Driving circuit for switching bridge arm and switching power supply

Abstract

The embodiment of the present invention provides a driving circuit for a switch bridge arm, including: a driving chip, a double-winding driving transformer and a driving module; The two ends of the primary side are connected; the two ends of the secondary side of the double-winding drive transformer are respectively connected to the first input end and the second input end of the drive module; the first output end of the drive module is used to connect with the upper tube of the switch bridge arm The gate connection of the drive module, the second output terminal of the driving module is used to connect with the source of the upper tube of the switch bridge arm; the second output terminal of the driver chip is used to connect with the gate of the lower tube of the switch bridge arm; wherein, the drive The module is used to make only the voltage higher than the preset threshold value act on the gate and source of the upper transistor of the switch bridge arm. The drive circuit can solve the overvoltage problem of the power supply pin and the ground terminal pin of the upper tube floating drive circuit, and can improve the reliability of the upper tube drive of the switch bridge arm.

Description

technical field [0001] Embodiments of the present invention relate to the communication field, and more specifically, relate to a driving circuit for a switching bridge arm and a switching power supply. Background technique [0002] Due to the advantages of small size, light weight and high efficiency, switching power supply has become more and more popular. Switching bridge arms widely exist in switching power supplies, and there are multiple sets of switching bridge arms in some topological scenarios. To make the switch bridge arm work normally, it is often the key to choose a suitable and reliable drive circuit. [0003] In the switch bridge arm, in order to prevent the upper and lower bridge arms from being turned on at the same time (also known as through), the drive of the upper and lower bridge arms needs to be set with a dead time (deadtime). In the existing technology, such as figure 1 As shown, due to the existence of the leakage inductance Ls1 and Ls2 of the po...

AI Technical Summary

Problems solved by technology

In the existing technology, such as figure 1 As shown, due to the existence of the leakage inductance Ls1 and Ls2 of the power loop, when the upper transistor Q1 is turned off, the current of Ls2 cannot change abruptly, and it is initially zero, which will cause negative overshoot of the Vsw network and cause the negative pressure of the pin Vs of the driver chip to exceed the standard , which will cause a latch-up of the driver chip, and the charging voltage of the bootstrap capacitor will be too high, which will damage the power supply pin Vb of the upper tube.

A similar situation will also occur when the lower tube Q2 is turned off, resulting in positive overshoot of the Vsw network, resulting in overstress damage to the driver chip

Therefore, the bridge arm driver chip has become a short board for the reliability of the switching power supply.

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