BQ76952: Discharge FET opening after about 6 seconds

Kyle Garland

Part Number: BQ76952

Hi all,

I am working on switching from SPI to I2C and am running into a few interesting errors. I am using the same RAM settings that have been in production, the same schematic that hasn't changed for 6+ months, just only switching from a SPI based BQ driver to I2C.

I sent our command to close the FETs and I noticed the Discharge FET was opening up after about 6 seconds. There are no faults, no safety alerts, the device is unable to enter sleep, it is at nominal conditions, and no current. The charge FET stays closed, but the Discharge FET opens up. Is there any reason that this could happen? The DDSG pin is asserted after 6 seconds which means the chip thinks it shouldn't be allowed to close the FET.

Thanks,

Kyle Garland

over 2 years ago

0 Luis Torres over 2 years ago

TI__Expert 3425 points

Hi Kyle,

Can you elaborate on how this switch was done? Are you simply dropping in a different part variant of the BQ76952?

If you have simply replaced the device with a different version can you comment on what the old part# was vs the new part# being used?

Best,

-Luis Torres

0 Kyle Garland over 2 years ago in reply to Luis Torres

Prodigy 70 points

By switch, I just mean we are moving from a SPI driver to an I2C driver, so just writing a new communications driver for the BQ. The part number boots into I2C mode (0x00), and then I OTP changing it to I2C w/ CRC (0x11).

0 Luis Torres over 2 years ago in reply to Kyle Garland

TI__Expert 3425 points

Hi Kyle,

Are you able to provide your exact command sequence from the start up to when you begin seeing the behavior you have previously described?

Best,

-Luis Torres

Power management

Power management forum

BQ76952: Discharge FET opening after about 6 seconds