| 摘要 |
PURPOSE: To obtain a starting circuit for a power-control integrated circuit, without requiring an additional external part by installing an internal timer circuit which monitors output-off time of a power supply in the starting circuit of the self-oscillating power-control integrated circuit, etc. CONSTITUTION: An RS flip-flop 30 is set and an FET 50 is turned on, a transformer 52 is DC-excited, the current of the DC excitation is converted into a voltage by a resistor 58 and input to a PWM comparator 20. The RS flip-flop 30 is reset when the current exceeds a control voltage VCTRL, and the FET 50 is turned off. When the transformer 52 releases stored energy and a capacitor 54 for an output circuit is charged and the charging current reaches zero, an output is conducted from a comparator 24 and the RS flip-flop is set again, and the FET 50 is turned on. When a timer circuit 32 is mounted and a time when an output from the RS flip-flop 30 is at a low logical level is monitored and a fixed passage of time passes, the output from the RS flip-flop 30 is set at a high logical level and the FET is turned on, and the circuit is started.
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