BQ29209: Balance current for external circuit

Beginner

Part Number: BQ29209

In page 14 of DS, it mentioned the balance current for external circuit. I am confused if the equation is simplifed or not.

Need you comments to provide more detail for Icb1 and Icb2 in exnteral circuit.

over 7 years ago

0 Vish Nadarajah over 7 years ago

TI__Expert 6085 points

when VC2 is ON for BALANCING, the current comes from the VDD. Here is the path ICB1 and ICB2 for the cell configuration.

0 Beginner over 7 years ago in reply to Vish Nadarajah

TI__Intellectual 2261 points

Hi Vish,

What I need to put more comments is Fig.11 in DS. I am confused the equation of balance current.

0 Vish Nadarajah over 7 years ago in reply to Beginner

TI__Expert 6085 points

yes, thanks for the feedback.

0 Andreas Weber38 over 7 years ago in reply to Vish Nadarajah

Prodigy 60 points

Vish, your calculation for the balancing current makes much more sense than the one in the datasheet:

For me it makes absolutely no sense why RCB1 and RBC2 should influence the balancing current. As far as I see they are only for the RC low-pass filter for the comparators.

Can you confirm, taht the formula in the datasheet is wrong? And what do you expect for RGS_ON (Rint in your image)? 150mOhm?

Edit: The error has been introduced between Revision A (September 2010) and Revision B (December 2014)

Edit2: And for the record: between RevB and RevC the Mosfet Type for external cell balancer changed from enhancement type to depletion type (I guess Rev.C is wrong here, right?)

Thank you, Andy

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BQ29209: Balance current for external circuit