UG-478 Datasheet, PDF (17/40 Pages) Analog Devices – Evaluation Board for the AD7176-2—24-Bit, 250 kSPS Sigma-Delta ADC with 20 μs Settling

Evaluation Board User Guide
Noise Test—Quick Start Demonstration
To perform a noise test using the AD7176-2 evaluation board,
LK5 to LK9 should be inserted so that the analog inputs are
connected together. The internal reference should be enabled
and made available at the REFOUT pin. The internal reference
biases the analog inputs to an appropriate voltage.
1. Click ADC Setup to open the AD7176-2 Register Interface
window. The AD7176-2 should be configured as follows:
a. In the ADCMODE register, the internal refer-
ence is enabled and outputs a buffered 2.5 V to
the REFOUT pin.
b. In the CHMAP1 register, AIN2 is connected to the
positive input, AIN3 is connected to the negative
input of the ADC for this channel, and Setup 1 is
selected. Therefore, the AIN2 to AIN3 conversion is
mapped using the Setup 1 configuration.
c. Setup 1 is configured with the following register settings:
i. In the SETUPCON1 register, the external reference
is selected as the reference source for the ADC
conversion.
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ii. In the FILTCON1 register, the output data rate is
set to 1 kHz, and the fast settling filter (Sinc5 +
Sinc1) is enabled.
iii. In the OFFSET1 register, the default offset
register value is selected.
iv. In the GAIN1 register, the factory trimmed gain
error value is selected.
2. Figure 21 shows the contents of this window and the state
of the AD7176-2 registers. Click OK to return to the main
window. Figure 22 shows an example of the main window
after running a noise test.
3. Set the number of samples to be collected in each batch in
the Samples box, which is located just to the left of Start
Sampling, near the top right hand corner of the main
window.
4. Click Start Sampling to acquire samples from the ADC.
Figure 21. Configuration for Noise Test
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