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ADP3171

Synchronous Buck Controller

with Dual Linear Regulator Controllers

FUNCTIONAL BLOCK DIAGRAM

OSCILLATOR

PWM

LOGIC

SET

RESET

CROWBAR

1.8V

LRFB2

LRDRV2

REFERENCE

REF

1

GND

DAC +20%

DAC –20%

CMP

UVLO

AND BIAS

DRVH

VCC

COMP

DRVL

PWRGD

CS–

CS+

FB

CT

ADP3171

5

7

1.5V

LRFB1

LRDRV1

3

4

8

1.2V

FEATURES

Fixed 1.2 V N-Channel Synchronous Buck Driver

Two On-Board Linear Regulator Controllers

Total Accuracy

±1% over Temperature

High Efficiency Current-Mode Operation

Short Circuit Protection

Power Good Output

Overvoltage Protection Crowbar Protects Switching

Output with No Additional External Components

APPLICATIONS

Auxiliary System Supplies for Desktop

Computer Systems

General-Purpose Low Voltage Supplies

GENERAL DESCRIPTION

The ADP3171 is a highly efficient output synchronous buck

switching regulator controller optimized for converting a 5 V

main supply into the auxiliary supply voltages required by

processors and chipsets. The ADP3171 provides a fixed

output voltage of 1.2 V at up to 15 A, depending on the

power ratings of the external MOSFETs and inductor. The

ADP3171 uses a current-mode, constant off time architecture to

drive two N-channel MOSFETs at a programmable switching

frequency that can be optimized for regulator size and efficiency.

The ADP3171 provides accurate and reliable short circuit

protection and adjustable current limiting. It also includes an

integrated overvoltage crowbar function to protect the load in

case the output voltage exceeds the nominal programmed

voltage by more than 20%.

The ADP3171 contains two fixed output voltage linear regulator

controllers that are designed to drive external N-channel

MOSFETs. These linear regulators are used to generate the

auxiliary voltages required in most motherboard designs and have

been designed to provide a high bandwidth load-transient response.

The ADP3171 is specified over the commercial temperature

range of 0

°C to 70°C and is available in a 14-lead SOIC package.