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Thread: ILI9341: how to increase intensity? (100 ohm resistor used)

  1. #1

    ILI9341: how to increase intensity? (100 ohm resistor used)

    I am testing an ILI9341 in a Teensy 3.6 project. I think the intensity of the light / objects shown on the screen is too weak. I use a 100 ohm resistor to the LED pin of the ILI9341 display.
    Is it safe to reduce this resistor to increase the intensity or may this damage the display?

  2. #2
    Senior Member+ defragster's Avatar
    Join Date
    Feb 2015
    What voltage is going across the resistor? This shows using VIN with the 100 Ohms:

  3. #3
    That pin is a logic input that simply switches a transistor ON/OFF. That input already has a 1K ohm series resistor, so the 100 ohm resistor doesn't really have any practical use.

    When the transistor is turned on, an on-board 10 ohm resistor is what is actually limiting current thru the backlight which is powered off the 3.3V regulator that is built into the display module.

    It won't hurt to connect the pin straight to 3.3V or 5V, but I don't think you will see a brightness difference.

    Here are the generic schematics for most of these displays:

  4. #4
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
    Older displays had that pin directly connected to LEDs.

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