Flyback Controller Charges Any Size Capacitor

21st May 2009

ES Admin

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Datasheet

Linear Technology has announced the LT3751, a flyback controller designed to rapidly charge large capacitors to voltages as high as 1000V. The LT3751 drives an external N-Channel MOSFET and can charge a 1000uF capacitor to 500V in less than 1 second, making it ideal for applications such as professional photoflash systems, RF security, inventory control systems and specialized high voltage power supplies.

The LT3751 can be configured for primary-side output voltage sensing without needing an optocoupler. For lower noise and tighter regulation applications, a resistor divider network from output voltage can be used to regulate the output, making it well suited for high voltage power supply requirements.

Boundary mode control minimizes transition losses and delivers up to 88% efficiency. The VCC input voltage ranges from 5V to 24V, enabling it to operate from a variety of power sources and the VTRANS supply voltage range is dependent upon the choice of external components with the LT3751’s internal shunt regulator. A low 106mV differential current sense threshold accurately limits peak switch current. Additional features include an on-board selectable 5.6V or 10.5V powerful 2A N-channel MOSFET gate driver, a CHARGE pin which offers control to the user of initiating a new charge cycle and remote shutdown, along with undervoltage and overvoltage lockout on the VTRANS and VCC input voltages. The DONE pin indicates when the capacitor has reached its programmed voltage and has stopped charging.