January 2008

Rev 16

1/17

17

L5973D

2.5 A switch step down switching regulator

Features

Applications

LCD monitors

optical storage, hard disk drive

converters

Figure 1.

Test application circuit

Description

The L5973D is a step down monolithic power

switching regulator with a minimum switch current

limit of 2.5 A so it is able to deliver more than 2 A

DC current to the load depending on the

application conditions.

The output voltage can be set from 1.235 V to

35 V. The high current level is also achieved

thanks to an SO8 package with exposed frame,

that allows to reduce the Rth(j-amb) down to

approximately 40 °C/W.

The device uses an internal P-channel D-MOS

transistor (with a typical Rdson of 250 m

Ω) as

switching element to minimize the size of the

external components.

An internal oscillator fixes the switching frequency

at 250 kHz.

Having a minimum input voltage of 4 V only, it is

particularly suitable for 5 V bus, available in all

computer related applications.

Pulse by pulse current limit with the internal

frequency modulation offers an effective constant

current short circuit protection.

HSOP8 exposed pad

www.st.com

D03IN1439

8

4

5

1

7

L5973D

C1

10

µF

35V

CERAMIC

C2

330

µF

10V

VOUT=3.3V

VIN = 4.4V to 35V

R1

5.6K

R2

3.3K

R3

4.7K

C4

22nF

C3

220pF

3

L1 15

µH

D1

STPS340U

COMP

VCC

OUT

FB

GND

INH

2

6

3.3V

SYNC.

VREF