Datasheet

DIGITAL MULTIMETERS & SYSTEMS
A Greater Measure of Confidence
www.keithley.com
1.888.KEITHLEY
(U.S. only)
Ordering Information
7708 40-channel Differential
Multiplexer Module
with Automatic CJC
and Screw Terminals
• 40 differential channels for
general-purpose measurements
• Two- or four-wire
measurements
• 300V, 1A capacity for voltage
channels; 60W, 125VA
• Oversize screw terminal
connection blocks are standard
for easier connection
• Relay closures stored in
onboard memory
CAPABILITIES
CHANNELS 1–40: Multiplex one of 40 2-pole or one of 20
4-pole signals into DMM.
INPUTS
MAXIMUM SIGNAL LEVEL:
Channels (1–40): 300V DC or rms, 1A switched, 60W, 125VA
maximum.
CONTACT LIFE (typ): >10
5
operations at max. signal level.
>10
8
operations no load
1
.
1
Open thermocouple detector on during thermocouple measurements.
Minimum signal level 10mV, 10µA.
CONTACT RESISTANCE: <1W at end of contact life.
CONTACT POTENTIAL:
<±500nV typical per contact, 1µV max.
<±500nV typical per contact pair, 1µV max.
OFFSET CURRENT: <100pA.
CONNECTOR TYPE: Screw terminal, #20 AWG wire size.
ISOLATION BETWEEN ANY TWO TERMINALS: >10
10
W,
<100pF.
ISOLATION BETWEEN ANY TERMINAL AND EARTH: >10
9
W,
<200pF.
CROSS TALK (10MHz, 50W Load): <–40dB.
INSERTION LOSS (50W Source, 50W Load): <0.1dB below
1MHz. <3dB below 2MHz.
COMMON MODE VOLTAGE: 300V between any terminal and
chassis.
TEMPERATURE ACCURACY USING INTERNAL CJC:
1.0°C (see mainframe specification for details).
GENERAL
40 CHANNELS: 40 channels of 2-pole relay input. All channels
configurable to 4-pole.
RELAY TYPE: Latching electromechanical.
ACTUATION TIME: <3ms.
FIRMWARE: Specified for Model 2700 rev. B02, 2701 rev. A01,
and 2750 rev. A01 or higher.
ENVIRONMENTAL
OPERATING ENVIRONMENT: Specified for 0°C to 50°C.
Specified to 80% R.H. at 35°C.
STORAGE ENVIRONMENT: –25°C to 65°C.
WEIGHT: 0.52kg (1.16 lb).
ACCESSORIES AVAILABLE
7401 Type K Thermocouple Wire, 30.5m (100 ft).
The Model 7708 plug-in module offers 40
channels of 2-pole or 20 channels of 4-pole
multiplexer switching that can be configured
as two independent banks of multiplexers. The
built-in CJC sensors automatically linearize
thermocouples, making the Model 7708 ideal for
RTD, thermistor, and thermocouple temperature
applications. It is also well suited for mixed-
signal measurement applications that require
multi-point monitoring, such as environmental
stress screening.
Channel 1
HI
LO
Channel 20
HI
LO
(Channels 2–19)
Channel 21
HI
LO
Channel 40
HI
LO
(Channels 22–39)
HI
LO
Sense
HI
LO
Input
Channel 41
2-Pole (Open)
4-Pole (Closed)
(see Note)
To Model 2700,
2701, or 2750
Backplane
Channel 43
(see Note)
Backplane
isolation
Channel 42
(see Note)
Backplane
isolation
NOTE:
Card Sense
HI
LO
Card Input
HI
LO
Cold Junction
Ref
× 5
Cold Junction
Ref
×
4
Channels 41–43 in this schematic refer to the
designations used for control and not actual
available channels.
For more information, refer to the ROUTe:MULTiple
command section in the Model 2700, 2701, or
2750 User’s Manual.
Channels 42 and 43 can be individually controlled
using ROUTe:MULTiple if the module is not to be
connected to the internal DMM.
7708
40-channel Differential Multiplexer Module
with Automatic CJC and Screw Terminals
SERVICES AVAILABLE
7708-3Y-EW 1-year factory warranty extended to 3 years
from date of shipment
Use with Integra Series mainframes: 2700, 2701, 2750 Use with Integra Series mainframes: 2700, 2701, 2750