Switching power supply circuit

Abstract

The invention relates to a switching power supply circuit. The switching power supply circuit comprises a rectifying circuit, a filter circuit, a controller and a voltage stabilizing chip, and the rectifying circuit is connected with the controller through the filter circuit, the controller is connected with a communication bus through the voltage stabilizing chip, and a time delay unit is connected in series between a second pin of the controller and a fifth pin of the voltage stabilizing chip. According to the technical scheme, a large, flexible and easy-to-adjust time delay circuit is constructed by utilizing a plurality of phase inverters and two input AND gates; in addition, the two capacitors are connected in parallel among the three inverters connected in series, so that compared with a resistor-capacitor charging and discharging structure, the delay precision is improved; and the time-delay circuit realizes time-delay combination by utilizing the phase inverter and is not easyto be interfered, so that the robustness is strong.

Description

technical field [0001] The invention relates to the technical field of switching power supplies, in particular to a switching power supply circuit. Background technique [0002] Switching power supply is a kind of power supply that uses modern power electronic technology to control the time ratio of switching on and off to maintain a stable output voltage. Switching power supply is generally composed of pulse width modulation (PWM) control IC and MOSFET. With the development and innovation of power electronics technology, switching power supply technology is constantly innovating. [0003] The existing switching power supply circuits all include a delay part, and the existing delay circuits adopt a resistor-capacitor charge-discharge structure or a current-capacitor charge-discharge structure, and these two methods have obvious defects in realizing a relatively large delay time. Resistor-capacitance delay circuits require resistors or capacitors that occupy a large chip are...

AI Technical Summary

Problems solved by technology

Resistor-capacitance delay circuits require resistors or capacitors that occupy a large chip area, which will increase the chip area, and the accuracy is not high; the charging and discharging of current capacitors requires large capacitors or small currents. Large capacitors mean large areas and low currents. Susceptible to interference, poor robustness

In summary, it is very difficult for the traditional resistance-capacitor delay circuit and current-capacitance delay circuit to achieve a delay time of millisecond level and above with a small chip area.

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