High Voltage Synchronous Current Mode Step-Down Controller with Adjustable Operating Frequency

The LT3845 is a high voltage, synchronous, current mode controller used for medium to high power, high efficiency supplies. It offers a wide 4V to 60V input range (7.5V minimum start-up voltage). An on-board regulator simplifies the biasing requirements by providing IC power directly from VIN.

Burst Mode® operation maintains high efficiency at light loads by reducing IC quiescent current to 120μA. Light load efficiency is also improved with the reverse inductor current inhibit function which supports discontinuous operation.

Additional features include adjustable fixed operating frequency that can be synchronized to an external clock for noise sensitive applications, gate drivers capable of driving large N-channel MOSFETs, a precision undervoltage lockout, 10μA shutdown current, short-circuit protection and a programmable soft-start.

The LT3845 is available in a 16-lead thermally enhanced TSSOP package and 16-pin through hole N package.

Features

LT3845

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LT3845A

Improved Performance In Over Current Conditions

Applications

* 12V and 42V Automotive and Heavy Equipment

* 48V Telecom Power Supplies

* Avionics and Industrial Control Systems

* Distributed Power Converters

* High Voltage Operation: Up to 60V

* Synchronizable Up to 600kHz

* Adjustable Constant Frequency: 100kHz to 500kHz

* Output Voltages Up to 36V

* Adaptive Nonoverlap Circuitry Prevents Switch Shoot-Through

* Reverse Inductor Current Inhibit for Discontinuous Operation Improves Efficiency with Light Loads

* Programmable Soft-Start