Switching power supply output peak eliminating circuit

Abstract

The invention relates to a switching power supply output peak eliminating circuit which comprises a first diode, wherein a cathode end of the first diode is connected with an anode power supply end of an operational amplifier, one end of a first capacitor, one end of a first resistor and a cathode end of a second diode; anode end of the second diode is connected with an in-phase end of the operational amplifier and a fifth resistor, the other end of the first resistor is grounded through a fourth diode, and two ends of the fourth diode are connected in parallel with a fourth capacitor; a cathode end of the fourth diode is connected with a grid electrode end of an MOS (metal oxide semiconductor) tube, the other end of the first capacitor is connected with a source electrode end of the MOS tube and an anode end of a third diode, and a cathode end of the third diode is connected with the in-phase end of the operational amplifier; an antiphase end of the operational amplifier is grounded through the fourth resistor, and is connected with an output end of the operational amplifier through a third capacitor; and the output end of the operational amplifier is connected with a front electrode of a high-power-factor switching power supply through an optocoupler. The switching power supply output peak eliminating circuit provided by the invention avoids impact of peak current to a load.

Description

technical field [0001] The invention relates to a peak elimination circuit, in particular to a switching power supply output peak elimination circuit. Specifically, the switching power supply is started slowly by using the non-variable charging and discharging characteristics of the capacitor voltage, eliminating the peak of the output voltage or current, and protecting the load. A circuit that is not damaged by impact belongs to the technical field of switching power supplies. Background technique [0002] Generally, the feedback circuit of the switching power supply is in the form of integral compensation, which can improve the stability of the circuit, so that the driver chip can output a stable duty ratio signal to drive the MOS field effect transistor (metal-oxide-semiconductor field effect transistor) to achieve Current or voltage feedback, but an unavoidable problem that the integral compensation circuit will bring is that the feedback is slow at the moment of startin...

AI Technical Summary

Problems solved by technology

[0002] Generally, the feedback circuit of the switching power supply is in the form of integral compensation, which can improve the stability of the circuit, so that the driver chip can output a stable duty ratio signal to drive the MOS field effect transistor (metal-oxide-semiconductor field effect transistor) to achieve Current or voltage feedback, but an unavoidable problem that the integral compensation circuit will bring is that the feedback is slow at the moment of starting up, resulting in a peak voltage at the output; that is, an overshoot phenomenon. If the load cannot withstand this peak voltage, it will It will cause damage to the load, such as the LED constant current driver of traffic lights, because the voltage and current of the LED are nonlinear, and the voltage drop of the LED will decrease with the increase of temperature. The rising current will increase with the decrease of the tube voltage drop, so the LED driver should be made into a constant current form to ensure that it will not be damaged under high temperature

If there is a peak current impact, too many impacts will shorten the service life of the LED, or even damage it directly. However, traffic lights need to be switched on and off frequently, and even flash continuously.

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