Input voltage bleeder circuit and overvoltage protection switch

Abstract

The invention provides an input voltage bleeder circuit which comprises a resistance detection circuit, a voltage comparison circuit and a feedforward capacitor selection circuit. The resistance detection circuit detects the resistance of a lower voltage-dividing resistor input to the input voltage bleeder circuit, and obtains a voltage value of the lower voltage-dividing resistor by conversion; the voltage comparison circuit compares the received voltage value of the lower voltage-dividing resistor with reference voltages, and outputs a corresponding electrical signal; and the electrical signal is used to control the opening / closing state of a corresponding switch in the feedforward capacitor selection circuit so as to select a corresponding feedforward capacitor. Via the input voltage bleeder circuit, the corresponding feedforward capacitor is selected according to the resistance of the lower voltage-dividing resistor during occurrence of surge voltage, response time of the input voltage bleeder circuit is shortened effectively, switch-off time of the overvoltage protection switch is reduced greatly, and is more reasonable, and the possibility that the overvoltage protection switch is switched off for mistake is reduced.

Description

technical field [0001] The invention relates to the technical field of semiconductor integrated circuits, in particular to an input voltage divider circuit and an overvoltage protection switch. Background technique [0002] When a surge voltage is generated in various integrated circuit boards, the surge voltage will damage the performance of the semiconductor device in the electronic equipment and reduce the life of the semiconductor device. There are many factors, such as lightning strikes, electrostatic discharges and industrial events, etc.; the surge voltage is characterized by a very short generation time, usually at the microsecond level, and its voltage and current are many times the normal value. In order to reduce the impact of the surge voltage on To prevent damage to electronic equipment, overvoltage protection switches (Over Voltage Protection, OVP) are widely used in various electronic equipment. [0003] The overvoltage protection switch is a device that redu...

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Problems solved by technology

[0003] The overvoltage protection switch is a device that reduces the voltage of the controlled device or disconnects the power supply when the external input voltage exceeds the preset voltage threshold. To protect the stress of the post-stage chip of the switch, but during the use of the existing overvoltage protection switch, due to the mismatch between the feedforward capacitor and the voltage dividing resistor, it is very easy to turn off by mistake, that is, the input voltage value is lower than the preset voltage In the protection range, the overvoltage protection switch will also be turned off, and the turn-off accuracy of the overvoltage protection switch directly affects the user's experience with the device

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