A delay start overcurrent protection circuit

Abstract

The invention discloses a delayed start overcurrent protection circuit, which includes a controlled switch circuit, a sampling circuit, a control circuit and a controlled switch circuit, the control circuit includes a comparison output unit and a delay unit, a comparison output unit and a delay unit The output ends of both are connected to the control end of the controlled switch circuit; the comparison output unit is used to compare the sampled voltage value obtained by the sampling circuit with the preset first reference voltage, and control when the sampled voltage value is higher than the first reference voltage The controlled switch circuit is disconnected; the delay unit is used to clamp the voltage signal at the control terminal of the controlled switch circuit when the sampled voltage value is higher than the first reference voltage, so that the sampled voltage value is lower than the first reference voltage after the controlled switch circuit is disconnected voltage to prolong the off-time of the controlled switching circuit. The circuit responds quickly and has a time-delay function, that is, when an overcurrent occurs, the switching circuit is quickly shut down and has a certain recovery time, and has the characteristics of simple structure, low cost and strong versatility.

Description

technical field [0001] The invention belongs to the technical field of circuit design, in particular to an overcurrent protection circuit with delayed start. Background technique [0002] Overcurrent protection is also called overload protection. Overload means that the load is too large, exceeding the rated load of the device itself. The phenomenon of overload is that the current is too large, and the electrical equipment heats up. The long-term overload of the line will reduce the insulation level of the line, or even burn the equipment or line. Therefore, the corresponding equipment should be protected by an over-current protection circuit, and a reasonable over-current threshold should be set in the over-current protection circuit. [0003] The overcurrent protection circuit disclosed in the prior art generally includes a sampling unit, a comparison unit, and a control unit. The sampling unit is used to sample the real-time current of the loop and convert it into a real...

AI Technical Summary

Problems solved by technology

This circuit realizes the delay start effect of overcurrent, but the delay start control circuit contains two RC charging and discharging circuits, and there is a defect that it cannot act immediately when the main circuit is overcurrent

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