EVAL-AD7686CBZ Analog Devices Inc, EVAL-AD7686CBZ Datasheet - Page 3

• Manufacturer Part Number: EVAL-AD7686CBZ
• Description: BOARD EVALUATION FOR AD7686
• Manufacturer: Analog Devices Inc
• Series: PulSAR®r

Specifications of EVAL-AD7686CBZ

• Number Of Adc's: 1
• Number Of Bits: 16
• Sampling Rate (per Second): 500k
• Data Interface: Serial
• Inputs Per Adc: 1 Differential
• Input Range: ±VREF
• Power (typ) @ Conditions: 15mW @ 500kSPS, 5 V
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Utilized Ic / Part: AD7686
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Preliminary Technical Data
Detailed Description
The EVAL-AD76XXCB 8/10-Pin includes a 5V ultrahigh
precision reference (ADR435), and a signal conditioning circuit
with two opamps (ADA4841-x) and digital logic. The board
interfaces with a 96-way connector for the EVAL-CONTROL
BRDx and a 26-pin IDC connector for the serial output
interface.
The evaluation board is a four-layer board carefully laid out and
tested to demonstrate the specific high accuracy performance of
the AD768x/ AD769x/AD794x/AD798x. Figure 2 through
Figure 5 show the schematics of the evaluation board. The
layouts of the board are shown in the following figures:
Figure 6: Top-Side Silk-Screen
Figure 7: Top-Side Layer
Figure 8: Ground Layer
Figure 9: Shield Layer
Figure 10: Bottom-Side Layer
Figure 11: Bottom-Side Silk-Screen
The evaluation board has a flexible design that enables the user
to choose among many different board configurations. A
description of each selectable jumper is listed in Table 1, and the
available test points are listed in Table 2.
The evaluation board is configured in the factory with the
front-end amplifiers U6 and U7 set to a gain of 1. The board is
set to be powered through the EVAL-CONTROL BRDx.
Buffered conversion data is available at the output parallel bus
BD on U3 and on the 96-pin connector P3 and is valid during
the falling edge of BBUSY on P3. Activity of the ADC turns on
the on-board LED
Power Supplies and Grounding
The evaluation board has two power supply blocks:
-SJ1 for the digital interface circuitry and the digital section of
the ADC.
-SJ2 for the analog section including the signal conditioning
and the reference voltage circuitry.
These offer flexibility to evaluate the ADC and the surrounding
circuitry with any power supply combination.
Analog Input Ranges and Multiplexing
The analog front-end amplifier circuitry U6 and U7 allows
flexible configuration changes such as positive or negative gain,
input range scaling, filtering, addition of a DC component, and
the use of different op-amp and supplies.
The factory configuration of the analog input of U6 and U7 is
set at midscale. This allows a transition noise test without any
other equipment. An FFT test can be done by applying a very
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low distortion AC source.
As an option, an
the ADC to demonstrate performances for multichannel
applications.
A second ADC can be mounted on the board to demonstrate
the daisy-chain feature.
Using the Software
This configuration requires to use the EVAL-CONTROL BRDx
to interface the evaluation board with the PC.
Software Description
The evaluation board comes with software for analyzing the
AD768x/AD769x/AD794x/AD798x. One can perform a
histogram to determine code transition noise, and Fast Fourier
Transforms (FFT's) to determine the Signal-to-Noise Ratio
(SNR), Signal-to-Noise-plus-Distortion (SINAD) and Total-
Harmonic-Distortion (THD). The AC performances can also
been evaluated after digital filtering (averaging) with enhanced
resolution (up to 32 bits). The front-end PC software has four
screens:
Figure 12 is the Setup Screen where sample rate, number of
samples are selected.
Figure 13 is the Histogram Screen, which allows the code
distribution for DC input and computes the mean and standard
deviation.
Figure 14 is the FFT Screen, which performs an FFT on the
captured data, computes SNR, SINAD and THD.
Figure 15 is the time domain representation of the output.
When the on-board conversion (CNV) generation is used, a
synchronous FFT can be achieved by synchronizing an external
AC generator with the 10MHz Fsync signal (J4) a 10 MHz
signal, exact division of master clock (MCLK).
Figure 16 is the FFT Screen when averaging is used.
Software Installation (executable)
There is no need to have LabVIEW installed to run the
executable.
Double-click on Setup.exe in the LabVIEW exe folder from the
CD-ROM shipped with the evaluation board (do not use the
CD shipped with the EVAL-CONTROL BRDx) and follow the
installation instructions.
Developing your own application using LabVIEW
You need LabVIEW 7.1 or above to do this. Install the
executable first, copy the folder LabVIEW VI and run the ADC
vi example.vi
Testing Methods
Histogram
To perform a histogram test, apply a DC signal to the input. It is
ADG739
EVAL-AD76XXCB 8/10-Pin
multiplexer can be used in front of