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TPS65381A-Q1: WDT fail by device/ by temperature

KANJI SHIBATANI
Mastermind 6205 points
Part Number: TPS65381A-Q1
Other Parts Discussed in Thread: TPS65381-Q1,

 

Hello

 

My customer is evaluating TMS570LS0704 and TPS65381-Q1 for FY19 atutomobile.

They had made 30 sets, but 5set has problem.

 

Problem:

After Power ON, WDT_FAIL_COUNT reaches 7. ENDRV goes Low

: 5sets ==> Re-sychronize should be perfomed.

 

After Power ON, everything is Okay. 

: 15sets.

 

*Customer's Software is same.

*The problem likely to occur when ambient temperature is below minus 10 degree-C.

Question 1 from customer

Would you please advise the cause ?

If it is depends on internal circuit of TPS65381-Q1,would you please which portion may have problem?

They  guess any internal oscillator something is fail depends on device/ temperature but can not be observed from externally.

 

Question 2 from customer

Customer is evaluating TPS65381-Q1. ( not -A )

Do you think to change device to TPS65381A-Q1 is helpfully?

Is it no-meaning?

 

With My Best Regards

  • 0
    TI__Mastermind 20590 points

    Hi Shibatani-san,    

    For all new designs the TPS65381A-Q1 should be used.  The datasheet for the TPS65381A-Q1 also has many updates and clarifications on how the device operates so it is recommended to use it:  http://www.ti.com/lit/gpn/tps65381a-q1  The TPS65381-Q1 datasheet is in change management sign off and will be updated shortly with the same changes.

    However the differences between the devices will not explain what the customer is seeing, this device is in high volume production and we have not see temperature dependencies outside the specified range so I suspect it is they have either set the timing too close to the margin of either the TMS570 and its clocking or the TPS65381(A)-Q1 and its timing so they are already close to being out of range at normal and higher temperatures and then the slight reduction in temperature pushes system timing a little bit and it falls apart.  

    Please find attached a spreadsheet that can help the customer check the way they have configured the TPS65381(A)-Q1 watchdog and they can put timing margin from the MCU system in to make sure how they have configured both the TPS and the MCU should provide "good events" all the time.  This spreadsheet also has some graphics explaining where all the timing margins are for the TPS65381(A)-Q1 so the customer can make sure the timing of the MCU will send either the trigger events or answers at the right time.

    2017-06-13 tps65381-wd-clock-tolerance-calculation.xlsx

    Best Regards,

    Scott

  • 0 in reply to Scott Monroe
    Mastermind 6205 points

    Dear Scott san

     

    Thank you for your answer quickly!

    Is there any errata / PCN from transition from TPS65381-Q1 to TPS65381A-Q1 ? ( customer inquires .)

    I will suggest customer to use TPS65381A-Q1, but  I don't find any errata/PCN yet.

     

    Thank you and with my best regards

     

     

  • 0 in reply to KANJI SHIBATANI
    TI__Mastermind 20590 points

    Hi Shibatani-san,

    The PCN is in process for the TPS65381-Q1.  It should be sent to customers who purchased any TPS65381-Q1 in the past, hopefully within the next two weeks.  The same datasheet changes were made to an up coming revision for the TPS65381-Q1 datasheet so when it releases to www.ti.com the customer can see the revision history and it will also be in the PCN.  Since TPS65381-Q1 is NRND, we recommend all new designs start with TPS65381A-Q1.  From an electrical and functional viewpoint there is no difference between them on the PCN and new datasheet have been released.

    Attached is an overview of the changes for your and the customers information.

    2017-06-01_TPS65381-Q1 Rev F to G and TPS65381A-Q1 datasheet revision history.pdf

    Best Regards,

    Scott