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ADS125H01: ADC design support

Part Number: ADS125H01
Other Parts Discussed in Thread: ADS1262

Hi

I'd like to used ADS125H01 which is 32bit ADC and our signal is include 60Hz frequency .

Unfortunately, I found some comment that 50Hz and 60Hz rejection function in data sheet of ADS125H01.

is this can be disable to this function?

Someone let me know.

Thanks

  • Hi Byungtaeg,

    A point of clarification: the ADS125H01 is a 24-bit ADC, not a 32-bit ADC. The ADS1262 is our 32-bit ADC, but does not offer the high voltage measurement capabilities like the ADS125H01. If you need help selecting an ADC for your application, please let me know.

    The digital filter in a delta-sigma ADC is usually a sinc filter, and its frequency response looks similar to the two images below. These two images are taken from the ADS125H01 data sheet. The 50 / 60 Hz rejection is a characteristic of the filter that you choose, and cannot really be turned off. But, if you select a higher data rate, the filter bandwidth will be sufficient to measure a 60 Hz signal.

    As you can see in Figure 37, the sinc filter has its first null at 10 Hz, as well as additional nulls at multiples of the data rate including at 60 Hz, so that frequency will be rejected. Note that the output data rate in this case 10 SPS, which matches the location of the first null (10 Hz).

    In Figure 35, the device is operating at 14,400 SPS, so much faster, and the first null is at 14,400 Hz. This is far beyond your signal of interest (60 Hz), so you would be able to measure a signal with this BW using the 14,400 data rate. You can review table 13 in the ADS125H01 datasheet for the filter 3dB bandwidth at every data rate and filter setting. Please choose one that is greater than 60 Hz. For example, at sinc 3 and data rate = 400 SPS, the 3dB bandwidth is 105 Hz - that should theoretically work for your system.

    -Bryan