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How to power a board


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Hi,

I've got a general question about powering up of projects.

MSP430 requires 1.8v - 3.6v (if I remember correctly the lower bound), so it could run of a single CR2032 battery, or two 1.5v batteries (or 1.2v if NiMH, but either way two big sticks that). But most of the components that I would like to connect to it (DS18B20, MKT3339 and most others) require 3.3v so it's not enough for a single CR2032, and using two would mean that most of the second batteries power would go out as heat on LDO. Using three 1.5v batteries would add unnecessary maintenance burden and add too much weight and dimensions to the finished "product".

 

So my question is, what kind of batteries are you guys using, are there any other batteries out there that would be small enought, provide anough power and could be easily replacable (the last one is optional, assuming low power consumption)?

 

I was thinking of using step-up converter (like http://www.sparkfun.com/products/10967 (NCP1402-3.3V), I actually order a sample of TPS61097-33) and would want to try it out, but first I have to learn how to use Eagle and how to design a board :) (or just order the sparkfun one)

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Most 3.3v will run at 3.0v as a recommended minimum, but can run a bit lower as well, the manufacturer just won't support undervolting it, you can always just try it.

 

That tps61097-33 is a good idea as it only needs two caps and a common inductor, but only gives you about 100ma. Microchip MCP1253 is similar, but needs no inductor, can provided 3.3 or 5v out and 120ma.

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Did you think about rechargeable Li-ion or Li-po batteries? They give 3.6v (4.2v when fully charged really) and are pretty compact for the amount of energy stored. They also come in infinite number of shapes. Maybe it's worth a look. The other option is coin cell style sandwich of 3 NiMH cells, for 3.6v, pretty common in minor rechargeable household electronics, I bet you could find them on eBay or somewhere else.

 

EDIT: just found a stack of 3 "1/3 AA" NiMH, in the space of 1AA you get 3 cells NiMH at 480 mAh, should do the trick... http://www.ebay.com/itm/140790250490

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Did you think about rechargeable Li-ion or Li-po batteries? They give 3.6v (4.2v when fully charged really) and are pretty compact for the amount of energy stored. They also come in infinite number of shapes. Maybe it's worth a look. The other option is coin cell style sandwich of 3 NiMH cells, for 3.6v, pretty common in minor rechargeable household electronics, I bet you could find them on eBay or somewhere else.

 

EDIT: just found a stack of 3 "1/3 AA" NiMH, in the space of 1AA you get 3 cells NiMH at 480 mAh, should do the trick... http://www.ebay.com/itm/140790250490

 

Only concerns with those (lipo and non-""standard"" shaped) is charging. You either need to create and make a lipo recharging board/section, or you need a specialized charger. Also, you need to watch out for overcharging (nimh cells at 100% charge tend to be at 1.7~1.8v) and sharp discharge rates at around 80% discharged.

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Most 3.3v will run at 3.0v as a recommended minimum, but can run a bit lower as well, the manufacturer just won't support undervolting it, you can always just try it.

Yeah, I saw that, but I heard that CR2032 quickly drops to 2.6-2.7v, and it might stop working, I'm just wondering if it is enough.

 

That tps61097-33 is a good idea as it only needs two caps and a common inductor, but only gives you about 100ma. Microchip MCP1253 is similar, but needs no inductor, can provided 3.3 or 5v out and 120ma.

Nice find :), I really don't like the required inductor, the appropriate value is quite to find in local/net stores where I am. The only downside of the MCP1253 is that it requires >= 2v, wheres tps61097 is >= 0.9v, I need to give it a try with 1 AA battery :)

As soon as I get the inductor.

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I really don't like the required inductor, the appropriate value is quite to find in local/net stores where I am. The only downside of the MCP1253 is that it requires >= 2v, wheres tps61097 is >= 0.9v, I need to give it a try with 1 AA battery :)

As soon as I get the inductor.

I have couple of NRH3012T100MN to spare

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I have different power sources depending on my project. I've got a lightning detector that uses a AA sized Lithium Ion battery and I've run it for days with the little battery icon still saying full charge.

 

For smaller projects I'll use LIR2450, offers rechargablity of a lithium ion and 120mAh. Also available is the LIR2032, it has the benefits of an easy to find socket but only offers 60 or so mAh. I've had to build my own small lithium charger for these. Haven't tried LiPO yet.

 

For plug-in stuff I tend to get small transformers from the surplus store(old 9vdc portable phone adapters) and use 75L33(this one requires only a couple caps) or 317L regulators, whatever I have on hand. They only handle up to 100mA but so far haven't really needed more than that except on the 5V rail for my VFDs which I run off a standard 7805 or 317.

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Thanks, but I don't need those right now, still have try out SMD soldering :)

You may have no choice, both (TPS61097 and MCP1253) are SMD.

Besides, you can use NRH3012 inductors on a through hole board, just add couple of wires :)

 

You can also try this one.

 

post-197-135135556227_thumb.jpeg

post-197-13513555623_thumb.jpeg

post-197-135135556232_thumb.jpeg

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Yeah, I am planing to do some SMD soldering, just because of availability (or lack of) of the through-hole components :)

I just want to minimize shipping costs, so I'm gathering information what I would need to order for my projects.

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