bq29312A cell balancing

Danilo Porcarelli37

Other Parts Discussed in Thread: BQ29312A, BQ76PL536A

Hello,

I have a question about the balancing feature of the bq29312A.

More precisely I don't understand well how the balancing is performed. Are there internal FETs in parallel with each cell? Or external FET are needed?

The datasheet states that the maximum current for cell balancing is 10 mA (absolute maximum ratings table). Is this value the maximum current I can draw from the cells during the balancing process? Is it possible to increase this value?

In my project I need to balance two or four 150-200 Ah lithium cells. So I need greater current for cells balancing.

Thank you in advance

Danilo

over 8 years ago

0 WM5295 over 8 years ago

TI__Guru 54715 points

The bq29312A has internal balance FETs between the cell inputs. The 10 mA is an absolute current through the internal FET, so design the internal current to provide some lower current to allow for tolerances. External balancing can be done as described in www.ti.com/lit/slua420, the internal balance current then controls the external FETs as described in the apnote.

0 Danilo Porcarelli37 over 8 years ago in reply to WM5295

Prodigy 45 points

Hello,

thank you for the very useful answer.

I have another question. Is the bq29312A stackable to control more than four cells (i.e, 6, 7, 8 etc...)?

All the best

Danilo

0 Roger Hwang over 8 years ago in reply to Danilo Porcarelli37

TI__Genius 10785 points

Danilo,

bq29312A is not stackable device.

Is it possible? Probably with isolation circuits but it will get complex and won't be cheap solution.

What is your application? We have protectors for high cell counts. Perhaps, I can propose you a better solution.

0 Danilo Porcarelli37 over 8 years ago in reply to Roger Hwang

Prodigy 45 points

Hello,

thanks for your reply.

For my application I need a stackable AFE which can control a minimum of two cells in series, but I did not find a product with such features.

The bq76PL536A has similar features but it works with a minimum of three cells in series.

Best regards

Danilo

0 Roger Hwang over 8 years ago in reply to Danilo Porcarelli37

TI__Genius 10785 points

Danilo,

I am bit confused with your configuration. Is it possible to draw your cell configuration and send it to me? If it's confidential then you can invite me as your friend and we can discuss offline.

0 Danilo Porcarelli37 over 8 years ago in reply to Roger Hwang

Prodigy 45 points

Hello Roger,

sorry for late reply. I can't give detailed description of application in this forum as some specifications are confidential.

What do you mean when you say "you can invite me as your friend"?

Thank you

Danilo

0 Roger Hwang over 8 years ago in reply to Danilo Porcarelli37

TI__Genius 10785 points

Request me as Friend then we can discuss your issue offline.
Click on my name and you will see "request friendship".

I really need to see your cell configuration before I can comment.
Request friendship only if you are willing to share information with me.
This is private so nobody else can see it.

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bq29312A cell balancing