• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 2 answers
  • Subscribers 62 subscribers
  • Views 616 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.

BQ40Z50-R2: if NR=1, not use the pres pin， do i have a soft smb cmd to remove battery（turn off DSG fet）to load，initiatively？

user5141498
Intellectual 380 points
Part Number: BQ40Z50-R2


deer ti engineer.

                    if NR=1, not use the pres pin， do i have a soft smb cmd to remove battery（turn off DSG fet）to load，initiatively？

                    is there a soft cmd to cut off power to load, and turn on power to load, initiatively.  ?

                    ago, i used the pres pin to control the battery remove, and present,  but if my mcu get a emi, then mcu will wdt reset,  so  my mcu can't ensure  output a low level to pres pin at reset stage before gpio init. right?  i must be sure my mcu reset and keep bq send power to load.

                    

thank you 

  • 0
    TI__Mastermind 42535 points
    this post will be answered after 26th.
  • 0 in reply to Batt
    TI__Mastermind 42535 points
    No, there's no way to actually do it if the NR bit is set to 1. The FETs are automatically controlled by the gauge. Any esd or emi can equally affect the gauge as well as your mcu. You may want to consider the host watchdog setting which might help turn off the FETs in the absence of valid smbus comms.
  • 0 in reply to Batt
    Intellectual 380 points

    deer batt:
    thank you for your reply.
    1. first , i can't turn off FET in the absence of valid smbus comms , maybe it caused by emi , because UAV flying in the air , can't cut off power.
    2. ok，NR=0, use the pres pin to control battery output is ok now. because i have add a external pull down resistor at pres pin， so when my mcu get a emi at UAV flying，my mcu（MSP430） wdt reset , at reset stage ， the gpio of msp430 is input ， so pres pin is pull down by external resistor，this make sure bq to keep DSG FET close (send out of power) continuely. this is ok , i have test it.
    3. when bq get emi , the internal mcu of bq is wdt reset , can it keep the DSG FET close continuely （stay on the state before wdt reset）? if no safety or PF alert, bq code dead by emi

    4.  i have test device reset cmd at full access mode,  the DSG will close transient.  actually this is no problem ,because at seal mode ,this is a invalid cmd.  but i can't test bq wdt reset at seal mode, help me batt, thank you very much

  • 0 in reply to user5141498
    TI__Mastermind 42535 points
    You can actually test wd reset in seal mode, for that you need to spoof an interrupted smbus transmission. The easiest way to do that would be stopping clock when the data line is toggling without actually sending a stop signal. If HWDF is set in enabled protections C, you can detect a host watchdog in the registers.

    I think if you mcu watchdogs, the gauge will have the dsg fet on until the wd reset time.
  • 0 in reply to Batt
    Intellectual 380 points

    deer  batt：

           i have test the （SBS Host Watchdog Protection ） HWDF  enable in sale mode，   stop smb communication， after 10sec （default delay time）， XCHG=1, CHG fet close，  DSG CHG is still on.   

           this result  is same as the TRM description.

           but What I want to confirm is   ：

              For the impact of DSG FET ,  the SBS Host Watchdog  caused bq reset，  is equal to  the EMI caused bq reset？  

             

    thank you

  • 0 in reply to user5141498
    TI__Mastermind 42535 points
    If you are asking if the DSG fet will be turned off, the answer is no. Only the chg fet will be turned off. WD Resets for the gauge however they happen will have the same effect, whether it is because of lack of comms from the system or because of emi induced wd reset. Only the chg fet will be turned off after a wd reset. The fet turns back on after the condition clears.