chemical fuse

From the FAQ Knowledge Base

These two companies are known to manufacture the 3-terminal chemical fuses:

Sony Chemicals Corporation
Electronic Devices Business Group
1-11-2, Osaki, Shinagawa-ku, Tokyo, 141-0032 Japan
TEL +81-3-5435-3943 FAX+81-3-5435-3072
http://www.sonycid.jp/en/products/dd6/

Uchihashi Estec Co., Ltd.
Headquarters and Overseas Sales Department
9-14, Imazu-Kita 2-chome, Tsurumi-ku, Osaka 538-0041 Japan
TEL (06) 6962-6661 (INT-81-6-6962-6661)
FAX (06) 6962-6669 (INT-81-6-6962-6669)
http://www.uchihashi.co.jp/english/

Hi

There is something to know about the Sony product: You mustn't use it for medical applications

An Other Company offering such fuses is NEC but I dont know the exact type name

I tracked down the NEC fuses,

http://www.nec-schott.co.jp/english/cutoff/sh_type.html

Also, why do you say that the sony fuses cannot be used for medical applications? Do they state that somewhere? Is there another reason other than liability?

Sony wants to know the end Application and if it`s a medical there will be no dellivery

I don't know why but we had this @ two customers

They will also refuse to supply fuses for any military projects

Hi  I have a large selection of chemical fuses.  NOS of about 200 on hand.  Let me know and I can send out what you need.  I have tons of NOS tubes and transistors as well.  Todd  540-641-4536 

Is there any alternate solution (logic) for the chemical fuse?

Sony Chemicals has recently become Dexerials, and the devices referenced can be found here:

[http://www.dexerials.jp/en/products/c3/sfj0815.html]

However, I have contacted them regarding purchasing and samples and haven't heard anything back from them.  Which is putting an unfortunate cramp in my development, I would have thought triggerable fuses like this would be easier to get.

As for an alternative, you'd need a way to fire the fuse very quickly without that surge reaching the load.  Maybe force the series-pass MOSFETS off, then short the pack across the fuse to blow it?  might be able to pull this off with a small device like a 2n7002 to drive the series-pass devices out of conduction and then something with a large peak current capability like a CSD series device to short the pack across the fuse.  But that's assuming you can get enough current out of the cells to blow the fuse quickly and reliably.. not a lot of safety in that I think.

Hello,

I am wondering if these Chemical Fuses are a mandatory element of Lithium-ion battery packs.  I am working with a Chinese Li-ion pack
supplier, and they produced a pack design based on a bq20z45-R1 fuel gauge IC, but there was no Chemical Fuse circuit.  Also, there
was no secondary-overvoltage-protection IC such as the bq29412.  Are the Chemical Fuse and bq29412 (or similar IC) required for commercial
Li-ion battery pack applications?  Is there a Regulatory requirement? 

BTW, I am working on a medical device design.

Thanks for any advice.

Regards,

Mohan Gurunathan

Hi Jorg,

Thanks for the advice.  I also have advice from another source confirming that there is currently no regulatory requirement to have a chemical fuse, but it is highly recommended, especially for high reliability applications.