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TMS320F28075: Internal Oscillator stability

Mir Hossein Ghoreishi
Intellectual 490 points
Part Number: TMS320F28075

Hello,

On other Picolo devices with internal oscillator like F2806x or F2803x, the Frequency drift over temperature and voltage were indicated in the datasheet.

I noticed the initial accuracy in F28075 is specified to be 0.1% which is great. But I do not see the drift values for this device.

Here I have 3 questions:

1) What is the frequency drift over temperature and voltage for F28075?

2) Does the "Oscillator Compensation Guide Application Report SPRAB84" valid for F28075?

3) Is there any migration guide available for those who have experience on previous devices to highlight the new features and differences?

With regards,

MHG

  • 0
    TI__Guru 60865 points
    Hi Mir,

    (1)The frequency drift is specified as 9.7MHz to 10.3MHz, so +/-3% over conditions.

    (2)This method is not valid for this device.

    (3) For the oscillator, or in general? In general, you can look at the peripherals guide. This will give an idea of what peripherals have changed and what the high level changes are.

    www.ti.com/.../spru566l.pdf
  • 0 in reply to Devin Cottier
    Intellectual 490 points

    Hello Devin,

    Thank you for your reply.

    Previous devices of Piccolo family when the compensation applied have +/-1% frequency stability.

    Is there any procedure to compensate this device to have at least similar performance?

    Can you please address this +/-3% value in the datasheet?

    It would be a big disadvantage for a new device of this family to perform in lower spec.

    By migration guide I mean something like SPRAB40C, that was a very helpful and small document when we migrated from F2808/9 to F26035/069.

    MHG

  • 0 in reply to Mir Hossein Ghoreishi
    TI__Guru 60865 points
    Hi Mir,

    Yeah, for these new devices the accuracy is +/-3%. This is better natural accuracy, but there isn't a way to compensate further to get the accuracy to 1% like was possible on some previous Piccolo series devices.

    We don't have a migration guide similar to SPRAB40C.
  • 0 in reply to Devin Cottier
    Intellectual 490 points
    Hello Devin,
    I still can not find +/-3% value in datasheet.
    A degrade from previous devices is a big surprise and disappointment.
    I need the detailed curves of internal oscillator's frequency drift by voltage and temperature to specify the operation condition with +/-1% limit of frequency error.

    In many SCI applications, +/-3% tolerance for baud rate is not acceptable, specially in a device with 4 SCI ports. This parameter should be clearly indicated.

    With regards,
    MHG
  • 0 in reply to Mir Hossein Ghoreishi
    TI__Guru 60865 points

    Hi Mir,

    The tolerance is specified here:

    Of the 3%, the supply voltage accounts for approximately 0.2% of the worst-case drift.  The rest is based on temperature.  This module does not have a linear temperature drift.  The worst case will be at -40C and the second worst case will be somewhere between 30C and the maximum rated temperature.