| 摘要 |
<p>A power conserving integrated circuit (20) is coupled to its external power supply (28) only in response to an external event sensed by closure of a switch (30). An initial power connection is made by a transistor (34) in the circuit (22) in response to the external event. After the initial power connection, the transistor (34) remains conducting so as to couple the power supply (28) to the integrated circuit (22) for a predetermined period of time sufficient for a function (40) to be executed by the integrated circuit. The initial power connection is detected by an activity monitor (37) which in response resets a down counter (38) that, through a connection (39) to the transistor (34), holds the transistor (34) in its conducting state until the counter (38) finishes counting clock pulses. The connection is then terminated and is not re-initiated until another external event. Therefore, power is consumed only when necessary, thereby preserving the power source (28). <IMAGE></p> |
