• State TI Thinks Resolved
  • Locked Locked
  • Replies 1 reply
  • Answers 1 answer
  • Subscribers 63 subscribers
  • Views 442 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.

BQ76952: OCD1 & OCD2 Protection using BQ76952

Subhrajit Majumder
Prodigy 110 points

Part Number: BQ76952
Other Parts Discussed in Thread: EV2400

I want to enable the OCD1 & OCD2 protection through the EV2400 on BQ76952. I use 0.0005 ohm sense resistor. 
Unfortunately it only enable for OCD3 protection. Most important: When the OCD3 Protection is triggered the Discharge FET is only OFF, the charge FET is remain ON. I want to OFF both with OCD1, OCD2 & OCD3 protection.

setting2010.gg.csv

  • 0
    TI__Expert 8526 points

    Hi Subhrajit,

    It is not possible to turn both FETs off with OCD1, 2, or 3 protections; however, SCD protection will open both FETs.  Additionally, you can use the DDSG pin or Alert pin output as an interrupt for the MCU.  The MCU can then determine which fault was triggered and open the CHG FET if it was OCD1, 2, or 3.  You can accomplish this through either the CFETOFF or BOTHOFF command.

    To answer your second question: there could be several reasons why your OCD1 and OCD2 protections are not triggering.

    1) The CC Gain for your system is showing a value of 0.454 mOhms, although you stated that you are using a 0.5 mOhm sense resistor.  With the 0.5 mOhm sense resistor, the fault will trigger at 8 A, but with the 0.454 value, it will trigger around 8.8 A.  This is a significant discrepancy and could be causing your problems.

    2) Your Vcell Mode setting shows that you shorted the top cells together.  This may be indirectly causing system issues.  For the BQ76952, the top and bottom cell connects need to have a cell connected.  The EVMUG has more information in Section 4.5 Reducing the Cell Count.  I will attach a link here: BQ76952EVM User's Guide (Rev. A) (ti.com).

    I hope this helps!

    Best,

    Andria