XBee Pro adapter current

XBee projects like the adapter, xBee tutorials, tweetawatt/wattcher, etc. from Adafruit

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xanatos
 
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Re: XBee Pro adapter current

Post by xanatos »

Hi! Just finished soldering up the adapters I got here, and I LOVE Them. Thought I'd jump in with a quick question/confirmation, and a thought. The confirmation/question is: I can just omit the TO-92 regulator altogether if I choose to use my beefy TO-220 LM2937ET-3.3 and pump that voltage into pin 1 of the connector, correct? I think I need to do this as I am using the Xbee Pro XSC which has whopping TX power....

The footprint of that module is also about 1/4" longer on the bottom end, and it covers the entire area of the regulator and cap. While the reg can fit just exactly beneath the board, I am having to use a different cap as the supplied unit prevents the XSC from seating.

Also - looks like pin 6 is different on the XSC - probably won't get any D1 LED action as pin 6 is the CONFIG pin on the XSC... but I digress.

Lastly - if there were a SM version of this board, I'd buy that! But I know what you mean about soldering skills - I've seen people post pics of projects that look a little like a barbecued turkey leg. Scarey!

Thanks for a great kit!

Dave X

adafruit
 
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Re: XBee Pro adapter current

Post by adafruit »

yup "3V" is input or output
just solder the cap to the other side if you need more space

grapeghot
 
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Joined: Wed Feb 18, 2009 7:19 pm

Re: XBee Pro adapter current

Post by grapeghot »

How about designing the board to accommodate both TO-92 and SOT-223? Anybody who wants to use a higher power regulator has that option. Also, the dropout for the LD1117 is 1.1v@100ma!

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ericwertz
 
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Re: XBee Pro adapter current

Post by ericwertz »

One solution might be to parallelize two of the TO-92 VRegs, which would keep it through-hole. The output traces could be cut between two extra through-holes where the ORing diodes would go if one wanted to add the second VReg. It looks like the XBee supply can handle a modest one-diode drop from 3.3V, as long as the supplies don't sag much lower.

Basically the supply section would be VReg1out to a serial pair of through-holes joined by a trace, in parallel with another similar VReg2out path. If one wants the second supply, one cuts the two traces between the through-hole pairs, jumpers them with their ORing diodes, and installs the second VReg.

It would certainly require not-insignificant extra board space for the second VReg and the two extra jumperable lead-outs. Perhaps too high a cost if only 5% of the people are going to want the second supply. The extra VReg and pair of diodes could be sold a la carte, but everyone would be forced to buy the extra real estate.

Interested parties could even cut the output trace on their single VReg, install a jumperable 2-pin header (if the diode through-holes were on standard centers) and measure their actual current in-line, be they anal enough to want to do so.

This all might be design overkill compared to just going up to a TO-220, if through-hole is still priority#1. Now that I think of it, it might be easier (and smaller) to just come up with a layout that can grok either a TO-92 or a TO-220.

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