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