Switching power supply voltage type output short circuit protection circuit and design method thereof

Abstract

The invention discloses a switching power supply voltage type output short circuit protection circuit. The protection circuit comprises a comparator U1, a switching diode D2, a non-polar capacitor C2, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5. The anode of the switching diode D2 is connected with one end of the resistor R1 and serves as the input end V-IN of the output short circuit protection circuit. The cathode of the switching diode D2 is connected with one end of the non-polar capacitor C2 and one end of the resistor R3, and the other end of the resistor R3 is connected with the inverted input end of the comparator U1. The connecting end of the resistor R1, the connecting end of the resistor R2 and one end of the resistor R5 are all connected with the in-phase input end of the comparator U1, and the output end of the comparator U1 serves as the output end V-OUT of the output short circuit protection circuit. The invention further discloses a design method of the switching power supply voltage type output short circuit protection circuit. Due to the switching power supply voltage type output short circuit protection circuit and the design method of the switching power supply voltage type output short circuit protection circuit, hiccup type short circuit protection can be achieved, the self-restoration is achieved, and practicability is high.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to a switching power supply voltage-type output short-circuit protection circuit and a design method thereof. Background technique [0002] With the rapid development of electronic technology, switching power supply protection circuit has become a crucial part of circuit design. At present, there are many protection schemes commonly used for power supply or switching power supply: (1) According to the difference of sampling signal, it is divided into: current type protection circuit and voltage type protection circuit. Most of the general protection circuits use current-type protection circuits. This type requires a current sampling resistor, and a large current will flow through the resistor. If a current sampling resistor with a small resistance value is used, the signal needs to be processed and amplified. This makes the circuit complex and increases the cost. ...

AI Technical Summary

Problems solved by technology

The disadvantage is: the protection speed is slow, and when the output is short-circuit protected, there is still a large current flowing, and the power consumption is large

The disadvantages are: the protection circuit is more complicated, the circuit debugging is more troublesome, and the power supply is not easy to recover after the fault is eliminated.

③Complete shut-off protection circuit, that is, once the protection circuit operates, even if the overcurrent or short circuit fault is eliminated, the power supply is still in the off state, and the power supply must be turned off and the system restarted to resume work, and the circuit cannot achieve self-recovery , unable to meet the requirements of intrinsically safe power supply

④ A self-recovery protection circuit that can completely turn off the switch tube. This type of protection circuit usually requires a current detection circuit, a short circuit or overload judgment circuit, and a delay circuit. The circuit is relatively complicated; After the circuit breaks down, although the output voltage can be limited to a relatively low range, the current is very large at this time, because the switching power supply is actually still working

Therefore, for intrinsically safe explosion-proof power supplies used in hazardous environments, the spark energy generated by short-circuit faults is considerable, which is likely to detonate flammable, explosive gases and their mixtures, making it difficult to achieve intrinsically safe output

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