ADP3155

a 5-Bit Programmable Triple Power Supply Controller for Pentium® III Processors ADP3155 FUNCTIONAL BLOCK DIAGRAM VCC DRIVE1 DRIVE2 PGND AGND PWRGD SENSE+ SENSE– NONOVERLAP DRIVE SD CROWBAR IN OFF CMPI Q S R gm REFERENCE CMPT OFF-TIME CONTROL VIN SENSE– VLDO2 FB2 VLDO1 FB1 VREF +5% VT1 VREF VREF –5% DELAY VREF +15% 2R 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 Two Onboard Linear Regulator Controllers Total Output Accuracy ؎1% Over Temperature High Efficiency, Current-Mode Operation Short Circuit Protection Overvoltage Protection Crowbar Protects Microprocessors, with No Additional External Components Power Good Output TSSOP-20 Package APPLICATIONS Desktop PC Power Supplies for: Pentium II and Pentium III Processor Families AMD-K6 Processors VRM Modules GENERAL DESCRIPTION R VT2 CT CMP ADP3155 DAC 1.20V The ADP3155 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 ADP3155 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 ADP3155 uses a currentmode, constant off-time architecture to drive...