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hitsware
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Joined: 23/11/2012
Location: United States
Posts: 535

Posted: 03:13am 03 Sep 2014

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Does the capacitor (pin 19 to 20) on the VT100 chip need to meet
the same specs as for the MicroMite ?

MicroBlocks

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Joined: 12/05/2012
Location: Thailand
Posts: 2209

Posted: 04:35am 03 Sep 2014

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Yep. Get a multilayer ceramic XR5 10uF. They work fine.

Microblocks. Build with logic.

Lou

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Joined: 01/02/2014
Location: United States
Posts: 229

Posted: 04:42am 03 Sep 2014

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hitsware,

The VT100 chip is the same chip as the MicroMite, so use the same cap. I use a 10uF SMD multilayer ceramic on my PC boards now, I have used a 22uF thru-hole tantalum in the past on my protoboards without problem.

Lou

Microcontrollers - the other white meat

Grogster

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Joined: 31/12/2012
Location: New Zealand
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Posted: 12:36pm 03 Sep 2014

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I agree with other posters.

If you are making a PCB, I recommend the multilayer ceramic as mentioned by others - 10uF, but just make sure you get the X5R type. They are a little more expensive then the cheaper SMD caps, but there is a reason that this cap needs to be X5R, so don't use anything else if you are using SMD ceramic.

Otherwise, as others say - you can use a standard Tantalum type - 22uF - 47uF.

@ Lou - the VT100 chip is a different part to that of the uM chip, but the cap requirements are the same.

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hitsware
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Posted: 01:02pm 03 Sep 2014

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When I got the caps for the MicroMite, I ended up with 470uF in order to
meet the ESR specified (which I now forget).
I'm looking for ceramic, but with leads .... I'll add X5R ....

hitsware
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Posted: 01:13pm 03 Sep 2014

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Here we go ............

Grogster

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Posted: 01:32pm 03 Sep 2014

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Those should do the job nicely, and are from a quality brand name too.

Smoke makes things work. When the smoke gets out, it stops!

hitsware
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Posted: 01:44pm 03 Sep 2014

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What's the significance of 'XR5' ?

Grogster

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Posted: 02:12pm 03 Sep 2014

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There are others more qualified to answer that then me, but from what I understand, it is essentially a quality rating. From what I gather, standard ceramic caps can vary in capacitance quite a bit depending on voltage, temperature etc. X5R are more stable across variations then cheaper ones, and I think they also have better ESR then cheaper caps.

Hopefully, someone will chime in here with the correct knowledge, and explain it better then me.

I do remember there were threads in the past on this subject, and from what I can remember, it was important that you chose X5R type caps, if you were using multi-layer ceramics. The X5R thing does not apply for standard Tantalum caps.

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Geoffg

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Joined: 06/06/2011
Location: Australia
Posts: 3165

Posted: 05:47pm 03 Sep 2014

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You got it right Grogs! XR5 is the type of dielectric and its features are as you described.

Geoff Graham - http://geoffg.net

Grogster

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Posted: 06:13pm 03 Sep 2014

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Yay!

Smoke makes things work. When the smoke gets out, it stops!

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