High-voltage-resistant clamping circuit with alternating current detection and direct current detection

Abstract

The invention discloses a high-voltage-resistant clamping circuit with alternating-current detection and direct-current detection. The high-voltage-resistant clamping circuit comprises a voltage division module, an alternating-current detection module, a direct-current detection module, a logic control module and an electrostatic discharge module, when electrostatic discharge occurs, the voltage of the node ACOUT is low, and the direct current detection module is started and performs direct current detection on the voltage on the PAD; if the voltage of the PAD is higher than a set value VH, the Mesd1 and the Mesd2 are started and ESD current is discharged. In the ESD discharging process, when the voltage of the PAD is lower than a set safety value VL, the Mesd2 is turned off, and ESD discharging is finished. The clamping circuit has a direct current detection function, and has the advantage that the clamping circuit is not easily mistakenly triggered by a non-ESD condition. Moreover, when the ESD triggers the circuit, the voltage of the PAD is not discharged too low, so that the circuit can still keep a normal working state when the PAD is attacked by the ESD, in addition, the circuit also has the characteristic of high voltage resistance, 3.3 V working voltage resistance is realized by using 1.8 V devices, and the circuit has more flexible and wide application.

Description

technical field [0001] The invention relates to the technical field of electrostatic protection circuits, in particular to a high-voltage-resistant clamping circuit with AC detection and DC detection. Background technique [0002] When electronic components are manufactured, produced, assembled, tested, stored, and transported, static electricity will accumulate in the human body, instruments, storage equipment, etc., and even the electronic components themselves will accumulate charges. When the electrostatic source is in contact with other objects, there is a charge flow, which will generate potentially destructive voltage, current, and electromagnetic fields. Because the instantaneous voltage of electrostatic discharge is very high, usually greater than several thousand volts, the damage is devastating and permanent. Sexuality, it will cause the circuit to burn directly, which is electrostatic discharge (ESD: Electrostatic Discharge). Therefore, preventing electrostatic ...

AI Technical Summary

Problems solved by technology

[0003] The clamp circuit plays a vital role in the electrostatic protection circuit. With the continuous improvement of integrated circuit technology and process level, the size of transistors and devices on the chip is getting smaller and smaller, and the integration of the chip is getting higher and higher. The working voltage is getting lower and lower, and many applications have fixed voltage requirements. For example, 28nm process devices can only withstand 1.8V voltage, while many peripheral applications are still 3.3V. In the prior art, the publication number is CN110994574A The invention patent proposed a high-voltage power supply clamping circuit, such as figure 1 As shown, the problem of withstand voltage is well solved, but the RC time constant of the clamping circuit is generally set to hundreds of nanoseconds, and its disadvantage is that it is easy to be affected by non-ESD events (such as the power-on speed of hundreds of nanoseconds) False triggering; in addition, once the ESD discharge FET is triggered, it is easy to pull the voltage of the PAD very low

Therefore, in some special applications or special chip pins, such as special application requirements for fast power-on speed or open drain (open drain) pins, the clamping circuit is easily triggered by mistake and affects the normal operation of the chip. working status or function

In the prior art, the invention patent with publication number CN107465180A proposes a clamping circuit with AC detection and DC detection, such as figure 2 As shown, it solves the problem of being easily falsely triggered, but the working voltage of this circuit cannot exceed the withstand voltage of the device, and the application is subject to certain restrictions.

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