A low-impedance current-limiting anti-high voltage protection circuit

Abstract

The invention provides a low-impedance current limiting type high-voltage resisting protective circuit. The low-impedance current limiting type high-voltage resisting protective circuit comprises a switching tube 1, a switching tube 2, a current detection and feedback circuit and a current limiting control device. The switching tube 1 and the switching tube 2 are connected between an input end and an output end in series, the current detection and feedback circuit is connected between the switching tube 1 and the switching tube 2 and used for detecting the passing current and converting the current into a voltage signal to be fed back to the current limiting control device, and the current limiting control device is connected with the current detection and feedback circuit, the switching tube 1 and the switching tube 2. When the switching tube 1 and the switching tube 2 work normally, input signals are transmitted to the output end with the low-resistance state, and once the output end is in short circuit to the ground by accident or is mistakenly connected with high voltage, the state of the switching tubes is rapidly switched into the constant-current and high-resistance state, and the voltage between the input end and the output end is safely blocked. The current limiting control device is used for outputting control signals according to voltage signals fed back by the current detection and feedback circuit, and then the switching tube 1 or the switching tube 2 is in the low resistance state or the constant-current and high-resistance state. By means of the technical scheme, the low-impedance current limiting type high-voltage resisting protective circuit has the low-impedance characteristic when working normally, when the high voltage is mistakenly connected, high-voltage and safe blocking is carried with the constant-current and high-resistance state, and therefore an output circuit can be protected against damage by outside voltage impact.

Description

technical field [0001] The present invention relates to the field of electronic technology, in particular to a low-impedance state when the current flowing through is within the allowable range, and will automatically turn into a constant-current high-impedance state after exceeding the range, limiting and safely blocking the current flowing through Low-impedance current-limiting anti-high voltage protection circuit for voltage at both ends. Background technique [0002] "Industrial process calibrator" is a multi-purpose measurement standard instrument integrating output and measurement of various signals. It is the working standard of industrial enterprises and plays an important role in measurement traceability. Since this product is mainly used in industrial sites, it is very likely to be mistakenly connected to high voltage or high current. However, the best calibrator on the market today has a withstand voltage capacity of only 36V at the output end. Once it is mistaken...

AI Technical Summary

Problems solved by technology

[0004] 1. The self-recovery fuse has a maximum current limit, exceeding it will cause damage to itself, so the wrong connection voltage should not be too high, and the above circuit can only protect ±36VDC voltage;

[0005] 2. Due to the long action time of the self-recovery fuse, in some cases it will cause the TVS tube D1 to burn out due to overpower;

[0006] 3. The internal resistance of the self-recovery fuse will gradually increase due to impact and aging, resulting in a decrease in the load capacity of the circuit and an increase in output noise.

[0007] 4. The protection limit current is too large, and the output current of the calibrator is generally below 30mA, so it is necessary to design a current limit protection circuit

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