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LTC3770 - Fast No RSENSE Step-Down Synchronous Controller with Margining, Tracking and PLL

The LTC3770 is a synchronous step-down switching regulator controller with output voltage up/down tracking capability and voltage margining. Its advanced functions and high accuracy reference are ideal for powering high performance server, ASIC and computer memory systems.

The LTC3770 uses a constant on-time, valley current mode control architecture to deliver very low duty factors without requiring a sense resistor. The operating frequency is selected by an external resistor and is compensated for variations in input supply voltage. An internal phase-lock loop allows the IC to be synchronized to an external clock.

Fault protection is provided by an overvoltage comparator and input undervoltage lockout. The regulator current limit is user programmable. A wide supply range allows voltages as high as 32V to be stepped down to as low as a 0.6V output. Power supply sequencing is accomplished using an external soft-start timing capacitor.

Features Wide VIN Range: 4V to 32V ±0.67% 0.6V Reference Voltage Output Voltage Tracking Capability Programmable Margining Sense Resistor Optional True Current Mode Control 2% to 90% Duty Cycle at 200kHz tON(MIN) ≤ 100ns Phase Lock Loop Frequency Synchronization Powerful Dual N-Channel MOSFET Driver Adjustable Cycle-by-Cycle Current Limit Adjustable Switching Frequency Programmable Soft-Start Current Foldback Protection (Disabled at Start-Up) Output Overvoltage Protection Micropower Shutdown: IQ < 30µA Power Good Output Voltage Monitor Tracks the Reference Input Pin Available in (5mm × 5mm) QFN and 28-Lead SSOP Packages Typical Application

Applications Distributed Power Systems Server Power Supply Packaging

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