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
PLEASE SEE THE LAST PAGE FOR AN IMPORTANT
WARNING AND LEGAL TERMS AND CONDITIONS. Rev. 0 | Page 1 of 16
FEATURES
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
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
GENERAL DESCRIPTION
This user guide describes the evaluation boards for evaluating the
AD5242, a single-channel, 256-position, I2C-compatible digital
potentiometer.
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 E VA L -AD5242DBZ daughter board and the E VA L -MB-
LV-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.
PHOTOGRAPH OF EVAL-AD5242DBZ WITH MOTHERBOARD AND SDP-B
11879-001
Figure 1. Digital Picture of Evaluation Board with Low Voltage DigiPOT Motherboard and System Demonstration Platform
UG-627 EVAL-AD5242DBZ User Guide
Rev. 0 | Page 2 of 16
TABLE OF CONTENTS
Features .............................................................................................. 1
Evaluation Kit Contents ................................................................... 1
General Description ......................................................................... 1
Photograph of EVAL-AD5242DBZ with Motherboard
and SDP-B .......................................................................................... 1
Revision History ............................................................................... 2
Evaluation Board Hardware ............................................................ 3
Power Supplies .............................................................................. 3
Link Options ................................................................................. 3
Logic Outputs................................................................................ 3
Test Circuits ...................................................................................4
Evaluation Board Software ...............................................................6
Installing the Software ..................................................................6
Running the Software ...................................................................6
Operating the Software .................................................................7
Evaluation Board Schematics and Artwork ...................................8
Motherboard ..................................................................................8
Daughter Board .......................................................................... 12
Bill of Materials ............................................................................... 14
REVISION HISTORY
5/14—Revision 0: Initial Version
EVAL-AD5242DBZ User Guide UG-627
Rev. 0 | Page 3 of 16
EVALUATION BOARD HARDWARE
POWER SUPPLIES
The EVAL-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.
LINK OPTIONS
Several link and switch options are incorporated on the EVAL-
MB-LV-SDZ and E VA L -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.
LOGIC OUTPUTS
Header P6 of the evaluation board is connected to the O1 and
O2 logic outputs of the AD5242.
Table 1. Connector Functions
Voltage
Connector No. Label Description Min Max
J1-1 VDD Analog positive power supply, VDD 2.7 V 5.5 V
J1-2 AGND Analog ground
J2-1 VLOGIC Digital supply 2.7 V VDD
J2-2 DGND Digital ground
Table 2. Link Functions
Link No. Power Supply Options Default Position
A5 VLOGIC Digital supply select options: 3.3 V
3.3 V (from the SDP board)
VLOGIC EXT (external supply from the J2 connector)
A11 VDD Positive power supply select options: 3.3 V
5 V (from the SDP board)
3.3 V (from the SDP board)
VDD (external supply from the J1 connector)
A12 GND AGND AGND
UG-627 EVAL-AD5242DBZ User Guide
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TEST CIRCUITS
The E VA L -AD5242DBZ and E VA L -MB-LV-SDZ incorporate
several test circuits to evaluate the performance of the AD5242.
DAC
The RDAC can be operated as a digital-to-analog converter (DAC),
as shown in Figure 2.
VOUT1
R34
R35
A1
W1
RDAC
A
BW
VDD
VDD
AC+
VDD
2
VDD
2AGND
BIAS
B1
BUF-W1
11879-002
Figure 2. DAC
Table 4 shows the options available for the voltage references.
The output voltage is defined in Equation 1.
256
)( RDAC
VVV B
A
OUT ×−=
(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).
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.
VOUT1
R34
R35
A1
W1
RDAC
A
BW
AC
AC+
AGND
BIAS
B1
BUF-W1
AC_INPUT
1kHz
HPF
V
DD
2
V
DD
2
11879-003
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 3.
Table 3. 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/2.1
AC All other conditions.
A10 BIAS Use in conjunction with AC+ link.1
AGND All other conditions.
1 Recommended to ensure optimal total harmonic distortion (THD) performance.
The signal attenuation is defined in Equation 2.
+
×=
−− END
TOEND
WWB
R
RR
nAttenuatio log20
)dB(
(2)
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
Link Settings
Terminal Daughter Board Motherboard Description
A1 Hardwired to RDAC1
of daughter board
A9: AC+ position Connects Terminal A1 to VDD/2
A9: VDD position Connects Terminal A1 to VDD
W1 Hardwired to RDAC1
of daughter board
BUF-W1: inserted Connects Terminal W1 to an output buffer
B1 Hardwired to RDAC1
of daughter board
A10: BIAS position Connects Terminal B1 to VDD/2
A10: AGND position Connects Terminal B1 to analog ground
P5: inserted Closes the feedback loop of the second op amp in the AD8618
EVAL-AD5242DBZ User Guide UG-627
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Signal Amplifier
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.
The noninverting amplifier with linear gain is shown in Figure 4,
and the gain is defined in Equation 3.
R38
R
G
WB
+= 1
(3)
where RWB is the resistance between the W and B terminals.
VOUT2
VIN
RDAC
R42
C1
10nF
W2
B2
W B
R41
1.7kΩ
R38
2.7kΩ
11879-004
Figure 4. Noninverting Amplifier with Linear Gain
The noninverting amplifier with pseudologarithmic gain is
shown in Figure 5, and the gain is defined in Equation 4.
AW
WB
R
R
G+=1
(4)
where:
RWB is the resistance between the W and B terminals.
RAW is the resistance between the A and W terminals.
VOUT2
V
IN
RDAC
R42
C1
10nF
W2
B2
AB
W
R41
1.7kΩ
A2
R43
11879-005
Figure 5. Noninverting Amplifier with Pseudologarithmic Gain
R43 and R42 can be used to set the maximum and minimum
gain limits.
The inverting amplifier with linear gain is shown in Figure 6,
and the gain is defined in Equation 5.
R38
R
GWB
−=
(5)
where RWB is the resistance between the W and B terminals.
Note that the input signal, VIN, must be negative.
VOUT2
VIN
RDAC
R42
C1
10nF
W2
B2
W B
R41
1.7kΩ
R38
2.7kΩ
11879-006
NOTES
1. THE INPUT SIGNAL, V
IN
, MUST BE NEGATIVE.
Figure 6. Inverting Amplifier with Linear Gain
Table 5. Amplifier Selection Link Settings
Link Settings
Amplifier Gain Daughter Board Motherboard VIN Range
Noninverting Linear Hardwired to RDAC2 of
daughter board,
A7: LIN position, 0 V to VDD
A6: N-INV position,
P5: not inserted A8: N-INV position
Pseudologarithmic Hardwired to RDAC2 of
daughter board,
A7: LOG position, 0 V to VDD
A6: N-INV position,
P5: not inserted A8: N-INV position
Inverting
Linear
Hardwired to RDAC2 of
daughter board,
A7: LIN position,
−V
DD
to 0 V
A6: INV position,
P5: not inserted A8: INV position
UG-627 EVAL-AD5242DBZ User Guide
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EVALUATION BOARD SOFTWARE
INSTALLING THE SOFTWARE
The E VA L -AD5242DBZ kit includes evaluation board software
provided on a CD. The software is compatible with Windows® X P,
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.
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 the installation is complete, power up the evaluation
board as described in the Power Supplies section.
4. Connect the E VA L-AD5242DBZ and E VA L -MB-LV-SDZ to
the SDP board and the SDP board to the PC.
5. When the software detects the evaluation board, follow the
instructions that appear to finalize the installation.
RUNNING THE SOFTWARE
To run the program, do the following:
1. 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.)
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.
11879-007
Figure 7. Pop-Up Window Error
The main window of the E VA L -AD5242DBZ software then
opens, as shown in Figure 8.
11879-008
Figure 8. EVAL-AD5242DBZ Software Main Window, Visual Mode Tab
EVAL-AD5242DBZ User Guide UG-627
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OPERATING THE SOFTWARE
The main window of the E VA L -AD5242DBZ software is
divided into two tabs: Visual Mode and Manual Control.
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.
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.
Manual Control Tab
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 Wr i te
Registers. Data can also be read by clicking Read Registers.
Exiting the window closes the program.
11879-009
Figure 9. EVAL-AD5242DBZ Software Main Window, Manual Control Tab
UG-627 EVAL-AD5242DBZ User Guide
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EVALUATION BOARD SCHEMATICS AND ARTWORK
MOTHERBOARD
11879-010
Figure 10. SDP Connector and Power Supply
EVAL-AD5242DBZ User Guide UG-627
Rev. 0 | Page 9 of 16
11879-011
Figure 11. Schematic of Test Circuits
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11879-012
Figure 12. Schematic of Connectors to Daughter Board
EVAL-AD5242DBZ User Guide UG-627
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11879-013
Figure 13. Component Side View
11879-014
Figure 14. Component Placement Drawing
11879-015
Figure 15. Layer 2 Side PCB Drawing
UG-627 EVAL-AD5242DBZ User Guide
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DAUGHTER BOARD
INS E RT P1, P 2, P3, AND P4
ON THE SOL DE R S IDE OF THE BO ARD
LOGIC OUTPUT
OP AMP PROTECTION
15
3
12
5
6
8
7
13
1
11
14
4
10
9
16
2
U1
2
1
P6
2
1
P5
11
9
7
5
3
1
P2
12
10
8
6
4
2
P2
5
4
3
2
1
P4
5
4
3
2
1
P3
8
7
6
5
4
3
2
1
P1
C4C2C1 C3
O2
SDA
A2
ADDR1
ADDR0
SCL
B2
DIS
W2
B1
W1
A1
AD5242BRZ10
10µF 0.1µF
VSS
O2
O1
O1
VDD
69157-102
69157-102
ADDR1
TSW-105-08-G-S
DIS
LRDAC_N
INDEP
ADDR0
VSS
22-03-2081
RESET_N
W2
B2
0.1µF
VDD
SDO
SYNC_N
WP_N
SDA
SCL
SDI B4
VDD
10µF
A3
W3
B3
A4
W4
TSW-105-08-G-S
TSW-106-08-G-D
TSW-106-08-G-D
VDD
VSS
VLOGIC
B2
A2
B1
W1
A1
SCLK
W2
A2
W2
B2 O2
VSS DGND
AD1
AD0
SDA
SCL
SHDN_N
VDD
B1
W1
A1 O1
AGND
DGND
DGND
DGND
11879-016
Figure 16. Schematic of Daughter Board
EVAL-AD5242DBZ User Guide UG-627
Rev. 0 | Page 13 of 16
11879-017
Figure 17. Component Side View
11879-018
Figure 18. Component Placement Drawing
11879-019
Figure 19. Layer 2 Side PCB Drawing
UG-627 EVAL-AD5242DBZ User Guide
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BILL OF MATERIALS
Table 6. Motherboard Bill of Materials
Qty Reference Designator Description Supplier1/Part Number
3 BUF-3, BUF-4, BUF-W1 2-pin (0.1" pitch) header and shorting shunt FEC 1022247 and FEC 150411
3 A6, A7, A8 3-pin SIL header and shorting link FEC 1022248 and FEC 150410
5 A5, A9, A10, A11, A12 6-pin (3 × 2), 0.1" header and shorting block FEC 148535 and FEC 150411 (36-pin strip)
1 J1 3-pin terminal block (5 mm pitch) FEC 151790
2 J7, J8 4-pin SIL header FEC 1098035
1 J4 Receptacle, 0.6 mm, 120-way Digi-Key H1219-ND
1 J10 8-pin inline header; 100 mil centers FEC 1098038
1
J5
12-pin (2 × 6), 0.1" pitch header
FEC 1098051
2 J2, J3 2-pin terminal block (5 mm pitch) FEC 151789
17 R1, R3, R6, R7, R8, R9, R10, R11, R12,
R13, R20, R22, R23, R34, R35, R42,
R43
SMD resistor, 0 Ω, 0.01, 0603 FEC 9331662
1 R2 SMD resistor, 2.2 kΩ, 0.01, 0603 FEC 1750676
1 R41 SMD resistor, 1.7 kΩ, 1%, 0603 FEC 1170811
1 R21 Resistor, surge, 1.6 Ω, 1%, 0603 FEC 1627674
1 R38 SMD resistor, 2.7 kΩ, 1%, 0603 FEC 1750678
1 R14 SMD resistor, 100 Ω, 1%, 0603 FEC 9330364
1 R4 SMD resistor, 1 kΩ, 0.01, 0603 FEC 9330380
3
R5, R25, R26
SMD resistor, 100 kΩ, 1%, 0603
FEC 9330402
5 R15, R16, R17, R18, R19 SMD resistor, 33 kΩ, 1%, 0603 FEC 9331034
1 C1 SMD capacitor, 100 nF, 10%, 0805 FEC 1650863
8 C4, C9, C10, C11, C12, C17, C19, C21 SMD capacitor, 0.1 µF, ±10%, 0603 FEC 1759122
4 C2, C6, C7, C14 SMD capacitor, 0.1 µF, ±10%, 0603 FEC 3019482
2 C8, C13 SMD capacitor, 10 µF, ±10% FEC 197130
4 C18, C20, C22, C5 Capacitor, 10 µF, ±20% FEC 1190107
2 C3, C15 Capacitor, 470 nF, ±10%, 0603 FEC 1414037
1 C16 Capacitor, 4.7 nF, ±10%, 0603 FEC 1414642
1 C34 Capacitor, 4.7 nF, ±20% FEC 1432350
1 L2 Inductor, SMD, 600Z FEC 9526862
1
D1
Green SMD LED
FEC 5790852
1 U1 Two-port level translating bus switch ADG3247BCPZ
1 U2 Dual op amp AD8652ARZ
1 U3 Precision low dropout voltage regulator ADP3303ARZ-3.3
1 U4 Operational amplifier AD8618ARZ
1 U5 I2C serial EEPROM, 64k, 2.5 V, MSOP-8 FEC 1331335
18 LRDAC, RESET, SYNC, WP, A1, A2, A3,
A4, AGND, B1, VOUT_C1, VOUT_C2,
VOUT3, VOUT4, W1, W2, W3, W4
Terminal, PCB, black, PK100, test point FEC 8731128
5 +3.3V, +5V, EXT_VDD, VLOGIC,
EXT_VSS
Terminal, PCB, red, PK100 FEC 8731144
1 FEC refers to Farnell Electronic Component Distributors; Digi-Key refers to Digi-Key Corporation.
EVAL-AD5242DBZ User Guide UG-627
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Table 7. Daughter Board Bill of Materials
Qty Reference Designator Description Supplier1/Part Number
1 U1 256-position digital potentiometer AD5242BRZ10
1 P8 2-pin (0.1" pitch) header and shorting shunt FEC 1022247 and FEC 150411
3 P5, P6, P7 3-pin SIL header and shorting link FEC 1022248 and FEC 150410
2 C2, C4 6.3 V, X5R, ceramic capacitor, 10 µF, ±20% GRM188R60J106ME47D
2 C1, C3 50 V, X7R, ceramic capacitor, 0.1 µF, ±10% GRM188R71H104KA93D
1 P1 Header, 2.54 mm, PCB, 1 × 8-way FEC 1766172
1 P2 12-pin (2 × 6), 0.1" pitch header FEC 1804099
2 P3, P4 5-pin SIL header FEC 1929016
1 FEC refers to Farnell Electronic Component Distributors.
UG-627 EVAL-AD5242DBZ User Guide
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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 engi
neer 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)
