Pull-up resistor circuit for preventing inverse current transmission and input-output port circuit

Abstract

The invention relates to a pull-up resistor circuit for preventing inverse current transmission and an input-output port circuit. The pull-up resistor circuit comprises an input-output port, a switching circuit, a first P-type field effect transistor, a first N-type field effect transistor and a power supply, wherein the switching circuit is connected between the input-output port and the power supply in series; the first N-type field effect transistor and the first P-type field effect transistor are in common grid connection with the power supply; a drain electrode of the first N-type field effect transistor is connected with a drain electrode of the first P-type field effect transistor and is connected with a control end of the switching circuit; when the power supply has no power and the input-output port has the power, the first N-type field effect transistor is switched off and the first P-type field effect transistor is conducted; and the voltage of the drain electrode of the first P-type field effect transistor controls the switching circuit to switch off the connection between the power supply and the input-output port.

Description

technical field [0001] The invention relates to an input and output circuit, in particular to a pull-up resistor circuit and an input and output port circuit for preventing reverse current transmission. Background technique [0002] With the rapid development of the electronic information industry, chips are usually connected through input / output (Input / Output, abbreviated: IO) interfaces to transmit information. When there are multiple I O interfaces connected, because the power-on sequence of each I O interface is different, the power supply of some I O interfaces has no power, while the power supply of some I O interfaces has power. When the powered I O interface has a pull-up resistor, then It will cause the electric I O interface to leak electricity to the non-electric I O interface. [0003] like figure 1 As shown, the interface circuit of the equipment in the prior art, the interface circuit pulls up the voltage of the I O interface to the power supply VCCO through ...

AI Technical Summary

Problems solved by technology

When there are multiple I O interfaces connected, because the power-on sequence of each I O interface is different, the power supply of some I O interfaces has no power, while the power supply of some I O interfaces has power. When the powered I O interface has a pull-up resistor, then It will cause the electric I O interface to leak electricity to the non-electric I O interface

[0003] like figure 1 As shown, the interface circuit of the equipment in the prior art, the interface circuit pulls up the voltage of the I O interface to the power supply VCCO through the resistance RO, when the I O interface is connected to another I O interface with power, and at this time VCCO has no power , it will cause the I O interface to leak electricity to VCCO through the resistance RO, that is, there is a reverse current transmission. When multiple I O interfaces transmit reverse current at the same time, the reverse current is too large. In severe cases, the voltage of the I O interface can be pulled down. Even a functional error of the I O interface

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