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7701
User Manual
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Keithley 7701 User Manual

Model 7701
User’s Guide
PA-769 Rev. B / 8-03
The Model 7701 can be used with Keithley Models 2700, 2701, and 2750. All references to the Model 27xx apply to the Models 2700, 2701, and 2750.
A GREATER MEASURE OF CONFIDENCE
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Phone 781-665-1400 Toll Free 1-800-517-8431
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Safety Precautions

The following safety precautions should be observed before using this product and any associated instrumentation. Although some in­struments and accessories would normally be used with non-haz­ardous voltages, there are situations where hazardous conditions may be present.
This product is intended for use by qualified personnel who recog­nize shock hazards and are familiar with the safety precautions re­quired to avoid possible injury. Read and follow all installation, operation, and maintenance information carefully before using the product. Refer to the manual for complete product specifications.
If the product is used in a manner not specified, the protection pro­vided by the product may be impaired.
The types of product users are:
Responsible body
and maintenance of equipment, for ensuring that the equipment is operated within its specifications and operating limits, and for en­suring that operators are adequately trained.
Operators
trained in electrical safety procedures and proper use of the instru­ment. They must be protected from electric shock and contact with hazardous live circuits.
Maintenance personnel
to keep it operating properly, for example, setting the line voltage or replacing consumable materials. Maintenance procedures are de­scribed in the manual. The procedures explicitly state if the operator may perform them. Otherwise, they should be performed only by service personnel.
Service personnel
safe installations and repairs of products. Only properly trained ser­vice personnel may perform installation and service procedures.
Keithley products are designed for use with electrical signals that are rated Measurement Category I and Measurement Category II, as described in the International Electrotechnical Commission (IEC) Standard IEC 60664. Most measurement, control, and data I/O sig­nals are Measurement Category I and must not be directly connect­ed to mains voltage or to voltage sources with high transient over­voltages. Measurement Category II connections require protection for high transient over-voltages often associated with local AC mains connections. Assume all measurement, control, and data I/O connections are for connection to Category I sources unless other­wise marked or described in the Manual.
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.
that hazardous voltage is present in any unknown circuit before measuring.
is the individual or group responsible for the use
use the product for its intended function. They must be
perform routine procedures on the product
are trained to work on live circuits, and perform
A good safety practice is to expect
Operators of this product must be protected from electric shock at all times. The responsible body must ensure that operators are pre­vented access and/or insulated from every connection point. In some cases, connections must be exposed to potential human con­tact. Product operators 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,
the circuit may be exposed.
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 con­necting sources to switching cards, install protective devices to lim­it fault current and voltage to the card.
Before operating an instrument, make sure the line cord is connect­ed to a properly grounded power receptacle. Inspect the connecting cables, test leads, and jumpers for possible wear, cracks, or breaks before each use.
When installing equipment where access to the main power cord is restricted, such as rack mounting, a separate main input power dis­connect device must be provided, in close proximity to the equip­ment and within easy reach of the operator.
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 jump­ers, 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.
The instrument and accessories must be used in accordance with its specifications and operating instructions or the safety of the equip­ment may be impaired.
Do not exceed the maximum signal levels of the instruments and ac­cessories, as defined in the specifications and operating informa­tion, 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 ap­plied to the device under test. Safe operation requires the use of a lid interlock.
no conductive part of
5/03
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 re­fer to the operating instructions located in the manual.
The symbol on an instrument shows that it can source or mea­sure 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 symbol indicates a connection terminal to the equipment frame.
The
WARNING
result in personal injury or death. Always read the associated infor­mation very carefully before performing the indicated procedure.
The
CAUTION
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.
heading in a manual explains dangers that might
heading in a manual explains hazards that could
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 Instru­ments. 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 se­lected 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 an 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. Products that consist of a circuit board with no case or chassis (e.g., data acquisition board for installation into a computer) should never require cleaning if handled according to in­structions. If the board becomes contaminated and operation is af­fected, the board should be returned to the factory for proper cleaning/servicing.
Keithley Instruments, Inc.
28775 Aurora Road Cleveland, Ohio 44139 (440) 248-0400 Fax: (440) 248-6168 www.keithley.com
The information in this section is organized as follows:
• Card configuration – schematic on page 2.
• Connections and wiring on page 4.
• Screw terminals on page 4.
• D-shell connectors on page 6.
• Wiring on page 7.
• Typical connections on page 12.
• Connection log on page 14.
• Operation on page 14.
• Channel assignments on page 15.
• System channel operation on page 15.
• Multiple channel operation on page 16.
• Applications on page 17.
• Service on page 25.
• Performance verification on page 25.
• Replaceable parts on page 25.
• Specifications on page 30.
Model 7701
User’s Guide
PA-769 Rev. B / 8-03

Introduction

NOTE The 7701 module can be used with Keithley Models 2700, 2701, and 2750. All references to the
Model 27xx apply to the Models 2700, 2701, and 2750.
The Model 7701 is a 32-channel high speed differential multiplexer module and has the following features:
• Voltage measurements (DC and AC).
• Frequency and period measurements.
• Normal ohms measurements:
• 2-wire ohms to test up to 32 DUT.
• 4-wire ohms to test up to 16 DUT. Normal Ω 4 automatically pairs switches for four wire measurements — n + 16.
• Common-side 4-wire ohms measurements – Configures the module to allow use of a common bus to perform 4-wire ohms measurements on up to 32 DUT.
• Temperature applications (RTD or thermistor).
• 50-pin female D-Shell connector (DB-50) for channels 1 through 24.
• 25-pin female D-Shell connector (DB-25) for channels 25 through 32.
• Screw terminals and supplied jumpers to access the DMM of the Model 27xx mainframe.
WARNING The Model 7701 is configurable to be connected to the internal DMM via the supplied
jumpers and the screw terminals. When connected to the internal DMM, all other modules must be derated to 150VDC or 150Vrms (212V peak) for AC waveforms.
NOTE The Model 7701 is shipped from the factory with the screw terminal jumpers NOT installed. See
“Screw terminals” to install the jumpers.
WARNING Before operating the Model 27xx with an accessory card, verify that the card is properly
installed and the mounting screws are tightly fastened. If the mounting screws are not properly connected, an electrical shock hazard may be present.
Card configuration – schematic
Figure 1 shows a simplified schematic diagram of the Model 7701 module. As shown, the Model 7701 has input channels that
are grouped into two banks of sixteen channels (thirty-two channels total). A backplane isolation relay is provided for each bank. The first bank contains channels 1 through 16 while the second bank contains channels 17 through 32. Each input chan­nel of the 32-channel multiplexer card is wired with separate inputs for HI/LO providing fully isolated inputs.
As shown in Figure 1, all Model 7701 channels are isolated from the DMM of the Model 27xx by screw terminals. Supplied jumpers must be installed in the screw terminals to connect switching module channels to the DMM.
For added flexibility, the Model 7701 is equipped with four extra screw terminals. These user-configurable screw terminals are hard-wired to the female DB-25 connector of the switching module. These screw terminals allow external input to bypass the switching module channels.
Although the Model 7701 relays are the latching type (relays hold their state even after power has been removed), all relay states are set to open a few seconds after either a power cycle or an *RST command is issued.
System channel operation ( ROUT:CLOS command) is used to close measurement channels to connect a DUT to the DMM. With a 2-wire function selected (i.e., DCV), system channels 1 through 32 can be closed. When one of these channels is closed, channel 35 automatically closes to connect the channel to the DMM Input.
2
3
Figure 1
Simplified schematic for Model 7701
P12
External
Wiring Access
P13 P24 P25
Multiplexer 1
Channel 1
(Channels 215)
Channel 16
Channel 17
(Channels 1831)
Channel 32
Multiplexer 2
= Jumper to be installed by user to connect 7701 channels to DMM (Figure 3).
HI
LO
HI
LO
HI
LO
HI
LO
HI
LO
HI
LO
Channel 33
2-Pole (Open)
4-Pole (Closed)
(See Note)
P12 P13
User Configurable
Screw Terminals
P24 P25
Channel 35
(See Note)
Backplane
Isolation
Channel 34
(See Note)
Backplane
Isolation
The Model 7701 is rated for low-voltage applications. When connecting the 7701 to the internal DMM via the screw terminals, all other modules in the mainframe must be derated to 150VDC or 150Vrms (212V peak) for AC waveforms.
Notes: Channels 3335 in this schematic refer to the designations used for
control and not actual available channels. Channels 33, 34, and 35 can be individually controlled using multiple
channel operation (ROUT:MULT commands). For more information, see Section 2 of the Model 27xx Users Manual.
MUX 1
MUX 1
MUX 2
MUX 2
HI
LO
Screw
Terminals
HI
LO
DMM
HI
HI
Input
LO
DMM
LO
To Model
27xx DMM
DMM
SHI
HI
Sense
LO
DMM
SLO
With a normal 4-wire function selected (i.e., Ω 4), system channels 1 through 16 can be closed. These 16 channels are paired to channels 17 through 32 (channel 1 paired to channel 17, channel 2 paired to channel 18, and so on). When one of these system channels is closed, its paired channel, and channels 33 and 34 also close to connect the DUT to the DMM.
With common-side (CSID) 4-wire ohms selected, system channels 1 through 32 can be measured by the DMM. For this ohms mode, the module is to be configured as shown in Figure 12. With CSID ohms selected, channel 33 remains open and channel 35 remains closed. In Figure 12, the bold lines show the signal path to test DUT1.
Dual independent multiplexers
WARNING Multiple channel operation should only be performed by experienced test engineers who
recognize the dangers associated with multiple channel closures.
Multiple channel operation ( ROUT:MULT:CLOS command) allows individual control of switching module channels. Multiple channel operation allows the switching module to be configured as two independent multiplexers. The Model 7701 is normally used as a single 1 × 32 multiplexer, but it can also be configured as two 1 × 16 multiplexers.
In Figure 1, the open position of channel 33 is shown. When channel 33 is closed, Multiplexer 1 (channels 1 through 16) are isolated from Multiplexer 2 (channels 16 through 32).
For the dual multiplexer configuration, only Multiplexer 1 channels can be internally connected to the DMM of the Model 27xx. Closing channel 35 allows channels 1 through 16 to be measured by the DMM.
When using the dual multiplexer configuration, Multiplexer 2 must be isolated from the sense terminals of the DMM. This can be done by keeping channel 34 open, or by not installing the screw terminal jumpers to DMM Sense.

Connections and wiring

WARNING The following information is intended for qualified service personnel. Do not make
switching module connections unless qualified to do so. To prevent electric shock that could result in serious injury or death, adhere to the
following safety precautions:
• Before removing or installing the switching module in the mainframe, make sure the mainframe is turned off and disconnected from line power.
• Before making or breaking connections, make sure power is removed from all external circuitry.
• Do not connect signals that may exceed the maximum specifications of the Model 7701. Specifications are provided at the end of this section.
WARNING The Model 7701 is configurable to be connected to the internal DMM via the supplied
jumpers and the screw terminals. When connected to the internal DMM, all other modules must be derated to 150VDC or 150Vrms (212V peak) for AC waveforms.
Screw terminals
The screw terminals of the Model 7701 are shown in Figure 2. As shown, screw terminals are provided to connect the switch­ing module channels to the DMM. User-configurable screw terminals are also provided to allow external input to bypass the switching module channels.
Four jumpers are supplied with the Model 7701 for use with the screw terminals. As shown in Figure 2, the Model 7701 is shipped with the jumpers not installed. With the jumpers not installed, all input to the Model 7701 is electrically isolated from the DMM.
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Figure 2
DMM HI
MUX 1 HI
DMM SHI
MUX 2 HI
DMM SLO
MUX 2 LO
DMM LO
MUX 1 LO
P12 P13
P24
P25
Model 7701 screw terminals
5
User-Configurable
Screw Terminals
Screw Terminals to
Connect 7701
Channels to DMM
DMM HI
P12 P13
P24
P25
MUX 1 HI
MUX 2 HI
DMM SHI
DMM SLO
MUX 2 LO
MUX 1 LO
DMM LO
Connecting Model 7701 channels to DMM
Perform the following steps to internally connect the channels of the Model 7701 to the DMM of the Model 27xx:
1. Remove the top cover of the Model 7701. It is secured to the module case by a single screw.
2. Install the four supplied #22 AWG jumpers in the screw terminals as shown in Figure 3. Position the jumpers to allow clear­ance for the top cover and make sure the jumper wires do not come in contact with each other or other electrical conductors.
3. Replace the top cover.
Figure 3
Jumper installation to connect 7701 channels to DMM
DMM HI
A
MUX 1 HI
Jumper A
Jumper B
Jumper C
Jumper D
Connects HI terminals of Multiplexer 1 channels (1 through 16) to DMM Input HI.
Connects HI terminals of Multiplexer 2 channels (17 through 32) to DMM Sense HI.
Connects LO terminals of Multiplexer 2 channels (17 through 32) to DMM Sense LO.
Connects LO terminals of Multiplexer 1 channels (1 through 16) to DMM Input LO.
Jumper (1 of 4)
MUX 2 HI
B
DMM SHI
DMM SLO
C
MUX 2 LO
MUX 1 LO
D
DMM LO
D-shell connectors
Figure 4 shows the pin numbers for the Model 7701 rear panel connectors. The 50-pin D-shell is used to access channels 1
through 24, and Multiplexer 1 terminals. The 25-pin D-shell is used to access channels 25 through 32, and Multiplexer 2 terminals. The user-configurable screw terminals are also accessed at the 25-pin D-shell. Terminal identification for the female connector pins is provided in Table 1.
Figure 4
Rear view – Model 7701 pinouts
50-Pin D-Shell Connector (Female)
17
33
50
1
18
34
25-Pin D-Shell Connector (Female)
13
6
1
1425
Table 1
D-shell pin identification
50-pin D-shell (DB-50)
7701
Pin
Terminal Pin
1 Ch 1 Hi 11 Ch 16 Hi 21 Ch 6 Lo 31 Ch 21 Lo 41 Ch 12 Hi 2 Ch 2 Lo 12 Ch 17 Lo 22 Ch 8 Hi 32 Ch 23 Hi 42 Ch 13 Lo 3 Ch 4 Hi 13 Ch 19 Hi 23 Ch 9 Lo 33 Ch 24 Lo 43 Ch 15 Hi 4 Ch 5 Lo 14 Ch 20 Lo 24 Ch 11 Hi 34 Ch 1 Lo 44 Ch 16 Lo 5 Ch 7 Hi 15 Ch 22 Hi 25 Ch 12 Lo 35 Ch 3 Hi 45 Ch 18 Hi 6 Ch 8 Lo 16 Ch 23 Lo 26 Ch 14 Hi 36 Ch 4 Lo 46 Ch 19 Lo 7 Ch 10 Hi 17 Mux 1 Hi 27 Ch 15 Lo 37 Ch 6 Hi 47 Ch 21 Hi 8 Ch 11 Lo 18 Ch 2 Hi 28 Ch 17 Hi 38 Ch 7 Lo 48 Ch 22 Lo 9 Ch 13 Hi 19 Ch 3 Lo 29 Ch 18 Lo 39 Ch 9 Hi 49 Ch 24 Hi 10 Ch 14 Lo 20 Ch 5 Hi 30 Ch 20 Hi 40 Ch 10 Lo 50 Mux 1 Lo
7701
Pin
Terminal Pin
1 Ch 25 Hi 7 Ch 31 Hi 14 Ch 25 Lo 20 Ch 31 Lo 2 Ch 26 Hi 8 Ch 32 Hi 15 Ch 26 Lo 21 Ch 32 Lo 3 Ch 27 Hi 9 Mux 2 Hi 16 Ch 27 Lo 22 Mux 2 Lo 4 Ch 28 Hi 10, 11 — 17 Ch 28 Lo 23 — 5 Ch 29 Hi 12 P12 18 Ch 29 Lo 24 P24 6 Ch 30 Hi 13 P13 19 Ch 30 Lo 25 P25
7701
Terminal Pin
25-pin D-shell (DB-25)
7701
Terminal Pin
Terminal Pin
Terminal Pin
7701
7701
7701
Terminal Pin
7701
Terminal
7701
Terminal
Wiring
NOTE The Model 7701 is shipped with plastic connector covers installed on the D-shell connectors. Each
cover is secured to the connector by two screws. After removing a connector cover, retain it and the screws for future use. Any unused D-shell connector must have the connector cover installed.
The Model 7701 is supplied with one 50-pin male IDC ribbon cable connector, and one 25-pin male IDC ribbon cable connec­tor. These ribbon cable connectors mate to the D-shell connectors of the switching module.
WARNING When using IDC ribbon cable connections, DO NOT exceed 42V anywhere in the test
system or at the front panel inputs of the Model 27xx. For higher voltage applications, use larger wire (up to #20 AWG) and solder cup D-shell connectors.
There are two connector kits that have connectors that can be used with the Model 7701:
• Model 7790 ribbon cable adapter kit — Contains one female DB-50, one male DB-50 and one male DB-25 IDC ribbon cable connectors. The two male IDC connectors mate to the D-shell connectors on the Model 7701.
• Model 7789 50/25-pin solder cup connector kit — Contains one male DB-50 and one male DB-25 solder cup con­nectors. These connectors mate to the D-shell connectors on the Model 7701.
7
IDC ribbon cable connections
Connect an appropriate length of 50-conductor IDC ribbon cable to a 50-pin male D-shell IDC connector, and connect an appropriate length of 25-conductor IDC ribbon cable to a 25-pin male D-shell IDC connector. Table 2 and Figure 5 provides terminal identification for the 50-pin ribbon cable connections. Table 3 and Figure 6 provides terminal identification for the 25-pin ribbon cable connections.
The connectors of the prepared ribbon cable assemblies mate to the 50- and 25-pin D-shell connectors of the Model 7701 (Figure 7). Make sure an unused D-shell connector has the connector cover installed.
Table 2
Terminal identification for 50-conductor IDC ribbon cable and 7701 DB-50 connector
Ribbon Cable*: 7701 DB-50 Ribbon Cable*: 7701 DB-50
Conductor Color Terminal Pin # Conductor Color Terminal Pin #
1 Brown Ch 1 Hi 1 26 Blue Ch 13 Lo 42 2 Red Ch 1 Lo 34 27 Violet Ch 14 Hi 26 3 Orange Ch 2 Hi 18 28 Grey Ch 14 Lo 10 4 Yellow Ch 2 Lo 2 29 White Ch 15 Hi 43 5 Green Ch 3 Hi 35 30 Black Ch 15 Lo 27 6 Blue Ch 3 Lo 19 31 Brown Ch 16 Hi 11 7 Violet Ch 4 Hi 3 32 Red Ch 16 Lo 44 8 Grey Ch 4 Lo 36 33 Orange Ch 17 Hi 28
9 White Ch 5 Hi 20 34 Yellow Ch 17 Lo 12 10 Black Ch 5 Lo 4 35 Green Ch 18 Hi 45 11 Brown Ch 6 Hi 37 36 Blue Ch 18 Lo 29 12 Red Ch 6 Lo 21 37 Violet Ch 19 Hi 13 13 Orange Ch 7 Hi 5 38 Grey Ch 19 Lo 46 14 Yellow Ch 7 Lo 38 39 White Ch 20 Hi 30 15 Green Ch 8 Hi 22 40 Black Ch 20 Lo 14 16 Blue Ch 8 Lo 6 41 Brown Ch 21 Hi 47 17 Violet Ch 9 Hi 39 42 Red Ch 21 Lo 31 18 Grey Ch 9 Lo 23 43 Orange Ch 22 Hi 15 19 White Ch 10 Hi 7 44 Yellow Ch 22 Lo 48 20 Black Ch 10 Lo 40 45 Green Ch 23 Hi 32 21 Brown Ch 11 Hi 24 46 Blue Ch 23 Lo 16 22 Red Ch 11 Lo 8 47 Violet Ch 24 Hi 49 23 Orange Ch 12 Hi 41 48 Grey Ch 24 Lo 33 24 Yellow Ch 12 Lo 25 49 White Mux 1 Hi 17 25 Green Ch 13 Hi 9 50 Black Mux 1 Lo 50
*50-conductor IDC ribbon cable is available from Keithley, Part #15020.
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