The Design Method of the Voltage Type Output Short Circuit Protection Circuit of Switching Power Supply

Abstract

The invention discloses a switching power supply voltage type output short-circuit protection circuit, which includes a comparator U1, a switching diode D2, a non-polar capacitor C2, and a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a resistor R5; The anode is connected to one end of the resistor R1 and is the input terminal V-IN of the output short-circuit protection circuit, the cathode of the switching diode D2 is connected to 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 to the comparator The inverting input terminal of U1 is connected, the connection terminal of resistor R1 and resistor R2 and one end of resistor R5 are connected with the non-inverting input terminal of comparator U1, and the output terminal of comparator U1 is the output terminal V of the output short circuit protection circuit. OUT; the invention also discloses a design method of a switching power supply voltage type output short-circuit protection circuit. The invention can realize hiccup type short-circuit protection, has self-recovery function, and has strong practicability.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to a design method for a voltage-type output short-circuit protection circuit of a switching power supply. 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. It ...

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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