4/3/2/1-Phase PWM Controller with Embedded Drivers for CPU Core Power Supply


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The RT8857 is a 4/3/2/1-phase synchronous buck controller with 2 integrated MOSFET drivers for Intel VR11.1/VR10.x and AMD K8/K8_M2 CPUs power application. The RT8857 uses differential inductor DCR current sense to achieve phase current balance and active voltage positioning. Other features include adjustable operating frequency, adjustable soft start, power good indication, external error-amp compensation, over voltage protection, over current protection, VRHOT sensing and IMON for various applications. The RT8857 comes to a small footprint with WQFN-48L 7x7 package.


  • Desktop CPU Core Power
  • Low Voltage, High Current DC/ DC Converter
Key Spec.
Status Active
VID Table Support K8;K8_M2;VR10.x;VR11.1
Number of Phases 4
Vcc (typ) (V) 12
Vin (min) (V) 10.8
Vin (max) (V) 13.2
Accuracy (Vout>=1V) (+/- %) 0.5
Freq (typ) (kHz) 300
Built-in DAC Generator Yes
Number of MOSFET Drivers 2
Features Adjustable Current Limit;Adjustable Frequency;Adjustable Soft-Start;Built-in Bootstrap Switch;Current Mode Control;Cycle-by-Cycle Current Limit;DCR Current Sense;Diode Emulation Mode;Droop Control;Enable Input;Fast Transient Response;OVP;Power Good;SCP;UVP
Package Type WQFN7x7-48
  • 12V Power Supply Voltage
  • 4/3/2/1-Phase Power Conversion
  • 2 Embedded MOSFET Drivers
  • Internal Regulated 5V Output
  • VID table for INTEL VR11.1/VR10.x and AMD K8/K8_M2 CPUs
  • Continuous Differential Inductor DCR Current Sense
  • Adjustable Soft Start
  • Adjustable Frequency
  • Power Good Indication
  • Adjustable Over Current Protection
  • Over Voltage Protection
  • VRHOT Sensing with External Thermistor
  • IMON Output Current Indication
  • Power State Indicator (PSI)
  • Small 48-Lead WQFN Package
  • RoHS Compliant and Halogen Free
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4/3/2/1-Phase PWM Controller with Embedded Drivers for CPU Core Power Supply2018/06/08