June 2012

Doc ID 9553 Rev 4

1/24

AN1723

Application note

Designing with the L5973AD high efficiency DC-DC converter

Introduction

The L5973AD is a step-down monolithic power switching regulator capable of delivering up

to 2 A at output voltages from 1.235 V to 35 V. The operating input voltage ranges from

4.4 V to 36 V. It is realized in BCDV technology and the power switching element is realized

by a P-channel D-MOS transistor. It doesn’t require a bootstrap capacitor, and the duty cycle

can range up to 100%. An internal oscillator fixes the switching frequency at 500 kHz which

minimizes the LC output filter. The synchronization pin is available in case a higher

frequency is required. Pulse-by-pulse and frequency foldback overcurrent protection offer an

effective short-circuit protection. Other features include voltage feed-forward, protection

against feedback disconnection, and inhibit and thermal shutdown. The device is housed in

a HSOP8 package with exposed pad that helps to reduce the thermal resistance junction to

Figure 1.

EVAL5973AD demonstration board

www.st.com