Wireless battery charging in ultra small board

Javier Herrero de la Cal

Other Parts Discussed in Thread: BQ5000

Hello. One of my customer has told me if it is possible to charge an small battery (15mAh) by Wireless power. The problem is that the area that I can use for everything is 15mmx15mm. I have being reading about Tesla power charging (you (TI) will have the BQ5000 series prepared for the 1st semester 2011, Induction charging etc, but the smaller coils need I have seen are 35 mm diameter.

Anyone knows any possibility to get power by wireless into a 15x15 mm board? I think it is not possible, but I am not sure.

Thanks

Javier

over 14 years ago

0 Steve Bramhall over 14 years ago

TI__Prodigy 50 points

Javier,

You can get wireless power to a small footprint. However, the amount of power required may be a challenge. The amount of required power can be affected by the wireless distance, transmit power, antenna size, antenna material, and antenna matching.

Best regards,

Steve

0 Javier Herrero de la Cal over 14 years ago in reply to Steve Bramhall

Intellectual 370 points

Hello Steve,

Thank you very much for your answer,

The size of the board is 15x15 mm and it must contain the antenna in one side (so the space for the antenna are 15x15 mm). And in the other side the regulator and any other component needed for the battery charging.

About the wireless distance we are considering about up to 1 cm. And the battery to be charged is a 18 mAh buttom battery (Lithium Manganese Dixide Rechargeable Battery) and we have up to 12 hours for the charging.

Do you think that it is possible to design something like that? Do you recomend me any system or something we can use?

Thanks for your attention,

Kind regards,

Javier

0 Steve Bramhall over 14 years ago in reply to Javier Herrero de la Cal

TI__Prodigy 50 points

Javier,

Sorry for the long delay. I like to think that anything is possible, however, without a model and simulation I won't be able to provide you a definite answer. Here is a link to a great application note that may provide you with some good basic concepts regarding antenna circuits.

http://ww1.microchip.com/downloads/en/AppNotes/00710c.pdf

Best regards,

Steve

0 Javier Herrero de la Cal over 14 years ago in reply to Steve Bramhall

Intellectual 370 points

Thanks for your answer Steve.

I already told to my customer that at least today it is not possible to design a system like they wanted so maybe they need to wait some years can make what they wanted, not only because of the induction charging but because other micro embedded technologies they wanted.

Anyway, thanks for the link because that document is very interesting to understand how antennas works.

Kind regards,

Javier

0 Javier Herrero de la Cal over 14 years ago

Intellectual 370 points

Hello,

Thanks for the reply,

Just one question, how much small?

Thanks,

Javier

0 Steve Bramhall over 14 years ago in reply to Javier Herrero de la Cal

TI__Prodigy 50 points

Javier,

There are a lot of factors to considers like RF power in, complexity of the circuit, etc... but I worked a wireless device that was small enough to be injected into the body through a large needle.

Best regards,

Steve

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Wireless battery charging in ultra small board