In-parallel sampling over-current protection circuit

Abstract

The invention discloses an in-parallel sampling over-current protection circuit. The in-parallel sampling over-current protection circuit comprises a temperature-drift suppression circuit, an in-parallel sampling circuit, an output power component, a reference input end, a first output end and a second output end, wherein the temperature-drift suppression circuit consists of a first resistor, a first thermistor, a second resistor, a second thermistor and an operation amplifier; the in-parallel sampling circuit consists of a first switching tube, another second thermistor and a second resistor; the output power component is formed by N second switching tubes in a parallel connection manner; output current flows through the first output end and the second output end; when the output current is overlarge, voltage of a second input end of the operation amplifier is higher than voltage of a first input end, the signal level of the output end of the operation amplifier is changed, the first switching tube and the second switching tubes are disconnected to realize over-current protection; and the temperature-drift suppression circuit carries out compensation by the first thermistor and the second thermistor, and by voltage distribution between the first resistor and the first thermistor and voltage distribution between the second resistor and the second thermistor, a proportional relation is formed, and flexible adjustment of over-current protection points is realized.

Description

technical field [0001] The present invention relates to an overcurrent protection circuit, more specifically, to a parallel overcurrent sampling protection circuit with temperature stability and low power consumption, which can be used inside a solid-state relay or a solid-state power controller to realize overcurrent at the output end Protect. Background technique [0002] Usually, the overcurrent protection circuit of the solid state relay or the solid state power controller adopts the method of series sampling resistor. The disadvantage of this method is that the series sampling resistor increases the power consumption, the greater the control current, the greater the power consumption, resulting in an increase in the temperature rise of the device during normal operation, which has a certain impact on the reliability of the device. Therefore, various overcurrent sampling circuits have been developed in the prior art for overcurrent protection of devices. [0003] Among...

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Problems solved by technology

The disadvantage of this method is that the series sampling resistor increases the power consumption, the greater the control current, the greater the power consumption, resulting in an increase in the temperature rise of the device during normal operation, which has a certain impact on the reliability of the device

[0004] 1. The series sampling method increases the power consumption, thereby increasing the temperature rise of the device. In the application, the heat dissipation requirements are higher, and the product consistency is greatly affected by the process, which is not conducive to mass production;

[0005] 2. The smart MOSFET is limited by the device, and the application range is narrow, it is difficult to adapt to the flexible application of different voltages and different currents, and the adjustment of the protection point is restricted;

[0006] 3. The sampling method of the thermal device is indirect sampling, the reaction speed is slow, the consistency is poor due to the influence of the process, and the accuracy of overcurrent protection is low

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