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LTC3775 - High Frequency Synchronous Step-Down Voltage Mode DC/DC Controller

The LTC3775 is a high efficiency synchronous step-down switching DC/DC controller that drives an all N-channel power MOSFET stage from a 4.5V to 38V input supply voltage. A patented line feedforward compensation circuit and a high bandwidth error amplifier provide very fast line and load transient response.

High step-down ratios are made possible by a low 30ns minimum on-time, allowing extremely low duty cycles. MOSFET RDS(ON) current sensing maximizes efficiency. Alternatively, a sense resistor can be used for higher current limit accuracy. Continuous monitoring of the voltages across the top and bottom MOSFETs allows cycle-by-cycle control of the inductor current, configurable by external resistors.

The soft-start function controls the duty cycle during start-up, providing a smooth output voltage ramp up. The operating frequency is user programmable from 250kHz to 1MHz and can be synchronized to an external clock.

Features Wide VIN Range: 4.5V to 38V Line Feedforward Compensation Low Minimum On-Time: tON(MIN) < 30ns Powerful Onboard MOSFET Drivers Leading Edge Modulation Voltage Mode Control ±0.75%, 0.6V Reference Voltage Accuracy Over Temperature VOUT Range: 0.6V to 0.8VIN Programmable, Cycle-by-Cycle Peak Current Limit Sense Resistor or RDS(ON) Current Sensing Programmable Soft-Start Synchronizable Fixed Frequency from 250kHz to 1MHz Selectable Pulse-Skipping or Forced Continuous Modes of Operation Low Shutdown Current: 14μA Typical Thermally Enhanced 16-Lead MSOP and 3mm × 3mm QFN Packages Typical Application

Applications Automotive Systems Telecom and Industrial Power Supplies Point of Load Applications Packaging

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