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ADS1262: ADS1262 50Hz and 60Hz Noise rejection

Part Number: ADS1262

Hi TI team,

In ADS1262 does all the filter provide 50Hz and 60Hz rejection and  for what data rates.

In datasheet

Section 9.3.10(Pg 43)

"The FIR filter provides simultaneous rejection of 50-Hz and 60-Hz power-line frequencies with data
rates 2.5 SPS through 20 SPS with single-cycle settled conversions."

Section 9.3.10.1.1(Pg 46)

"The 50-Hz or 60-Hz fundamental
frequency and harmonics are suppressed by increasing the second-stage filter order,"

Again in the same page

"As shown in the plots, the best 50-Hz or
60-Hz rejection is provided by the sinc4 order, but has longer filter latency compared to the sinc1 order."

Section 9.3.10.3 50-Hz and 60-Hz Line Cycle Rejection

"If the ADC connection leads are in close proximity to industrial motors and conductors, coupling of 50-Hz and
60-Hz power line frequencies can occur. The coupled noise interferes with the signal voltage, and may lead to
inaccurate or unstable conversions. The digital filter provides enhanced rejection of power-line coupled noise for
data rates of 60 SPS and less."

Its littlebit confusing. Can anyone clarify.

Regards,

Venkatavel.

  • Hi Venkatavel,

    The ADS1262, like many low speed delta-sigma ADCs, offers rejection of 50 and/or 60 Hz line cycle frequencies at the lower data rates due to the digital filter frequency response. You can see this in Figure 9.17 specifically, where the sinc filter nulls occur at multiples of 10 Hz, thereby offering native rejection of 50 and 60 Hz. Figures 9-18 through 9-21 show how setting the data rate to 50 or 60 SPS rejects those frequencies as well. For the ADS1262, the line cycle rejection is quantified in Table 9.6 in the datasheet.

    -Bryan