BQ78350-R1A: How to have automatic control?

jan stappers

Part Number: BQ78350-R1A
Other Parts Discussed in Thread: BQ76940,

Dear,

We use the BQ76940 in combination with BQ78350-R1A, we can controll the discharge and charge mosfets manually when we set fet_enable to low. But if we set fet_enable to high, then the BQ78 should do it all automatically right? it is not clear to us in the reference manual what else should happen to have it work autonomous. Can someone point us in the right direction?

None of the PF flags are active:

Best regards,

Jan

over 2 years ago

0 Caleb Perez over 2 years ago

TI__Genius 11315 points

Hey Jan,

Yes, if the FET_EN bit is high then the firmware will control the FETs during charging. Any recovery from a fault would have to be handled by the host.

Thanks,
Caleb

0 jan stappers over 2 years ago in reply to Caleb Perez

Prodigy 150 points

Hi Caleb,

As you can see fet_en is high, but the outputs are still low. But we don't see any fault conditions.

Best regards,

Jan

0 Caleb Perez over 2 years ago in reply to jan stappers

TI__Genius 11315 points

Hey Jan,

Do you mind sending me your .gg file? You can export your settings by clicking the export button on the data memory page.

Thanks,
Caleb

0 jan stappers over 2 years ago in reply to Caleb Perez

Prodigy 150 points

Hi,

Here you go!

link to click here for gg-file, couldn't find it to post directly here.

Best regards,

Jan

0 Caleb Perez over 2 years ago in reply to jan stappers

TI__Genius 11315 points

Hey Jan,

I tried loading your config file but it seems to be the wrong format. Can you export your settings again and make sur it has the .gg.csv extenstion?

Thanks,
Caleb

0 jan stappers over 2 years ago in reply to Caleb Perez

Prodigy 150 points

Hey Caleb,

I've added a gg.csv too now (same link as before).

Best regards!

+1 Caleb Perez over 2 years ago in reply to jan stappers

TI__Genius 11315 points

Hey Jan,

How is the PRES pin tied? It should be tied to VSS if you're not using it.

We tested your settings on an EVM and the FETs are operating normally.

Thanks,
Caleb

0 jan stappers over 2 years ago in reply to Caleb Perez

Prodigy 150 points

Hi,

There is a pull down and the pin also goes to the MCU, but that one is also low.

Best regards,

Jan

0 jan stappers over 2 years ago in reply to jan stappers

Prodigy 150 points

Hi Caleb,

Our firmware engineers took another look at this and it seems that there was something wrong with the software configuration of that pin. at this moment it looks resolved, but we have to further investigate this. We will confirm this later.

Follow up question, at the end of the charge cycle, is there a way to see if balancing is active at that moment. We know that there is a register (BAL_OK), which shows that if it is necessary balancing is possible. Is it possible to see if balancing is happening at that moment?

Best regards,

Jan

+1 Caleb Perez over 2 years ago in reply to jan stappers

TI__Genius 11315 points

Hey Jan,

There is a Cell Balancing status bit in the OperationStatus 0x0054 command. See section 17.2.38 of the technical reference manual. https://www.ti.com/lit/ug/sluuc78/sluuc78.pdf?ts=1658249029078&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FBQ78350-R1A

Thanks,
Caleb

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

Power management

Power management forum

BQ78350-R1A: How to have automatic control?