Power by Linear™ / Analog Devices’ LT3751 is a high-input-voltage capable flyback controller. This controller is designed to rapidly charge a large capacitor to a user-adjustable high-target voltage set by the transformer turns ratio and three external resistors. Optionally, a feedback pin can be used to provide a low-noise, high-voltage regulated output.

The LT3751 has an integrated rail-to-rail MOSFET gate driver that allows for efficient operation down to 4.75 V. A low 106 mV differential current sense threshold voltage accurately limits the peak switch current. Added protection is provided via user-selectable overvoltage and undervoltage lockouts for both V_CC and V_TRANS. A typical application can charge a 1,000 μF capacitor to 500 V in less than one second.

The CHARGE pin is used to initiate a new charge cycle and provides ON/OFF control. The DONE pin indicates when the capacitor has reached its programmed value and the part has stopped charging. The FAULT pin indicates when the LT3751 has shut down due to either V_CC or V_TRANS voltage exceeding the user-programmed supply tolerances. The LT3751 was designed for high-voltage capacitor charging, photoflash systems, and emergency strobe applications.