BQ27520-G4: Mobile products that use an external charger

user6092183

Part Number: BQ27520-G4

Hello,

I have been using the bq27520-G4 in one of our products for several years now (so have experience with the software/tools/processes).
I am now designing a new product and would appreciate some advice on the best fuel gauge chips to meet our needs.

New product information.

a) It couldn't enter relaxation mode because full charge and end-of-discharge conditions without requiring battery relaxation.
b) It may use external charger so it may not enter charge mode.
c) It may use different batteries.

I think that (a) can solve Fast Qmax function.
But I don't have any idea for (b) and (c).

So please answer me some specific questions.

1.If I use an external charger, it can read the accurate RM value?
2.Is there a way to improve the accuracy of the RM value when using it like (b) or (c)?

Shun.

over 3 years ago

0 Nick Brylski over 3 years ago

TI__Mastermind 19195 points

Hi Shun,

Can you explain current charging solution you are using here? Not sure I understand the question 1. Normally host controller will read the RM.

2. Make sure correct chemID is programmed and learning cycle has been completed.

Best regards,

0 user6092183 over 3 years ago in reply to Nick Brylski

Prodigy 200 points

Hi,Nick

I think that RM value cannot be measured accurately when using an external charger.
Because host controller can't measure Passed Charge.
I read slua450.
Qmax=Passed Charge/(DOD1-DOD2).
RM=(DODfinal-DODstart)×Qmax

If after using an external charger or using different battery,the host controller can only read the RM value accurately after discharging for a while?

Regards,

Shun.

0 Nick Brylski over 3 years ago in reply to user6092183

TI__Mastermind 19195 points

Hi SHun,

The gauge measures the passed charge.

Best regards,

0 user6092183 over 3 years ago in reply to Nick Brylski

Prodigy 200 points

Hi,Nick

The RM value read by the host controller may change.
For example,
①Read RM value immediately after inserting a new battery.
②Discharge with a new battery for a while.
③Read RM value immediately after inserting a old battery.
④Discharge with a old battery for a while.
⑤Read RM value immediately after inserting a new battery again.

It is different RM value ① and ⑤.
What do you think is the cause of the change in RM value?

I did do writing CHEM_ID and Learning Cycle.

Regards,

Shun.

0 Nick Brylski over 3 years ago in reply to user6092183

TI__Mastermind 19195 points

Hi Shun,

Can you upload your .gg and logs showing this behavior.

Thanks,

Power management

Power management forum

BQ27520-G4: Mobile products that use an external charger