GENERAL DESCRIPTION

The ADP3157 is a highly efficient synchronous buck switching regulator controller optimized for converting the 5 V main supply into the core supply voltage required by the Pentium III and other high performance processors. The ADP3157 uses an internal 5-bit DAC to read a voltage identification (VID) code directly from the processor, which is used to set the output voltage between 1.3 V and 3.5 V. The ADP3157 uses a current mode, constant off-time architecture to drive two external Nchannel MOSFETs at a programmable switching frequency that can be optimized for size and efficiency. It also uses a unique supplemental regulation technique called active voltage positioning to enhance load transient performance.

FEATURES

Active Voltage Positioning with Gain and Offset

Adjustment

Optimal Compensation for Superior Load Transient

Response

VRM 8.2, VRM 8.3 and VRM 8.4 Compliant

5-Bit Digitally Programmable 1.3 V to 3.5 V Output

Dual N-Channel Synchronous Driver

Total Output Accuracy 61 Over Temperature

High Efficiency, Current-Mode Operation

Short Circuit Protection

Overvoltage Protection Crowbar Protects Microprocessors

with No Additional External Components

Power Good Output

SO-16 Package

APPLICATIONS

Desktop PC Power Supplies for:

Pentium II and Pentium III Processor Families

AMD-K6 Processors

VRM Modules