L5973AD datasheet(1/21 Pages) STMICROELECTRONICS

部件名	L5973AD

功能描述	2 A switch step down switching regulator

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制造商	STMICROELECTRONICS [STMicroelectronics]

网页	http://www.st.com

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1 / 21 page

January 2008

Rev 9

1/21

21

L5973AD

2 A switch step down switching regulator

Features

■ 2 A Internal switch

■ Operating input voltage from 4 V to 36 V

■ 3.3 V / (±2 %) reference voltage

■ Output voltage adjustable from 1.235 V to 35 V

■ Low dropout operation: 100 % duty cycle

■ 500 kHz Internally fixed frequency

■ Voltage feedforward

■ Zero load current operation

■ Internal current limiting

■ Inhibit for zero current consumption

■ Synchronization

■ Protection against feedback disconnection

■ Thermal shutdown

Applications

■ Consumer: STB, DVD, TV, VCR, car radio,

LCD monitors

■ Networking: XDSL, modems, DC-DC modules

■ Computer: printers, audio/graphic cards,

optical storage, hard disk drive

■ Industrial: chargers, car battery, DC-DC

converters

Description

The L5973AD is a step down monolithic power

switching regulator with a switch current limit of

2A so it is able to deliver more than 1.5 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 RthJA down to

approximately 40 °C/W.

The device uses an internal P-Channel D-MOS

transistor (with a typical of 200 m

Ω) as switching

element to avoid the use of bootstrap capacitor

and guarantee high efficiency.

An internal oscillator fixes the switching frequency

at 500 kHz to minimize the size of external

components.

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

Figure 1.

Test application circuit

D03IN1453

8

4

5

1

7

L5973AD

C1

10

µF

35V

CERAMIC

C2

330

µF

10V

VOUT=3.3V

VIN = 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

www.st.com

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