BQ76PL455A-Q1: High current consumtion

Manuel Raeber

Part Number: BQ76PL455A-Q1
Other Parts Discussed in Thread: BQ76PL455EVM

we have a BMS test board based on bq76PL455EVM. Waking up and communication with TI software works fine but the power consumption is far too high.

The current into pin Vdig is around 60 mA. Vdig is 5.2 V.

Is the IC damaged or could there be another reason for the high current consumption?

Thanks for any help!

Manuel

over 6 years ago

0 Taylor Vogt over 6 years ago

TI__Genius 17370 points

Hi Manuel,

Can you please explain the schematic changes from the EVM or send the schematic?

Thanks,

Taylor

0 Andreas Heinzelmann over 6 years ago in reply to Taylor Vogt

Prodigy 10 points

Hi Tayler

Thanks for the quick answer.
In our opinion, we have not made any relevant changes.
The relevant schematic you can find below.
Thank you very much for your support.

Andreas

BMS-Modular-m#1s.pdf

0 Taylor Vogt over 6 years ago in reply to Andreas Heinzelmann

TI__Genius 17370 points

Hi Andreas,

There are several areas that could contribute to this, can you please explain the idea between the VCC to VIO circuitry and what the U51C part is? Please also explain how you measured the current and please take V/I measurements at the other power pins as well.

Thanks,

Taylor

0 Manuel Raeber over 6 years ago in reply to Taylor Vogt

Prodigy 140 points

Hi Taylor,

we have added the V/I information to page 2 of the schematic. COM_HOST is not connected, so P5V is not present.

V5AO drops from 4.5 V to 3.4 V after wake-up. I suppose this is due to the internal connection to VP1.

U51 is an analog switch (SN74LVC2).

Thanks,

Manuel

0 Manuel Raeber over 6 years ago in reply to Manuel Raeber

Prodigy 140 points

BMS-Modular-measured.pdfHere is the schematic..

0 Taylor Vogt over 6 years ago in reply to Manuel Raeber

TI__Genius 17370 points

Hi Manuel,

I think it will be best to remove some of your external circuitry one at time connected to VCC, VP1 and V5VA0 including the analog switch to see what may be loading VDIG. V5VA0 should be 5V or else it is not woken up correctly. And also you say that P5V on VCC is unconnected but then it does not make sense to measure 4.47V at VCC.

Regards,

Taylor

0 Manuel Raeber over 6 years ago in reply to Taylor Vogt

Prodigy 140 points

Hi Taylor,

thanks for your help. We found the main mistake: The protection diodes on COMM+/- and FAULT+/- were reversed.

Best regards,

Manuel

0 Manuel Raeber over 6 years ago in reply to Manuel Raeber

Prodigy 140 points

Hi Taylor,

what is the reason for the costly common-mode filter on bq76PL455EVM? Is it necessary? Is there an application note for the filter design for the COMM and FAULT lines?

And is it possible to receive the source code of the SW-tool "bq76PL455_GUI"?

Thanks,

Best regards Manuel

0 Roger Hwang over 6 years ago in reply to Manuel Raeber

TI__Genius 10785 points

Hi Manuel,

I am sorry that we can't share the SW-tool software.
But, you can find the example code and software references application note in the product folder.
I think you can get good ideas with those files.

thanks

Roger

Power management

Power management forum

BQ76PL455A-Q1: High current consumtion