ADP3156

a FEATURES Active Voltage Positioning with Gain and Offset Adjustment Optimal Compensation for Superior Load Transient Response Fixed 1.5 V, 1.8 V and 2.5 V Output Versions Dual N-Channel Synchronous Driver On-Board Linear Regulator Controller Total Output Accuracy ؎1% Over Temperature High Efficiency, Current-Mode Operation Short Circuit Protection Overvoltage Protection Crowbar Protects Loads with No Additional External Components Power Good Output SO-16 Package APPLICATIONS Desktop Computer Supplies ACPI-Compliant Power Systems General Purpose DC-DC Converters GENERAL DESCRIPTION Dual Power Supply Controller for Desktop Systems ADP3156 FUNCTIONAL BLOCK DIAGRAM VCC DRIVE1 DRIVE2 PGND AGND PWRGD SENSE+ SENSE– DELAY NONOVERLAP DRIVE VREF +15% 2R CROWBAR IN OFF CMPI S R gm VREF REFERENCE VLDO 1.20V FB OFF-TIME CONTROL VIN SENSE– R VT1 VREF +5% VREF –5% SD Q VT2 CT CMPT ADP3156 The ADP3156 is a highly efficient synchronous buck switching regulator controller optimized for converting the 3.3 V or 5 V main supply into lower supply voltages required on the motherboards of Pentium® III and other high performance processor systems. The ADP3156 uses a current mode, constant off-time architecture to drive two external N-channel 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 res...