Hello I have circuit with LCD driver PCF8576 and VIM878 LCD Vdd and VLCD for PCF I connected to 3.3V, but conrast is not good. Only when I look at an angle, I can see well.

I'm using 4 backplanes 1/2 and 1/3 bias give this common effect. Regards

  • \$\begingroup\$ Both Vdd and Vlcd are connected to 3.3V? \$\endgroup\$
    – Justme
    Mar 30, 2021 at 12:00
  • \$\begingroup\$ yes PCF8576 Vdd and Vlcd are connected to 3.3V \$\endgroup\$ Mar 30, 2021 at 12:31
  • \$\begingroup\$ Could you share a schematic? It would be really usefull. I cannot understand what do you mean by 1/3 and 1/2 bias to the backplanes. \$\endgroup\$ Mar 31, 2021 at 22:27

1 Answer 1


Vlcd must not be set to Vdd.

Use the datasheet to calculate how to set Vlcd correctly based on your backplane count and bias requirements.

  • \$\begingroup\$ Ok now I see the note information. I think best way to set good contrast is using potentiometer, but my device is battery powered \$\endgroup\$ Mar 31, 2021 at 7:29

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