PWM primary side regulation and control method compatible with simulation and digital dimming

Abstract

The present invention discloses a PWM primary side regulation and control method compatible with simulation and digital dimming. Especially constructed charging and discharging branches for a COMP capacitor are provided, for the charging branch, the valid charging time of a fixed reference current Iref on the COMP capacitor is controlled by PWM signals to influence a voltage Vcomp of the COMP capacitor; for the discharging branch, a variable current Ics performs discharge of the COMP capacitor; a discharge current Ics is formed by conversion of a voltage Vcs of a sampling resistor Rcs when a power switch MOS tube is opened, the opening time Ton of the MOS tube is obtained by conversion of the Vcomp through V-Ton, a switched controlled after the PWM and the control signals MD are subjectedto phase or is connected with the gate electrode of the MOS tube so as to form a closed-loop control loop for Vcomp regulation, corresponding '1' and '0' of the MD can be selectively worked in a simulation or digital PWM dimming mode, a discharging current is in one-to-one correspondence with a duty ratio of the PWM signals, namely, the duty ratio of the PWM signals is changed to finally correspondingly change a LED drive current so as to achieve the effect of simulation or digital dimming.

Description

technical field [0001] The invention relates to the field of primary-side PWM dimming, in particular to a PWM primary-side regulation method compatible with analog and digital dimming. Background technique [0002] With the development of science and technology and the continuous improvement of living standards, the demand for lighting is not only the most primitive switch lighting, but also the dynamic adjustment of brightness, chromaticity, etc., combined with various wall switches, APPs, sensors, etc. Control means to achieve the goals of flexibility, convenience, freedom of movement, green energy saving, etc. [0003] In fact, now it is very common to use cold and warm two-color lamps, and the use of RGB three-color mixed light is also becoming popular. This kind of progress of LED lamps will inevitably promote the corresponding development of dimming drive technology. [0004] At present, there are mainly primary-side technologies such as 0-10V analog dimming and PWM ...

AI Technical Summary

Problems solved by technology

Due to technical limitations, generally speaking, the existing analog dimming has defects such as poor anti-interference and insufficient dimming depth, while digital PWM dimming can easily lead to the reduction of PF value and problems such as flicker and noise.

[0005] In fact, if analog dimming is used, it generally exists in low-brightness dimming areas. Due to the existence of blanking time, the dimming depth can only reach about 7%; if PWM digital dimming is used, although the dimming Optical depth can reach 1‰, but there will be a problem of PF value reduction, resulting in products that cannot meet the relevant PF value requirements in areas with high power

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