ADP3157 Datasheet | Analog Devices

FEATURES Active Voltage Positioning with Gain and Offset Adjustment Optimal pensation for Superior Load Transient Response VRM 8.2, VRM 8.3 and VRM 8.4 pliant 5-Bit Digitally Programmable 1.3 V to 3.5 V Output Dual N-Channel Synchronous Driver Total Output Accuracy ؎1% Over Temperature High Efficiency, Current-Mode Operation Short Circuit Protection Overvoltage Protection Crowbar Protects Microprocessors with No Additional External ponents Power Good Output SO-16 Package APPLICATIONS Desktop PC Power Supplies for: Pentium II and Pentium III Processor Families AMD-K6 Processors VRM Modules GENERAL DESCRIPTION VT2 CMPT OFF-TIME CONTROL VID3 VID4 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. Active voltage positioning results in a dc/dc converter that meets the stringent output voltage specifications for Pentium II and Pentium III processors, with the minimum number of output capacitors and smallest footprint. Unlike voltage-mode and standard current-mode architectures, active voltage positioning adjusts the output voltage as a function of the load current so that it is always optimally positioned for a system transient. The ADP3157 provides accurate and reliable short circuit protection and adjustable current limiting. It also includes an integrated overvoltage crowbar function to...