Adaptive output current ripple removing circuit and method

Abstract

The invention provides an adaptive output current ripple removing circuit and method. The method comprises that a negative end voltage of an LED load is detected; when the negative end voltage is lower than a set voltage, a first constant current source is switched off, a second constant current source is switched on and discharges a compensation capacitor, the compensation voltage is reduced, theoutput current is reduced, and the negative end voltage of the LED load is increased; and when the negative end voltage of the LED load is greater than the set voltage, the first constant current source is switched on, the second constant current source is switched off, the first constant current source charges the compensation capacitor, the compensation voltage is increased, the output currentis increased, and the negative end voltage of the LED load is reduced. Only the minimal value of the output ripple voltage is detected, and the method and device are suitable for ripple removing application of silicon controlled rectifier light modulation and linear output; and overheating protection does not influence work of a pre-stage system, flickering is avoided from influencing the experience, and heat loss of an MOSFET can be controlled independently.

Description

technical field [0001] The invention relates to the field of circuit design, in particular to an adaptive output current elimination ripple circuit and a ripple elimination method thereof. Background technique [0002] Usually in the application of high power factor (PF, Power Factor), due to the limitation of the output capacitor, the output current has the AC component of the power frequency, which may cause flicker in some occasions, and it is necessary to add a ripple circuit to filter the power frequency Element. [0003] Such as figure 1 Shown is a traditional MOSFET ripple removal circuit, including resistor R1 and capacitor C1 connected in series and parallel to the output terminal, the positive-phase output terminal Vo+ is connected to the positive terminal LED+ of the LED through the transistor Q1, and the inverting output terminal Vo- is connected to the negative terminal of the LED LED-; the positive pole of diode D1 is connected to the positive phase output te...

AI Technical Summary

Problems solved by technology

[0007] In view of the shortcomings of the prior art described above, the purpose of the present invention is to provide an adaptive output current ripple removal circuit and a ripple removal method thereof, which are used to solve the low efficiency of the ripple removal scheme in the prior art and the current application range. Small, does not support thyristor dimming applications, does not support linear output ripple applications, etc.

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