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Original question:

RM48L952: RM48L952_SIL3_JTAG

RM48L952: RM48L952_SIL3_ EXT watchdog

Ganesh VInayagam
Prodigy 170 points

Part Number: RM48L952

Hi,

In RM48L952 MCU we have used External watchdog timer IC (TPS3430WDRCR) this WDO output and Voltage supervisor (TPS3703A7330DSERQ1)  output both together connected to NPORRST W7 pin of MCU is it Right ? Could you please confirm it.

Also How can we handle B14 NERROR pin.

Is it mandatory to connect any where?

Could you please suggest. 

Thanks and Regards,

Ganesh V

  • 0 in reply to Ganesh VInayagam
    TI__Guru**** 200256 points

    One of the first steps in any safety project is to identify your safety requirements at the system level. It could include fault tree analysis, FMEA analysis, etc. to help in identifying how the SYSTEM can fail. Once you identify the failure modes, you then have to determine how to detect the failures and what to do in light of the failures to protect the safety function of the system.

    The nERROR can be used by an external logic to enable/disable relays so that the system can be taken off line if a critical MCU defect is detected (nERROR pin or WD failure, etc). 

    You can connect WD output to one of the MCU reset (nPORRST or nRST). The out of power supervisor should be connected to nPORRST. 

  • 0 in reply to Ganesh VInayagam
    Prodigy 170 points

    Hi,

    I assumed the nERROR pin  used by an external logic to enable/disable purpose if any malfunction occurred in MCU,

    If our application doesn't required that external logic to enable/disable means how can we proceed can we left open ?

    Can we archive the SIL-3 by using external Watchdog timer TPS3430WDRCR and Voltage supervisor TPS3703A7330DSERQ1 ?

  • 0 in reply to Ganesh VInayagam
    TI__Guru**** 200256 points

    For SIL3 application, the nERROR pin should be used somehow. Otherwise how does external component get notification of the severe fault on MCU?

    I don't know about those two parts. Are there safety manual, FMEDA for these two parts? You may get help from your assessors.