Bq20z45R-1 conflicts with bq24610?

Wally Lowry

Other Parts Discussed in Thread: BQ24610, BQ20Z45-R1

We’re planning on using the bq20z45r-1 fuel gauge IC in our design. The bq20z45r-1 has a “pre-charge” feature that can be used to limit charge current under certain conditions.

We are also considering using the bq24610 as the charge controller IC. The bq24610 also has a “preconditioning” mode, where it also limits the charge current.

With both ICs having their own low current charge control mode. Can this cause any issues or conflicts? Is there any reason that the transitions might not behave well? I understand that both units will not change from one mode to another at the same time.

Any precautions that I need to be aware of with this approach?

Thanks,

Wally

over 15 years ago

0 BatteryBorne over 15 years ago

TI__Intellectual 1430 points

bq24610 is a stand alone charger and will not communicate with the battery management IC. it will manage the voltage and current with no digital feedback from the pack.

bq20z45-r1 needs to communicate with a SMBus charger to manage charge current and voltages

0 Wally Lowry over 15 years ago in reply to BatteryBorne

Prodigy 230 points

BatteryBorne,

Thanks for the reply. I believe our plan will be to use the bq24610 to control the precharging and charging voltage and current, we desire the stand alone feature.

We will also disallow the bq20z45-r1 to control the precharge current by connecting the PMS pin to Vss. It would have been good to have seen this type of arrangement in the data sheet.

Thanks,

Wally

0 ken thompson over 14 years ago in reply to Wally Lowry

Intellectual 630 points

Wally,

I think the data sheet has a typo in regards to the PMS for disabling precharging.

Vss is 0v. One ties PMS to enable precharging control. I think PMS needs to go high to disable precharging.

0 ken thompson over 14 years ago in reply to ken thompson

Intellectual 630 points

Well maybe there is some confusion as to what allowing precharge means. If PMS is low that disables use of the CHG fet. Does this imply that a separate Zero volt FET, and resistor, is needed? Does this also mean that without the zero volts FET is PMS required to be tied high?

What if we do not want zero volt charging? Tie PMS low and leave out the zero volt FET?

0 Wally Lowry over 14 years ago in reply to ken thompson

Prodigy 230 points

I have working prototypes now. We have PMS tied low and don't have a precharge FET. The bq24610 handles the precharge and charge current. The charge and dscharge FETs still work in their safety capacity (over temp, over current,...).

0 ken thompson over 14 years ago in reply to Wally Lowry

Intellectual 630 points

Wally,

Now I am confused. We have PMS tied HIGH on our prototype (without the 0V FET and the 24620 handling all charging). Ours is working OK too.

Power management

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Bq20z45R-1 conflicts with bq24610?