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Can I have verification on this diagram?

Discussion in 'General Electronics Discussion' started by mrblobby, Jun 25, 2013.

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  1. mrblobby


    Jun 25, 2013
    Newbie here.
    Have I made this iphone 4 diagram correct. The numbering on the lcd chip doesn't follow my logic.:confused:
    4,5 and 6, I can see the physical trace

    Attached Files:

  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    Hi mrblobby and welcome to the electronics point forums :)

    Two of the pin numbers you've marked on the PCB are wrong.

    Have a good look at the data sheet: On page 7 there's an illustration of how the pins are numbered. When you view the device from above, i.e. looking down on it, with the package's pin 1 indentation at bottom left (as shown in the "Top view" and "Recommended land pattern" at the top of that page), pin 1 is in the bottom left corner, and pins are numbered working in an ANTICLOCKWISE direction around the edges of the device. Therefore, the pin on the opposite side of pin 1 is actually pin 6, not pin 4 as you had marked on your photo.

    In your case, the device is installed rotated 180 degrees, so the package indentation is in the top right corner on your photo of the circuit board.

    To correct your photo, you need to SWAP THE PIN 1 MARKING WITH THE PIN 3 MARKING.

    The rest of the pins are correct, apart from the two pins under the middle of the chip, which are NOT NUMBERED in the data sheet. You have assigned numbers of 7 and 8, which may or may not match what Fairchild (the designer of that package) intended.

    Edit: Your schematic shows the output of the boost converter feeding a node called LCD_BL_CA, which presumably means that it powers the backlight LED string that backlights the LCD display. If the CA at the end means "cathode", then I think it's wrong; the boost converter output is positive, and should drive the ANODE of the backlight LED string, not the cathode.
    Last edited: Jun 26, 2013
  3. mrblobby


    Jun 25, 2013
    Thank you KrisBlueNZ, you have been very helpful. Much appreciated:)
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