• State
  • Locked Locked
  • Replies 4 replies
  • Subscribers 64 subscribers
  • Views 1094 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

switch on/off BQ76940 with BQ78350

Armin
Intellectual 290 points
Other Parts Discussed in Thread: BQ76940, BQ78350

hello everybody,

i want to realize a bms with an bq76940 and bq78350 for a battery powered device. i also want to use an µC witch should be connected with the bq78350 via sm-bus to use some data from the two bq-ICs and witch is power by regout of bq76940. i want to power the bq78350 with the regout of the bq76940 as well. i only have one magnetic switch on my device for power on and off the described system. if my device is not in use the system has to be in ship-mode(bq76940) and in sleep-mode(bq78350) to reduce power as much as possible.is it possible to switch on and off the system with only one switch? if yes what pins on the bq-ICs i have to connect with that switch? this is not really clear to me!

 thanks  a lot

armin

  • 0
    TI__Guru 73830 points
    Armin,
    If you place the bq76940 in shutdown, then the REGOUT will drop and the bq78350 will not be powered. It will be in shutdown as well and not sleep mode.
    Tom
  • 0 in reply to ThomasCosby
    Intellectual 290 points
    hello Tom,

    oh yes of course. sorry for my bad question.
    the only one way i can see now is to power the bq78350 and my µC with an seperate step-down ic and put both bq78350 and bq76940 into sleep or normal mode with my µC right. sorry i am a very beginner with this topics!

    i have a nother question:
    is there a good way to use only the bq76940 with the bq78350 without my µC with my one magnetic switch. could i use the gpio on the bq78350 as input for my switch to wake the system (bq76940 and bq78350) up and put into sleep mode as well? i cant find some information about this.

    thaks a lot
    armin
  • 0 in reply to Armin
    TI__Guru 54715 points

    It seems your independently powered uC might boot the bq76940 which would power the bq78350.  At shutdown the uC would tell the bq78350 to shutdown through SMB.  Powering the bq78350 without the bq76940 may be a bad idea since current consumption will increase as it spends its time trying to find the bq76940.

  • 0 in reply to WM5295
    Intellectual 290 points

    Hello Thomas,

    ok. Thanks a lot. I will try this.