BQ34Z100: The response of reading the current is slow

sherry yang

Prodigy 240 points

Part Number: BQ34Z100
Other Parts Discussed in Thread: BQ34110

Our customer find that the response of reading the current is slow. It may related to the sleep mode of BQ34Z100.

How to improve it?

over 6 years ago

0 Batt over 6 years ago

TI__Mastermind 42535 points

Hi Sherry,

By default the wake comparator is enabled and should wake up the device as soon as it's thresholds are met. Please see TRM chapter 6, section 6.2. If you have changed it, please set RSNS1, RSNS0 to 01 and IWAKE to 0. You can also choose to disable sleep.

0 sherry yang over 6 years ago in reply to Batt

Prodigy 240 points

Current sensing resistor is six 3mΩ resistors connected in parallel. When use 1A to discharge(or charge), need 10s～15s to read the current.

Have set RSNS1, RSNS0 to 01 and IWAKE to 0.

0 Batt over 6 years ago in reply to sherry yang

TI__Mastermind 42535 points

Hi Sherry,

You cannot put sense resistors in parallel. This device is designed for use with a 10mOhm sense resistor.

0 sherry yang over 6 years ago in reply to Batt

Prodigy 240 points

Hi Batt,

It is not practical to use a resistance of 10MOHM. A continuous current of over 100A will pass through the PCBA board. Is there any other method to slove it?

I think maybe we can use small sense resistor to sample large current and use big resistor to sample small current. Can this be realized and how to realize? Thanks!

0 Batt over 6 years ago in reply to sherry yang

TI__Mastermind 42535 points

Hi Sherry,

From my discussions with hw, it is not feasible. The design was not meant to use such resistors in parallel. I'm afraid for the device we don't have solutions as it's design limited.

0 sherry yang over 6 years ago in reply to Batt

Prodigy 240 points

Hi Batt,

OK, thanks!

Could you help recommend a part to replace it? Is BQ34110 OK?

0 Batt over 6 years ago in reply to sherry yang

TI__Mastermind 42535 points

Hi Sherry,

No. You will run into the same issues with the sense resistor there.

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BQ34Z100: The response of reading the current is slow