Switching power supply device and method

摘要: A switching power supply includes a switch, bias-sensor to sense the switch-voltage, and zero-crossing detector (ZCD) time instances when voltage crosses zero. ZCD generates ZCD-signal, which transitions between first second level at sensed crossing instances, with delay. ZCD-signal is coupled blanking circuit, generating blank-signal pulse-signal, controlling switch. The on-time of switch can be modified by input load. on-times adjusted compensate for this modification, keeping frequency below predetermined limit reducing frequency. further pulse width modulation (PWM) signal generator, circuit PWM generator turns on controlled pulse-signal circuit. Blanking either or control voltage.