Backlight Driver STLD41 producing disturbance on TFT

balmukund66 · ‎2012-04-04

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

emalund · ‎2012-04-04

Posted on April 04, 2012 at 16:26

layout, layout, layout

Erik

Tesla DeLorean · ‎2012-04-04

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 · ‎2012-04-04

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 · ‎2012-04-04

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