Digital panel meter - Ref voltage at 36 pin is oscillating

[vundela]

Digital panel meter

Hi,
Iam using IC 7107 LED Driver for my ³½ Digital panel meter.Some DPM's are working properly.In some DPMs Ref voltage at 36 pin is oscillating.Why this problem is coming.Some one help me.

 

[betwixt]

Re: Digital panel meter

Have you got a 'CReference' capacitor fitted between pins 33 & 34 ?

If you have, the most likely cause is noise on the supply line to the IC, try fitting an extra capacitor (try 10uF) across the supply pins, you may have feedback from the LED multiplexing current.

Brian.

 

[pranam77]

Digital panel meter

Also in addition to the sugession by Betwixt, i would like to add that in India, many spurious and sub standared IC's from china are pushed by dealers which are not so accurate. Try with those Ic's from Intersil which are available with a price difference. Cheers