UG-581 Datasheet, PDF (6/28 Pages) Analog Devices – Full-featured evaluation board

EVAL-AD7961FMCZ
REFERENCE OPTIONS
The EVAL-AD7961FMCZ board allows three reference voltage
options. The user can select either the 5 V or 4.096 V option
using the solder link LK7 or the 2.048 V on-board reference
voltage using solder link JP7 as described in Table 1. The
various options for using this reference are controlled by the
EN1 and EN0 pins (EN bits on software) as described in detail
in the AD7961 data sheet.
LAYOUT GUIDELINES
When laying out the printed circuit board (PCB) for the
AD7961, follow the recommended guidelines described in
this section to obtain the maximum performance from the
converter. Figure 30 to Figure 35 show the recommended layout
for the AD7961 evaluation board.
• Solder the AD7961 exposed paddle (Pin 33) directly to
the PCB and connect the paddle to the ground plane of
the board using multiple vias.
• Decouple all the power supply pins (VDD1, VDD2 and
VIO) and the REF pin with low ESR and low ESL ceramic
capacitors, typically 10 µF and 100 nF, placed close to the
DUT (U1) and connected using short, wide traces to
provide low impedance paths and to reduce the effect of
glitches on the power supply lines.
• Use 50 Ω single-ended trace and 100 Ω differential trace.
• Separate analog and digital sections and keep power supply
circuitry away from the AD7961.
• Avoid running digital lines under the device and crossover
of digital and analog signals because these couple noise
into the AD7961.
• Fast switching signals, such as CNV± or CLK±, should
not run near analog signal paths.
• Remove the ground and power plane beneath the input
(including feedback) and output pins of the amps (U14,
U15, and U16) as they create an undesired capacitor.
Evaluation Board User Guide
BASIC HARDWARE SETUP
The AD7961 evaluation board connects to the (EVAL-SDP-
CH1Z) system demonstration board. The EVAL-SDP-CH1Z
board is the controller board, which is the communication link
between the PC and the main evaluation board.
Figure 1 shows a photograph of the connections made between
the EVAL-AD7961FMCZ daughter board and the EVAL-SDP-
CH1Z board.
1. Install the AD7961 software. Ensure the EVAL-SDP-CH1Z
board is disconnected from the USB port of the PC while
installing the software. The PC must be restarted after the
installation.
2. Before connecting power, connect the EVAL-AD7961FMCZ
board’s 160-pin FMC connector, J7, to the connector J4 on
the EVAL-SDP-CH1Z board. Nylon screws are included in
the EVAL-AD7961FMCZ evaluation kit and can be used to
ensure theEVAL-AD7961FMCZ and the EVAL-SDP-CH1Z
boards are connected firmly together.
3. Connect the +12 V power supply adapter included in the
kit to the EVAL-SDP-CH1Z.
4. Connect the EVAL-SDP-CH1Z board to the PC via the
USB cable. For Windows XP you may need to search for
the EVAL-SDP-CH1Z drivers. Choose to automatically
search for the drivers for the EVAL-SDP-CH1Z board if
prompted by the operating system.
5. Launch the EVAL-AD7961FMCZ software from the
Analog Devices subfolder in the Programs menu. The full
software installation procedure is detailed in the Evaluation
Board Software section.
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