PMOS power tube grid clamping driving module, driving circuit and switching power supply

Abstract

The invention provides a PMOS power tube grid clamping driving module, a driving circuit and a switching power supply. An energy storage capacitor is externally connected to a clamping power supply; the clamping power supply charges the energy storage capacitor with a small current, and charges the gate-source parasitic capacitor with the electric quantity in the energy storage capacitor in a short time when the PMOS power tube needs to be turned on, so that the clamping power supply circuit can achieve the purpose of quickly charging the large gate-source parasitic capacitor through small current output. By quickly opening and closing the power tube, the problem of large opening and closing loss of the PMOS power tube applied to a switching power supply chip is solved, and meanwhile, thevoltage difference between the gate voltage and the source voltage is controlled to be -9V, so that the conduction loss of the PMOS tube is further reduced.

Description

technical field [0001] The invention relates to the field of switching power supplies, in particular to a PMOS power transistor grid clamp drive module, a switching power supply drive circuit and a switching power supply. Background technique [0002] There are two types of power transistors and power MOS tubes inside the switching power supply chip. The power MOS tubes are divided into PMOS power tubes and NMOS power tubes. For buck chips, PMOS tubes are selected as the control circuit of the switch tube. It is completely different from the control circuit that chooses NMOS tube as the switch tube. [0003] For common MOS transistors, the withstand voltage between the drain and the source can be 80V, 100V or even greater, but the withstand voltage of the gate and source of the MOS transistor is limited by the process and cost, and it is generally controlled at + / - Within -20V, for the sake of insurance, in actual use, we will control the voltage difference between the gate...

AI Technical Summary

Problems solved by technology

[0004] Due to the parasitic capacitance between the gate and the source (there is a parasitic capacitance between the gate and the source of the MOS transistor, when the PMOS power transistor is to be turned on, it is necessary to charge the parasitic capacitance between the gate and the source of the PMOS power transistor, and the charging time The shorter the PMOS tube is, the faster the PMOS tube is turned on; when the PMOS power tube is to be turned off, the parasitic capacitance between the gate and the source of the PMOS power tube needs to be discharged, the shorter the discharge time, the faster the PMOS tube is turned off). The switching loss of the MOS power tube will be generated when the power tube is turned on and off (the loss of the power tube at the moment of turning on and off is called switching loss). The switching loss of the power tube is related to the speed of turning on and turning off the power tube. The PMOS gate drive scheme cannot quickly turn on and off the PMOS tube, resulting in relatively large switching losses, which affects the conversion efficiency. At the same time, it cannot effectively clamp the gate and source of the PMOS tube. Generally, it can only be used for low power within 40V. In switching power supplies, the application is limited

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