Input / output circuit

Abstract

The invention discloses an input and output circuit, which comprises an input and output module, a high selection module, a control module and a protection switch module, and is characterized in that the input and output module comprises a pull-up PMOS (P-channel Metal Oxide Semiconductor) tube and a logic driving module. The high selection module compares the PAD end voltage with the power supply voltage and outputs the higher voltage as the substrate control signal end voltage, so as to ensure that the substrate voltage of the pull-up PMOS tube is not lower than the PAD end voltage; meanwhile, a transmission gate switch structure in the related technology is replaced by a structure that an inverter is connected with a PMOS in series, a control module generates a protection control signal based on the working state of a power supply voltage end, and a logic protection unit and a driving protection unit in a protection switch module are used for respectively controlling a current path of a logic unit and the working state of a pull-up PMOS tube. Therefore, the current backflow phenomenon is prevented, and the chip and connection equipment are protected.

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