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LTC3823 - Fast No Rsense Step-Down Synchronous DC/DC Controller with Differential Output Sensing, Tracking and PLL

The LTC3823 is a synchronous step-down switching regulator controller with true remote differential output sensing and output voltage up/down tracking capability. Its advanced functions and high accuracy reference are ideal for powering high performance server, ASIC and computer memory systems.

The LTC3823 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-locked 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 36V to be stepped down to as low as a 0.6V output. When using remote sense, output voltages up to 3.3V can be developed, and up to 90% of VIN without remote sense. Power supply sequencing is accomplished using an external soft-start timing capacitor.

Features Wide VIN Range: 4.5V to 36V ±0.67%, 0.6V Reference Voltage Output Voltage Tracking Capability True Remote Sensing Differential Amplifier Sense Resistor Optional True Current Mode Control 2% to 90% Duty Cycle at 200kHz tON(MIN) < 100ns Phase-Locked 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: 30μA Power Good Output Voltage Monitor Tracks the Reference Input Pin Available in (5mm × 5mm) 32-Lead QFN and 28-Lead SSOP Narrow Packages Typical Application

Applications Distributed Power Systems Server Power Supplies Packaging

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