| 摘要 |
<p>In a battery operated, remote transmitter for a consumer instrument, a microprocessor controls operation of the transmitter. The collector current path of an on-off transistor is coupled between the battery and a voltage supply terminal of the microprocessor. To power up the microprocessor,a keyboard switch in the transmitter is depressed to activate a separate latch that is coupled to the base of the on-off transistor. Base current flows to the latch to turn on the transistor and apply the battery voltage to the voltage supply terminal of the microprocessor. After completion of the transmitter signaling, the microprocessor switches an output port to the ground state. The output port is coupled to a control terminal of the latch and bypasses holding current from a portion of the latch to initiate the regenerative deactivation of the latch. With the latch deactivated, conduction of the on-off transistor is cut off. The voltage supply terminal of the microprocessor is disconnected from the battery to power down the remote transmitter.</p> |
