I have an AFY480272A0-4.3INTH TFT LCD and I'm confused about how to control the backlight using PWM. After googling it, I found this similar problem.

Here are my backlight LED characteristics:

enter image description here

After I read the similar problem, I drew some circuit schematics. I am still confused about some parameters.

enter image description here


  1. Can I control the backlight like the picture above? I'm using an IRLML2803 MOSFET that has drain-source voltage of 30 V.
  2. Is my R1 value right? I did some LED calculations in https://www.digikey.com/en/resources/conversion-calculators/conversion-calculator-led-series-resistor with LED forward voltage 18 V, forward current 40 mA and supply voltage 24 V.
  3. What is the value of R2?

1 Answer 1

  1. Yes, you can do that.
  2. (24-18)/150=40 mA. Be aware that you will be burning 240 mW in the resistor so size it appropriately.
  3. Depends on what you are driving the MOSFET from (PWM source). 10-100 Ω is a good starting point.

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