Under-voltage protection method of high-voltage half-bridge driving chip and high-voltage half-bridge circuit

Abstract

The invention discloses an under-voltage protection method of a high-voltage half-bridge driving chip and a high-voltage half-bridge circuit. According to the method, when low-side power voltage VCC is lacking, an under-voltage protection circuit blocks high-end and low-end signal channels; if the low-side power voltage VCC is greater than a low-side under-voltage threshold VCCU and high-side power voltage VBS is smaller than a high-side under-voltage threshold VBSU, low level is forcedly output from a high-side channel of the high-voltage half-bridge driving chip, and high level is output from a low-side channel; an upper power tube is closed, and a lower power tube is opened, so the low-side power voltage VCC charges a bootstrap capacitor CB through an external diode until the high-side power voltage VBS is greater than the high-side under-voltage threshold VBSU; and the high-side power voltage and the low-side power voltage are greater than the high-side under-voltage threshold and the low-side under-voltage threshold, and the high-voltage half-bridge driving chip normally works. A circuit comprises the high-voltage half-bridge circuit, the upper power tube M1, the lower power tube M2, the diode DB and the bootstrap capacitor CB.

Description

technical field [0001] The invention relates to an undervoltage protection method for a high-voltage half-bridge drive chip and a high-voltage half-bridge circuit, which is specially aimed at the high-voltage half-bridge drive chip, and the chip is widely used in motor drive, high-power LED lighting, fluorescent lamp lighting, inverter power supply, etc. on the application system. Background technique [0002] The newly developed silicon-based and SOI (Silicon On Insulator)-based high-voltage and low-voltage compatible processes can integrate high-voltage power devices and reliable isolation technology, driving the rapid development of high-voltage power integrated circuits. It monolithically integrates high-voltage power devices with control and protection circuits, reduces the number of components, interconnections and solder joints in the system, not only improves the reliability and stability of the system, but also reduces the power consumption, volume, Weight and cost...

AI Technical Summary

Problems solved by technology

[0005] First, the high-side undervoltage signal of the chip is connected to the high-side RS flip-flop. Once the voltage on the bootstrap capacitor is lower than the voltage threshold, the undervoltage protection circuit will reset the RS flip-flop and turn off the upper tube, and the pulse generator Turn on the N-channel lateral double-diffused MOS transistor in the high-voltage level shift circuit as normal, and the charge on the bootstrap capacitor is discharged through the resistance of the level shift circuit and the N-channel lateral double-diffused MOS transistor, wasting the bootstrap capacitor energy stored on

[0006] Secondly, when the chip is powered on or the charge on the bootstrap capacitor is excessively discharged due to the external environment, it may take hundreds of microseconds to charge the bootstrap capacitor to reach the high-side undervoltage threshold. The tube is always on, and according to the current chip design, it is impossible to

Because the input signals of the two channels of the high-voltage driver chip are high level alternately, when the input signal of the low side channel is high level, the bootstrap capacitor is charged through the lower tube, and when the input signal of the high side channel is high level, Due to the excessive discharge of the charge on the bootstrap capacitor, the capacitor is still in an undervoltage state, and the high side has not been turned on, but the charge on the bootstrap capacitor is consumed by a circuit such as a high-voltage level shift, so that the lower tube charges the bootstrap capacitor Part of the charge is released again, so that it is charged first and then part of the charge is cycled until the voltage on the bootstrap capacitor is higher than the undervoltage threshold, which greatly reduces the efficiency of charging the bootstrap capacitor

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