Capacitor Selection - ceramic and electrolytic capacitors ?

[vaibhav.k]

Capacitor Selection

Hi all,
Normal tendency for coupling and decoupling capacitors is that normally we use
100nF Ceramic and along with that electrolytic.My questions is that Now a days High value ceramic capacitors are available.Is it possible to use both the capacitors ceramic type 1st one 100nf and 2nd one 10uF/16V.

Vaibhav

 

[zx_sa]

Capacitor Selection

Depends on your application. On a PCB with a decent power regulator, you do not need more than a single 100nF ceramic cap at each IC power pin.

If you're running high frequency signals at all (higher than say 2MHz), you can also have smaller ceramic caps at each IC.

Large caps (>1uF) are only needed at the power regulator to stabilise it. Ceramic are usually better than electrolytic because electrolytic caps deteriate over time losing capacitance.

 

[teekay_tk]

Re: Capacitor Selection

I do not see any reason why you cant use these. If you are trying to achieve very low noise system, especially near ADC you can use multiple decoupling capacitors, my chain is usually 10uF, 100nF and 100pF to achieve low noise.

 

[vaibhav.k]

Capacitor Selection

Exactly
You are using 10uF.If i will use 10uF in ceramic type will instead of Electrolytic or Tantlum it affect my noise

 

[teekay_tk]

Re: Capacitor Selection

Originally Tantalums were used as they were the smallest size. HOwever, ceramics are much better and now that they are smaller they should be used instead if possible plus they are cheaper (i think)

 

[dipnirvana]

Re: Capacitor Selection

ceramic's capacitance is voltage moduled but that of tantalum is very immune from this effect . Look out for this when you make choice of ceramic or Tantalum