REV. A

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a

ADM1052

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781/329-4700

World Wide Web Site: http://www.analog.com

Fax: 781/326-8703

© Analog Devices, Inc., 2001

Precision Dual Voltage

Regulator Controller

FEATURES

Two Independent Controllers on One Chip

Two 2.525 V Outputs

Shutdown Inputs to Control Each Channel

2.5% Accuracy Over Line, Load, and Temperature

Low Quiescent Current

Low Shutdown Current

Works with External N-Channel MOSFETs for Low Cost

“Hiccup Mode” Fault Protection

No External Voltage or Current Setting Resistors

Small, 8-Lead SO Package

APPLICATIONS

Desktop Computers

Servers

Workstations

GENERAL DESCRIPTION

The ADM1052 is a dual, precision, voltage regulator controller

intended for power rail generation and active bus termination

on personal computer motherboards. It contains a precision

1.2 V bandgap reference and two channels consisting of con-

trol amplifiers driving external power devices. Each channel has a

shutdown input to turn off amplifier output and “Hiccup Mode”

protection circuitry for the external power device.

The ADM1052 operates from a 12 V supply. This gives suffi-

cient headroom for the amplifiers to drive external N-channel

MOSFETs, operating as source-followers, as the external series

pass devices. This has the advantage that N-channel devices are

cheaper than P-channel devices of similar performance, and the

circuit is easier to stabilize than one using P-channel devices in

a common-source configuration.

FUNCTIONAL BLOCK DIAGRAM

SHDN1

BANDGAP

REFERENCE

SHUTDOWN

CONTROL

HICCUP

COMPARATOR

100 F

2

100 F

3.3V

CONTROL

AMPLIFIER

FORCE 1

SENSE 1

50 A

ADM1052

3.3V

FORCE 2

SENSE 2

SHDN2

SHUTDOWN

CONTROL

HICCUP

COMPARATOR

CONTROL

AMPLIFIER

50 A

GND

CLOCK

OSCILLATOR

POWER-ON

RESET

CLK/DELAY

GENERATOR

100 F

2

100 F