GENERAL DESCRIPTION
The ADP31981 is a highly efficient, multiphase, synchronous buck switching regulator controller optimized for converting a 12 V main supply into the core supply voltage required by high performance Intel processors. It uses an internal 8-bit DAC to read a voltage identification (VID) code directly from the processor, which is used to set the output voltage between 0.5 V and 1.6 V.
This device uses a multimode PWM architecture to drive the logic-level outputs at a programmable switching frequency that can be optimized for VR size and efficiency. The phase relationship of the output signals can be programmed to provide 2-, 3-, or 4-phase operation, allowing for the construction of up to four complementary buck switching stages.
The ADP3198 also includes programmable no load offset and slope functions to adjust the output voltage as a function of the load current, optimally positioning it for a system transient. The ADP3198 also provides accurate and reliable short-circuit protection, adjustable current limiting, and a delayed power good output that accommodates on-the-fly output voltage changes requested by the CPU.
The ADP3198 has a built-in shunt regulator that allows the part to be connected to the 12 V system supply through a series resistor.
The ADP3198 is specified over the extended commercial temperature range of 0°C to 85°C and is available in a 40-lead LFCSP.

FEATURES
  Selectable 2-, 3-, or 4-phase operation at up to 1 MHz per phase
  ±11 mV worst-case differential sensing error over temperature
  Logic-level PWM outputs for interface to external high power drivers
  Enhanced PWM flex mode for excellent load transient performance
  Active current balancing between all output phases
  Built-in power-good/crowbar blanking supports on-the-fly VID code changes
  Digitally programmable 0.5 V to 1.6 V output supports both
  VR10.x and VR11 specifications
  Programmable short-circuit protection with programmable latch-off delay
 
APPLICATIONS
  Desktop PC power supplies for next generation
     Intel® processors
     VRM modules