Compensation capacitor precharge circuit for high power factor led controller

Abstract

The invention provides a compensation capacitor precharging circuit suitable for a high power factor LED controller. The circuit comprises a precharging circuit body for a compensation capacitor, and a charging control module which is connected to the precharging circuit body and is used for adaptively adjusting the precharging duration time of the compensation capacitor of the precharging circuit body. When the precharging is ended, the initial voltage in the compensation capacitor is equal to the 1 / 2 of the steady state voltage in the compensation capacitor when the LED controller works stably. According to the compensation capacitor precharging circuit, the time needed from system start-up to output establishment stability can be reduced, and the starting process output overshoot generated by a condition that the initial voltage is higher than steady strate voltage is prevented at the same time.

Description

technical field [0001] The invention relates to the field of LED control circuits, in particular to a compensation capacitor precharging circuit suitable for high power factor LED controllers. Background technique [0002] In order to achieve high power factor, the existing high power factor LED controllers often need to connect a compensation capacitor outside the control chip. The compensation capacitor is used to generate a low-frequency DC voltage relative to the frequency of the AC input power supply and control the on-time of the switch in the circuit. . When the control chip is started, the compensation capacitor will be precharged to the initial voltage, and then the control chip will slowly adjust the initial voltage on the compensation capacitor to the steady-state voltage for stable operation according to the loop feedback signal. When the overall circuit system composed of the control chip and peripheral circuits works stably, the steady-state voltage on the com...

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Problems solved by technology

[0005] It can be seen that the working process of the existing compensation capacitor precharging circuit is only to precharge the compensation capacitor Ccomp' to a fixed reference voltage vref, but at this time the voltage of the compensation capacitor Ccomp' is not what the compensation capacitor Ccomp' should be when the current system is stable. Therefore, it is necessary to adjust the compensation capacitor Ccomp' from the initial voltage at the end of pre-charging to the steady-state voltage when the system works stably, especially when the deviation between the initial voltage and the stable voltage is large. takes longer

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