I am trying to connect a 21" LED Display driver's input pins to my power board. There is a datasheet also but it doesn't have the input pin diagram. Therefore, I have got the below attached input pin diagram from the Chinese manufacturer.

The things that I have understood by looking at pinout and datasheet of LED Display driver's is that on/off control takes 5V and that brightness takes the PWM input.

The questions I have in mind is:

  1. Which ground is for which voltage. Does both 12V have common ground and the ground for on/off is separate.

  2. Will the system still work if I don't give the adj brightness (PWM input) input? I just quickly want to test it, so will the brightness default to a certain value or is it necessary to connect the adj.

  3. Will the on/off take 5V momentarily like a switch or do I need to supply constant 5V to keep the display on.


Input pin specs:

Pin Diagram

  • 1
    \$\begingroup\$ Keep in mind, the datasheet for the m215hw02 lcd display states the led backlight max current should be 80mA. Don't drive it too hard or you might kill the driver or leds. \$\endgroup\$
    – Passerby
    Feb 26, 2014 at 12:22
  • \$\begingroup\$ how can i make sure that the max current is 80-mA?, i am using a normal display adapter that comes with our laptop exertnal display, it has a output of 12V , 3.3Amp but i thought the driver will automatically take the amount of current it requires and not more. \$\endgroup\$
    – rajat
    Feb 26, 2014 at 13:05

1 Answer 1

  1. There is only one ground, and it is for all the connections.

  2. Possibly. It's not noted, in the datasheet, so you should assume it requires some form of input to work properly.

  3. Unknown. It's not noted, so assume it requires an external 5V source.

I'm being vague because the answers to the questions you're asking are largely not in the documentation for the LED driver. It's possible the driver has internal pull-up/pull-downs that would make it operate without external controls inputs, when fed 12V, but it's not noted in the datasheet.

You should contact the manufacturer, and ask for a proper datasheet.

  • \$\begingroup\$ why are there 2 grounds in the pin diagram, that is pin 5 and 6, are they just for current distribution? Also, can i feed regular digital input of 5v to pin requiring PWN. What consequences can that have? \$\endgroup\$
    – rajat
    Feb 26, 2014 at 6:42
  • \$\begingroup\$ @rajat - they are presumably just to provide a better ground. Re: 5V in the PWM input: I have no way of knowing. I would, by default, assume probably, but the datasheet specifies intensity at 0% and 94% PWM, which makes me suspect the driver may have stability issues at 100%. As I said in my answer, you do not have enough information, really. You need a proper datasheet. \$\endgroup\$ Feb 26, 2014 at 6:45
  • 1
    \$\begingroup\$ Actually, scratch that. It looks like increasing the PWM duration decreases the brightness. PWM 0% produces 240 mA in constant-current mode (CCM). PWM 94% produces 80 mA. I think you can probably just strap the PWM input to ground. This is also supported by the Constant-voltage more measurements (CVM). \$\endgroup\$ Feb 26, 2014 at 6:47
  • \$\begingroup\$ Nice. Thanks a lot :). I will let you know if it works. \$\endgroup\$
    – rajat
    Feb 26, 2014 at 7:07

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