Forget about using a ceramic cap in parallel when using OSCON. Try to place the OSCON as close to the pins as possible with short tracks.
I don't know what to answer on the first point, I use MRS 25 for everything.
jean-paul said:
Why? Because it's not necessary, or because it will ring?
And will 0.1uF film caps be OK?
As you refer to the document of Guido Tent I advise you to read it again for reference. The man knows his stuff and he also knows to explain it well. Way better than I can, I just try and test.
I like the comment of Peter Daniel on OSCON although I use them in digital circuits often. In analog I will never use them again as they are responsible for a metallic sound there as experienced by me several times. Decouple an opamp with them and you'll know 😉 OSCON has a break in period too but less than BG.
I like the comment of Peter Daniel on OSCON although I use them in digital circuits often. In analog I will never use them again as they are responsible for a metallic sound there as experienced by me several times. Decouple an opamp with them and you'll know 😉 OSCON has a break in period too but less than BG.
Let me quote
Let me quote:
"When selecting an electrolytic, the series inductance must be taken into account, and properly compared with the total inductance of the supply loop the cap is in. That inductance of the (for a DIL28) package for example) is about 12nH. the ESL of the capacitor shall be relatively small compared to this value; it does not make sense to look for 2nH as the loop itself dominates!"
- i.e. the effect of a ceramic capacitor will be insignificant.
Let me quote:
"When selecting an electrolytic, the series inductance must be taken into account, and properly compared with the total inductance of the supply loop the cap is in. That inductance of the (for a DIL28) package for example) is about 12nH. the ESL of the capacitor shall be relatively small compared to this value; it does not make sense to look for 2nH as the loop itself dominates!"
- i.e. the effect of a ceramic capacitor will be insignificant.
Let me quote further...
"Modern electrolytics are far better RF performers. Their construction is such that the series inductance is very low (both films are terminated at the same side). They have very low impedance over up to 4 decades in frequency; Enough to say goodbye to the additional ceramic capacitor. It saves money and space as well and eliminates the risk of yet another resonance."
i.e. Os-Cons are good (enough) for the RF we are dealing with. Using a ceramic capacitor in parallel is asking for trouble.
"Modern electrolytics are far better RF performers. Their construction is such that the series inductance is very low (both films are terminated at the same side). They have very low impedance over up to 4 decades in frequency; Enough to say goodbye to the additional ceramic capacitor. It saves money and space as well and eliminates the risk of yet another resonance."
i.e. Os-Cons are good (enough) for the RF we are dealing with. Using a ceramic capacitor in parallel is asking for trouble.
I simply didn't believe it!
I had read Guido's words of knowledge, but I lacked confidence in applying what they were telling me. Indeed, Sanyo give PDF examples on their website where OsCons alone are used as decoupling devices.
So why do so many people believe in using ceramics and low impedance electrolytics in parallel? Are they simply wrong?
My asynchronous reclocker operates at 66Mhz. Are 0.1uF ceramic capacitors alone a better choice?
I had read Guido's words of knowledge, but I lacked confidence in applying what they were telling me. Indeed, Sanyo give PDF examples on their website where OsCons alone are used as decoupling devices.
So why do so many people believe in using ceramics and low impedance electrolytics in parallel? Are they simply wrong?
My asynchronous reclocker operates at 66Mhz. Are 0.1uF ceramic capacitors alone a better choice?
If you don't believe an analog designer with a good reputation I doubt that you'll believe me ( I wouldn't ) as a DIYer so I won't comment anymore on the subject.
I have used the OSCON because of Radial design and they have great ESR, also I can get them in one day. I normally use Sprague 550D low ESR tantalums which are great but cost 6 time as much as the OSCONs. I have not tried out the BG's, their are harder to get and they cost more.
Also, I have found if you running fast logic it still best to decouple with .1 or .01 on ever chip and the size depend on the ringing.
The last time I checked carbon film had a better tempco than carbon comps and I hate carbon comp's.
Also, I have found if you running fast logic it still best to decouple with .1 or .01 on ever chip and the size depend on the ringing.
The last time I checked carbon film had a better tempco than carbon comps and I hate carbon comp's.
I respect his authority!
I find reassurance in the experience of others.
I already intend to implement Guido's ground plane, IC interfacing and inductive supply decoupling. I respect his authority!
From your experience what decoupling is best for Op-Amps.
I find reassurance in the experience of others.
I already intend to implement Guido's ground plane, IC interfacing and inductive supply decoupling. I respect his authority!
From your experience what decoupling is best for Op-Amps.
I had a feeling that even an OsCon electrolytic would only go so far....
Thanks Jim,
I had a feeling that even an OsCon electrolytic would only go so far....
On my fast logic I will stick to ceramics on each chip. This is exactly the broad opinion I seek.
P.S. I read that carbon film resistors can become capacitive
Thanks Jim,
I had a feeling that even an OsCon electrolytic would only go so far....
On my fast logic I will stick to ceramics on each chip. This is exactly the broad opinion I seek.
P.S. I read that carbon film resistors can become capacitive
and inductors that become.....
and inductors that become.....
Now we're just being silly!
(You're point is taken)
Sooooo what do you use for op-amps? BGs?
and inductors that become.....
Now we're just being silly!
(You're point is taken)
Sooooo what do you use for op-amps? BGs?
Oli,
That depends on the application. There are lot of AD and Burr Brown part that are very good.
That depends on the application. There are lot of AD and Burr Brown part that are very good.
Sorry I was not being clear.
Sorry I was not being clear.
What single 'capacitor' is best to decouple op-amps?
Quite a number of people believe the OsCon to sound harsh in this application.
Sorry I was not being clear.
What single 'capacitor' is best to decouple op-amps?
Quite a number of people believe the OsCon to sound harsh in this application.
Which are best?
Panasonic FC- Easy to get from RS
Black gates- any special type?
Which are best?
Panasonic FC- Easy to get from RS
Black gates- any special type?
Which are best?
In my experience, with the DAC, BG N type sounded the best. BG NX Hi Q are fine too, but they don't provide the resolution that N type gives you. Low voltage NX seem to be veiled and rather laid back in comparison. But they are good choice in a bright system.
I'm still using a triple bypass configuration, with 0.01 and 0.1u X7R caps (0612 type) stacked on each other and soldered directly to the pins of IC. I don't think big value cap is necessay and the electolytics are 33/16 BG N. It sounds good and I'm not tempted to look for any other bypass configuration yet. Those tripltes are influenced by the article by Pete Goudreau.
http://groups.google.com/groups?selm=4te25c$hcn@agate.berkeley.edu&output=gplain
I'm still using a triple bypass configuration, with 0.01 and 0.1u X7R caps (0612 type) stacked on each other and soldered directly to the pins of IC. I don't think big value cap is necessay and the electolytics are 33/16 BG N. It sounds good and I'm not tempted to look for any other bypass configuration yet. Those tripltes are influenced by the article by Pete Goudreau.
http://groups.google.com/groups?selm=4te25c$hcn@agate.berkeley.edu&output=gplain
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