• State Resolved
  • Locked Locked
  • Replies 4 replies
  • Answers 1 answer
  • Subscribers 64 subscribers
  • Views 829 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.

BQ76920-REGOUT not needed

David Klug
Prodigy 30 points

I'm not needing to use the REGOUT pin and I am also not needing to use this chip as a charger/discharger so I'm leaving CHG and DSG unconnected.  In the datasheet it says that internal functions need the power from the REGSRC pin (Which I have connected to + side of battery).  Can I leave the REGOUT pin completely unconnected or does it need to go to ground(negative side of battery through a capacitor)?  

  • 0
    Prodigy 30 points
    I finally found my answer here.
    www.ti.com/.../sluub41.pdf

    10.25 I will not use the REGOUT voltage from the AFE. Do I still need to supply REGSRC
    and a capacitor on REGOUT?
    Yes, REGSRC and REGOUT are required. REGSRC powers the FET drivers, and REGOUT powers
    assorted internal circuitry, including the communication buffers and coulomb counter. If you are not using
    the REGOUT voltage externally, a capacitor value on the low side of the recommended range should be
    fine. The REGSRC pin should have an approximately 1-µF capacitor.
  • 0 in reply to David Klug
    TI__Prodigy 385 points
    David,

    The capacitor on REGOUT is necessary to stabilize the voltage used internally.

    The device is not a charger/discharger, but a protection device meant to enable and disable the CHG and DCHG FETs. If you're not using this functionality, what is your goal for the use of the device?

    Todd
  • 0
    TI__Expert 6085 points

    Hi David,

    The REGOUT is LDO with the ability to source 20mA at 2.5V or 3.3V( depending on the version of the bq and configured via EEPROM when shipped out from the factory); If <REGOUT> is not to be in used to power any external circuits ( LED, Pullup  source etc), I would suggest using the recommended 4.7uF cap to GND at the pin. This will ensure compliance of the boot-up sequence when the part is commanded from SLEEP to WAKE.

    as per hook REGSRC to  BATT +, please be reminded, the REG SRC is spec from 6-16V with the recommended norm of 12V.

  • 0 in reply to Todd Vanyo
    Prodigy 30 points
    Thanks for your reply Todd. I'm basically going to use it as a battery fuel gage. I chose this ic vs a battery fuel gage ic because I understand the datasheet more(seems better documented to me). Basically alert pin goes to host microcontroller as interrupt for undervoltage alert. Also will read pack voltage to determine how much charge is left until it will need to be charged.