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Sneak preview of the new χ1 LiPo battery board

chi1

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Re: Sneak preview of the new χ1 Li-Po battery board

Postby Coughinhk » September 24th, 2011, 4:13 am

Hi,

This is looking so good.

I'm gonna order some parts for other projects so I thought I'd get some for Xi in advance. So I'd like to know if it's possible to replace the UCC3911-3 with the higher voltage UCC3911-4 ? I fully understand that it is not what you've tested and I'm sure you won't recommend anyone doing this, but my question is really will it function ? From reading the datasheet and looking at the batteries, it seems to me it will. Of course, I'll test it to make sure Xi charges and discharges over several cycles and doesn't generate excessive heat. You might wonder why - yes, it is cheaper but more importantly it is more easily available here. If I go for the UCC3911-3 then it'll have to wait several months before I next do a digi-key order (also waiting for the release of the Crystek CCHD-957).

Thanks,

Tom
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby MisterX » September 24th, 2011, 4:42 am

1352.5 and counting.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby amb » September 24th, 2011, 4:55 am

We chose UCC3911-3 because its overvoltage protection threshold voltage is just right for the battery we selected. If you use the UCC3911-4 then the protection threshold is higher, thus the batteries may be subjected to more stress in certain circumstances and is less safe. Using UCC-3911-2 or UCC3911-1 may cause the overvoltage protection to kick in prematurely and shut the whole thing off before the batteries are fully charged.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby Coughinhk » September 24th, 2011, 5:47 pm

Hi,

Thanks ! So I think it'll probably mean a little more heat and a shorter battery life for no real benefit, except it's convenient. Seems like a bad idea so maybe I'll just try one and order any others from RS. Thanks guys !

Tom
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby dougigs » September 25th, 2011, 5:41 pm

Ti, I'm probably missing something here, but from your renderings it looks like you've got the "SUBS" pins of the UCC3911-3 connected to the ground plane. The datasheet seems to say they should be isolated from all signals, including ground: "The SUBS pins
(4, 5, 12, 13) are internally connected to the substrate of the UCC3911, which is internally referenced to B0 or
GND depending on the direction of pack current. If high battery currents are anticipated, the SUBS pins can be
thermally connected to a heat sink to control the device temperature. However, this heat sink must be electrically
isolated from all other device pins including ground. This is a critically important point, as heat sinking to the
system ground is not possible."

I'm sure you've given this plenty of scrutiny, so this question is just for my curiosity.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby MisterX » September 25th, 2011, 5:44 pm

They're not connected to the ground plane.
1352.5 and counting.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby dougigs » September 25th, 2011, 5:52 pm

You're right, the schematic shows that clearly - - the PCB layout just makes it look that way. Must be an illusion.
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Good news: production PCBs are here

Postby amb » October 5th, 2011, 1:45 pm

I am working on the χ1 website. As soon as it's ready the boards will become available.
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby goldkenn » October 5th, 2011, 10:04 pm

Any date of open sale? I need a date since many enquiry to me
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Re: Sneak preview of the new χ1 Li-Po battery board

Postby amb » October 5th, 2011, 10:11 pm

I can't promise a date, but I hope it will be within a few days. I only have a limited amount of time each day to work on the website, and I will not ship boards before all documentation is in place.
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