Super Simple Li-Ion charger for <$1

How about this for low component count Li-Ion charger, 2 small caps and 1 resistor - adjustable CC current to 500mA, no programming/software , no sense resistor:



The chip is an MCP73812. May not be quite as flexible as using an MCU, but at about $1 each, you can put together any number of independently controlled chargers as needed.

Re: Super Simple Li-Ion charger for about $1

What component adjusts the current? Is the resistor intended to be variable or is that the component that adjusts current?

Re: Super Simple Li-Ion charger for about $1

You can use a fixed (or variable) resistor to adjust the charge current.

Re: Super Simple Li-Ion charger for about $1

rmteo said:

How about this for low component count Li-Ion charger, 2 small caps and 1 resistor - adjustable CC current to 500mA, no programming/software , no sense resistor:

The chip is an MCP73812. May not be quite as flexible as using an MCU, but at about $1 each, you can put together any number of independently controlled chargers as needed.

Click to expand...

As far as I remember, it was the easiest to use IC that I found some time ago. The good things were simplicity, low cost and the thermal regulation. The bad was that it is a linear regulator so will heat up (although it may not be a problem with 500mA current). I didn't like its low current, the lack of possibility to power it from a 12V source, the lack of 4.1V regulation option and the lack of a status LED but these may be non-issues, depending on application.

BTW, I hate this annoying CPF database error - it ate my previous response and I had to write it again

Re: Super Simple Li-Ion charger for about $1

Why didn't you mention the MCP73811? Same thing, just only 2 current choices. But 1 less resistor. 3 part Li Ion charger (heck, you might get away without the cap on the battery side, so *possibly* 2 part)... if only NiMH chargers were so simple. :mecry:

I could have but I felt that the ability to adjust the charge current is worth the one extra resistor - especially for those wanting to charge smaller cells such as the 10280, coin cells, etc.

I bought a couple chips like these. They would've worked really well because of how little components they needed. One of them even had an LED status indicator and selectable currents. It was amazing!
But...when I got them I found out they were surface mount. Not just SOP-8 or any of those slightly manageable ones, but ones you could sniff into your nose and lose it forever. Heck, breathing on it would probably send it airborne. I almost could use them... I should find them and figure out what the part number was.

What package were these ones you mentioned???

Mugrunty said:

But...when I got them I found out they were surface mount. Not just SOP-8 or any of those slightly manageable ones, but ones you could sniff into your nose and lose it forever. Heck, breathing on it would probably send it airborne. I almost could use them... I should find them and figure out what the part number was.

Click to expand...

Yeah, that was also a problem for me. A few ICs can still be bought in solderable packages (MSOP, SOIC etc.) but I couldn't find any switching charger in such a package, only BGA, QFN, DFN or another epitome of convenience.

The MCP73811/2 come in a SOT23-5 package. This is no worse than MSOP, and probably easier, as far as hand soldering is concerned. There is very little new these days that does not come in some kind of compact/tiny SMD package.

The MCP73831/2 have a charge status feature by adding an LED and a current limiting resistor. It also features a selectable pre-conditioning mode.

Nice proyect.I was going to make one,but cant find MCP73831-2 in my local stores and online ones charges me about 9$ for shipping a 0.4$ component...lol

Someone would sell me one and send it by mail?

Thanks.

I am actually finding surface mount easier to work with than TH types these days, esp. since I just use paste for all of them anyway.

1206 size stuff is not that bad to position.