BQ24070: BQ2407x device selection and battery selection

Rudnik

Intellectual 350 points

Part Number: BQ24070
Other Parts Discussed in Thread: BQ24074, BQ25071

Hello,

I would like to design a project with the BQ2407x. The problem is I have never done anything like it.

My main question is, which of the devices do I choose and what battery can I use with it?

Are there any Reference designs or projects or literature?

My application is a MSP430 running in very low power. The system is usually supposed to run from a USB adapter and the BQ circuit should work as a sort of UPS which can run for several days (or years I guess).

Any tips for this?

Thank you!

Best regards

over 6 years ago

0 Raheem over 6 years ago

TI__Mastermind 21590 points

Hello

First you'll need to select a battery for your application and figure out what the battery regulation voltage is. Next you want to know what charge current you want to charge the battery which will depend on the maximum charge rate stated in the battery datasheet. Then i can recommend a device.

0 Rudnik over 6 years ago in reply to Raheem

Intellectual 350 points

Hi,

thanks for the reply. I don't really have any idea of what battery to use. Sorry for being so unknowing, but I never used something like that.

Could it be such a cell for example:

www.reichelt.de/industriezelle-li-ion-16340-3-7-v-650-mah-flat-top-nc-nl166-p151097.html

Thank you!

0 Raheem over 6 years ago in reply to Rudnik

TI__Mastermind 21590 points

Hello,

That a good example. 18650 are also popular lithium iron batteries. You wan to select them based on capacity, how long you want them to last and your load.

When you select a battery based on your project, let me know

0 Rudnik over 6 years ago in reply to Raheem

Intellectual 350 points

Hello,

thanks very much for the support.

I would settle for this battery: www.reichelt.de/industriezelle-li-ion-18650-3-7-v-2300-mah-flat-top-nc-nl183-p151100.html

Another question: for security reasons I would like to use an NTC. I looked out this type www.reichelt.de/ntc-widerstand-595-mw-10-kohm-mit-ch25-3h103f-p240102.html . It seems to have about the same characteristics as the 103AT-4. Is this correct?

0 Raheem over 6 years ago in reply to Rudnik

TI__Mastermind 21590 points

Hello,

The link for the NTC is broken. For our chargers, i'll suggest using the 103AT-2 since that's what our TS pin is configured to work with. I'll suggest you use the BQ24074 to charge your battery. It charges the battery to 4.2V.

0 Rudnik over 6 years ago in reply to Raheem

Intellectual 350 points

Hello,

thank you for the info. How did you know to what voltage the battery can be charged (4.2V)? There is no info on that in the datasheet.

Also would it be possible to charge an LiFePo4 battery with the BQ2407x?

Kind regards

0 Raheem over 6 years ago in reply to Rudnik

TI__Mastermind 21590 points

Hello,

Since the battery website states the nominal voltage as 3.7V, this typically translates to a max charge voltage of 4.2V. You can confirm this with the battery vendor. The BQ2407x cannot be used to charge LiFePo4 since that has a different charge cycle. You can use the BQ25071 for LiFePo4.

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BQ24070: BQ2407x device selection and battery selection