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UCD3138A: ADC12

user4661984
Prodigy 190 points
Part Number: UCD3138A

Hi TI,

I have 2 question about adc mode of UCD3138A

1. In datesheet " NOTE: Even though the ADC12 sampling frequency is preset to 267 Ksps as default by setting the

ADC_SAMPLINGSEL to zero, in order to achieve the best measurement results it is
recommended to set the sampling rate to 267 Ksps by setting the ADC_SAMPLINGSEL to 6"

so do I have to configure this  ADC_SAMPLINGSEL ? What will happen if I  don't  configure, because in default it is 267 Ksps?

2. The ADC12 control provides capability for averaging of ADC results,  Set 100us to trigger adc mode in the code. If I choose 8-sample moving average, so 800us later I can get the averaging of ADC value at the beginning?

If the ADC conversion is complete, you check .ADC_INT? what is the different between ADC_INT_RAW and ADC_INT? 

If I used ADC averaging, must I use .ADC_INT ?

Best Wishes

  • 0
    TI__Mastermind 18370 points

    For acheiving the best performance you should use ADC_SAMPLINGSEL of 6.
    The performance in this setting is tested, other setting (0) may be fine as well, but not gurantied.

    Averaging is actually an IIR (Infinite Impulse Response) and remembers even older than 8 results.
    After the power up, you may need to wait for a while (much more than 800 uS) for the averaging to settle, but from that point and on, you can read it every 100 uSeconds.

    Use ADC_INT, the raw value is not latched and ins not good for polling.
    Actually if you poll every 100 uS and number of channels multiply by 4 uS is less than 100 uS, you do not even need to check this bit.

    Regards,