Short circuit detection circuit, short circuit protection circuit and switching power supply circuit

Abstract

The invention discloses a short circuit detection circuit, a short circuit protection circuit and a switching power supply circuit. The short circuit detection circuit comprises a sampling circuit which is connected with a communication line, avoltage follower, a controller and avoltage stabilizing circuit, wherein the sampling circuit is used for collecting the working voltage of the communication line; the input end of the voltage follower is connected with the sampling circuit, and the output end of the voltage follower is connected with the input end of the controller; the controller is used for judging whether the communication line is short-circuited or not according to the voltage output by the voltage follower; one end of the voltage stabilizing circuit is connected with the output end of the voltage follower; and the voltage stabilizing circuit has a charging state and a discharging state. According to the arrangement, when the communication line works normally and the voltage fluctuates, the voltage stabilizing circuit can enable the voltage obtained by the input end of the controller to be maintained at a high value, so that the condition of triggering short circuit protection is met, and the reliability of the short circuit detection circuit is improved.

Description

technical field [0001] The invention relates to the technical field of electronic circuits, in particular to a short circuit detection circuit, a short circuit protection circuit and a switching power supply circuit. Background technique [0002] In the prior art, the communication voltage on the communication line is output by the switching power supply. When the communication line is short-circuited, the load power on the communication line increases instantaneously. Due to the feedback circuit, the switching power supply adjusts the duty cycle to increase the output voltage. Because the total energy remains unchanged and the load power suddenly increases, the output of the feedback circuit will be pulled down. When the feedback circuit is adjusted to be stable, it is still in a short circuit state, resulting in repeated adjustments. Therefore, the switching power supply cannot provide enough energy to maintain voltage stability in an instant. [0003] In this case, the vo...

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Problems solved by technology

[0004] Therefore, the technical problem to be solved by the present invention is that the detection value of the short-circuit voltage detected in the prior art is relatively small, so that it is impossible to determine whether it is short-circuited, thereby providing a short-circuit detection circuit, a short-circuit protection circuit and a switching power supply circuit

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