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ADC12D500RF / about Addr; 5h Calibration Values

Ryuji
Guru 20090 points

Other Parts Discussed in Thread: ADC12D500RF, ADC12D1800

Hello,
 
Please let me know about ADC12D500RF calibration values.
 
(1)
Our customer read 0xFFFF of Addr: 5h values on the Read Calibration Settings.
Our customer considered that this value is incorrect value.
Is this value correct ? If yes, please let me know this meaning.
If no please let me know this reason or should we check what?
 
(2)
Please let me know the Value range of the Addr: 5h.
Is this from 0x0000 to 0xFFFF ?
 
Best Regards,
Ryuji Asaka
  • 0
    TI__Mastermind 44680 points

    Hi Asaka-san

    Please ensure the customer is following all steps in the Calibration Settings Read/Write procedure as described in the ADC12D500RF datasheet:

    6.3.3.6 Read/Write Calibration Settings

    When the ADC performs a calibration, the calibration constants are stored in an array which is accessible via the Calibration Values register (Addr: 5h). To save the time which it takes to execute a calibration, tCAL, or to allow re-use of a previous calibration result, these values can be read from and written to the register at a later time. For example, if an application requires the same input impedance, RIN, this feature can be used to load a previously determined set of values. For the calibration values to be valid, the ADC must be operating under the same conditions, including temperature, at which the calibration values were originally determined by the ADC.

     

    To read calibration values from the SPI, do the following:

    1. Set ADC to desired operating conditions.

    2. Set SSC (Addr: 4h, Bit 7) to 1.

    3. Read exactly 240 times the Calibration Values register (Addr: 5h). The register values are R0, R1, R2...R239 where R0 is a dummy value. The contents of R<239:1> should be stored.

    4. Set SSC (Addr: 4h, Bit 7) to 0.

    5. Continue with normal operation.

     

    To write calibration values to the SPI, do the following:

    1. Set ADC to operating conditions at which Calibration Values were previously read.

    2. Set SSC (Addr: 4h, Bit 7) to 1.

    3. Write exactly 239 times the Calibration Values register (Addr: 5h). The registers should be written with stored register values R1, R2... R239.

    4. Make two additional dummy writes of 0000h.

    5. Set SSC (Addr: 4h, Bit 7) to 0.

    6. Continue with normal operation.

     

    If this procedure is followed, the register reads should be values of 0000h to FFFFh.

    I hope this is helpful.

    Best regards,

    Jim B

  • 0 in reply to Jim Brinkhurst1
    Guru 20090 points
    Hello Jim san,
     
    I checked our customer's operation.
     
    Our customer use 4ch/boards of ADC12D500RF.
    They noticed that Addr:5h is FFFFh value when one channel of THD performance is no good.
    If you send to my e-mail(asaka-r@clv.macnica.co.jp) directly, I can send the measurement result of calibration data(this data is our customer's cofidential).
     
    Please see the their operation step as follwoing.
    Could you please let me know if there is any problem point ?
    -----------
    1) Boards Power ON(i.e. ADC power ON)
    2) On command calibration done by all channel.
       In this time, all channel calibration is effected correctly.
    3) Read all channel of the Addr:5h data and stored as Calibration file
    4) ADC Power down
    5）ADC Power ON
    6) Write the calibration file to all channel of the Addr:5h
    7) Measured THD. As a result, one of the all channel THD data is no good.
       This channel was not calibrated.
    8）Read the all channel of the Addr:5h
    　 As a result, one of the channel Cal data is difference from other channel.
    9）read the Addr:5h data again.
       As a result, all register data are 0xFFFF.
    10）Write the other channel's calibration data to no good channel.
        And read the data.
        As a result , all register has 0xFFFF.
    11）Write&Read to Addr:0h, Eh of no good channel.
        This is effected.
    -----------
    Best Regards,
    Ryuji Asaka
  • 0 in reply to Ryuji
    TI__Mastermind 44680 points

    Hi Ryuji

    Since we have closed this issue via email I'm going to close the E2E thread as well.

    Let me know if you need anything else.

    Best regards,

    Jim B

  • 0 in reply to Jim Brinkhurst1
    Prodigy 10 points

    What was the resolution to this issue?  

    I have an ADC12D1800 that I always read 0xFFFF's from the calibration register whether the SSC bit (Addr: 4h, Bit 7) is either 0 or 1.  The signal looks distorted so I think the calibration isn't running, though when I perform an on demand calibration I can see the CalRun pin toggle.

    I have tried the procedure in 6.3.3.6 in the user manual to read back these calibration values.

  • 0 in reply to George Bishop
    TI__Mastermind 44680 points

    Hi George

    Given the behavior of this single part (all other devices they have respond normally) we have determined that it has been damaged.

    The customer is submitting a Failure Analysis request through their sales support channel.

    Best regards,

    Jim B