| 摘要 |
<p>PURPOSE:To generate a power on reset signal for initializing control surely by providing a level shifting circuit in the later stage of a CR time constant circuit and compensating rising up of power source voltage due to sneaking in of external power source current. CONSTITUTION:The base of a transistor TR15 of a level shifting circuit 14 is connected to CR connection point A of a CR time constant circuit 10, and a diode D16 and a resistance 17 are connected in series to the emitter to operate the TR15 as an emitter follower. Accordingly, when the TR15 is looked from the point A, it is high impedance and the connection point C of D16 and resistance 17 is low impedance. As voltage at the point C is level shifted from the point A in the direction of low potential, sufficient initializing signal, i.e. power on reset signal can be obtained by output B of a Schmidt trigger gate 18 even when there is rise up voltage due to sneaking in of external power source current.</p> |
