| 摘要 |
PURPOSE:To prevent the transmission of wrong signals and to improve the reliability of an interface circuit by counting the time during which the power supply voltage reaches a prescribed level and delivering a state signal from the 1st means when the counted time elapses. CONSTITUTION:A controller 1 of a microprocessor, etc. is connected to the input terminal of a gate IC1 consisting of a TTL IC, and the IC1 is connected to a power supply VCC. The output terminal of the IC1 is connected to the base of a transistor TR1 via a resistance R1, and a resistance R2 and a capacitor C1 are connected in parallel between the emitter and the base of the TR1. The output of the TR1 is connected to an integrated circuit IC2 via a resistance R3 and a transmission circuit 2. Therefore the TR1 is kept nonconductive for a delay time due to a time constant of the C1 and the R1 respectively until the power supply voltage reaches the action securing level of the IC1 at the time of application of the VCC. |
