Example Data Capture For The Dc Signal - Analog Devices EVAL-ADAQ7767-1 User Manual

User Guide

EXAMPLE DATA CAPTURE FOR THE DC SIGNAL

A sinc3 filter with ODR = 50 SPS is a sweet spot for measurement
of a pure DC signal because the sinc notch appears at 50 Hz and
can be used to reject the 50 Hz line frequency. Take the following
steps to setup the device under test (DUT) for a 50 SPS sinc3 filter:
1. As an example for RMS noise, short the AINP and AINN
connectors to GND and use IN2+ and IN2− as input pins to the
ADAQ7767-1 by setting the P1 and P2 jumpers (default: IN2+
and IN2−, and G = 4/11 V/V).
2. Within the ADAQ7767-1 Board Chip View the ACE Software,
click the Filter Configuration icon.
3. Use the drop-down menu to select Sinc3 (programmable deci-
mation rate) option as shown in
4. To configure the Sinc3 Dec-Rate, type 13FF in the text box
near the lower right corner as shown in
reflected in the SINC3_DEC_RATE_LSB and SINC3_DEC_
RATE_MSB registers located within the memory map of the
ACE software. Then, click Apply Changes for this to take
effect.
analog.com
Figure 4.
Figure 5, which is also
Figure 4. Set the Digital Filter Type
EVAL-ADAQ7767-1
5. Adjust the number of samples to be collected accordingly be-
fore Run Once is clicked. Collecting the default 8192 samples
at 50 SPS takes 8192/50/60 = 2.73 minutes.
6. Set to 1024 samples, which takes approximately 20 seconds.
7. The same condition (sinc3 = 50 SPS) is used to measure the
low frequency noise, as specified in the
sheet. In the ADAQ7767-1 Board Histogram tab, noise is
displayed as a transition noise in LSB. To compare the referred
to input (RTI), low frequency noise in μV RMS found in the
ADAQ7767-1 data sheet, apply the following formula:
RTI Noise
= Transition Noise × 1 LSB
= Transition Noise ×
= Transition Noise ×
For example, using IN2+ and IN2− with the measured transition
noise = 0.778 LSB = 1.044 μV RMS RTI.
ADAQ7767-1 data
4.096
24 − 1
2 × AFE_GAIN
488 nV
AFE_GAIN
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