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ADS8924B: About SDI

Qi Liu
Intellectual 2610 points
Part Number: ADS8924B

Hi, support team

My customer has the questions as follow:

If I do not set the register through SDI, could I also use the AD function in the initial state?
Or do I have to configure some registers through SDI before AD conversion?

Thanks so much.

Best regards,
Yuki

  • +1
    TI__Mastermind 37680 points

    Hello Yuki,

    Yes, you can use the ADS8924B without writing to any of the internal registers by connecting the SDI pin to ground (LO).  In this case, the ADS8924B will interpret the SDI input as a NOP (No OPeration) command, and will output the latest conversion result on the SDO pin.

    You will be limited to the power-up default settings, such as SPI-00, single SDO mode, and so forth.  Also note that the input offset voltage specification assumes the use of a 5V reference when using the default power-up setting.  For different reference voltage values, you would normally update the OFST_CAL register, but in your case, you cannot change this value.  You can still use the ADS8924B with a reference voltage less than 5V and not update this register, but the Input Offset Error specification may not be met.  However, if the customer does a system level offset calibration, then this error will be calibrated at the system level and will not be a concern.

    I hope this is clear!

    Regards,
    Keith Nicholas
    Precision ADC Applications