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RM48L530: Clarification on undervoltage requirement of RM48 core in SIL application

Tom Schultz
Expert 4140 points
Part Number: RM48L530
Other Parts Discussed in Thread: TPS65381-Q1

Team,

I'm posting this on behalf of my customer:

"We are using the RM48 processor in a SIL application, we need to implement voltage supervision. I was working on the undervoltage supervision for the core voltage and I implemented it with a device which combines a watchdog with an undervoltage monitor. This turns out to be quite tricky since the nominal core voltage of the RM48 and the lower limit of the core voltage range of the RM48 are extremely close, especially if you consider also the regulator’s accuracy.

Can you tell me if the 1.14V is the very lowest absolute threshold for the undervoltage monitor on the RM48 for functional safety applications?

Or in other words; how critical is it for SIL when the undervoltage has a minimum warning level at 1.10V instead of 1.14?"

Thanks,

Tom

  • 0
    TI__Guru 59540 points
    Hi Tom,

    I understand that the tolerance on the Vcc supply is very tight however, it is critical to device operation that any external monitor assert reset if the voltage drops below 1.14. In essence, we cannot provide any evidence that the CPU will behave properly if the voltage drops below the 1.14 spec limit. In regard to SIL applications this would be critical since if the CPU operation is indeterminate below 1.14, then the protection of the safety function would then be indeterminate. I am sure there are Vmon devices out there that can meet this spec, although I can't sight any specific device other than our companion device TPS65381-Q1 that many of our customer use. If this isn't a possible solution for you, let me know and I can check with our more hardware-centric apps guys for other suggestions/possibilities.