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BQ76930: Sleep mode issues; TS pin toggle

marc heinemann
Prodigy 70 points
Part Number: BQ76930
Other Parts Discussed in Thread: BQ78350, BQ78350-R1, BQSTUDIO

Hi there fellow engineers, 

I try to bring my board (consisting of a BQ76930 and a BQ78350) to sleep mode. After i disconnected SMBus, the PWRM Pin goes from HIGH Z to LOW after 5s. I guess, thats what happens, when the system goes to sleep mode. The TS1 Pin is toggles each 2 s, no matter what mode is active. I thought, the toggling would get less in sleep mode. 

1. What times determine the toggling time of the TS1 Pin?

2. Can i change those times in BQ Studio?

3. Whats the purpose of this toggling? Does it toggle the pin, when it measures a value?

I think, thats it...thanks in advance!!

regards, Marc

  • 0
    TI__Guru 54715 points
    Hi Marc,
    In sleep mode the bq78350-R1 keeps the bq76930 awake and measuring voltages so that it can have a value available when it needs. The CC is turned off. (1) As part of the voltage measuring the scheduler of the bq76930 measures the temperature every 2 seconds. That is the pulse you see, (3) to save power the TS1 pin is biased only when a temperature measurement is taken. TS2 toggles also on an independent 2 s interval.
    (2) bqStudio does not have an option to disable voltage measurement in sleep mode. You can change the times the voltage is read from the bq76930, but not the operation of the bq76930. For lower power the bq78350 can go to shutdown mode which will require boot to re-start the battery and SOC will be estimated on re-start.