MAX1981A

19-2678; Rev 0; 9/02 www.DataSheet4U.com Quick-PWM Master Controllers for VoltagePositioned CPU Core Power Supplies (IMVP-IV) General Description The MAX1907A/MAX1981A are single-phase, QuickPWM™ master controllers for IMVP-IV™ CPU core supplies. Multi-phase operation is achieved using a Quick-PWM slave controller (MAX1980). Multiphase operation reduces input ripple current requirements and output voltage ripple while easing component selection and layout difficulties. The MAX1907A/ MAX1981A include active voltage positioning with adjustable gain and offset, reducing power dissipation and bulk output capacitance requirements. The MAX1907A/MAX1981A are intended for two different notebook CPU core applications: either bucking down the battery directly, or 5V system supply to create the core voltage. The single-stage conversion method allows these devices to directly step down high-voltage batteries for the highest possible efficiency. Alternatively, two-stage conversion (stepping down the 5V system supply instead of the battery) at higher switching frequency provides the minimum possible physical size. The MAX1907A/MAX1981A meet the IMVP-IV specifications and include logic to interface with the CPU power good signals from the VCCP and VCCMCH rails within the system. The regulator features power-up sequencing, automatically ramping up to the Intel-specified boot voltage. The MAX1907A/MAX1981A feature independent four-level logic inputs for setting the boot voltage (B0–B2) and ...