Analog Devices UG-397 User manual

Evaluation Board User Guide
UG-397
One Technology Way •P. O. Box 9106 •Norwood, MA 02062-9106, U.S.A. •Tel: [phone] •Fax: [phone] •www.analog.com
Evaluation Board for the AD5247 Digital Potentiometer
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.Rev. 0 | Page 1 of 16
FEATURES
Full-featured board in conjunction with low voltage digiPOT
motherboard (EVAL-MB-LV-SDZ)
Various test circuits
Various ac/dc input signals
PC control via a separately purchased system demonstration
platform (SDP-B or SDP-S)
PC software for control
PACKAGE CONTENTS
EVAL-AD5247DBZ
EVAL-MB-LV-SDZ motherboard
CD that includes
Self-installing software that allows users to control the
board and exercise all functions of the device
Electronic version of the AD5247 data sheet
Electronic version of the UG-397 user guide
GENERAL DESCRIPTION
This user guide describes the evaluation board for evaluating the
AD5247, a single channel, 128-position digital potentiometer.
The AD5247 supports a single-supply 2.7 V to 5.5 V operation,
making the device suited for battery-powered applications and
many other applications with a superior low temperature
coefficient performance.
In addition, the AD5247 uses a versatile I2C serial interface that
operates in fast mode, allowing speeds of up to 400 kHz.
The E VA L -AD5247DBZ and E VA L -MB-LV-SDZ can operate in
single-supply mode and incorporate an internal power supply
from the USB.
Complete specifications for the AD5247 part can be found in
the AD5247 data sheet, which is available from Analog Devices,
Inc., and should be consulted in conjunction with this user
guide when using the evaluation board.
EVAL-AD5247DBZ WITH MOTHERBOARD AND SDP-B
10625-001
Figure 1. Digital Picture of Evaluation Board with Low Voltage digiPOT Motherboard and System Demonstration Platform

UG-397 Evaluation Board User Guide
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TABLE OF CONTENTS
Features .............................................................................................. 1
Package Contents .............................................................................. 1
General Description ......................................................................... 1
E VA L-AD5247DBZ With Motherboard and SDP-B ................... 1
Revision History ............................................................................... 2
Evaluation Board Hardware ............................................................ 3
Power Supplies .............................................................................. 3
Link Options ................................................................................. 3
Test Circuits................................................................................... 4
Evaluation Board Software...............................................................6
Installing the Software ..................................................................6
Running the Software ...................................................................6
Software Operation .......................................................................7
Schematics and Artwork ..................................................................8
Motherboard ..................................................................................8
Daughter Board .......................................................................... 12
Ordering Information.................................................................... 15
Bill of Materials........................................................................... 15
REVISION HISTORY
5/12—Revision 0: Initial Version

Evaluation Board User Guide UG-397
Rev. 0 | Page 3 of 16
EVALUATION BOARD HARDWARE
POWER SUPPLIES
The EVA L -MB-LV-SDZ supports using single power supplies.
The evaluation board can be powered either from the SDP port
or externally by the J1 and J2 connectors as described in Table 1.
All supplies are decoupled to ground using 10 µF tantalum and
0.1 µF ceramic capacitors.
Table 1. Maximum and Minimum Voltages of the Connectors
Connector No. Label Voltage
J1-1
EXT VDD
Analog positive power supply, V
DD
;
from 2.7 V to 5.5 V.
J1-2 GND Analog ground.
J2-1 VLOGIC Digital supply, from 2.7 V to VDD.
J2-2 DGND Digital ground.
LINK OPTIONS
Several link and switch options are incorporated in the EVAL-
MB-LV-SDZ evaluation board and should be set up before
using the board. Table 2 describes the positions of the links to
control the evaluation board by a PC, via the SDP board. The
functions of these link options are described in detail in Table 3
through Table 6.
Table 2. Link Options Setup for SDP Control (Default)
Link No. Option
A11 3.3 V
A12 AGND
A5 3.3 V
Table 3. Link Functions
Link No.
Power Supply
Options
A11 VDD This link selects one of the following as the positive power supply:
5 V (from SDP).
3.3 V (from SDP).
VDD (external supply from the J1 connector).
A5 VLOGIC This link selects one of the following as the digital supply:
3.3 V (from SDP).
VLOGIC EXT (external supply from the J2 connector).
A12 GND AGND.

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TEST CIRCUITS
The EVAL-AD5247DBZ and EVAL-MB-LV-SDZ incorporate
several test circuits to evaluate the AD5247 performance.
DAC
RDAC can be operated as a digital-to-analog converter (DAC),
as shown in Figure 2.
VOUT1
R34
RDAC
AC+
A
B
W
BUF-W1
+
–
A1
B1
W1
V
DD
– V
SS
V
DD
VDD
2
10625-002
Figure 2. DAC
Table 4 shows the options available for the voltage references.
Table 4. DAC Voltage References
Terminal
Link
(DB1)
Link
(MB2) Options Description
A1 A2-B A9 AC+
Connects Terminal
A1 to VDD /2
VDD
Connects Terminal
A1 to VDD
W1 A3-B
BUF-
W1
Connects Terminal
W1 to an output
buffer
B1 A10 AGND
A1
inserted
1Daughter board
2Motherboard
The output voltage is defined in Equation 1.
128
)( RDAC VV A
OUT  (1)
where:
RDAC is the code loaded in the RDAC register.
VAis the voltage applied to the A terminal (A9 link).
However, by using the R34 external resistor, the user can reduce
the voltage of the voltage references. In this case, use the A1 test
point to measure the voltage applied to the A terminal and
recalculate VAin Equation 1.
AC Signal Attenuation
RDAC can be used to attenuate an ac signal, which must be
provided externally using the AC_INPUT connector, as shown
in Figure 3.
VOUT1
R34
RDAC
AC+
AC
A
B
W
BUF-W1
+
–
A
C_INPUT
A1
B1
W1
V
DD
–
V
SS
2
HPF
1kHz
10625-003
Figure 3. AC Signal Attenuator
Depending on the voltage supply rails and the dc offset voltage
of the ac signal, various configurations can be used as described
in Table 5.
Table 5. AC Signal Attenuation Link Options
Link Options Conditions
A9 AC+ No dc offset voltage.
AC signal is outside the voltage supply rails
due to the dc offset voltage.
DC offset voltage ≠ VDD/2.
AC All other conditions.
A10 AGND All other conditions.
The signal attenuation is defined in Equation 2.









 ENDTOEND
WWB
R
RR
nAttenuatio log20)dB( (2)
where:
RWB is the resistor between the W and ground.
RWis the wiper resistance.
REND-TO-END is the end-to-end resistance value.

Evaluation Board User Guide UG-397
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Signal Amplifier
RDAC can be operated as a noninverting signal amplifier
supporting pseudo logarithmic gain. Table 6 shows the available
configurations.
The noninverting amplifier with pseudologarithmic gain is
shown in Table 6, and the gain is defined in Equation 4.
WB
AW
R
R
G1 (4)
where:
RAW is the resistor between the W and A terminals.
RWB is the resistor between the W and B terminals.
VOUT2
VIN
RDAC
A
B
W
+
–
W2
A2 B2
C1
10nF
R41
1.7kΩ
R42
10625-004
Figure 4. Pseudologarithmic Noninverting Amplifier
R42 can be used to set the maximum and minimum gain limits.
Table 6. Amplifier Selection Link Options
Amplifier Gain Link(DB1) Link (MB2) Label VIN Range
Noninverting Pseudo logarithmic A2 = A3 = A4-A A7 LOC 0 V to VDD
A6 N-INV
A1 not inserted A8 N-INV
1Daughter board
2Motherboard

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EVALUATION BOARD SOFTWARE
INSTALLING THE SOFTWARE
The E VA L -AD5247DBZ evaluation kit includes evaluation
board software provided on a CD. The software is compatible
with Windows® XP, Windows Vista, and Windows 7 (both
32 bits and 64 bits).
Install the software before connecting the SDP board to the USB
port of the PC to ensure that the SDP board is recognized
when it is connected to the PC. To install the software, use
the following steps:
1. Start the Windows operating system and insert the CD.
2. The installation software opens automatically. If it does
not, run the setup.exe file from the CD.
3. After installation is completed, power up the evaluation
board as described in the Power Supplies section.
4. Connect the E VA L -AD5247DBZ and EVA L-MB-LV-SDZ
into the SDP board and the SDP board into the PC using
the USB cable included in the evaluation kit.
5. When the software detects the evaluation board, follow the
instructions that appear to finalize the installation.
RUNNING THE SOFTWARE
To run the program, use the following steps:
1. Click Start > All Programs > Analog Devices > AD5247
>AD5247 Eval Board. To uninstall the program, click
Start > Control Panel > Add or Remove Programs >
AD5247 Eval Board.
2. If the SDP board is not connected to the USB port when
the software is launched, a connectivity error displays (see
Figure 5). Simply connect the evaluation board to the USB
port of the PC, wait a few seconds, click Rescan, and follow
the instructions.
10625-005
Figure 5. Pop-Up Window Error
The main window of the E VA L -AD5247DBZ evaluation
software then opens, as shown in Figure 6.
10625-006
Figure 6. EVAL-AD5247DBZ Evaluation Board Software Main Window

Evaluation Board User Guide UG-397
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SOFTWARE OPERATION
The main window of the E VA L -AD5247DBZ software is divided
into the following sections: RDAC and MANUAL DATA.
RDAC
WRITE can be used to update the RDAC registers by entering a
desirable value into the text box and clicking WRITE. When
WRITE is clicked, a write/read operation is performed, and the
value displayed in this section is updated with the actual RDAC
register value. This function can be used to verify whether the
write operation was completed successfully.
MANUAL WRITE
SEND DATA is a customized I2C data-word can be sent by
manually switching the scroll bars from 0 to 1 or from 1 to 0
as desired and then clicking SEND DATA.
In addition, the scroll bars are updated on each write transfer,
showing the command sent to the part.
EXIT closes the program.

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SCHEMATICS AND ARTWORK
MOTHERBOARD
10625-007
Figure 7. SDP Connector and Power Supply

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10625-008
Figure 8. Schematic of Test Circuits

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10625-009
Figure 9. Schematic of Connectors to Daughter Board
10625-010
Figure 10. Component Side View