• State TI Thinks Resolved
  • Locked Locked
  • Replies 5 replies
  • Answers 2 answers
  • Subscribers 63 subscribers
  • Views 273 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.

BQ78350-R1: Charging circuit design

user
Intellectual 255 points
Part Number: BQ78350-R1
Other Parts Discussed in Thread: BQ78350, BQ76930,

AFAIK the BQ78350 provides only recommendations for the charging voltage and current based on various factors and the requires a separate circuit to enforce the same.

Does Ti recommend a internal charging circuit on the BMS or a external circuit on the charger? What are the advantages and disadvantages of both designs? Are there any reference designs for smart charging circuits?

Assuming a design where the smart charging circuit is on the charger, would the charge protections FETs open if a dumb charger which provides a higher voltage or current than recommended is connected?

  • 0
    TI__Guru* 81034 points

    Hi, 

    Yes, that is correct that the BQ78350 only provides recommended charging voltage and current and this information can be used by a smart charger or MCU. 

    Since your question is concerning the BQ78350, it has been assigned to the gauging product experts. I'll get this post reassigned to our charging IC experts.

    There are lots of charger reference designs available here: http://www.ti.com/power-management/battery-management/charger-ics/reference-designs.html

    This site has several training videos on TI charger ICs including a video on selecting the right IC for your application: http://www.ti.com/power-management/battery-management/charger-ics/support-training.html

    Best regards,

    Matt

  • 0 in reply to Matt Sunna
    Intellectual 255 points

    Hi Matt,

    Thank you for reassigning it to the proper forum. Can you please answer the later part of my question?

    Assuming a design where the smart charging circuit is on the charger, would the charge protections FETs open if a dumb charger which provides a higher voltage or current than recommended is connected?

  • 0 in reply to user
    TI__Guru* 81034 points

    The recommendations in the charging section of the data flash will not cause the protection FETs to switch. The FETs would switch based on the Protection settings only for the BQ76930 and BQ78350-R1. 

    Matt

  • 0 in reply to Matt Sunna
    Intellectual 255 points

    Let's the temperature of the battery is outside of its optimal range. In this case the charging current will be less than the usual current. The BQ78350 gives recommendations based on the temperature. If the pack is connected to the smart charger, the charger should adjust the current to the recommended value. But, if it's connected to a dumb charger, it won't be able to adjust the current accordingly which can affect the battery pack. I am trying to tackle this problem. Can I use a microprocessor to get the recommended current from the BQ78350 and the drive the CHG FET accordingly? The FET must be able to be controlled by both the BQ78350 and the microprocessor.

  • 0 in reply to user
    TI__Guru* 81034 points

    The MCU can also read the recommended current from the BQ78350 and use this information to control the charge parameters if it is able. However, opening the CHG FET is not the right thing to do in this case since this will completely disable charging instead of lowering the current.