Help identify the IC found on Lipo battery

[btfdev]

Here we have a small Lipo battery found within a portable MP3 player. The top section of battery has a simple circuit board and IC.

http://www.binarytaskforce.com/photocontact-album-16

Help identify please!! Could that be a charging function? Take a closer look!

Team BTF

[NiHaoMike]

That's a solid state circuit breaker with overvoltage and undervoltage protection.

[amyk]

Pinout and package suggests MOSFET; the actual protection IC is usually in a much smaller package (although there are some integrated ones.)

[dr_p]

Yes, it's probably just a MOSFET.
Hint: what's on the other side of the PCB?

[Experimentonomen]

No its definately not a mosfet, the pinout does not match any smd mosfet i ever seen before.

Its guranteed a integrated UV/OV/short circuit protection single chip solution.

[btfdev]

Thanks guys for the reply

@dr_p : There is nothing on the other side of PCB, that's where they solder the Lipo terminal tabs to the board.

Now that most of us think its a protection solution, anyone can provide a datasheet or part number for this puppy?

Thanks, Team BTF.

[Experimentonomen]

Just google lipo cell protection.

[TerraHertz]

As stated, it's definitely a protection circuit. Lipo cells are immediately destroyed if they are discharged below a critical point. And so to protect the battery they have to be used with a circuit that electrically disconnects the battery from the load before the battery exceeds its permitted discharge voltage.

Every Lipo battery pack will have a similar protection board in it.

I too have been trying to find an available protection part, and circuit, so I can use a box of salvaged Panasonic 18650s I have. Without the protection they're useless, unless you don't mind throwing one away each time it runs flat in normal use. I can charge them, but so far don't have a circuit to protect them in use.
Anyone know of a part that is a) cheap in qty 1-100, and b) big enough to manually solder?

Here's a photo of an equivalent protection board, from a nokia phone battery. And also the box of nice but so far almost unusable 18650s I have - so you can see my incentive.

By an odd coincidence, one thing I want to do is make a small, simple MP3/WAV player/recorder that uses removable uSD cards, and replacable 18650 battery - for a play time of weeks, and a 'recharge time' of zero - just replace the battery. There's *nothing* sensible in the MP3 player market that I can find. They all try to be either tiny (makes for stupidly short play time and non-removable battery) or fancy hi-res LCD (expensive & still too-short play time.) I have an old Thompson MP3 player that uses AAA batteries and uSD slot. I like it, but it can only take 2GB uSD cards and an AAA battery gives only a few days play time.

[NiHaoMike]

There's a TI part (UCC3952-1) that's available in a SOIC package.

[amyk]

Ready to use: http://dx.com/p/charge-discharge-protective-circuit-board-for-rechargeable-li-ion-batteries-13-4mm-1-7mm-26114

An MP3 player will likely have a battery voltage monitor and automatically shut off on low battery anyway...

UCC3952 is obsolete. The UB24205 may still be in production.

[TerraHertz]

Yeah, obsolete.
There are quite a few pre-built protection units around, but all the ones I've found are intended to be attached to the battery. Same as the one linked above. And another:
  http://www.batteryspace.com/pcb-for-3.7v-li-ion-18650/18500-cell-battery-2.0a-limit.aspx
  http://www.batteryspace.com/prod-specs/2578.pdf
  (How much do you want to bet that's made in China, and the US co are resellers.)

But I'd rather have a circuit that I can design into my own board, that takes bare 18650s. Many batteries, one protection circuit in the unit. All L-ion chargers have overvoltage protection anyway.
When I said MP3 player, I meant designing my own. Oh, and the old MP3 player I have that uses AAA alkaline batteries has no battery protection - it just runs them till they are dead.

That's the biggest drawback with tiny surface mount stuff - how do you reverse engineer circuits from it, when the semiconductors are just anonymous little blocks? Even if they do have a couple of letters or numbers on them, how to find out even who made them? And then it's not as if you can usually find data sheets.

[Monkeh]

TI seem to have plenty of TSSOP ICs available.

[TerraHertz]

But not one that does single cell under-voltage protection.

[Monkeh]

http://www.digikey.com/product-detail/en/S-8241ABKMC-GBKT2G/728-1032-1-ND/1628435

[TerraHertz]

Hmm. Getting closer. That one's intended for use inside a 1-cell battery pack, to handle both load and charging.  It requires external FETs for load and charge control. Could be used for what I want, but check out the way they 'adjust' the threshold voltages. A different part number for each band - of which Digikey carries one variant.

Amusing to see "Lead-free, Sn 100%"
I suppose everything like this IC is that way now. It sure isn't going to be fun in a decade or so when everything electronic is dying of tin whisker growth. Classic case of forgetting lessons of history.

[peter.mitchell]

but check out the way they 'adjust' the threshold voltages. A different part number for each band - of which Digikey carries one variant.

I hate this method too, Maxim does it, and so do seiko-epson (both of which I have used parts form before)