Features

• Charges Any Size Capacitor
• Low Noise Output in Voltage Regulation Mode
• Stable Operation Under a No-Load Condition
• Integrated 2A MOSFET Gate Driver with Rail-to-Rail Operation for V_CC ≤ 8V
• Selectable 5.6V or 10.5V Internal Gate Drive Voltage Clamp
• User-Selectable Over/Undervoltage Detect
• Easily Adjustable Output Voltage
• Primary or Secondary Side Output Voltage Sense
• Wide Input V_CC Voltage Range (5V to 24V)
• Available in 20-Pin QFN 4mm × 5mm and 20-Lead TSSOP Packages

Typical Application

Description

The LT3751 is a high input voltage capable flyback controller 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 4.75V. A low 106mV 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 1000μF capacitor to 500V 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.