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

The RH3845 is a high voltage, synchronous, current mode controller used for medium to high power, high efficiency supplies. It offers a wide 7.5V to 60V input range. With an external VCC supply, the input can drop to 4V and continue to operate after startup. An onboard regulator simplifies the biasing requirements by providing IC power directly from VIN.

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

Note that Burst Mode® operation, available in the LT3845, is not available in the RH3845 version.

RH3845MW-1 operates in pulse skip mode where reverse inductor current is disallowed. Regulation is achieved at light loads by skipping cycles. Operation in pulse skip mode yields higher light load efficiency, but higher output voltage ripple.

RH3845MW-2 operates in forced continuous mode where reverse inductor current is allowed. This mode of operation maintains a constant frequency over all loads making it suitable for noise sensitive applications. However, forced continuous mode is less efficient at light loads.

THIRD PARTY VENDOR AVAILABILITY We partner with third party vendors who assemble and test packaged products with RH Dice inside.

Part Number

Description

MSK5055RH

High Voltage Switching Controller (RH3845A IC only)

MSK5063RH

10A ,60V DC-DC Buck Regulator Module (External Inductor)

Applications

* Intermediate Bus Power Supplies

* Avionics and Control Systems

* Distributed Power Converters

* Processed in Compliance with LTC Certified MIL-PRF-38535 Class V Flow

* High Voltage Operation: Up to 60V

* Review of the published Single Event Reports supplied in the “Radiation Reports” section below is recommended for applications above 30V.

* Output Voltages Up to 36V

* Synchronizable Up to 600kHz

* Adjustable Constant Frequency: - 100kHz to 500kHz

* 100μA Shutdown Supply Current

* Capable of Driving Large Power MOSFETs

* Short-Circuit Protection and Soft-Start

* Radiation Performance