Decoupling capacitors on SO-8 to DIP-8 adapters

[joze7205]

Hi!

I'm about to build a Pimeta with AD8610/AD8620. Since I forgot to order the Browndog adapters from Tangent, I ordered similar adapters from a swedish company. They recommend putting some decoupling caps on the adapter boards. Would this improve anything in a Pimeta?

Link with pics of the PCB

/Johan

 

[Pars]

Extra decoupling certainly won't hurt anything. Depending upon how the opamp is configured, you may or may not have ground available to decouple to (you may need to run an extra wire just for ground).

 

[HIPPOhifi]

I just saw the picture and that is a good use of board space on the SOIC/DIP adapter. Decoupling caps wont hurt but you only need them if there is say 3" inches or more between the power supply and opamp or the path is shorter but runs past/through/over components likely to create noise.

 

[Filburt]

.

 

[mono]

Quote:

Originally Posted by HIPPOhifi /img/forum/go_quote.gif I just saw the picture and that is a good use of board space on the SOIC/DIP adapter. Decoupling caps wont hurt but you only need them if there is say 3" inches or more between the power supply and opamp or the path is shorter but runs past/through/over components likely to create noise.

That's not entirely accurate, decoupling caps are always best placed as close to the opamp pins as possible no matter how many millimeters, not inches, away the rest of the supply lines are. Further with a fast opamp it's even best to use surface mount caps just to get them that much closer w/o leads to go through, but our opamps and frequencies are low enough so it's forgiven in use/results.

 

[joze7205]

OK, I'll try it. I guess I will go for 100 nF underneath (the recommendation of both Filburt and the company) and 5.6 nF on the upper side.

I'm not quite quite sure what it does yet, but I'll try to find out.

Thanks for all help!