BQ78350-R1A: Unpowered on an active 5V I2C bus

kevin ludlam

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

Hi,

We have a BQ78650-R1A connected to a 5V I2C bus with other devices. Will the BQ78350-R1A get damaged if it is connected to an active 5V I2C bus but it has no 2.5V going to VCC (due to a dead or disconnected battery)?

Thanks,

Kevin

over 4 years ago

0 kevin ludlam over 4 years ago

Prodigy 30 points

Ooops, that should have been SMBus, not I2C.

Kevin

0 Jessica H. over 4 years ago in reply to kevin ludlam

TI__Genius 11535 points

Hi Kevin,

It shouldn't damage the device.

Best,

Jessica

0 kevin ludlam over 4 years ago in reply to Jessica H.

Prodigy 30 points

Hi Jessica,

That's the answer I was hoping for, but that means something else may have broken my eval module.

I probably should have mentioned this in the original post, but I was running some tests and drained a battery down to the point that the 2.5V to the BQ78350 was off. The I2C bus was still active at the time and when I applied power and the 2.5V came back, I could no longer communicate with the BQ78350. I thought maybe the SMBus pins weren't tolerant of an active bus with no VCC.

Thanks,

Kevin

0 Matt Sunna over 4 years ago in reply to kevin ludlam

TI__Guru* 81034 points

Hi Kevin,

It might be good to try to flash the firmware to the BQ78350 to see if it recovers. This will help determine if it is physically damaged. You can try to load the .srec file in BQStudio on the Firmware screen. I do not expect this to work, but it is worth trying.

The pins should not be damaged since the voltages are within the abs max range.

Best regards,

Matt

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BQ78350-R1A: Unpowered on an active 5V I2C bus