The Keithley 7700 is a 20-channel differential multiplexer module for signal routing in automated test and data acquisition systems. It integrates automatic cold junction compensation for thermocouple measurements and uses latching electromechanical relays to achieve signal bandwiths up to 50 MHz. The module supports both general-purpose and dedicated current measurements, making it suited for temperature sensing applications involving RTDs, thermistors, and thermocouples.
Technical Specifications
Channel Configuration
• 20 general-purpose channels: configurable as 20 channels of 2-pole switching or 10 channels of 4-pole switching
• 2 dedicated current measurement channels (21–22)
• Latching electromechanical relays with actuation time < 3 ms
• Signal bandwidth: up to 50 MHz
Voltage and Current Ratings
Channels 1–20:
• DC voltage: 300 V maximum
• AC voltage: 300 V rms (425 V peak)
• Switched current: 1 A maximum
• Power: 60 W, 125 VA maximum
Channels 21–22 (current input):
• DC voltage: 60 V maximum
• AC voltage: 30 V rms maximum
• Switched current: 3 A maximum
• Power: 60 W, 125 VA maximum
Minimum signal level: 10 mV, 10 µA
Electrical Performance
• Contact resistance: < 1 Ω at end of contact life
• Contact potential: typical < ±500 nV per contact; maximum 1 µV per contact
• Offset current: 10¹⁰ Ω, 10⁹ Ω, < 200 pF
• Crosstalk (10 MHz, 50 Ω load): < –40 dB
• Insertion loss below 1 MHz: < 0.1 dB; below 2 MHz: < 3 dB
• Common mode voltage: 300 V between any terminal and chassis
– Key Features
• Automatic cold junction compensation eliminates external accessories
• Fast relay actuation (< 3 ms) for high-speed switching applications
• Low contact potential (< ±500 nV typical) suitable for precision measurements
• High RF bandwidth (50 MHz) for demanding signal integrity
• Oversized screw terminals (#20 AWG) for robust wiring
– Typical Applications
• Temperature measurement via RTD, thermistor, and thermocouple transducers
• Multi-channel data acquisition and signal conditioning
• Automated test environments requiring fast switching
• Current and voltage measurements across wide dynamic ranges
– Compatibility & Integration
The 7700 integrates with Keithley DAQ6510 Data Acquisition and Multimeter Systems and the 2700, 2701, and 2750 Multimeter/Switch System families. Operating temperature: 0°C to 50°C. Module weight: 0.45 kg.
