interfacing analog and digital circuitary

[shreekalak]

i am using two analog inputs from one board which is given to a pic µc board...
µc board is interfaced with a LCD..
my problem is when i am switching on the supply of analog board my µc board gets a minimal supply which switches on my power LED...
and LCD's backlight partially on... then when i switched µc board LCD does not display anything.
if both grounds r shorted then also same thing happens..
wht exactly problem is i am unable to understand..
please help me...
thnx in advace

 

[cameo_2007]

I assume that is the leakage current.Due to the potential difference between both the grounds.

check out these:-
1.Instead of directly shorting both the grounds,connect both through a ferrite bead or an inductor.
2.At the Vcc point of the LCD,connect an electrolytic capacitor and an MLC (multi layer ceramic) parallely.Connecting a similar pair at the Vcc of the whole uC board is also suggested.
3.Hope star grounding is not taken care in your uC board.If so,short all the ground points to a common point with a wire and then short this wire to the analog board ground

This is my assumption.I am not sure,anyways check it up and let me know.

 

[jit_singh_tara]

use more ampere power supply if u are turning the backlight of lcd.....

 

[shreekalak]

i Have used one supply cord and two separate transformers for two circuits.....

 

[saeed_pk]

I have seen such a problem but i found my 7805 malfunctioning jit is right use more ampere power supply
are u using vero board?
there might be some leakage.