Smallest coil for bq5105X?

Glenn Zelniker

Does anyone know if there are any off-the-shelf coils that would work with the bq5105X and that would fit into a 35mmx35mm area? Thickness isn't a big constraint, but floorplan certainly is. I can live with low efficiency and furthermore, the device in question only uses the bq part for charging -- I have no need to power the system while the battery is charging.

over 12 years ago

0 Bill Johns over 12 years ago

TI__Guru* 76506 points

Take a look at the Wurth Elektronik P/N 760308201, data sheet is on their web site.

Also see the Mingstar 312-00015, info on their web site.

0 Glenn Zelniker over 12 years ago in reply to Bill Johns

Prodigy 70 points

Thanks for the suggestions, Bill. I had given up on the Mingstar coil, which looks like exactly what I need, because my emails to Mingstar kept bouncing. Do you happen to know what these coils cost and do you have a valid email address for a representative?

0 Bill Johns over 12 years ago in reply to Glenn Zelniker

TI__Guru* 76506 points

Try

Minstar contact is Alen.

alenliaw@mingstar.com.tw

0 Pat over 12 years ago in reply to Bill Johns

Intellectual 460 points

Glenn,

Did you have any luck with these coils or did you find an alternative? I was designing around one of the Vishay IWAS coils but apparently we can't fit it into the enclosure due to screw hole clearances.

Regards,

Pat

0 Steffen Netz over 12 years ago in reply to Pat

Intellectual 950 points

Hi,

we have just ordered the coil at http://www.micro-electronic.shop2go.biz/produkte/

But I have questions about the resonance capacitors C1+C2. Is there any reference design?

Mingstar gives only Ls not Ls-.

Regards

Steffen

0 Pat over 12 years ago in reply to Steffen Netz

Intellectual 460 points

Did you have any luck with these calculations? I've gotten it working through trial and error but the calculated capacitance values are not working for me and I'm not sure how close the values I'm using are, I don't want to be right on the edge and have some builds not work due to slight changes in the assembly or fab.

The default values (on the EVM and advised elsewhere) don't seem to work with this Mingstar coil.

Pat

0 Piotr Twardosz1 over 12 years ago

Prodigy 40 points

Hi!

Wuerth Elektronik offers a small coil which has a shield underneath. If you want to you can make a coil yourself and by doing that you will not be constrained to size, shielding, etc.

I am making custom coils using 0.3mm enamelled copper wire and they are doing the job just fine. Basically once you have your size constraints you need to see if the inductance will be sufficient to even consider using that coil. Good online calculator to help you with is: http://deepfriedneon.com/tesla_f_calcspiral.html

Once you have the coil, and know that it will have sufficient inductance (uH) then you need to determine its actual inductance and resonant capacitor values.

Keep in mind that coil inductance will be different depending on the objects close to it (PCB, batteries, metal parts and casing, etc.).

Piotr

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Smallest coil for bq5105X?