Keithley 7035 User manual

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I
nstruct
i
on
M
anua
l
Contains Operating and Servicing Information
Model 7035
9-Bank, 1×4 Multiplexer Card
7035-901-01 Rev. A / 5-97

WARRANTY
Keithley Instruments, Inc. warrants this product to be free from defects in material and workmanship for a period of 1 year from date of
shipment.
Keithley Instruments, Inc. warrants the following items for 90 days from the date of shipment: probes, cables, rechargeable batteries,
diskettes, and documentation.
During the warranty period, we will, at our option, either repair or replace any product that proves to be defective.
To exercise this warranty, write or call your local Keithley representative, or contact Keithley headquarters in Cleveland, Ohio.You will
be given prompt assistance and return instructions. Send the product, transportation prepaid, to the indicated service facility. Repairs
will be made and the product returned, transportation prepaid. Repaired or replaced products are warranted for the balance of the origi-
nal warranty period, or at least 90 days.
LIMITATION OF WARRANTY
This warranty does not apply to defects resulting from product modification without Keithley’s express written consent, or misuse of
any product or part. This warranty also does not apply to fuses, software, non-rechargeable batteries, damage from battery leakage, or
problems arising from normal wear or failure to follow instructions.
THIS WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, INCLUDING ANY IMPLIED
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR USE. THE REMEDIES PROVIDED HEREIN ARE
BUYER’S SOLE AND EXCLUSIVE REMEDIES.
NEITHER KEITHLEY INSTRUMENTS, INC. NOR ANY OF ITS EMPLOYEES SHALL BE LIABLE FOR ANY DIRECT, INDI-
RECT, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF ITS INSTRUMENTSAND
SOFTWARE EVEN IF KEITHLEY INSTRUMENTS, INC., HAS BEEN ADVISED IN ADVANCE OF THE POSSIBILITY OF
SUCH DAMAGES. SUCH EXCLUDED DAMAGES SHALL INCLUDE, BUT ARE NOT LIMITED TO: COSTS OF REMOVAL
AND INSTALLATION, LOSSES SUSTAINED AS THE RESULT OF INJURY TO ANY PERSON, OR DAMAGE TO PROPERTY.
Keithley Instruments, Inc. • 28775 Aurora Road • Cleveland, OH 44139 • 216-248-0400 • Fax: 216-248-6168 • http://www.keithley.com
CHINA: Keithley Instruments China •Yuan Chen Xin Building, Room 705 • 12 Yumin Road, Dewai, Madian • Beijing 100029 • 8610-62022886 • Fax: 8610-62022892
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GERMANY: Keithley Instruments GmbH • Landsberger Strasse 65 • D-82110 Germering, Munich • 49-89-8493070 • Fax: 49-89-84930759
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TAIWAN: Keithley Instruments Taiwan • 1FL., 1, MinYu First Street • Hsinchu, Taiwan, R.O.C. • 886-35-778462 • Fax: 886-35-778455

Model 7035 9-Bank, 1
×4 Multiplexer Card
Instruction Manual
©1997, Keithley Instruments, Inc.
All rights reserved.
Cleveland, Ohio, U.S.A.
First Printing, May 1997
Document Number: 7035-901-01 Rev. A

Manual Print History
The print history shown below lists the printing dates of all Revisions and Addenda created for this manual. The Revision
Level letter increases alphabetically as the manual undergoes subsequent updates. Addenda, which are released between Revi-
sions, contain important change information that the user should incorporate immediately into the manual. Addenda are num-
bered sequentially. When a new Revision is created, all Addenda associated with the previous Revision of the manual are
incorporated into the new Revision of the manual. Each new Revision includes a revised copy of this print history page.
Many product updates and revisions do not require manual changes and, conversely, manual corrections may be done without
accompanying product changes. Therefore, it is recommended that you review the Manual Update History.
RevisionA (Document Number 7035-901-01)......................................................................................... May 1997
All Keithley product names are trademarks or registered trademarks of Keithley Instruments, Inc.
Other brand and product names are trademarks or registered trademarks of their respective holders.

Safety Precautions
The following safety precautions should be observed before using
this product and any associated instrumentation.Although some in-
struments and accessories would normally be used with non-haz-
ardous voltages, there are situations where hazardous conditions
may be present.
This product is intended for use by qualified personnel who recog-
nize shock hazards and are familiar with the safety precautions re-
quired to avoid possible injury. Read the operating information
carefully before using the product.
The types of product users are:
Responsible body is the individual or group responsible for the use
and maintenance of equipment, and for ensuring that operators are
adequately trained.
Operators use the product for its intended function. They must be
trained in electrical safety procedures and proper use of the instru-
ment. They must be protected from electric shock and contact with
hazardous live circuits.
Maintenance personnel perform routine procedures on the product
to keep it operating, for example, setting the line voltage or replac-
ing consumable materials. Maintenance procedures are described in
the manual. The procedures explicitly state if the operator may per-
form them. Otherwise, they should be performed only by service
personnel.
Service personnel are trained to work on live circuits, and perform
safe installations and repairs of products. Only properly trained ser-
vice personnel may perform installation and service procedures.
Exercise extreme caution when a shock hazard is present. Lethal
voltage may be present on cable connector jacks or test fixtures.The
American National Standards Institute (ANSI) states that a shock
hazard exists when voltage levels greater than 30V RMS, 42.4V
peak, or 60VDC are present.A goodsafety practice is to ex-
pect that hazardous voltage is present in any un-
known circuit before measuring.
Users of this product must be protected from electric shock at all
times. The responsible body must ensure that users are prevented
access and/or insulated from every connection point. In some cases,
connections must be exposed to potential human contact. Product
users in these circumstances must be trained to protect themselves
from the risk of electric shock. If the circuit is capable of operating
at or above 1000 volts, no conductive part of the circuit may be
exposed.
As described in the International Electrotechnical Commission
(IEC) Standard IEC 664, digital multimeter measuring circuits
(e.g., Keithley Models 175A, 199, 2000, 2001, 2002, and 2010)
measuring circuits are Installation Category II. All other instru-
ments’ signal terminals are Installation Category I and must not be
connected to mains.
Do not connect switching cards directly to unlimited power circuits.
They are intended to be used with impedance limited sources.
NEVER connect switching cards directly to AC mains. When con-
necting sources to switching cards, install protective devices to lim-
it fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connect-
ed to a properly grounded power receptacle. Inspect the connecting
cables, test leads, and jumpers for possible wear, cracks, or breaks
before each use.
For maximum safety, do not touch the product, test cables, or any
other instruments while power is applied to the circuit under test.
ALWAYS remove power from the entire test system and discharge
any capacitors before: connecting or disconnecting cables or jump-
ers, installing or removing switching cards, or making internal
changes, such as installing or removing jumpers.
Do not touch any object that could provide a current path to the
common side of the circuit under test or power line (earth) ground.
Always make measurements with dry hands while standing on a
dry, insulated surface capable of withstanding the voltage being
measured.

Do not exceed the maximum signal levels of the instruments and ac-
cessories, as defined in the specifications and operating informa-
tion, and as shown on the instrument or test fixture panels, or
switching card.
When fuses are used in a product, replace with same type and rating
for continued protection against fire hazard.
Chassis connections must only be used as shield connections for
measuring circuits, NOT as safety earth ground connections.
If you are using a test fixture, keep the lid closed while power is ap-
plied to the device under test. Safe operation requires the use of a
lid interlock.
If a screw is present, connect it to safety earth ground using the
wire recommended in the user documentation.
The symbol on an instrument indicates that the user should re-
fer to the operating instructions located in the manual.
The symbol on an instrument shows that it can source or mea-
sure 1000 volts or more, including the combined effect of normal
and common mode voltages. Use standard safety precautions to
avoid personal contact with these voltages.
The WARNING heading in a manual explains dangers that might
result in personal injury or death.Always read the associated infor-
mation very carefully before performing the indicated procedure.
The CAUTION heading in a manual explains hazards that could
damage the instrument. Such damage may invalidate the warranty.
Instrumentation and accessories shall not be connected to humans.
Before performing any maintenance, disconnect the line cord and
all test cables.
To maintain protection from electric shock and fire, replacement
components in mains circuits, including the power transformer, test
leads, and input jacks, must be purchased from Keithley Instru-
ments. Standard fuses, with applicable national safety approvals,
may be used if the rating and type are the same. Other components
that are not safety related may be purchased from other suppliers as
long as they are equivalent to the original component. (Note that se-
lected parts should be purchased only through Keithley Instruments
to maintain accuracy and functionality of the product.) If you are
unsure about the applicability of a replacement component, call a
Keithley Instruments office for information.
To clean the instrument, use a damp cloth or mild, water based
cleaner. Clean the exterior of the instrument only. Do not apply
cleaner directly to the instrument or allow liquids to enter or spill
on the instrument.
!

M
ODEL
7035 S
PECIFICATIONS
MULTIPLEX CONFIGURATION: Nine independent 1×4 2-pole
multiplex banks.
CONTACT CONFIGURATION: 2-pole Form A (Hi, Lo).
CONNECTOR TYPE: 96-pin male DIN connector.
MAXIMUM SIGNAL LEVEL: 60VDC, 30V rms, 42V peak betwen any
two inputs or chassis, 1A switched. 30VA (resistive load).
CONTACT LIFE: Cold Switching: 108closures.
At Maximum Signal Levels: 105closures.
CHANNEL RESISTANCE (per conductor): <1Ω.
CONTACT POTENTIAL: <1µV per channel contact pair
<3µV typical per single contact.
OFFSET CURRENT: <100pA.
ACTUATION TIME: 3ms.
ISOLATION: Bank: >109Ω, <25 pF.
Channel to Channel: >109Ω, <50 pF.
Differential: >109Ω, <100pF.
Common Mode: >109Ω, <200pF.
CROSSTALK (1MHz, 50ΩLoad): Bank: <–40dB.
Channel: <–40dB.
INSERTION LOSS (50ΩSource, 50 Load): <0.25dB below 1MHz,
<3dB below 10MHz.
RELAY DRIVE CURRENT (per relay): 16mA.
ENVIRONMENT: Operating: 0° to 50°C, up to 35°C <80% RH.
Storage: –25°C to 65°C.
EMC: Conforms with European Union Directive 89/336/EEC
EN 55011, EN 50082-1, EN 61000-3-2 and 61000-3-3, FCC part 15
class B.
SAFETY: Conforms with European Union Directive 73/23/EEC
EN 61010-1, UL 3111-1.
Channel 1
HI
LO
Bank A
Channels 2–3
HI
LO
Channel 4
HI
Output
LO
Channel 1
HI
LO
Bank I
Channels 2–3
HI
LO
Channel 4
HI
Output
LO
Specifications are subject to change without notice.

Table of Contents
1 General Information
Introduction......................................................................................................................................................... 1-1
Features............................................................................................................................................................... 1-1
Warranty information.......................................................................................................................................... 1-1
Manual addenda.................................................................................................................................................. 1-2
Safety symbols and terms ................................................................................................................................... 1-2
Specifications...................................................................................................................................................... 1-2
Unpacking and inspection................................................................................................................................... 1-2
Inspection for damage................................................................................................................................. 1-2
Handling precautions ................................................................................................................................. 1-2
Shipping contents........................................................................................................................................ 1-2
Instruction manual....................................................................................................................................... 1-2
Repacking for shipment ...................................................................................................................................... 1-3
Optional accessories............................................................................................................................................ 1-3
2 Multiplexer Configuration
Introduction......................................................................................................................................................... 2-1
Basic multiplexer configuration.......................................................................................................................... 2-1
Typical multiplexer switching schemes.............................................................................................................. 2-2
Single-ended switching............................................................................................................................... 2-2
Differential switching ................................................................................................................................. 2-2
Sensing........................................................................................................................................................ 2-3
SMU connections........................................................................................................................................ 2-3
Multiplexer expansion......................................................................................................................................... 2-4
i

3 Card Connections and Installation
Introduction ......................................................................................................................................................... 3-1
Handling precautions........................................................................................................................................... 3-1
Multi-pin (mass termination) connections........................................................................................................... 3-1
Typical connection technique...................................................................................................................... 3-4
Typical connection scheme ......................................................................................................................... 3-6
Model 7035 installation and removal.................................................................................................................. 3-8
Card installation........................................................................................................................................... 3-8
Card removal............................................................................................................................................... 3-8
4 Operation
Introduction ......................................................................................................................................................... 4-1
Power limits......................................................................................................................................................... 4-1
Maximum signal levels................................................................................................................................ 4-1
Mainframe control of card................................................................................................................................... 4-1
Channel assignments................................................................................................................................... 4-2
Closing and opening channels..................................................................................................................... 4-4
Scanning channels....................................................................................................................................... 4-4
IEEE-488 bus operation .............................................................................................................................. 4-5
Multiplexer switching examples.......................................................................................................................... 4-6
Two-wire resistance tests ............................................................................................................................ 4-6
Four-wire resistance tests ............................................................................................................................ 4-7
Measurement considerations ............................................................................................................................... 4-7
Path isolation............................................................................................................................................... 4-7
Magnetic fields............................................................................................................................................ 4-8
Radio frequency interference ...................................................................................................................... 4-8
Ground loops............................................................................................................................................... 4-9
Keeping connectors clean............................................................................................................................ 4-9
AC frequency response................................................................................................................................ 4-9
5 Service Information
Introduction ......................................................................................................................................................... 5-1
Handling and cleaning precautions ..................................................................................................................... 5-1
Performance verification ..................................................................................................................................... 5-2
Environmental conditions............................................................................................................................ 5-2
Recommended equipment........................................................................................................................... 5-2
Multiplexer connections.............................................................................................................................. 5-2
Channel resistance tests............................................................................................................................... 5-3
Offset current tests....................................................................................................................................... 5-4
Contact potential tests.................................................................................................................................. 5-6
Bank and channel-to-channel isolation tests ............................................................................................... 5-8
Differential and common-mode isolation tests.......................................................................................... 5-12
Special handling of static-sensitive devices ...................................................................................................... 5-16
Principles of operation....................................................................................................................................... 5-16
Block diagram ........................................................................................................................................... 5-16
ID data circuits .......................................................................................................................................... 5-17
Relay control ............................................................................................................................................. 5-17
Relay power control .................................................................................................................................. 5-17
ii

Power-on safeguard................................................................................................................................... 5-18
Troubleshooting ................................................................................................................................................ 5-18
Troubleshooting equipment ...................................................................................................................... 5-18
Troubleshooting access............................................................................................................................. 5-18
Troubleshooting procedure ....................................................................................................................... 5-18
6 Replaceable Parts
Introduction......................................................................................................................................................... 6-1
Parts lists ..............................................................................................................................................................6-1
Ordering information .......................................................................................................................................... 6-1
Factory service.................................................................................................................................................... 6-1
Component layouts and schematic diagrams...................................................................................................... 6-1
Index
iii

List of Illustrations
2 Multiplexer Configuration
Figure 2-1 Model 7035 simplified schematic............................................................................................................... 2-1
Figure 2-2 Single-ended switching example................................................................................................................. 2-2
Figure 2-3 Differential switching example................................................................................................................... 2-2
Figure 2-4 Sensing example ......................................................................................................................................... 2-3
Figure 2-5 SMU connections........................................................................................................................................ 2-3
Figure 2-6 Multiplexer expansion example.................................................................................................................. 2-4
3 Card Connections and Installation
Figure 3-1 Multi-pin connector card terminal identification........................................................................................ 3-2
Figure 3-2 Typical round cable connection techniques................................................................................................ 3-4
Figure 3-3 Model 7011-MTR connector pinout ........................................................................................................... 3-5
Figure 3-4 Model 7011-KIT-R (cable) assembly ......................................................................................................... 3-5
Figure 3-5 Typical connection scheme for Model 7035............................................................................................... 3-7
Figure 3-6 Model 7035 card installation in Model 7001.............................................................................................. 3-8
4 Operation
Figure 4-1 Model 7001 channel status display............................................................................................................. 4-2
Figure 4-2 Model 7002 channel status display (slot 1)................................................................................................. 4-2
Figure 4-3 Display organization for multiplexer channels........................................................................................... 4-3
Figure 4-4 Channel assignments................................................................................................................................... 4-3
Figure 4-5 Two-wire resistance testing......................................................................................................................... 4-6
Figure 4-6 1x36 multiplex bank.................................................................................................................................... 4-6
Figure 4-7 Four-wire resistance testing ........................................................................................................................ 4-7
Figure 4-8 Path isolation resistance.............................................................................................................................. 4-8
Figure 4-9 Voltage attenuation by path isolation resistance......................................................................................... 4-8
Figure 4-10 Power line ground loops ............................................................................................................................. 4-9
Figure 4-11 Eliminating ground loops............................................................................................................................ 4-9
v

5 Service Information
Figure 5-1 Path resistance test connections................................................................................................................... 5-3
Figure 5-2 Differential offset current test connections ................................................................................................. 5-5
Figure 5-3 Contact potential test connections............................................................................................................... 5-7
Figure 5-4 Bank isolation test connections................................................................................................................... 5-8
Figure 5-5 Channel-to-channel isolation test connections.......................................................................................... 5-10
Figure 5-6 Differential isolation test connections....................................................................................................... 5-13
Figure 5-7 Common-mode isolation test connections................................................................................................. 5-15
Figure 5-8 Model 7035 block diagram........................................................................................................................ 5-16
Figure 5-9 Start and stop sequences............................................................................................................................ 5-17
Figure 5-10 Transmit and acknowledge sequence........................................................................................................ 5-17
vi

List of Tables
3 Card Connections and Installation
Table 3-1 Multi-pin connector card terminal designation cross-reference.................................................................. 3-3
Table 3-2 Mass termination accessories...................................................................................................................... 3-3
4 Operation
Table 4-1 Paired channels in four-wire resistance example........................................................................................ 4-7
5 Service Information
Table 5-1 Verification equipment ............................................................................................................................... 5-2
Table 5-2 Bank isolation test summary....................................................................................................................... 5-9
Table 5-3 Channel-to-channel isolation test summary.............................................................................................. 5-11
Table 5-4 Differential and common-mode isolation testing...................................................................................... 5-14
Table 5-5 Recommended troubleshooting equipment............................................................................................... 5-18
Table 5-6 Troubleshooting procedure ....................................................................................................................... 5-19
6 Replaceable Parts
Table 6-1 Relay board for Model 7035 parts list ........................................................................................................ 6-2
Table 6-2 Mass-terminated connector board for Model 7035 parts list...................................................................... 6-3
Table 6-3 Model 7011-KIT-R 96-pin female DIN connector kit parts list..................................................................6-3
vii

1
General Information
1-1
Introduction
This section contains general information about the Model
7035 9-Bank, 1
×4 Multiplexer Card.
The Model 7035 assembly consists of a multi-pin (mass ter-
mination) connector card and a relay card. External test cir-
cuit connections to the Model 7035 are made via the 96-pin
male DIN connector on the connector card. Keithley offers a
variety of optional accessories that can be used to make con-
nections to the connector card. See the available optional
accessories at the end of this section.
The rest of Section 1 is arranged in the following manner:
• Features
• Warranty information
• Manual addenda
• Safety symbols and terms
• Specifications
• Unpacking and inspection
• Repacking for shipment
• Optional accessories
Features
The Model 7035 is a general purpose multiplexer card with
nine independent, 1
×4, two-pole, multiplex banks. Some of
the key features include:
• Low contact potential and offset current for minimal
effects on low-level signals.
• High isolation resistance (>1G
Ω) for minimal load
effects.
• Model 7011-KIT-R connector kit that includes a 96-pin
female DIN connector that will mate directly to the con-
nector on the Model 7035 or to a standard 96-pin male
DIN bulkhead connector (see Model 7011-MTR). This
connector uses solder cups for connections to external
circuitry and includes an adapter for a round cable and
the housing.
Warranty information
Warranty information is located at the front of this instruc-
tion manual. Should your Model 7035 require warranty ser-
vice, contact the Keithley representative or authorized repair
facility in your area for further information. When returning
the card for repair, be sure to fill out and include the service
form at the back of this manual in order to provide the repair
facility with the necessary information.

General Information
1-2
Manual addenda
Any improvements or changes concerning the card or man-
ual will be explained in an addendum included with the card.
Addenda are provided in a page-replacement format.
Replace the obsolete pages with the new pages.
Safety symbols and terms
The following symbols and terms may be found on an instru-
ment or used in this manual.
The symbol on an instrument indicates that you
should refer to the operating instructions located in the
instruction manual.
The symbol on an instrument shows that high voltage
may be present on the terminal(s). Use standard safety pre-
cautions to avoid personal contact with these voltages.
The WARNING heading used in this manual explains dan-
gers that might result in personal injury or death. Always
read the associated information very carefully before per-
forming the indicated procedure.
The CAUTION heading used in this manual explains haz-
ards that could damage the card. Such damage may invali-
date the warranty.
Specifications
Model 7035 specifications may be found at the front of this
manual. These specifications are exclusive of the Model
7001/7002 mainframe specifications.
Unpacking and inspection
Inspection for damage
The Model 7035 is packaged in a resealable, anti-static bag
to protectit from damage due to static discharge and from
contamination that could degrade its performance. Before
removing the card from the bag, observe the following pre-
cautions on handling.
Handling precautions
1. Always grasp the card by the side edges and shields. Do
not touch the board surfaces or components.
2. When not installed in a Model 7001/7002 mainframe,
keep the card in the anti-static bag and store it in the
original packing carton.
After removing the card from its anti-static bag, inspect it for
any obvious signs of physical damage. Report any such dam-
age to the shipping agent immediately.
Shipping contents
The following items are included with every Model 7035
order:
• Model 7035 9-Bank, 1
×4 Multiplexer Card
• Model 7011-KIT-R 96-pin Female DIN Connector Kit
• Model 7035 Instruction Manual
• Additional accessories as ordered
Instruction manual
The Model 7035 Instruction Manual is three-hole drilled so
it can be added to the three-ring binder of the Model 7001 or
Model 7002 Instruction Manual. After removing the plastic
wrapping, place the manual in the binder following the main-
frame instruction manual. Note that a manual identification
tab is included and should precede the multiplexer card
instruction manual.
If an additional instruction manual is required, order the
manual package, Keithley part number 7035-901-00. The
manual package includes an instruction manual and any per-
tinent addenda.
!

General Information
1-3
Repacking for shipment
Should it become necessary to return the Model 7035 for
repair, carefully pack the unit in its original packing carton,
or the equivalent, and include the following information:
• Advise as to the warranty status of the card.
• Write ATTENTION REPAIR DEPARTMENT on the
shipping label.
• Fill out and include the service form located at the back
of this manual.
Optional accessories
The following accessories are available for use with the
Model 7035:
Model 7011-MTC-2 — This two-meter round cable assem-
bly is terminated with a 96-pin female DIN connector on
each end. It will mate directly to the connector on the
Model 7035 and to a standard 96-pin male DIN bulkhead
connector (see Model 7011-MTR).
Model 7011-MTR
⎯This 96-pin male DIN bulkhead con-
nector uses solder cups for connections to external circuitry.
It will mate to the Model 7011-KIT-R connector and Model
7011-MTC-2 cable assembly.

2
Multiplexer Configuration
2-1
Introduction
This section covers the basics for multiplexer switching and
is arranged as follows:
•Basic multiplexer configuration — Covers the basic
multiplexer configuration.
•Typical multiplexer switching schemes — Explains
some of the basic ways a multiplexer can be used to
source or measure. Covers single-ended switching, dif-
ferential (floating) switching, sensing, and SMU
connections.
•Multiplexer expansion — Discusses how to configure
a larger multiplexer configuration.
Basic multiplexer configuration
A simplified schematic of the Model 7035 multiplex banks is
shown in Figure 2-1. It is organized as nine independent
1
×4 banks. Each bank has four inputs and one output. Two-
pole switching is provided for each multiplexer input, with
HI and LO switched.
Figure 2-1
Model 7035 simplified schematic
Switching Topology
Model 7035
Bank A
14
Bank B
14
Bank C
14
Bank D
14
Bank E
14
Bank F
14
Bank G
14
Bank H
14
Bank I
14
Input (1 of 36)
HI
LO
HI LO
Bank
for all Channels

Multiplexer Configuration
2-2
Figure 2-2
Single-ended switching example
Typical multiplexer switching schemes
The following paragraphs describe some basic switching
schemes that are possible with a two-pole switching multi-
plexer. These switching schemes include some various
shielding configurations to help minimize noise pick-up in
sensitive measurement applications.These shields are shown
connected to chassis ground. For some test configurations,
shielding may prove to be more effective connected to circuit
common. Chassis ground is accessible at the rear panel of the
Model 7001/7002 mainframe.
Single-ended switching
In the single-ended switching configuration, the source or
measure instrument is connected to the DUT through a
single pathway as shown in Figure 2-2. The instrument is
connected to the output of one of the banks, and the DUT is
shown connected to one of the inputs for that bank.
Differential switching
The differential or floating switching configuration is shown
in Figure 2-3. The advantage of using this configuration is
that the terminals of the source or measure instrument are not
confined to the same pathway. Each terminal of the instru-
ment can be switched to any available input in the test
system.
Figure 2-3
Differential switching example
Source or
Measure
Bank A-I Input 1-4
7035
H
L
HI
LO
DUT
Optional
Shield
Out In
HI
LO
Source or
Measure
Bank A Input 1-4
7035
H
L
H
L
DUT
Out
Out
In
In
Bank B Input 5-8

Multiplexer Configuration
2-3
Figure 2-4
Sensing example
Sensing
Figure 2-4 shows how the multiplexer can be configured to
use instruments that have sensing capability. The main
advantage of using sensing is to cancel the effects of switch
card path resistance (<1
Ω) and the resistance of external
cabling.Whenever path resistance is a consideration, sensing
should be used.
SMU connections
Figure 2-5 shows how to connect a Keithley Model 236, 237,
or 238 Source Measure Unit to the multiplexer. By using
triax cables that are unterminated at one end, the driven
guard and chassis ground are physically extended all the way
to the card.
Figure 2-5
SMU connections
Source HI
Sense HI
Sense LO
Source LO
Source or
Measure
Bank A
Input 1-4
7035
H
L
H
L
DUT
Input 5-8
Out
Out
Bank B
In
In
Output HI
Guard
Sense HI
Guard
Bank A Input 1-4
7035
H
L
H
L
DUT
Sense LO
Output LO
Output LO
236/237/238
Triax
Cables (3)
WARNING: Hazardous voltages may be present on
GUARD. Make sure all cable shields are
properly insulated before applying power.
Out
Out
Bank B
In
In
Input 5-8
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