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TMS320F28027: Errata sheet issue

Federico Lucchini
Prodigy 30 points

Part Number: TMS320F28027

Dear Texas,

we need some help regarding the following points of errata sheet "TMS320F2802x, TMS320F2802xx MCUs Silicon Errata (Rev. S)":

ADC: DC Specifications: Linearity Limitation 

What are the performance characteristics with an ADC clock of 40 MHz? On the document SPRS523P we find only the value for ADC clock <= 30MHz

ADC: ADC Result Conversion When Sampling Ends on 14th Cycle of Previous Conversion, ACQPS = 6 or 7

Is this issue also present when we use a different channel for each acquired measure? In our system, we start the acquisition of four measures every 125 µs, and each measure has its own dedicated ADC channel. 

Memory: Prefetching Beyond Valid Memory 

In FLASH memory, are constants considered as code? In RAM memory, are variables considered as code? 

Thank you very much!

Federico

 

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  • 0
    TI__Intellectual 2070 points

    Hi, 

    Please expect a delay in response as the expert may be out-of-office due to the holidays.

    Kind regards,
    AJ Favela

  • 0 in reply to AJ Favela
    TI__Expert 6020 points

    Hi Federico,

    The ADC can be clocked up to 60 MHz on 60-MHz devices, but the published DC accuracy specs (INL/DNL) are only guaranteed/characterized at ADCCLK ≤ 30 MHz in the data manual.

    Regarding “ADC Result Conversion… ACQPS = 6 or 7”, no, this errata is not channel-dependent. It is a timing alignment issue that can occur when the sampling phase of the next conversion ends on the 14th ADCCLK cycle after the previous sampling ends, and the errata states this can occur only for ACQPS = 6 or 7.

    You can simply avoid ACQPS = 6 or 7 (use any other value), or Enable ADCNONOVERLAP, which prevents the condition from occurring.
    Regarding “Prefetching Beyond Valid Memory”, in this errata, code means executable instructions being fetched by the CPU. The CPU prefetches ahead (queue depth 8 * 16-bit words) and can fetch beyond valid memory, potentially seeing an invalid opcode. So constants in flash are data, not code, unless you’re actually executing from that region. And variables in RAM are data, not code unless you’re running code from that RAM region. Just do not place executable code within the last 8 words of the end of any valid memory block (flash/OTP/SARAM).

    Best Regards,

    Masoud

  • 0
    Prodigy 30 points

    It is all clear!

    Thank you very much.

    Federico