What are the effects on the board if you don't place decaps?

[deepak.sibi]

Hello All,

Is it necessary on every board you design you should have a Decap on the VCC Pin connectiong to Ground.

If you dont place any decaps what are the effects on the Board.

TIA.,


Regards
Deepak

 

[Khabree]

Re: Decoupling Capacitor

Here is alot of topics on this forum on decoupling caps: You can search for that. Two links are here:

LINK1
LINK2

ENJOY!

 

[rogerynt]

Re: Decoupling Capacitor

Yes, you must add decoupling cap. to gnd. Common practice uses

1.) Big ecap e.g 100uF, 220uF at regulator out
2.) 100nF in between Vcc and gnd. But please keep the loop small
3a.) High freq. decoupling cap. e.g 1nF


Rogerynt

 

[laktronics]

Re: Decoupling Capacitor

Hi,
You have to use a parallel combination of 4.7 to 10uF DIP Tantalum Capacitor with a 0.1 uF Ceramic Disc for all Major digital ICs, for All Analog ICs and for a group of about 7 to 8 standard logic Digital ICs. Additionally, you have to use a 0.1uF ceramic disc capacitor for each of the standard logic ICs. Try to use 1 to 1.5 mm PCB tracks for logic supply and gorund.

If you do not use decoupling, the board will malfunction due to power supply noise and transients. On analog circuits, it will also give rise to unwanted oscillations.

Regards,
Laktronics