Power supply circuit and power supply equipment

Abstract

The invention provides a power supply circuit and power supply equipment. The power supply circuit comprises a rectification filter circuit, a transformer and a control circuit, the transformer comprises an auxiliary winding, and the control circuit comprises a primary side control circuit connected with the auxiliary winding. The primary side control circuit comprises a control chip used for controlling the power supply circuit, the control chip comprises a first pin and a second pin which are connected with the auxiliary winding, the auxiliary winding supplies power to the control chip through the first pin, the second pin is used for detecting the voltage of the auxiliary winding, and a compensation resistor is connected between the first pin and the second pin. Compared with the prior art, the compensation resistor is arranged, so that the voltage of the second pin during output short circuit is increased, the demagnetization time of the control chip is prolonged, the working frequency and the power consumption during short circuit are reduced, and the loss of an MOS tube of the control chip without a short circuit protection mechanism is avoided.

Description

technical field [0001] The invention relates to a power supply circuit and power supply equipment, belonging to the technical field of power supply equipment. Background technique [0002] Output short-circuit protection is a basic requirement for stand-alone power supplies, but some chips do not have the short-circuit protection function. By increasing the demagnetization time of the inductor current when the output is short-circuited, the switching frequency is reduced, thereby reducing power consumption. However, in the constant voltage and high voltage output environment, the turn ratio of the secondary winding and the auxiliary winding is very large, resulting in a low voltage Vaux of the auxiliary winding, which can easily reach the chip’s turn-on falling edge threshold. At this time, the chip will work with the minimum turn-off time Toff_min , the chip will cause damage to the MOS tube due to the high operating frequency. [0003] In view of this, it is indeed necess...

AI Technical Summary

Problems solved by technology

However, in the constant voltage and high voltage output environment, the turn ratio of the secondary winding and the auxiliary winding is very large, resulting in a low voltage Vaux of the auxiliary winding, which can easily reach the threshold of the chip's turn-on falling edge. At this time, the chip will work with the minimum turn-off time Toff_min , the chip will cause damage to the MOS tube due to the high operating frequency

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