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balmukund66
balmukund66
Associate III
April 4, 2012
Question

Backlight Driver STLD41 producing disturbance on TFT

  • April 4, 2012
  • 4 replies
  • 752 views
Posted on April 04, 2012 at 14:08

Hello

I am using STLD41 as backlight driver for 5.7''controllerless TFT.

Whenever STLD41 gets on it produces lines on TFT & display gets disturbed.If i give backlight power seperately from power supply Display works  fine.I checked for VDD(Main 3.3V as well as Backlight 9.5V) while STLD41 is ON,it's almost ripple free. How to handle this problem?? Please share if any body have any experience about it.

Thanks & Regards

Balmukund Prasad 
    This topic has been closed for replies.

    4 replies

    emalund
    emalund
    Associate III
    April 4, 2012
    Posted on April 04, 2012 at 16:26

    layout, layout, layout

    Erik

    Tesla DeLorean
    Tesla DeLorean
    Guru
    April 4, 2012
    Posted on April 04, 2012 at 16:39

    Inadequate supply planes, or line widths, or ground paths.

    Inadequate bulk (instantaneous current) or decoupling (HF noise) capacitance. Locality.

    Inadequate supply/regulator.

    Crosstalk/inductance between supply lines, and signal lines.

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    balmukund66
    balmukund66Author
    Associate III
    April 4, 2012
    Posted on April 04, 2012 at 18:13

    Thanks for reply.

    For testing, I gave direct  3.3V supply from DC POWER SUPPLY to STLD41  & o/p of STLD41 is directly connected to Backlight of TFT  through thick wires.but still TFT is getting disturbed.In Layout the copper pour is present on both side of the board.

    should copper pour present??

    what can be the point to taken care in Layout ? For STLD41 Layout I have followed the datasheet.

    emalund
    emalund
    Associate III
    April 4, 2012
    Posted on April 04, 2012 at 18:40

    what can be the point to taken care in Layout ? For STLD41 Layout I have followed the datasheet.

     

    already answered. by Clive

    the simple solution: use a 4 layer board with solid ground and Vcc planes

    also DO NOT skimp on decoupling

    If you want general eduction in layout for high speed take a class

    ps ''high speed'' does NOT refer to frequency, but to rise and fall times.

    Erik
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