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ADS1263: converting measure samples to time

Art Mecina
Genius 16935 points

Part Number: ADS1263
Other Parts Discussed in Thread: ADCPRO,

Hello Guys,

Good day.

A customer is measuring with the ads1263 and read out the data with the adc pro program. The setting in his ADCpro is 7200sps. The program says the data rate is 5200Hz. 

He wants to calculate the time vector for his measured signal, and wants to switch from sample to time. Normally it should be sample divided by sps but for this ads1263 it doesnt work or its not correct, so he don't know how he can calculate or transform his measured samples correctly into time.

Thanks in advance!

Art

  • 0
    TI__Guru 59461 points

    Hi Art,

    ADCPro is likely calculating the effective data rate seen by the ADC, not just the nominal data rate.

    As you can see from Table 17 in the ADS1263 datasheet, the first conversion has a longer latency due to the digital filter and other various delays. Second and subsequent conversions come out of the ADC at ~1/data rate, assuming chop is not enabled. Therefore, the longer you sample the same channel, the closer to the specified data rate you get.

    For example, the conversion latency for the ADS1263 at 7200 SPS using the sinc1 filter is 0.494 ms, or ~2 kSPS. Second and subsequent conversions should come out at 1/7200 SPS = 0.139 ms. If you took 10 samples, the first would arrive in 0.494 ms while the last nine would come out at 0.139 ms. Your effective data rate for those 10 conversions = (0.494 + 9*0.139)/10 = 0.175 ms, or 5,731 SPS.

    -Bryan