Input circuit

Abstract

The invention provides an input circuit which comprises a diode, a resistance, a first transistor, a buffer, a matrix voltage generating unit and a strengthening unit. When an external input voltage is less than or equal to a first supply voltage (like an input / output supply voltage), the input circuit can utilize the matrix generating unit and the strengthening unit to lead an internal input voltage to be the same as the external input voltage. Furthermore, the input circuit can operate correctly even if the first supply voltage is extremely low. Therefore, the input circuit can be operated at the extremely low input / output supply voltage.

Description

Technical field [0001] The present invention relates to an input circuit, and more particularly, to a high-voltage-resistant input circuit having an extremely low input / output power supply voltage. Background technique [0002] figure 1 Shown is a circuit diagram of a traditional high-voltage withstand input circuit 100. Please refer to figure 1 The conventional input circuit 100 includes a diode D1, a resistor R1, an NMOS transistor NM1, and a buffer G1. Generally speaking, the diode D1 is an electrostatic discharge (ESD) protection element. The resistor R1 protects the NMOS transistor NM1 and the buffer G1 by increasing the delay, and reduces the noise intensity of the external input voltage VIN. The gate terminal of the NMOS transistor NM1 is biased at the input / output power supply voltage VDDIO, so that the NMOS transistor NM1 receives the external input voltage VIN and outputs the internal input voltage VINN to the buffer G1. [0003] However, the maximum voltage level of...

AI Technical Summary

Problems solved by technology

[0003] However, since the highest voltage level of the internal input voltage VINN is affected by the NMOS transistor NM1, it is limited to VDDIO-VthN, where VthN is the threshold voltage of the NMOS transistor NM1

Therefore, the voltage level of the high external input voltage (such as VDDIO) cannot be directly supplied to the buffer G1

In addition, the conventional input circuit 100 cannot operate at a relatively low input / output power supply voltage VDDIO

To be more clear, if the input / output supply voltage VDDIO is quite low, the internal input voltage VINN cannot reach the threshold voltage of the buffer G1

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