• State Resolved
  • Locked Locked
  • Replies 2 replies
  • Subscribers 64 subscribers
  • Views 625 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

Protection and gas gauge for 5 cell LiPo Battery when discharging

user4359238
Prodigy 90 points
Other Parts Discussed in Thread: BQ76920, BQ78350, BQ34Z100-G1, BQ34110, BQ78350-R1, BQ77905, BQ76200

I am working with a system that uses an off the shelf charger and 5-cell, 4Ah LiPo battery packs. The charger has protection and balancing built in, but the battery packs do not. I'm designing a motor control system that uses these battery packs: http://www.batteryspace.com/powerizer-polymer-li-ion-battery-18-5v-4ah-74wh-30c-w-o-pcb-for-rc-flight----ce-listed-un38-3-passed-ndgr.aspx

I need a gas gauge and protection for the battery during discharging. I looked at the BQ76920, BQ78350 combination for this, but I think it is overkill for my application since I do not require balancing or charge control. I am a bit confused by the other offerings TI has, and I am wondering if there is a more appropriate IC for this application. 

Also, I need some communication back to the MCU indicating faults, charge level, etc. 

  • 0
    TI__Guru 54715 points

    The bq76920 and bq78350-R1 are likely the most integrated and flexible solution. You could use a separate protector such as the bq77905 and gauge such as the bq34z100-G1 or bq34110. Gauging will perform best if cells are well balanced. You could also use a monitor with protection such as the bq76920 with a MCU and your own code, this lets you customize performance but you have to write the code.

  • 0 in reply to WM5295
    TI__Guru 54715 points

    You might look at the bq76200EVM as a guide for the bq76920 and bq78350-R1.  For an MCU implementation the TIDA-00449 may be a starting point and drop the features you don't need.  Both of those are low side switching examples, if you need to reference communication to the pack negative you will want some type of isolation or a high side switch, either P-channel or N-channel with a driver such as the bq76200. As you mention with the monitor, the bq76200 may be overkill since it has charge features.