AC-DC (alternating current-direct current) drive output filter capacitor quick active leakage circuit

Abstract

The invention discloses an AC-DC (alternating current-direct current) drive output filter capacitor quick active leakage circuit which comprises an output filter capacitor-side voltage detection circuit, a switch SW drive circuit, a switch SW and a low resistance load resistance RL, the switch SW drive circuit force the switch SW to be switched off when AC-DC convertor output filter capacitor-side voltage sensed by the output filter capacitor-side voltage detection circuit is larger than leakage voltage, and weak current flows through low resistance load RL; the switch SW drive circuit is in state overturn to force the switch SW to be switched when the AC-DC convertor output filter capacitor-side voltage sensed by the output filter capacitor-side voltage detection circuit is smaller than the set leakage voltage, and an output filter capacitor is enabled to discharge rapidly by the aid of the low resistance load RL. The AC-DC drive output filter capacitor quick active leakage circuit is quick in discharge, delayed start-up circuits are reset rapidly after power outage, discharge current is controlled to the greatest extent, and over-current damage to the switch SW is avoided; power consumption is lowered, and under the normal state, the discharge current can be integrally controlled under 100mW in power consumption.

Description

technical field [0001] The invention relates to the field of electronic technology, relates to an AC-DC driver, in particular to a fast active discharge circuit for an output filter capacitor of the AC-DC driver. Background technique [0002] In the AC-DC drive circuit, in order to obtain a stable DC voltage, it is inevitable to use a large-capacity capacitor as a low-voltage output filter capacitor in the high-frequency rectification filter circuit on the secondary side of the AC-DC converter. When the AC-DC driver is connected to a resistive load, the energy stored in the output filter capacitor will be quickly released by the resistive load after the mains is disconnected, and the voltage at the output filter capacitor terminal will also drop immediately, making the soft-start circuit in the AC-DC converter reliable. Reset, to ensure that there will be no instantaneous overvoltage at the output end when the power is turned on again. However, when the AC-DC driver is conn...

AI Technical Summary

Problems solved by technology

[0003] In order to shorten the discharge time of the output capacitor after power failure, the traditional technology connects a dummy load resistor to the output of the AC-DC converter, but the effect is very limited, because the dummy load resistor cannot be too small, otherwise it will seriously affect the efficiency of the power supply, and it will also Exacerbate the temperature rise inside the drive power supply

[0004] In the prior art, a patent document with the publication number CN102594111A and the patent name "A Quick Discharge Circuit" and a patent document with the publication number CN102869173A and the patent name "A LED drive power supply device" have been disclosed. These two inventions The patents all involve the output capacitor fast discharge circuit, but the reliability and practicability of the output capacitor fast discharge circuit are not high

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