LTC3720

U U LTC3720 Single Phase VRM8.5 Current Mode Step-Down Controller FEATURES s 5-Bit Programmable Output Voltage: 1.05V to 1.825V (VRM8.5) s No Sense Resistor Required s 2% to 87% Duty Cycle at 200kHz s tON(MIN) ≤ 100ns s Supports Active Voltage Positioning s True Current Mode Control s Stable with Ceramic COUT s Dual N-Channel MOSFET Synchronous Drive s Power Good Output Voltage Monitor s Wide VIN Range: 4V to 36V s ±1% 0.8V Reference s Adjustable Current Limit s Adjustable Switching Frequency s Forced Continuous Control Pin s Programmable Soft-Start s Output Overvoltage Protection s Optional Short-Circuit Shutdown Timer s Micropower Shutdown: IQ < 30µA s Available in 28-Lead Narrow SSOP Package U APPLICATIO S s Power Supplies for Pentium® Processors s Notebook Computers and Servers DESCRIPTIO The LTC®3720 is a synchronous step-down switching regulator controller for CPU power. An output voltage between 1.05V and 1.825V is selected by a 5-bit code (Intel VRM8.5 VID specification). The controller uses a valley current control architecture to deliver very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in VIN and VOUT. Discontinuous mode operation provides high efficiency operation at light loads. A forced continuous control pin reduces noise and RF interference and can assist secondary winding regulation by disabling discontinuous mode operation when the main output is lightly loade...