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Forum Index : Microcontroller and PC projects : Vcap for surface mount

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Grogster

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Joined: 31/12/2012
Location: New Zealand
Posts: 9593
Posted: 10:08pm 02 Mar 2016
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Cheers, mate.
Smoke makes things work. When the smoke gets out, it stops!
 
paceman
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Joined: 07/10/2011
Location: Australia
Posts: 1329
Posted: 02:03am 03 Mar 2016
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I'm no expert on this but I thought we'd pretty much tied it down some time ago. Caps using the X5R dielectric have the lower ESR, not X7R. X7R's are only 'better' in that they have a higher temperature rating, not a lower ESR. 10uF X5R's work with the PIC 32's, 10uF X7R's often don't. 47uF tantalums work because at 47uF their ESR is pretty low, if you use a 10uF tantalum it'll likely not work because generally, for a given dielectric, ESR is higher at lower capacitance.

I've got several varieties of 10uF X5R's and so far they've all worked. I've also got some 10uF X7R's that don't work. I've also used 47uF tantalums and they've also always worked.

Greg
 
bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2949
Posted: 02:27am 03 Mar 2016
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GDay Graeme, All,

When I had troubles with the UBW-32 (crikey how long ago was that) I used to solder another cap on top of the existing one.. If you have 100's of them I would suggest piggy backing another cap and see what happens..

I have been very reluctant to move away from the 47uf tantalums because of the UBW issues..

Mick
Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<
 
palcal

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Joined: 12/10/2011
Location: Australia
Posts: 1989
Posted: 11:55am 03 Mar 2016
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I have used RS Components part number 758-8093. They are X7R and work OK. I looked up the part no. at RS and under the description it states
  Quote  AVX 1206 MLCC Series
X7R formulations are called “temperature stable” ceramics and fall into EIA Class II materials, and COG (NPO) is the most popular “temperature-compensating” EIA Class I ceramic materials
Multilayer Ceramic Capacitors whose temperature variation is within ±15% from -55°C to +125°C
The capacitance change is non-linear
AVX high voltage chips have advantages of high value, low leakage and small size, thus applications include as snubbers in high frequency power converters, resonators in SMPS and high voltage coupling/DC blocking
These high voltage chip designs exhibit low ESRs at high frequencies

Take note of the last line. It would appear that you just have to check the specs. of the cap. before you buy.
Paul
"It is better to be ignorant and ask a stupid question than to be plain Stupid and not ask at all"
 
OA47

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Joined: 11/04/2012
Location: Australia
Posts: 982
Posted: 12:33pm 03 Mar 2016
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Bigmik said:
  Quote  I would suggest piggy backing another cap and see what happens.


I will try that out later today and report back.
GM
 
bigmik

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Joined: 20/06/2011
Location: Australia
Posts: 2949
Posted: 12:46pm 03 Mar 2016
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GDay Paul, All,

  palcal said   It would appear that you just have to check the specs. of the cap. before you buy.Paul


The Farnell/Element14 chip caps that Graeme bought do NOT mention ESR anywhere in the data sheet.. As such I would not have bought them myself.. I do have some X5R 10uF caps here that I have meant to put to the test but to date I have not done so.. I really think the Tantalum 47uf are so reliable there isn't much need for me to test them.. But that doesn't really help Graeme out with his 100's of Caps he bought, Of course if you want to build a lot of Mik-Matrix Boards up they should be OK to use.

Regards,

Mick

Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<<
 
viscomjim
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Joined: 08/01/2014
Location: United States
Posts: 925
Posted: 03:10pm 03 Mar 2016
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After actually starting this thread about 8 or so months ago, I wound up using THIS cap for my first ever smd board, and have been using it ever since with ZERO problems, and I'm talking quite a few boards. It was a somewhat educated "shot in the dark" and so far so good. So for the price and reliability, I have purchase a good amount of these for future use. Edited by viscomjim 2016-03-05
 
isochronic
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Joined: 21/01/2012
Location: Australia
Posts: 689
Posted: 07:02pm 03 Mar 2016
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One way without the hassle is to look at the similar microchip boards,
and see what is used there -
they usually have a schematic and BOM available in the info on-line.
I haven't used 0805s for the 10uF yet but eg looking at one board Microchip
use a murata GRM219R60J106KE19D. Then it becomes a search for suppliers.
 
centrex

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Joined: 13/11/2011
Location: Australia
Posts: 320
Posted: 11:19pm 03 Mar 2016
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I would agree with BigMick I have used his 47uF tant caps on a number of boards with no failures.
If you only want a few contact Mick I sure he will oblige.

Cliff
 
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