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TMS320F28376S: Vregenz not supportet for delfino's

Thomas Struchen
Prodigy 30 points
Part Number: TMS320F28376S

The use of the internal 1.2V is not supportet for delfino. Regardless this requirement we misconfigured the delfino TMS320F28376S by connecting the Vregenz to VSS (board ground). We have never seen any functional problems but we also use not the full internal functionallity. Now i try to figure out if we need a redesign to supply the 1.2V from external or not. Have you some performance datas from the internal 1.2V supply regarding max current, thermal aspects aso. What kind of failure can be triggered through this misconfiguration and which functionalities will be affected? Will the failure trigger the XRSn?

 

  • 0
    TI__Guru* 75800 points

    Thomas,

    I'll have to consult some folks within the team to better understand the limitations here.  I believe that in general the reason this was de-spec'd was that the max current draw of the device over its operational conditions was too great.  This would be mitigated by both device utilization as well as the temperature the device sees(T ambient).

    If you could comment back in parallel the temp range you expect to see in your system it may help bound the constraints a bit more.

    I'll post an update no later than tomm EOD, but hopefully sooner than that.

    Best,
    Matthew    

  • 0
    Prodigy 30 points

    Hi Matthew

    Thank you for the fast reply. The instruments temperature is between 15-30°C. The maximum exposed temperature for the device in our system is around 60°C.

    Hope it helps for further analysis

    best regards

    Thomas

  • 0 in reply to Thomas Struchen
    TI__Guru* 75800 points

    Thomas,

    There's some wiggle room here but I think if you are seeing IDDO current at 320mA or less you should be OK.  The uncertainty I have is that since we are using the VREG we don't know precisely which portion of this is going to the VREG/IDD portion and which is just the normal VDDIO/IDDIO current you would see on this rail if the VREG were disabled.

    I know from past experience the IDDIO load can vary quite a bit depending on what load(s) are on the GPIOs and their switching frequencies.  My point being if that you are over/close to the 320mA we likely have some margin and we can look at some other data points to make a decision.

    I would guess if your Tmax is 60C that you are going to be well under the above; as I mentioned at higher temps leakage currents start to become more a factor to the total allowed current.  If you have current measurements at 60C it would also help solidify this use case.

    In terms of what would happen if we are too high on the VDD/IDD current, your hypothesis is current, in that we would start to droop the supply and eventually trip the on-chip voltage monitors.  In this respect if you aren't seeing any issues thus far(and have some data at temp) we are likely OK.

    Best,

    Matthew