ANALOG DEVICES UG-397 Service Manual
Evaluation Board User Guide
UG-397
10625-001
One Technology Way • P. O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com
Evaluation Board for the AD5247 Digital Potentiometer
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
EVAL-AD5247DBZ WITH MOTHERBOARD AND SDP-B
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 I
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.
2
C serial interface that
Figure 1. Digital Picture of Evaluation Board with Low Voltage digiPOT Motherboard and System Demonstration Platform
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS.
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UG-397 Evaluation Board User Guide
TABLE OF CONTENTS
Features .............................................................................................. 1
Package Contents .............................................................................. 1
General Description ......................................................................... 1
EVAL-AD5247DBZ With Motherboard and SDP-B ................... 1
Revision History ............................................................................... 2
Evaluation Board Hardware ............................................................ 3
Power Supplies .............................................................................. 3
Link Options ................................................................................. 3
Test Circuits ................................................................................... 4
REVISION HISTORY
5/12—Revision 0: Initial Version
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
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Evaluation Board User Guide UG-397
J1-1
EXT VDD
Analog positive power supply, VDD;
Link No.
Power Supply
Options
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
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.
Table 3. Link Functions
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 V
A12 GND AGND.
This link selects one of the following as the digital supply:
LOGIC
3.3 V (from SDP).
VLOGIC EXT (external supply from the J2 connector).
LINK OPTIONS
Several link and switch options are incorporated in the EVALMB-LV-SDZ evaluation board and should be set up before
using the board. Tab le 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
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UG-397 Evaluation Board User Guide
A
V
V
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.
VDD – V
2
Table 4 shows the options available for the voltage references.
AC+
SS
VDD
V
DD
RDAC
R34
A1
W1
A
W
B
BUF-W1
B1
–
+
VOUT1
10625-002
Figure 2. DAC
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.
–
DD
1kHz
HPF
C_INPUT
SS
2
AC+
AC
R34
RDAC
A1
W1
A
W
B
BUF-W1
B1
–
+
VOUT1
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.
10625-003
Table 4. DAC Voltage References
Link
Terminal
(DB1)
A1 A2-B A9 AC+
VDD
W1 A3-B
Link
(MB2) Options Description
Connects Terminal
A1 to V
/2
DD
Connects Terminal
DD
BUFW1
A1 to V
Connects Terminal
W1 to an output
buffer
B1 A10 AGND
1
Daughter board
2
Motherboard
A1
inserted
The output voltage is defined in Equation 1.
RDAC
OUT
)(
VV
A
(1)
128
where:
RDAC is the code loaded in the RDAC register.
V
is the voltage applied to the A terminal (A9 link).
A
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 V
in Equation 1.
A
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.
nAttenuatio log20)dB(
RR
WWB
R
ENDTOEND
where:
R
is the resistor between the W and ground.
WB
R
is the wiper resistance.
W
R
END-TO-END
is the end-to-end resistance value.
(2)
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Evaluation Board User Guide UG-397
Signal Amplifier
RDAC can be operated as a noninverting signal amplifier
supporting pseudo logarithmic gain. Table 6 shows the available
R41
1.7kΩ
V
IN
W2
+
C1
–
10nF
VOUT2
configurations.
B
RDAC
W
R42
A
10625-004
The noninverting amplifier with pseudologarithmic gain is
A2 B2
shown in Table 6, and the gain is defined in Equation 4.
R
G 1 (4)
AW
R
WB
R42 can be used to set the maximum and minimum gain limits.
Figure 4. Pseudologarithmic Noninverting Amplifier
where:
R
is the resistor between the W and A terminals.
AW
R
is the resistor between the W and B terminals.
WB
Table 6. Amplifier Selection Link Options
Amplifier Gain Link(DB1) Link (MB2) Label V
Range
IN
Noninverting Pseudo logarithmic A2 = A3 = A4-A A7 LOC 0 V to VDD
A6 N-INV
A1 not inserted A8 N-INV
1
Daughter board
2
Motherboard
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