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ADS1282-SP: Interruption behaviour after a write register command

Hugo PREVOT
Prodigy 10 points
Part Number: ADS1282-SP


Tool/software:

It is indicated in the datasheet  SBAS691B –MARCH 2016–REVISED OCTOBER 2018 of  ADS1282-SP page 40:

"After a register write operation the ADC resets, resulting in an interruption of 63 readings"

1/ What is the meaning of this interruption ? Not possible to send commands through SPI ? Not possible to acquire values ? What can we do during this interruption ?

2/ Duration of the interruption: 63 readings = 63 / Fdata =~ 16 ms for 4000 SPS ?

3/ Start of the timing is from the end of the last byte of the command ?

  • +1
    TI__Mastermind 48490 points

    Hello Hugo,

    Welcome to the TI E2E community.

    1.  The register values are maintained after a write operation, but the digital filter is reset.  Once reset, there is a settling time required before conversion results are accurate.  This time is t-DR=63 readings, or 63*t-DATA, where t-DATA is the data rate period.

    2.  Yes, you are correct.  t-DR=63/Fdata=63/4000=15.75ms.  Note that 63 is also approximate.  The exact time is specified in the datasheet under pulse-sync timing.

    3.  The specific timing is shown in Figure 46.  At the end of the last byte of the command, the next rising edge of the system clock will be the beginning of the t-DR period.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    Prodigy 10 points

    Hello,

    Thanks for the answers.

    1. "The registers values are maintained" --> So just to be sure, we should not do acquisitions operations in ths phase. But as you say, the register values are maintained, AND it is still ok to perform different commands (READ, SDATAC, SYNC RDATAC, etc) ?

  • +1 in reply to Hugo PREVOT
    TI__Mastermind 48490 points

    Hello Hugo,

    Yes, that is correct.  You can perform other commands during the settling time of the digital filter.  However, if you send another register WRITE, or SYNC command, then this will reset the digital filter again, extending the time needed before the first conversion result is available.

    Regards,
    Keith