BQ27426: Configuration lost when USB is disconnected

Jayden Li

Expert 3265 points

Part Number: BQ27426
Other Parts Discussed in Thread: BQ76942EVM

Hi team,

If I disconnect the USB, would the configuration be lost? Is it normal? Thanks.

Sincerely,

Jayden Li

over 4 years ago

0 Wyatt Keller over 4 years ago

TI__Guru** 105760 points

Hello Jayden,

This is a ROM based gauge, any time the gauge loses power the defaults will be uploaded to RAM from ROM on power up. The MCU would need to re-program the gauge with the Qmax, Ra, design capacity, and other configurations upon initialization.

Sincerely,

Wyatt Keller

0 Jayden Li over 4 years ago in reply to Wyatt Keller

TI__Expert 3265 points

Hi Wyatt,

Thank you for your response!

However, I did not move away the battery, I just disconnected the USB for communication, would it also need configuration again?

Sincerely,

Jayden Li

0 Nick Brylski over 4 years ago in reply to Jayden Li

TI__Mastermind 19195 points

Hi Jayden,

It would not need config again in this case, as long as battery connection remains ok.

Best regards,

0 Jayden Li over 4 years ago in reply to Nick Brylski

TI__Expert 3265 points

Hi Nick,

Thank you for your reply.

However, the configuration lost when our customer disconnected the USB cable when using BQ27426. And I also lost the configuration when disconnected the USB cable of BQ76942EVM, could you help analyze how could this happen? Thanks~

Sincerely,

Jayden Li

0 Wyatt Keller over 4 years ago in reply to Jayden Li

TI__Guru** 105760 points

Hello Jayden,

When you mention USB, do you mean connecting a 5V+ supply on the load/charger terminals of the EVM? If the BAT pin loses temporarily the gauge will lose RAM data, can you monitor the BAT pin while you disconnect the power? As long as the battery is connected the gauge should be powered from BAT and not wipe the config.

Sincerely,

Wyatt Keller

Power management

Power management forum

BQ27426: Configuration lost when USB is disconnected