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ADS8331: Questions about ADS8331.

SY Yoon
Genius 3380 points
Part Number: ADS8331

Hi,

I have some questions.

1. Reserved command

    After the EMC (3.3Hz, 5kV) test, the operation is abnormal, and the register value is changed.

    If an arbitrary value is written to the reserved command (0x8h - 0xAh) in CMR register by EMC test, can there be a problem with the ADS8331 operation?

2. Write CFR in Tag mode.

    I read 24 bits (16bit read data command + 8bit tag) in tag mode. 

    Is the write CFR command also written in 24bits in tag mode?

  • 0
    TI__Mastermind 40950 points

    Hello SY,

    1.  Yes, an arbitrary write to one of these reserved commands can cause abnormal behavior of the device.  If the device gets into this undefined state, the /RESET pin should be asserted to force a hardware reset of the device.  If the EMC event is large enough, there is a possibility of an internal latch-up condition.  If this occurs, the only way to recover is a full power cycle.

    2.  Yes, the CFR command can be written in 24b tag mode.  The first 16 bits will be the CFR write command and the CFR register will be updated on the 16th SCLK falling edge.  After the first 16 SCLKS, SDI can be held low (logic 0) for the remaining 8 SCLKS.

    Regards,
    Keith Nicholas
    Precision ADC Applications

  • 0 in reply to Keith Nicholas
    Genius 3380 points

    HI,

    To solve the problem that an arbitrary write to one of reserved commands, I will try to repeat HW reset every 10 usec.

    ADS8331 converts from IN0 to IN3 and HW reset is asserted after converting every cycle.

    Is there no problem with this method?

  • 0 in reply to SY Yoon
    TI__Mastermind 40950 points

    Hello,

    This method should work.  Please follow the below timing requirements.

    1.  In order to RESET the device, the RESET pin must be held low for a minimum 25nS.

    2.  Communications should be delayed (/CS held high) for a minimum 2uS after RESET is asserted.

    Regards,
    Keith