Typical Application Circuit for LTC3895HFE High Efficiency 140V to 3.3V Step-Down Converter. The LTC3895 is a high performance step-down switching regulator DC/DC controller that drives an all N-channel synchronous power MOSFET stage that can operate from input voltages up to 140V. A constant frequency current mode architecture allows a phase-lockable frequency of up to 850-kHz