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ADS1248: the timing to calibration

Takumi Suzuki1
Mastermind 8430 points
Part Number: ADS1248
Other Parts Discussed in Thread: ADS1251, ADS1225, ADS1222, ADS1224, ADS1226

Hi,

I would like to ask you a simple question about the calibration.

The data sheet of ADS1248 describes about calibration as below. (40page)

According to this description, we should or must do calibration when we use ADS1248.

That is to say, before the start of ADC, we have to do calibration, every ADC.

Is this a correct way to use ADS1248? 

On the other hand, there are some delta-sgima ADCs without calibration, for example ADS1251.

I suppose ADS1251 is easier to use than ADS1248.

Will you tell me the reason why ADS1251 does not have calibration?

It has something auto-calibration circuits??

Sorry for my very basic question.

Best Regards,

  • 0
    TI__Guru* 92715 points
    Takumi-san,


    You are correct that the ADS1251 does not have calibration. The ADS1251 was designed before we started adding calibration features and commands to our devices. Note that the ADS1251 does not have a command set or registers and is a functionally simple ADC.

    For all devices, I recommend running an offset calibration to ensure that the offset is low. For simple devices like the ADS1222, ADS1224, ADS1225, and ADS1226, I also recommend a gain calibration once the device supplies and reference have settled to final value.

    For many devices, like the ADS1248, the gain calibration coefficient is trimmed in the factory. This applies for all gain settings. This will set the device to a low gain error already. Unless the device is operated at a high temperature, where the gain error may have drifted to a higher error, I think the gain error is already at a low enough value where the calibration is not necessary.


    Joseph Wu
  • 0 in reply to Joseph Wu
    Mastermind 8430 points
    Hi Joseph-san,
    Thank you for your reply, I understood!
    Best Regards,