| 摘要 |
PURPOSE:To initialize a logic circuit securely at the time of power-on operation by connecting a time constant circuit composed of a resistance and a capacitor to a power input terminal, inputting the charging voltage of a capacitor to the base of a transistor (TR), and connecting the collector of a TR to the power input terminal through the resistance. CONSTITUTION:The TR 6 is in an open state unless the charging voltage of the capacitor 4 exceeds the base-emitter saturation voltage of the TR 6, so its collector output is held at a high level securely with a voltage inputted from the power input terminal 3 through the 2nd resistance 9. The logic circuit 5 is therefore initialized when its reset terminal R is held at the high level and a logical level 0 is obtained at its output terminal Q. Then when the capacitor 4 is charged until the input to the TR 6 exceeds the base-emitter saturation voltage of the TR 6, the TR 6 turns on and the reset terminal R of the logic circuit 5 is grounded through the TR 6. Consequently, the high level is outputted securely at the time of power-on operation and the logic circuit is initialized.
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