36 V. It has been designed using BCDV technology and the power switching element is

implemented through a P-channel D-MOS transistor. It does not require a bootstrap

capacitor, and the duty cycle can range up to 100%. An internal oscillator fixes the switching

frequency at 250 kHz. This minimizes the LC output filter. A synchronization pin is available

for cases where a higher frequency (up to 500 kHz) is required. Pulse-by-pulse and

frequency foldback overcurrent protection offer effective short circuit protection. Other

features are voltage feed-forward, protection against feedback disconnection, inhibit and

thermal shutdown. The device is housed in an HSOP8 package with exposed pad that helps

40 °C/W.

Figure 1.

Evaluation board

L5973D (HSOP8) board dimensions: 23x20 mm

Figure 2.

Package

Figure 3.

Pin connection

HSOP8 - Exposed Pad

OUT

SYNC

INH

COMP

1

3

2

4

VCC

VREF

GND

FB

8

7

6

5

D98IN955

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