Switching power supply quick starting and VDD self-power supply circuit

Abstract

The invention discloses a switching power supply quick starting and VDD self-power supply circuit, which comprises a VDD voltage detection module, a PWM comparator module, a PWM drive module, a VDD charging time control module, a switch K1, a switch K2, a switch K3, a VDD capacitor C2, power supply diode D2, a starting resistor R2, a power triode Q2 and an inductive current sampling resistor RCS, wherein the VDD voltage detection module, the PWM comparator module, the PWM drive module, the VDD charging time control module, the switch K1, the switch K2, the switch K3, the VDD capacitor C2, the power supply diode D2 and the starting resistor R2 are arranged in a switching power supply controller chip; and the power triode Q2 and the inductive current sampling resistor RCS are arranged outside the switching power supply controller chip. The switching power supply quick starting and VDD self-power supply circuit is applied to a switching power supply; stand-by power consumption of a system can be reduced through relatively high starting resistance; meanwhile, quick starting can also be achieved; and the starting time is shortened. Furthermore, by the VDD self-power supply circuit, an auxiliary winding can be omitted; the volume of a power supply system is reduced; and meanwhile, the cost of the overall power supply system can also be reduced.

Description

technical field [0001] The invention relates to the technical field of electronic circuits, in particular to a switching power supply quick start and VDD self-power supply circuit. Background technique [0002] In the design of switching power supply system, we hope that the start-up time of the power system should be as short as possible, and at the same time, the standby power consumption of the power system should be as small as possible. If the traditional start-up circuit wants to have a short start-up time, the value of the start-up resistor should not be too large. It will cause the standby power consumption of the power system to be too large, so we need to make a compromise between the startup time and the standby power consumption. [0003] In addition, with the continuous improvement of the power system, customers hope that the smaller the size of the power system, the better the fewer external components, and the lower the cost of the entire power system. A swit...

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Problems solved by technology

[0005] For the same input voltage and VDD capacitance, if the standby power consumption of the switching power supply is to be kept small, the values ​​of R1 and R2 must be large, so the startup current of the traditional startup circuit is small, resulting in a longer startup time. If necessary If the start-up time is small, the start-up resistor R2 needs to be reduced, but this will increase the standby power consumption of the switching system

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