BQ33100: Cell balancing for super cap with discrete solution vs BQ33100

Wendy Wang1

Genius 11270 points

Part Number: BQ33100
Other Parts Discussed in Thread: LP2998

Hi,

I have two questions about cell balancing of BQ33100.

Should the cell balancing be enabled when the super-cap just starts to be charged or after the voltage of the super-caps reach a threshold?
Our customer wants to use the block diagram(attached below) to realize the cell balancing. Could you please list some pros and cons between this kind of method and our socket bq33100 for the customer?

Thanks&Best regards,

Wenxiu

over 4 years ago

0 Batt over 4 years ago

TI__Mastermind 42535 points

Can you please send us your configuration file

0 Wendy Wang1 over 4 years ago in reply to Batt

TI__Genius 11270 points

Hi Batt,

The schematic diagram is attached below.

Besides, we wish to know is the cell balancing of BQ33100 enabled when the super-caps just start to be charged or after the voltage of the super-caps reach a threshold?

0 Batt over 4 years ago in reply to Wendy Wang1

TI__Mastermind 42535 points

Hi,

The bq33100 uses voltage balancing. So, balanicng starts when the voltage thresholds are met. If they are met at start of charge balancing will start then.

The regulator in your design can reduce power consumption unlike the FETs externa to the default balancing circuit. So, that's a plus. I don't see any direct downsides to it it your voltage thresholds can be maintained.

0 Wendy Wang1 over 4 years ago in reply to Batt

TI__Genius 11270 points

Hi Batt,

Our customer says that the regulator in our design has internal FETs, so what does "reduce power consumption"mean?

Thanks&Best Regards,

Wenxiu

0 Batt over 4 years ago in reply to Wendy Wang1

TI__Mastermind 42535 points

Hi Wenxiu,

It means that the FETs can switch off using the regulator and not have static power dissipation at a high level.

0 Wendy Wang1 over 4 years ago in reply to Batt

TI__Genius 11270 points

Hi Batt,

Excuse me, could you please explain more specifically?

Thanks&Best Regards,

Wenxiu

0 Batt over 4 years ago in reply to Wendy Wang1

TI__Mastermind 42535 points

Hi Wenxiu,

Capacitor balancing here is done by an internal FET. What it does in that case is to bypass the chg from the cap to GND. The bypass circuit is internal to the gauge. It is triggered by a FET which is controlled by fw. That is what I meant.

0 Wendy Wang1 over 4 years ago in reply to Batt

TI__Genius 11270 points

Hi Batt,

Then what about BQ33100? In BQ33100, what controls the FETs? And why its power consumption is higher?

Our customer is really interested in the power consumption. And here below are the datasheets of LP2998 and BQ33100, does what you say have relationship with the leakage current and Ishutdown?

Thanks&Best Regards,

Wenxiu

0 Batt over 4 years ago in reply to Wendy Wang1

TI__Mastermind 42535 points

Hi Wenxiu,

We don't have access to the internal blocks to understand the power consumption of the bq33100. However, leakage current is definitely related to power consumption of device in shutdown.

Power management

Power management forum

BQ33100: Cell balancing for super cap with discrete solution vs BQ33100