| 摘要 |
PURPOSE: A power switching circuit is provided to reduce the loss of electric power. CONSTITUTION: The switching circuit can reduce the loss of electrical power through forming a parallel connection of transistors; a low (LOW) signal is inputted to the input terminal (IN) of a processor when a switch (SW) has been turned on (ON) for a given time; the processor outputs the low (LOW) signal to the output terminal (OUT); a pnp-type transistor (Q1) is turned on, and power is supplied to the processor and an external circuit through the emitter and collector of the pnp-type transistor (Q1); if the user turns off the switch, the pnp-type transistor (Q2) turns goes to its off state, but if the pnp-type transistor (Q1) remains in its on state and power provided continuously; if the switch continues to be in its on-position, a LOW signal is inputted to the input terminal (IN); then the processor checks whether the LOW signal is inputted to the input terminal for more than a given time, and outputs a high (HIGH) signal to the output terminal (OUT); the outputted high signal turns the pnp-type transistor (Q1) into its off (OFF) state; and if the switch is turned off, the pnp-type transistor (Q2) also turns into its off state and the power supply is shut off. |
