Step-down dc/dc controller needs no external surge protection devices

The LTC3895 non-isolated synchronous step-down switching regulator controller drives an all n-channel MOSFET power stage. Its 4 to 140-V (150-V max.) input voltage range operates from a high input voltage source or from an input that has high voltage surges, eliminating the need for external surge suppression devices. The device continues to operate at up to 100% duty cycle during input voltage dips down to 4 V, making it suited for transportation, industrial control, robotic and datacom applications.

The output voltage can be set from 0.8 to 60 V at output currents up to 20 A with up to 96% efficiency. The part draws only 40 µA in sleep mode with the output voltage in regulation, suitable for always-on systems. An internal charge pump allows for 100% duty cycle operation in dropout, a useful feature when powered from a battery during discharge. The controller’s 1 Ω, n-channel MOSFET gate drivers can be adjusted from 5 – 10 V to enable the use of logic- or standard-level MOSFETs to maximize efficiency. The device includes an NDRV pin that drives the gate of an optional external n-channel MOSFET. It operates with a selectable, fixed frequency between 50 kHz and 900 kHz and is synchronizable to an external clock from 75 kHz to 850 kHz. Two operating junction temperature grades are available, an industrial grade from –40° to 125°C and a automotive version from –40° to 150°C.