Short-circuit protection detection circuit and method

Abstract

The invention provides a short-circuit protection detecting circuit, and the circuit comprises a starting circuit and a comparator, and also comprises a positive temperature coefficient current generating circuit and a short-circuit protection threshold generating circuit. The positive temperature coefficient current generating circuit generates a difference of the base-emitter voltages of two bipolar transistors through enabling two currents at the same size generated through mirroring to land on the two bipolar transistors with different current densities, and then converts the voltage difference into a positive temperature coefficient current of short-circuit protection threshold compensation by the resistance, wherein the voltage difference is directly proportional to the absolute temperature. The short-circuit protection threshold generating circuit achieves the matching generation of a short-circuit protection threshold voltage matched with a temperature coefficient of the draindetection voltage of a switch NM1 through enabling the two positive temperature coefficient currents to land on two resistors with different numbers of unit resistors and designing the ratio of two positive temperature coefficient currents and the unit resistance ratio of the two resistors.

Description

technical field [0001] The invention relates to a short-circuit protection detection circuit of a switching power supply, in particular to a short-circuit protection detection circuit with temperature compensation and a detection method for short-circuit protection with temperature compensation. Background technique [0002] Safety and reliability are usually the first principles for evaluating the quality indicators of switching power supplies. Like other electronic equipment, short circuit is one of the most serious faults of switching power supply. Whether the short circuit protection is reliable or not is an important factor affecting the reliability of switching power supply. When a short-circuit fault occurs, the excessive current will not only shorten the withstand time of the power switching device flowing through it, but also cause the switch to turn off quickly and then withstand the transient high voltage, resulting in the breakdown of the switch tube, so the cont...

AI Technical Summary

Problems solved by technology

[0006] 1. Provide a detection method for short-circuit protection with temperature compensation, which can be applied to all switching power supply controllers integrated with switching tubes, and a corresponding temperature compensation circuit is designed to solve the requirements of 1) in the prior art The controller has a specific feedback loop and feedback pin. 2) Due to the influence of the conduction internal resistance of the positive temperature coefficient of the switch tube, the voltage cannot be directly taken from the drain of the switch tube to reflect the switch current information.

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