The Backlight

Adding to @cpixip comments to provide nuance in regard to PWM controlled drivers. In an oversimplification, I would group these in three types.

First ones, including the Mean Well, switch on/off the led based directly on the PWM control input, the current accross the LEDs will be close to a squarewave.

The second group, are switching current regulators, also with PWM control input. On these, the current across the LED is typically in the form of a sawtooth wave. The Fentobuck is a good example of this configuration, here the datasheet for the IC, see IL representations in Page 10.

Lastly, there may be some designs, that use a PWM control input for simplicity, but are providing a constant current. The drawback of this design is that to achieve constant current the PWM input is converted (low pass filtered) to a DC, which decreases the speed of control. My first driver design is based on this configuration, and this video shows the controlling input (PWM) and the resulting DC output which controls the LED current. The convenience of a single wire for 16bit control is at the expense of a very slow response (low pass filter).

The practical testing suggested by @cpixip is spot on.

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