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ADS8556 / data output when CONVST_x is fixed

Masanori Tachibana
Genius 5350 points
Other Parts Discussed in Thread: ADS8556

Dear support team,

Our customer is studying ADS8556 now.
I got some questions regarding ADS8556 from the customer.
So please advise me about it.

[Question]

1. If CONVST_x is fixed to ‘Hi’ after starting AD conversion with switching CONVST_x from ‘Lo’ to ‘Hi’,
what data will be output after enabling RD and CS?
I think that the last result of AD conversion will be output. Is it correct?

2. If CONVST_x is fixed to ‘Lo’ after AD conversion is completed normally in the previous cycle,
what data will be output after enabling RD and CS?
I think that the result of AD conversion of the previous cycle will be output. Is it correct?

Best regards,
M. Tachibana

  • 0
    TI__Expert 3785 points

    Hi Tachibana-san,

    You can keep CONVST_x either high or low during data read, after the conversion was completed successful.
    Please see figure below,

    Regards,
    Rahul

  • 0 in reply to RahulVK
    Genius 5350 points

    Dear Rahul-san,

    Thanks for your advice, and I'm sorry to my late reply.

    My explanation was insufficient.
    My question is as follows,

    1. If CONVST_x is kept to ‘Hi’ after starting AD conversion with switching CONVST_x from ‘Lo’ to ‘Hi’,
    what data will be output after enabling RD and CS?
    I think that the last result of AD conversion will be output. Is it correct?

    2. If CONVST_x is kept to ‘Lo’ after AD conversion is completed normally in the previous cycle,
    what data will be output after enabling RD and CS?
    I think that the result of AD conversion of the previous cycle will be output. Is it correct?

    Best regards,
    M. Tachibana

  • 0 in reply to Masanori Tachibana
    TI__Expert 3785 points

    Hi Tachibana-san,

    Case 1 - If CONVST_x is kept to ‘Hi’ after starting AD conversion with switching CONVST_x from ‘Lo’ to ‘Hi

    The previous conversion result will be available when CS/RD are pulled low.

    Case 2 - If CONVST_x is kept to ‘Lo’ after AD conversion is completed normally in the previous cycle

    The previous conversion result will be available when CS/RD are pulled low.

    As shown in Figure 2, the CONVST signal is a don't care when the read operation is inititated after a successful conversion.

    Regards,
    Rahul