| 摘要 |
A power MOSFET is controlled by illuminating a single photovoltaic generator which produces an output current which charges the gate capacitanace of the power MOSFET to turn on the device. A sensing impedance which may be a diode, MOSFET or other component is connected between the photovoltaic generator and the gate of the power MOSFET. The sensing impedance in the disclosed embodiment is a diode. The sensing impedance forces the power MOSFET gate voltage instantaneously to follow the photovoltaic generator output voltage. The diode is connected in series with the charging circuit and a switching transistor is connected in parallel with the gate capacitance of the MOSFET. The switching transistior base is coupled to the output of the photovoltaic source so that, when the photovoltaic source turns off, and the voltage of the photovoltaic source decays below a predetermined value, the switching transistor turns on to short-circuit the MOSFET gate capacitance so that it can immediately discharge to provide fast turn-off of the power MOSFET. A dV/dt clamping circuit is provided to prevent false charging of the power MOSFET gate through its drain-to-gate capacitance.
|
