Circuit for discriminating connection state of terminal

Abstract

Abstract PURPOSE: To enable to discriminate the connection state of a terminal without a clock by composing said circuit of a detecting circuit with making power, a gate circuit and a pulling-down transistor. CONSTITUTION: When the power supply is turned on in the case of no charge, the capacitor 71 is charged by current from the resistance 72, the charged voltage is inverted by the inverter 73 and is fed to the NAND gate circuit 8 as an output of the detecting circuit 7. When the power supply is turned ON in the state of the terminal opened, the floating capacity 9 is quickly charged. The transistor 2 is being turned ON. Also when the power supply is turned ON in connecting the terminal 1 to the VDD side electrode, the transistor 2 is turned OFF. No current flows to the transistor 2 when no power is applied thereto. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Hitoshi Ochiai

Bibliographic Details