EVAL-AD5242DBZ User Guide
UG-627
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 AD5242 Digital Potentiometer
FEATURES
GENERAL DESCRIPTION
Full featured evaluation board used in conjunction with
low voltage digiPOT motherboard (EVAL-MB-LV-SDZ)
Multiple test circuits
Multiple ac/dc input signals
PC control via a separately purchased system demonstration
platform (SDP-B or SDP-S)
PC software for control
This user guide describes the evaluation boards for evaluating the
AD5242, a single-channel, 256-position, I2C-compatible digital
potentiometer.
EVALUATION KIT CONTENTS
EVAL-AD5242DBZ evaluation board
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 AD5242 data sheet
Electronic version of the EVAL-AD5242DBZ user guide
The AD5242 supports single-supply 2.7 V to 5.5 V operation,
making the device suitable for battery-powered applications and
many applications requiring superior low temperature coefficient
performance.
In addition, the AD5242 uses a versatile I2C-compatible serial
interface that operates in fast mode, allowing speeds of up to
400 kHz. This interface can be used to read back the wiper register
and EEPROM content.
The EVAL-AD5242DBZ daughter board and the EVAL-MBLV-SDZ motherboard can operate in single-supply mode and
incorporate an internal power supply from the USB.
Complete specifications for the AD5242 can be found in the
AD5242 data sheet, which is available from www.analog.com
and should be consulted in conjunction with this user guide
when using the evaluation board.
11879-001
PHOTOGRAPH OF EVAL-AD5242DBZ WITH MOTHERBOARD AND SDP-B
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.
Rev. 0 | Page 1 of 16
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EVAL-AD5242DBZ User Guide
TABLE OF CONTENTS
Features .............................................................................................. 1
Test Circuits ...................................................................................4
Evaluation Kit Contents ................................................................... 1
Evaluation Board Software ...............................................................6
General Description ......................................................................... 1
Installing the Software ..................................................................6
Photograph of EVAL-AD5242DBZ with Motherboard
and SDP-B .......................................................................................... 1
Running the Software ...................................................................6
Revision History ............................................................................... 2
Evaluation Board Schematics and Artwork ...................................8
Evaluation Board Hardware ............................................................ 3
Motherboard ..................................................................................8
Power Supplies .............................................................................. 3
Daughter Board .......................................................................... 12
Link Options ................................................................................. 3
Bill of Materials ............................................................................... 14
Operating the Software .................................................................7
Logic Outputs................................................................................ 3
REVISION HISTORY
5/14—Revision 0: Initial Version
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EVALUATION BOARD HARDWARE
POWER SUPPLIES
LINK OPTIONS
The EVAL-MB-LV-SDZ supports using single power supplies.
Several link and switch options are incorporated on the EVALMB-LV-SDZ and EVAL-AD5242DBZ boards and must be set
up before using the evaluation system. The functions of these
link options are described in detail in Table 2 through Table 5.
By default, the evaluation system is set up to be controlled by a
PC via the SDP board.
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.
LOGIC OUTPUTS
Header P6 of the evaluation board is connected to the O1 and
O2 logic outputs of the AD5242.
Table 1. Connector Functions
Connector No.
J1-1
J1-2
J2-1
J2-2
Label
VDD
AGND
VLOGIC
DGND
Description
Analog positive power supply, VDD
Analog ground
Digital supply
Digital ground
Voltage
Min
Max
2.7 V
5.5 V
2.7 V
VDD
Table 2. Link Functions
Link No.
A5
Power Supply
VLOGIC
A11
VDD
A12
GND
Options
Digital supply select options:
3.3 V (from the SDP board)
VLOGIC EXT (external supply from the J2 connector)
Positive power supply select options:
5 V (from the SDP board)
3.3 V (from the SDP board)
VDD (external supply from the J1 connector)
AGND
Rev. 0 | Page 3 of 16
Default Position
3.3 V
3.3 V
AGND
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EVAL-AD5242DBZ User Guide
TEST CIRCUITS
1kHz
The EVAL-AD5242DBZ and EVAL-MB-LV-SDZ incorporate
several test circuits to evaluate the performance of the AD5242.
DAC
VDD
2
HPF
AC+
AC
AC_INPUT
R34
The RDAC can be operated as a digital-to-analog converter (DAC),
as shown in Figure 2.
VDD
2
RDAC
A
A1
W1
W
AC+
VOUT1
BUF-W1
B
B1
VDD
VDD
RDAC
A
R35
A1
W1
W
VOUT1
BUF-W1
B1
AGND
11879-002
BIAS
AGND
Table 3. AC Signal Attenuation Link Options
Figure 2. DAC
Link
A9
Options
AC+
A10
AC
BIAS
AGND
Table 4 shows the options available for the voltage references.
The output voltage is defined in Equation 1.
VOUT = (VA − VB ) ×
2
Depending on the voltage supply rails and the dc offset voltage
of the ac signal, various configurations can be used, as described
in Table 3.
R35
2
BIAS
Figure 3. AC Signal Attenuator
B
VDD
VDD
11879-003
R34
RDAC
256
(1)
where:
RDAC is the code loaded in the RDAC register.
VA is the voltage applied to the A terminal (A9 link).
VB is the voltage applied to the B terminal (A10 link).
1
However, by using the R34 and R35 external resistors, you can
reduce the voltage of the voltage references. In this case, use the
A1 and B1 test points to measure the voltage applied to the A and
B terminals and recalculate VA and VB in Equation 1.
AC Signal Attenuation
The RDAC can be used to attenuate an ac signal, which must be
provided externally using the AC_INPUT connector, as shown
in Figure 3.
Conditions
No dc offset voltage.
AC signal is outside the voltage supply rails
due to the dc offset voltage.
DC offset voltage ≠ VDD/2.1
All other conditions.
Use in conjunction with AC+ link.1
All other conditions.
Recommended to ensure optimal total harmonic distortion (THD) performance.
The signal attenuation is defined in Equation 2.
R + RW
Attenuation (dB) = 20 × log WB
REND −TO −END
where:
RWB is the resistance between the W and B terminals.
RW is the wiper resistance.
REND-TO-END is the end-to-end resistance value.
Table 4. DAC Voltage References
Terminal
A1
W1
B1
Link Settings
Daughter Board
Motherboard
Hardwired to RDAC1
A9: AC+ position
of daughter board
A9: VDD position
Hardwired to RDAC1
BUF-W1: inserted
of daughter board
Hardwired to RDAC1
A10: BIAS position
of daughter board
A10: AGND position
P5: inserted
Description
Connects Terminal A1 to VDD/2
Connects Terminal A1 to VDD
Connects Terminal W1 to an output buffer
Connects Terminal B1 to VDD/2
Connects Terminal B1 to analog ground
Closes the feedback loop of the second op amp in the AD8618
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EVAL-AD5242DBZ User Guide
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The RDAC can be operated as an inverting or noninverting
signal amplifier and can support linear or pseudologarithmic
gain. Table 5 shows the available configurations.
RWB
R38
R41
1.7kΩ
RDAC
Figure 5. Noninverting Amplifier with Pseudologarithmic Gain
G=−
C1
10nF
B2
B
R42
RDAC
RWB
R38
(5)
where RWB is the resistance between the W and B terminals.
11879-004
W
R42
B
The inverting amplifier with linear gain is shown in Figure 6,
and the gain is defined in Equation 5.
VOUT2
W2
B2
W
A
R43 and R42 can be used to set the maximum and minimum
gain limits.
where RWB is the resistance between the W and B terminals.
R38
2.7kΩ
C1
10nF
A2
R43
(3)
Note that the input signal, VIN, must be negative.
Figure 4. Noninverting Amplifier with Linear Gain
R41
1.7kΩ
The noninverting amplifier with pseudologarithmic gain is
shown in Figure 5, and the gain is defined in Equation 4.
R
G = 1 + WB
R AW
VIN
(4)
VOUT2
R38
2.7kΩ
C1
10nF
W2
B2
W
where:
RWB is the resistance between the W and B terminals.
RAW is the resistance between the A and W terminals.
B
R42
RDAC
NOTES
1. THE INPUT SIGNAL, VIN, MUST BE NEGATIVE.
11879-006
VIN
VOUT2
W2
The noninverting amplifier with linear gain is shown in Figure 4,
and the gain is defined in Equation 3.
G =1+
R41
1.7kΩ
VIN
11879-005
Signal Amplifier
Figure 6. Inverting Amplifier with Linear Gain
Table 5. Amplifier Selection Link Settings
Amplifier
Noninverting
Gain
Linear
Pseudologarithmic
Inverting
Linear
Link Settings
Motherboard
A7: LIN position,
A6: N-INV position,
P5: not inserted
A8: N-INV position
Hardwired to RDAC2 of
A7: LOG position,
daughter board,
A6: N-INV position,
P5: not inserted
A8: N-INV position
Hardwired to RDAC2 of
A7: LIN position,
daughter board,
A6: INV position,
P5: not inserted
A8: INV position
Daughter Board
Hardwired to RDAC2 of
daughter board,
Rev. 0 | Page 5 of 16
VIN Range
0 V to VDD
0 V to VDD
−VDD to 0 V
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EVAL-AD5242DBZ User Guide
EVALUATION BOARD SOFTWARE
2.
INSTALLING THE SOFTWARE
The EVAL-AD5242DBZ kit includes evaluation board software
provided on a CD. The software is compatible with Windows® XP,
Windows Vista, and Windows 7 (both 32-bit and 64-bit versions).
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.
3.
4.
5.
Start the Windows operating system and insert the CD.
The installation software opens automatically. If it does
not, run the setup.exe file from the CD.
After the installation is complete, power up the evaluation
board as described in the Power Supplies section.
Connect the EVAL-AD5242DBZ and EVAL-MB-LV-SDZ to
the SDP board and the SDP board to the PC.
When the software detects the evaluation board, follow the
instructions that appear to finalize the installation.
11879-007
1.
2.
If the SDP board is not connected to the USB port when
the software is launched, a connectivity error displays (see
Figure 7). If a connectivity error is displayed, connect the
evaluation board to the USB port of the PC and wait a few
seconds, and then click Rescan and follow the instructions
that appear on-screen.
RUNNING THE SOFTWARE
To run the program, do the following:
Click Start > All Programs > Analog Devices > AD5242
> AD5242 Eval Board. (To uninstall the program, click
Start > Control Panel > Add or Remove Programs >
AD5242 Eval Board.)
The main window of the EVAL-AD5242DBZ software then
opens, as shown in Figure 8.
11879-008
1.
Figure 7. Pop-Up Window Error
Figure 8. EVAL-AD5242DBZ Software Main Window, Visual Mode Tab
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OPERATING THE SOFTWARE
Manual Control Tab
The main window of the EVAL-AD5242DBZ software is
divided into two tabs: Visual Mode and Manual Control.
The Manual Control tab, as shown in Figure 9, allows customizing
an I2C data-word by manually switching each serial data-word
from 0 to 1 or from 1 to 0, as desired, and then clicking Write
Registers. Data can also be read by clicking Read Registers.
Visual Mode Tab
The Visual Mode tab, as shown in Figure 8, is divided into two
sections, with a block diagram on the right and command
buttons on the left.
Exiting the window closes the program.
11879-009
The block diagram allows updating the control register status.
Each register value can easily be updated by changing the value
in its respective block within the diagram.
Figure 9. EVAL-AD5242DBZ Software Main Window, Manual Control Tab
Rev. 0 | Page 7 of 16
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EVAL-AD5242DBZ User Guide
EVALUATION BOARD SCHEMATICS AND ARTWORK
11879-010
MOTHERBOARD
Figure 10. SDP Connector and Power Supply
Rev. 0 | Page 8 of 16
EVAL-AD5242DBZ User Guide
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11879-011
Figure 11. Schematic of Test Circuits
Rev. 0 | Page 9 of 16
EVAL-AD5242DBZ User Guide
11879-012
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Figure 12. Schematic of Connectors to Daughter Board
Rev. 0 | Page 10 of 16
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11879-013
EVAL-AD5242DBZ User Guide
11879-014
Figure 13. Component Side View
11879-015
Figure 14. Component Placement Drawing
Figure 15. Layer 2 Side PCB Drawing
Rev. 0 | Page 11 of 16
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EVAL-AD5242DBZ User Guide
DAUGHTER BOARD
VDD
U1
5
VDD
2
A1
A1
W1 3 W1
4
B1
B1
O1 1 O1
A2 16 A2
W2 15 W2
B2 14 B2
O2 13 O2
VDD
VDD
C1
0.1µF
SHDN_N
DIS 6
SCL 7 SCL
SDA
8
C2
10µF
C3
0.1µF
C4
10µF
SDA
DGND
9
ADDR0
AD0
ADDR1 10 AD1
VSS
VSS
DGND
11
12
VSS
AD5242BRZ10
DGND
RESET_N
WP_N
LRDAC_N
DIS
INDEP
OP AMP PROTECTION
P5
B2
1
W2
2
69157-102
INSERT P1, P2, P3, AND P4
ON THE SOLDER SIDE OF THE BOARD
1
2
3
4
5
LOGIC OUTPUT
P3
P1
1
2
3
4
5
6
7
8
P2
A3
W3
B3
A4
W4
B4
22-03-2081
1
3
5
7
9
11
P2
2
4
6
8
10
12
A1
W1
B1
A2
W2
B2
TSW-105-08-G-S
VSS
VDD
AGND
11879-016
DGND
VLOGIC
P4
1
2
3
4
5
69157-102
ADDR0
ADDR1
SDA
SCL
SYNC_N
SDO
SDI
SCLK
TSW-106-08-G-D
1
2
TSW-106-08-G-D
TSW-105-08-G-S
P6
O1
O2
Figure 16. Schematic of Daughter Board
Rev. 0 | Page 12 of 16
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11879-017
EVAL-AD5242DBZ User Guide
11879-018
Figure 17. Component Side View
11879-019
Figure 18. Component Placement Drawing
Figure 19. Layer 2 Side PCB Drawing
Rev. 0 | Page 13 of 16
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EVAL-AD5242DBZ User Guide
BILL OF MATERIALS
Table 6. Motherboard Bill of Materials
Qty
3
3
5
1
2
1
1
1
2
17
1
1
1
1
1
1
3
5
1
8
4
2
4
2
1
1
1
1
1
1
1
1
1
18
5
1
Reference Designator
BUF-3, BUF-4, BUF-W1
A6, A7, A8
A5, A9, A10, A11, A12
J1
J7, J8
J4
J10
J5
J2, J3
R1, R3, R6, R7, R8, R9, R10, R11, R12,
R13, R20, R22, R23, R34, R35, R42,
R43
R2
R41
R21
R38
R14
R4
R5, R25, R26
R15, R16, R17, R18, R19
C1
C4, C9, C10, C11, C12, C17, C19, C21
C2, C6, C7, C14
C8, C13
C18, C20, C22, C5
C3, C15
C16
C34
L2
D1
U1
U2
U3
U4
U5
LRDAC, RESET, SYNC, WP, A1, A2, A3,
A4, AGND, B1, VOUT_C1, VOUT_C2,
VOUT3, VOUT4, W1, W2, W3, W4
+3.3V, +5V, EXT_VDD, VLOGIC,
EXT_VSS
Description
2-pin (0.1" pitch) header and shorting shunt
3-pin SIL header and shorting link
6-pin (3 × 2), 0.1" header and shorting block
3-pin terminal block (5 mm pitch)
4-pin SIL header
Receptacle, 0.6 mm, 120-way
8-pin inline header; 100 mil centers
12-pin (2 × 6), 0.1" pitch header
2-pin terminal block (5 mm pitch)
SMD resistor, 0 Ω, 0.01, 0603
Supplier 1/Part Number
FEC 1022247 and FEC 150411
FEC 1022248 and FEC 150410
FEC 148535 and FEC 150411 (36-pin strip)
FEC 151790
FEC 1098035
Digi-Key H1219-ND
FEC 1098038
FEC 1098051
FEC 151789
FEC 9331662
SMD resistor, 2.2 kΩ, 0.01, 0603
SMD resistor, 1.7 kΩ, 1%, 0603
Resistor, surge, 1.6 Ω, 1%, 0603
SMD resistor, 2.7 kΩ, 1%, 0603
SMD resistor, 100 Ω, 1%, 0603
SMD resistor, 1 kΩ, 0.01, 0603
SMD resistor, 100 kΩ, 1%, 0603
SMD resistor, 33 kΩ, 1%, 0603
SMD capacitor, 100 nF, 10%, 0805
SMD capacitor, 0.1 µF, ±10%, 0603
SMD capacitor, 0.1 µF, ±10%, 0603
SMD capacitor, 10 µF, ±10%
Capacitor, 10 µF, ±20%
Capacitor, 470 nF, ±10%, 0603
Capacitor, 4.7 nF, ±10%, 0603
Capacitor, 4.7 nF, ±20%
Inductor, SMD, 600Z
Green SMD LED
Two-port level translating bus switch
Dual op amp
Precision low dropout voltage regulator
Operational amplifier
I2C serial EEPROM, 64k, 2.5 V, MSOP-8
Terminal, PCB, black, PK100, test point
FEC 1750676
FEC 1170811
FEC 1627674
FEC 1750678
FEC 9330364
FEC 9330380
FEC 9330402
FEC 9331034
FEC 1650863
FEC 1759122
FEC 3019482
FEC 197130
FEC 1190107
FEC 1414037
FEC 1414642
FEC 1432350
FEC 9526862
FEC 5790852
ADG3247BCPZ
AD8652ARZ
ADP3303ARZ-3.3
AD8618ARZ
FEC 1331335
FEC 8731128
Terminal, PCB, red, PK100
FEC 8731144
FEC refers to Farnell Electronic Component Distributors; Digi-Key refers to Digi-Key Corporation.
Rev. 0 | Page 14 of 16
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Table 7. Daughter Board Bill of Materials
Qty
1
1
3
2
2
1
1
2
1
Reference Designator
U1
P8
P5, P6, P7
C2, C4
C1, C3
P1
P2
P3, P4
Description
256-position digital potentiometer
2-pin (0.1" pitch) header and shorting shunt
3-pin SIL header and shorting link
6.3 V, X5R, ceramic capacitor, 10 µF, ±20%
50 V, X7R, ceramic capacitor, 0.1 µF, ±10%
Header, 2.54 mm, PCB, 1 × 8-way
12-pin (2 × 6), 0.1" pitch header
5-pin SIL header
FEC refers to Farnell Electronic Component Distributors.
Rev. 0 | Page 15 of 16
Supplier 1/Part Number
AD5242BRZ10
FEC 1022247 and FEC 150411
FEC 1022248 and FEC 150410
GRM188R60J106ME47D
GRM188R71H104KA93D
FEC 1766172
FEC 1804099
FEC 1929016
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EVAL-AD5242DBZ User Guide
NOTES
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).
ESD Caution
ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection
circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
Legal Terms and Conditions
By using the evaluation board discussed herein (together with any tools, components documentation or support materials, the “Evaluation Board”), you are agreeing to be bound by the terms and conditions
set forth below (“Agreement”) unless you have purchased the Evaluation Board, in which case the Analog Devices Standard Terms and Conditions of Sale shall govern. Do not use the Evaluation Board until you
have read and agreed to the Agreement. Your use of the Evaluation Board shall signify your acceptance of the Agreement. This Agreement is made by and between you (“Customer”) and Analog Devices, Inc.
(“ADI”), with its principal place of business at One Technology Way, Norwood, MA 02062, USA. Subject to the terms and conditions of the Agreement, ADI hereby grants to Customer a free, limited, personal,
temporary, non-exclusive, non-sublicensable, non-transferable license to use the Evaluation Board FOR EVALUATION PURPOSES ONLY. Customer understands and agrees that the Evaluation Board is provided
for the sole and exclusive purpose referenced above, and agrees not to use the Evaluation Board for any other purpose. Furthermore, the license granted is expressly made subject to the following additional
limitations: Customer shall not (i) rent, lease, display, sell, transfer, assign, sublicense, or distribute the Evaluation Board; and (ii) permit any Third Party to access the Evaluation Board. As used herein, the term
“Third Party” includes any entity other than ADI, Customer, their employees, affiliates and in-house consultants. The Evaluation Board is NOT sold to Customer; all rights not expressly granted herein, including
ownership of the Evaluation Board, are reserved by ADI. CONFIDENTIALITY. This Agreement and the Evaluation Board shall all be considered the confidential and proprietary information of ADI. Customer may
not disclose or transfer any portion of the Evaluation Board to any other party for any reason. Upon discontinuation of use of the Evaluation Board or termination of this Agreement, Customer agrees to
promptly return the Evaluation Board to ADI. ADDITIONAL RESTRICTIONS. Customer may not disassemble, decompile or reverse engineer chips on the Evaluation Board. Customer shall inform ADI of any
occurred damages or any modifications or alterations it makes to the Evaluation Board, including but not limited to soldering or any other activity that affects the material content of the Evaluation Board.
Modifications to the Evaluation Board must comply with applicable law, including but not limited to the RoHS Directive. TERMINATION. ADI may terminate this Agreement at any time upon giving written notice
to Customer. Customer agrees to return to ADI the Evaluation Board at that time. LIMITATION OF LIABILITY. THE EVALUATION BOARD PROVIDED HEREUNDER IS PROVIDED “AS IS” AND ADI MAKES NO
WARRANTIES OR REPRESENTATIONS OF ANY KIND WITH RESPECT TO IT. ADI SPECIFICALLY DISCLAIMS ANY REPRESENTATIONS, ENDORSEMENTS, GUARANTEES, OR WARRANTIES, EXPRESS OR IMPLIED, RELATED
TO THE EVALUATION BOARD INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTY OF MERCHANTABILITY, TITLE, FITNESS FOR A PARTICULAR PURPOSE OR NONINFRINGEMENT OF INTELLECTUAL
PROPERTY RIGHTS. IN NO EVENT WILL ADI AND ITS LICENSORS BE LIABLE FOR ANY INCIDENTAL, SPECIAL, INDIRECT, OR CONSEQUENTIAL DAMAGES RESULTING FROM CUSTOMER’S POSSESSION OR USE OF
THE EVALUATION BOARD, INCLUDING BUT NOT LIMITED TO LOST PROFITS, DELAY COSTS, LABOR COSTS OR LOSS OF GOODWILL. ADI’S TOTAL LIABILITY FROM ANY AND ALL CAUSES SHALL BE LIMITED TO THE
AMOUNT OF ONE HUNDRED US DOLLARS ($100.00). EXPORT. Customer agrees that it will not directly or indirectly export the Evaluation Board to another country, and that it will comply with all applicable
United States federal laws and regulations relating to exports. GOVERNING LAW. This Agreement shall be governed by and construed in accordance with the substantive laws of the Commonwealth of
Massachusetts (excluding conflict of law rules). Any legal action regarding this Agreement will be heard in the state or federal courts having jurisdiction in Suffolk County, Massachusetts, and Customer hereby
submits to the personal jurisdiction and venue of such courts. The United Nations Convention on Contracts for the International Sale of Goods shall not apply to this Agreement and is expressly disclaimed.
©2014 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
UG11879-0-5/14(0)
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