Direct-current overvoltage protection circuit

Abstract

The invention discloses a direct-current overvoltage protection circuit. The direct-current overvoltage protection circuit comprises an input filter circuit, an overvoltage detection circuit, a variable impedance electronic switch drive circuit, a variable impedance electronic switch circuit, a voltage stabilizing circuit, a reduced saturation voltage drop circuit, an output filter voltage stabilizing circuit and a load, wherein the input end of the input filter circuit is connected with an input signal; the output end of the input filter circuit is respectively connected with the overvoltage detection circuit and the reduced saturation voltage drop circuit; the output of the overvoltage detection circuit is connected with the variable impedance electronic switch drive circuit; the output of the variable impedance electronic switch drive circuit is connected with the variable impedance electronic switch circuit; the output of the variable impedance electronic switch circuit is connected with the voltage stabilizing circuit; the output of the voltage stabilizing circuit is connected with the reduced saturation voltage drop circuit; the output of the reduced saturation voltage drop circuit is connected with the output filter voltage stabilizing circuit; and the output of the output filter voltage stabilizing circuit is connected with the load.

Description

technical field [0001] The invention relates to a direct current overvoltage protection circuit, which belongs to the technical field of circuit design. Background technique [0002] Generally, electronic products have a limited range of input power requirements, and the power supply may exceed the upper limit. For example, when the charger charges the battery, the voltage at both ends of the battery is too high. This requires the ability of the product to have a wide operating range. Most products use a triode and a resistor in parallel. When the voltage is too high, turn off the triode and share part of the voltage drop to the resistor. Although this technical structure can play a certain protective role. But it is not very practical in practical application. On the one hand, since the output of the chip is constant power, when the protection circuit is used to supply power to the input terminal of the chip, when the voltage at the input terminal of the chip is low, a ...

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Problems solved by technology

Therefore, when the input voltage is low, the triode will produce a large saturation voltage drop, which will increase the calorific value of the triode, so the protection circuit cannot work at a lower voltage.

On the other hand, when the triode is turned off, the load capacity of the output terminal cannot be controlled

When the load at the output terminal changes (in most products, the lower the input terminal voltage, the greater the required input terminal current, and the greater the voltage shared by the resistor, causing the entire circuit to fail to work normally), therefore, this circuit The structure is unstable throughout the circuit and cannot be used in practical applications

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