Overvoltage protection circuit suitable for buck power supply

Abstract

The invention relates to an overvoltage protection circuit suitable for a buck power supply. The circuit comprises a Buck power supply module (1), a threshold circuit (2), a switch circuit (3), a drive circuit (4) and a switch tube (5). The output end of the Buck power supply module (1) is connected with the threshold circuit (2) and used for setting the threshold condition of overvoltage. The drive circuit (4) is connected with the input end of the Buck power supply module (1) and the switch circuit (3), and finally connected with the switch tube (5). The switch tube (5) is an NMOS tube connected with the output end of the Buck power supply module (1). When overvoltage is output, the threshold circuit (2) controls the switch circuit (3) to turn on, so that the drive circuit (4) is low level. The switch tube (5) is disconnected, realizing circuit overvoltage protection. The overvoltage protection circuit provided by the technical scheme of the invention is simple and practical, can reliably play the overvoltage protection function, has the ability to automatically restore the normal working state in time, uses devices which can be replaced equally, and has a low production cost.

Description

technical field [0001] The invention belongs to the technical field of electronic circuits, and in particular relates to an output overvoltage protection circuit of a Buck power supply, in particular to an overvoltage protection circuit suitable for a buck power supply with low voltage and high current output. Background technique [0002] In electronic circuit technology, the normal operation of various electronic devices requires a stable and reliable power supply, but usually, the circuit will inevitably be affected by external interference or human factors, making the output voltage of the power supply too high, and then Burn out components and loads, causing irreparable damage to electronic products. Therefore, it is necessary to add an overvoltage protection circuit at the output of the power supply. The existing Buck power supply overvoltage protection circuit has two main characteristics: 1. After the overvoltage phenomenon is eliminated, the circuit cannot automati...

AI Technical Summary

Problems solved by technology

Moreover, there are few types of PMOS tubes, and it is difficult to find a suitable replacement model

[0004] For example, the invention patent with the patent number CN201310365719.0 discloses an overvoltage protection circuit. The input end uses a thyristor and a fuse, and the output end is connected in parallel with a regulator tube. When the output end is overvoltage, the input end SCR is turned on, so that The silicon controlled rectifier and the fuse form a loop to cause overcurrent at the input end, and the fuse is blown, thereby cutting off the input voltage

Once the fuse is blown, it is irrecoverable, so even if the overvoltage disappears, the circuit cannot return to normal, and overcurrent may easily cause damage to the wiring or components on the PCB

[0005] For example, the invention patent with the patent number CN200710076239.7 provides an input overvoltage protection circuit composed of an overvoltage comparator and a Darlington tube. The input voltage range that can be supported is large. The circuit uses a three-terminal regulator tube and a PNP triode and 1 PNP Darlington tube, the output voltage loss is large, not suitable for low voltage and high current power supply

[0006] Another example is that the invention patent with the patent number CN201410412851.7 also uses a three-terminal voltage regulator tube, a triode and a MOS tube to form an overvoltage protection circuit. Although the MOS tube here is an NMOS tube, it is connected in series to GND. When the output voltage is less than At 1V, its VGS is up to 1V, it is difficult to turn on or the on-resistance is very large, resulting in a large voltage difference between the circuit output and input GND, not suitable for low output voltage, high output current power supply

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