• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 30 subscribers
  • Views 1045 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.

TMS570LC4357: Out of Recommended Operating Condition Behabior

matusan
Guru 10235 points
Other Parts Discussed in Thread: TMS570LC4357

Hello, TI Experts,

 

Our customer starts to design prototype board based-on TMS570LC4357-EVM(TMDX570LC43HDK).

They also design external circuit for protecting reset and power domain failure.

(ex: Regulator-IC broken case)

 

So, They sent  us questions about  out of Recommended Operating Condition(Vcc)specification

behavior and functional safety MCU design concept  for Hercules(TMS570LC4357) .

 

Their understanding is as follows based on datasheet(SPNS195C);

   6.2.2 Voltage Monitor Operation

      "  Voltage monitoring thresholds : VCC-high {max2.1V,min1.4V} , VCC-low {max1.13V, min 0.75V}".

   So, As Functional Safety MCU, TMS570LC4357 all functions are  guaranteed and work properly from 0.75V to 2.1V.

     

Is their understanding correct?

 

If some restrictions exist, please tell us the restrictions with TMS570LC4357-MCU design concept

from a point of view of Functional Safety.

 

Best regards,

  • 0
    TI__Guru**** 191266 points

    Hi,

      The internal voltage monitor only provides a very gross check of the power supply as you can see the range is quite wide from 0.75V to 2.1V. Please refer to the Device Recommended Operating Conditions where the Vcc max is limited to 1.32V beyond which the behavior of the MCU is not guaranteed. You must have have an external voltage supervisor to monitor and limit power supply within the recommended operating range. The internal voltage monitor is not replacement for the external voltage supervisor. 

  • 0 in reply to Charles Tsai
    Guru 10235 points
    Hi, Charles

    I really appreciate your help.
    I sent this answer to the customer.

    Then, our customer requests to explain the purpose of the internal Voltage Monitor(VMON).
    I would appreciate if you tell us more detail explanation of recommended use case of VMON.

    Best regards
  • 0 in reply to matusan
    TI__Guru**** 191266 points
    Hi,
    The internal Voltage Monitor ensures that the device is in reset until both the core and I/O power rails reach their threshold for proper operation. It alleviates any ramp up dependency between the core and I/O supplies.
  • 0 in reply to Charles Tsai
    Guru 10235 points
    Hi, Charles

    Thank you for your prompt reply.

    Regarding out of Recommended Operating Condition Behavior,
    our customer sent us additional request to explain about the device damaged/broken VCC limit.
    The device damaged/broken VCC limit is
    Absolute Maximum Ratings=1.43V
    or
    Voltage monitoring thresholds=2.1V

    Best regards,
  • 0 in reply to matusan
    TI__Guru**** 191266 points
    Hi,
    The absolute maximum as listed in the datasheet is 1.43V beyond which the silicon can potential damage. Certainly you should never operate at this or close to this voltage at all. This is why you must have an external voltage supervisor to ensure the voltage does not go beyond the recommended operating range which is 1.32V. As I mentioned the internal voltage monitor provides a very gross check (i.e. 2.1V) which should never be used to replace an external supervisor.
  • 0 in reply to Charles Tsai
    Guru 10235 points
    Hi, Charles

    I really appreciate your help.
    This information is very helpful!

    Best regards