BQ25890: What's the function of REG0A, bit 3

Vio Liu

Part Number: BQ25890

Hi team,

My customer is designing music player with BQ25890. They want to store one byte data when MCU is in power down mode. During MCU power down, BQ25890 is active.(At this time maybe BQ25890 is charging, but BQ25890 can't work in boost mode).

My customer think Reg0A has nothing to do with charging. They would like to store the one byte data into this register, and refres this register to its default value.

Only one concern is that the bit 3 of REG0A is reserved. Could you please help our customer verify whether it is safe to store one byte data, or could this bit be modified by BQ25890 internal circuit?

Thanks!

Best regards,

Vio Liu

over 8 years ago

0 Jeff F over 8 years ago

TI__Guru**** 167286 points

Hi Vio,

Unfortunately that bit resets to default when the charger goes back into standalone mode (i.e. the watchdog timer expires) when the MCU powers down. That would not be helpful, correct?

0 Vio Liu over 8 years ago in reply to Jeff F

TI__Expert 3045 points

Hi Jeff,

My customer didn't use watchdog timer, so is this register useful? If it isn't, could you advice some other registers? Thanks!

Best regards,
Vio Liu

0 Jeff F over 8 years ago in reply to Vio Liu

TI__Guru**** 167286 points

The registers are not intended to be used to store external data. Registers labeled not used may be used for test purposes.

0 Vio Liu over 8 years ago in reply to Jeff F

TI__Expert 3045 points

Hi Jeff,

After verified, my customer need to store only 1 bit. So this reserved bit's status is not cared by customer. Thanks!

Best regards,
Vio Liu

Power management

Power management forum

BQ25890: What's the function of REG0A, bit 3