| 摘要 |
<p>An intermittent switching power supply circuit prevents excessive output power on a secondary side of a circuit. An intermittent oscillator (3) is alternately switched on and off to maintain output voltage and/or current roughly constant. An output power monitoring circuit monitors output power from a rectifying/smoothing circuit (4,13). A control circuit outputs a stop control signal to a control terminal (3a) of the intermittent oscillator when the output power monitoring circuit (51) determines that the output voltage and/or current exceeds a reference value. The protection circuit (51) and a photocoupler receiver (39) element are connected in parallel with the control circuit. Where a circuit error occurs and the photocoupler receiver element fails to cycle the intermittent oscillator between active and inactive conditions for a predetermined time, the protection circuit provides a backup which outputs a stop control signal to stop oscillation of the intermittent oscillator element. <IMAGE></p> |
