| 摘要 |
PURPOSE: A switching power supply circuit is provided to achieve resonant operation in a load region and wide input voltage range, thereby acquiring high efficiency. CONSTITUTION: A voltage boost chopper circuit of a discontinuous current mode changes a first switching device(Q1) to an ON state from a zero current state of a reactor(L1). The voltage boost chopper circuit is arranged by connecting a series circuit of a second condenser(C2), a second switching device(Q2) comprised of a MOSFET(metal oxide semiconductor field effect transistor), and a first rectifier diode(D1) in an existing switching power supply circuit. A parallel circuit of a condenser(Cb) and diode(Db) is connected between a drain and source of the second switching device. A control circuit(10) creates a gate signal based on voltage from a current detection resistor, a first condenser(C1), and threshold detection coil(1b) of the reactor. The control circuit creates the gate signal by inverting the gate signal which turns ON/OFF the first switching device. |
