An overload hiccup protection circuit for a half-bridge topologyswitching power supply

Abstract

The invention discloses an overload hiccup protection circuit for a half-bridge topology switching power supply, which comprises an overload hiccup protection circuit and a power supply circuit. The overload hiccup protection circuit includes a driving circuit and a control circuit, the driving circuit comprises a field effect transistor Q5, thyristor SCR2, Diode D13, Resistance R58, Resistance R76, Capacitor C18, Hiccup interval delay control circuit, the capacitor C18 and the resistor R76 are connected in parallel between the cathode and the control electrode of the thyristor SCR2, the control electrode of the thyristor SCR2 is connected to the drain of the field effect transistor Q5, The cathode is connected to the source of the field effect transistor Q5, the anode of the thyristor SCR2 is connected to the cathode of the diode D13, the anode of the diode D13 is connected to the center end of the transformer T coil of the switching power supply circuit, and the source of the field effect transistor Q5 is connected to a hiccup interval delay control circuit for controlling the on-off of the field effect transistor Q5. The invention has the advantages that when the switching powersupply is overloaded, the switching power supply enters the intermittent protection mode, and after the overload phenomenon disappears, the switching power supply automatically resumes normal operation.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to an overload hiccup protection circuit for half-bridge topology switching power supplies. Background technique [0002] The half-bridge topology switching power supply circuit composed of FAN7500 (TL494) has a history of more than 30 years. It has reliable performance and low interference. It is still widely used in our company's general switching power supply products. Due to the design of the FAN7500 integrated circuit itself, the output overcurrent protection method of this circuit is generally a constant current limiting and additional output short-circuit shutdown method. The designed product generally needs to be powered on again after protection to restore normal output. If it is necessary to design a working mode that automatically restores normal output after the load returns to normal, it is generally to remove the short-circuit shutdown circuit. This me...

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Problems solved by technology

[0003] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to solve the problem in the prior art that the equipment needs to be powered on again after protection. Therefore, the present invention provides an overload hiccup protection circuit for half-bridge topology switching power supply

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