LED driver power for LED strip dimming applications

LEDs are used more and more widely in lighting fixtures. In addition to the uniqueness of traditional lighting methods, in addition to improving the quality of life, improving the performance of light sources and extending the life of lamps, they use their unique dimming function to color and brightness the lights. The changes and fully meet the biggest advantages of energy-saving applications.

led lamp with dimming performance but depends on the led light source with power and drive. In general, LED light sources can be easily divided into two broad categories: individual LED diode sources or LED diode sources with resistors. In applications, sometimes LED sources are designed as a module with a DC-DC converter. Such complex modules are beyond the scope of this article. If the LED light source or module is a separate LED diode itself, the common dimming method is to adjust the amplitude of the LED input current. Therefore, the selection of the LED driving power supply should refer to this characteristic. The characteristics of the HLG/ELG family of Mingwei Company are current. Adjusted and can be modulated by external 1-10VDC* or 10V PWM pulse width or even by an external variable resistor to control the output current modulation. Another type of LED diode light source (generally called led strip or LED STRIP) with resistors, LED strips are widely used as resistors with LED diodes in series, so the voltage is relatively stable, so users can access Any fixed voltage power supply is commercially available to drive led light strips . Common LED strips are generally driven by 12VDC or 24VDC, but it may be a bit difficult in dimming applications for LED strips. This article describes the application of the current amplitude dimming driver to the LED strip, and also discusses some common dimming problems, and also introduces the dimmable led power driver with output pulse width (PWM) modulation. The PWM family series launched by Mingwei Company and recognized by the National Technology Innovation Product Award is the most appropriate and simple LED light strip dimming solution on the market.

Common LED dimming conditions:

Dimming sounds like a simple matter. In fact, there are many factors to consider when you want to have a good and smooth dimming performance. There are many common LED dimming conditions, as shown in the following table (1):

Table (1): Common dimming problems

Dead travel is a frequent problem when using LED output drivers with adjustable output current for LED dimming. Although the LED driver can be operated well when it is fully loaded (as shown in Figure 1-a), when the LED driver is not fully loaded, the dimming is not smooth.

Figure 1: Mingwei LED driver HLG-100 is connected to LED strips under different load (length) conditions: (a) 100% full load - can produce the best dimming performance; (b) load 70% - display Imperfect dimming effect; (c) 30% load--shows poor dimming results because the dimming range is too narrow.

Output Pulse Width Modulation (Output PWM) Solution

If the LED light strip dimming application is used with LED drive power under full load conditions, then there is no problem with dead travel. The above arguments are correct, but they are not very practical. In fact, LED strips are often used in a variety of applications (decorative lighting / auxiliary lighting / advertising lighting) because the length can not be accurately estimated, so the simplest and best The application solution should correctly select the LED driver power supply with the output pulse width PWM dimming function to realize the LED light bar dimming requirements. The output brightness is reduced by the duty cycle of the dimming signal to achieve a dimming change that reduces the brightness. The important parameters for selecting the driving power supply are the dimming resolution and the output pulse width modulation PWM frequency. The minimum dimming capability should be as low as 0.1. %, to achieve 8bit dimming resolution to meet all LED strip dimming applications, the output pulse width modulation PWM frequency should be as high as possible to prevent the light flicker problem mentioned in Table (1), according to the correlation The technical research literature reports that frequency recommendations are at least above 1.25 kHz to reduce ghosting flicker visible to the human eye.

in conclusion

The best LED strip dimming solution uses the output pulse width modulation PWM dimming function to solve common dead travel dimming problems. The PWM models provided by Mingwei Company cover four series of 40/60/90/120W, which is an LED driver power supply suitable for dimming applications of various LED strips.