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ADC12DJ2700: Timing adjustment (TADJ_x_FGx)

cafain
Mastermind 6755 points
Part Number: ADC12DJ2700

Hi, staff

Timing adjustment (TADJ_x_FGx)

The data sheet recommends the use of INA (A input side) in single channel mode, but also plans to use INB (B input side) in single channel mode.
We think that the calibration mode needs to adjust the foreground mode (TADJ_x_FGx).

Adjust using the “TADJ_A_FG90” and “TADJ_B_FG0” registers of “Inter ADC core timing” shown in Table4.4 of the data sheet (SLVSEH9) page76 Table4.4.

Question
1. Write the adjustment value to the 8bit register of “TADJ_A_FG90” and “TADJ_B_FG0”.
   What is the adjustment resolution per 1 LSB of this register of 8 bits?

2. What is the adjustment range that can be adjusted with the 8Bit register?

3. If I rewrite this register during operation, is the setting reflected as it is?
   Or do you need to take any additional steps to make it work?
  (When is it set?)

4. I plan to use only foreground calibration, do I need to use background calibration as well?
  (What are the benefits?)

best regards
cafain

  • 0
    TI__Mastermind 20541 points

    Hi Cafain,

    Foreground operation requires ADC downtime, where the ADC is no longer sampling the input signal, to complete the process. Background calibration can be used to overcome this limitation and allow constant operation of the ADC. The adjustment range on TADJ register is not linear/monotonic. You will basically have to go through all the 256 values and see which give to best results. The factory trimmed value can be read and adjusted after the device reset.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Mastermind 6755 points

    Hello Gill san

    Thanks for the prompt response.
    From your answer I understood the following:

    ・ The adjustment amount for 1LSB of the TADJ register is not linear.
    ・ Background calibration is best for adjustment while the ADC is operating normally.
    ・ It is necessary to check the actual operation before making adjustments.

    Let me confirm it additionally.

    5. Is the timing to write the adjusted value to the TADJ register at power-on?

    6. The factory settings are written for the TADJ register settings. Can the user set values be overwritten?

    7. Foreground operation is performed without analog input to the ADC, and the result is written to the TADJ register.
    　 Is there any problem with this method?

    Please comment if I misunderstand the register setting.
    ※Is there any data on the calibration procedure?
    　I want to refer to.

    best regards
    cafain

  • 0 in reply to cafain
    TI__Mastermind 20541 points

    Hi Cafain,

    5. Is the timing to write the adjusted value to the TADJ register at power-on?

    On Power up the device will do a calibration and also load the all the trim values from the fuse. Once this process is done you can write to TADJ register.

    6. The factory settings are written for the TADJ register settings. Can the user set values be overwritten?

    Yes as mentioned in last answer you can overwrite the TADJ register with your settings.

    7. Foreground operation is performed without analog input to the ADC, and the result is written to the TADJ register.
    　 Is there any problem with this method?

    Only offset calibration required no analog input signal to be present near DC(aliased) at analog inputs of the ADC. If Foreground calibration is performed without offset calibration you can have the analog input signal applied to the ADC. TADJ values are programmed at the factory for each device which are determined to be optimal at the test system's operating conditions. The TADJ trim values are loaded during power or if the device is reset.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Mastermind 6755 points

    Hello Neeraj san

    Thank you for your support.
    Let me confirm again to convince myself a little more.

    page76 Table44. Trim Register Descriptions Let me reconfirm the setting of “Inter-ADC core timing”.

    TADJ will be adjusted by register setting of TADJ_A_FG90 and TADJ_B_FG0.

    <Reconfirmation of previous inquiry.>

    Q1:If the two register settings of TADJ_A_FG90 and TADJ_B_FG0 are rewritten during ADC operation,
    are the settings reflected as they are?
    Is there anything wrong with the running configuration?

    Q2:Or do you need any additional procedures (register settings) to reflect?

    I do not understand the calibration operation method using only TADJ_A_FG90 and TADJ_B_FG0.

    best regards
    cafain

  • 0 in reply to cafain
    Mastermind 6755 points

    Hello Neeraj san

    Let me ask you an additional question.

    Q3:
    When re-trimming using the TADJ_A_FG90 and TADJ_B_FG0 registers, do I need to control registers related to Foreground calibration, such as CAL_SOFT_TRIG(CAL_TRIG-pin), CAL_TRIG_EN ?.

    Q4:
    Datasheet page97 TADJ_A_FG90 "Description" says "background", but I think Foreground is correct.


    Please tell me the setting procedure.

    best regards
    cafain

  • 0 in reply to cafain
    TI__Mastermind 20541 points

    Hi Cafain,

    Q1:If the two register settings of TADJ_A_FG90 and TADJ_B_FG0 are rewritten during ADC operation,
    are the settings reflected as they are? Yes they are reflected as they are.
    Is there anything wrong with the running configuration? No I don't see an issue.

    Q2:Or do you need any additional procedures (register settings) to reflect? No you don't need

    I do not understand the calibration operation method using only TADJ_A_FG90 and TADJ_B_FG0.

  • 0 in reply to cafain
    TI__Mastermind 20541 points

    Hi Cafain,

    Q3:
    When re-trimming using the TADJ_A_FG90 and TADJ_B_FG0 registers, do I need to control registers related to Foreground calibration, such as CAL_SOFT_TRIG(CAL_TRIG-pin), CAL_TRIG_EN ?. No

    Q4:
    Datasheet page97 TADJ_A_FG90 "Description" says "background", but I think Foreground is correct. The comment is saying if background cal or different modes are used different register will need adjustment.

    Regards,

    Neeraj

  • 0 in reply to Neeraj Gill
    Mastermind 6755 points

    HI, Neeraj san

    I asked a question because the operation method of the TADJ_x_x register is unknown.

    I'm sorry to ask a lot of similar questions.

    I understand with your detailed description.
    Thank you.

    Regards,

    cafain