Electronic circuits

摘要

A high voltage AC power supply circuit for a capacitive load CL, such as an electroluminescent lamp, includes an inductive component T and an output FET S1 in series. The output FET S1 can be pulsed so that the inductive component T generates a voltage to charge the capacitive load CL via an H-bridge H. A diode D1 prevents current discharging from the capacitive load CL while the output FET S1 Is closed. The circuit also includes a reservoir capacitor CR and a reservoir FET S3 in series with the inductive component T. The reservoir FET S3 can be pulsed so that the inductive component T generates a voltage to charge the reservoir capacitor CR by transferring energy from the capacitive load CL. A diode D2 Prevents current discharging from the reservoir capacitor CR while the reservoir FET S3 is closed. Energy can be transferred from the capacitive load CL to the reservoir capacitor CR and back again to reduce the amount of energy that must be discarded during operation of the circuit.