BQ29200: BQ29200 cell balancing

Alen%2520Chen

Intellectual 2320 points

Part Number: BQ29200

Hi,

I have a question about BQ29200 cell balancing. Could you please explain how does the cell balance circuit work?

The block diagram in the datasheet shows it will short VC1_CB to GND or VDD.

So I think the cell balancing current should be :

ICB1=VC1/RCB

ICB2=(VC2-VC1)/(RVD+RCB)

I don't understand the cell balancing current calculation formula? Could you please explain how to calculate the balancing current.

Thanks!

Alen Chen

over 6 years ago

0 WM5295 over 6 years ago

TI__Guru 54715 points

Hi Allen,
The RCB2 and RCB1 in the equation represent the internal switch resistances which have no values in the electrical characteristics table. This conflicts with the description under the equation and on the simplified schematic component names as you point out.
The internal RCB2 might be typically 250 ohm and the internal RCB1 might be typically 300 ohm.
The data sheet author apparently used the VC pin voltages to derive the cell voltages in the equation and re-used the component names for both internal and external resistors. It is confusing. The external sensing input resistors should not affect the cell balancing.
If I find something different I will post it here.