Overcurrent detection circuit, overcurrent protection circuit and switching power supply

Abstract

The invention discloses an overcurrent detection circuit, which is applied to an overcurrent protection circuit in a switching power supply chip. The overcurrent protection circuit includes a current sampling module for generating a sampling voltage. The overcurrent detection circuit includes a current bias module, a current generation module and a current sink module, the current generation module is connected to the current bias module and the current sink module respectively. The overcurrent detection circuit of the present invention is applied to the overcurrent protection circuit inside the switching power supply chip, and can judge whether the input is overcurrent based on the sampling voltage generated by the current sampling module of the overcurrent protection circuit. The overcurrent protection circuit of the present invention is realized based on the integrated circuit manufacturing process of transistors, and is applied inside the power supply chip. The chip power tube output overcurrent protection circuit has the advantages of simple structure, low production cost and low noise.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to an overcurrent detection circuit, an overcurrent protection circuit and a switching power supply. Background technique [0002] In the prior art, technical problems such as short circuit and overcurrent at the output end of the switching power supply chip will inevitably occur in actual use, and these problems will cause damage to the chip power tube or load. In order to avoid these problems, ensure the normal operation of the circuit and increase the The stability of the system generally requires a built-in overcurrent detection circuit in the switching power supply chip to realize the overcurrent protection function. [0003] At present, many technologies have been disclosed or mentioned: when the switching power supply chip is working normally, in order to limit the current within a certain safety range and avoid damage to the circuit and load caused by the ex...

AI Technical Summary

Problems solved by technology

[0004] In the prior art, in switching power supply management chips that use power triodes as switching tubes, since the on-resistance of the triode and the switching current are not linear, it is impossible to judge the overcurrent by detecting the voltage on the on-resistance of the triode.

Under normal circumstances, the overcurrent detection method commonly used by power triodes as switching power supply management chips is to directly connect the detection resistor in series with the power transistor, or connect the detection resistor in series with the system output to obtain the voltage on the sampling resistor to limit the maximum output current. , and then realize the overcurrent protection function. Although this method can solve the problem, the circuit is complicated, and the power consumption of the detection resistor is large, which affects the conversion efficiency of the chip.

Images