The Tektronix/Keithley 3750 Multifunction I/O Card integrates 40 bidirectional digital I/O bits, two isolated analog output channels, and four 32-bit counters into a single card for automated test, process control, and data logging. Each of the five 8-bit digital banks is independently programmable as input or output, supporting logic levels to 30V external and featuring internal pull-up resistors with jumper-selectable removal. The analog output section delivers ±12V at 10mA (voltage mode) or 0–20mA/4–20mA (current mode) with 1mV and 1µA resolution respectively. Digital outputs sink to 300mA per line with 3.0A total card capacity and include integrated fly-back diode protection for inductive loads. Pattern-matching triggers activate on maskable state changes across any input bank. System I/O throughput reaches 1000 readings/second for both input and output operations. The card installs in Tektronix/Keithley 3700A series mainframes, delivering flexible expansion for complex multi-channel switching and control.
Technical Specifications
-# Digital I/O
• 40 bidirectional bits organized into five independently programmable 8-bit banks
• Input logic threshold: 0.8V max (low), 2.0V min (high)
• Selectable internal pull-up resistor (~68 kΩ per line) to 5V or external voltage up to 30V
• Output sink current: 300mA per line, 3.0A maximum per card
• Output levels: 2.4V min high (10mA source), 0.5V max low (300mA sink)
• Input impedance: ±600µA max @ 0V (low), 50µA max @ 5V (high)
• Maximum external voltage on any line: 30V
• System I/O speed: 1000 readings/second (input and output)
• Pattern-match triggering on any of five banks with maskable conditions
-# Analog Outputs
• Two isolated channels, individually selectable as voltage or current output
• Voltage mode: ±12V, 10mA max, 1mV resolution, ±(0.15% + 16mV) @ 23 ± 5°C
• Voltage settling: 1ms to 0.1% full scale, 350µs update @ 1% accuracy
• Temperature coefficient: ±(0.02% + 1.2mV)/°C
• Current mode: 0–20mA or 4–20mA unipolar, 1µA resolution, 11V min compliance
• Current settling: 1ms to 0.1% full scale
• Maximum capacitive load: 10nF stable operation
– Key Features
• High-current digital drivers with fly-back diode protection
• Short-circuit and over-temperature protection on all outputs
• Selectable pull-up voltage enables mixed logic-level systems
• Isolated analog outputs for noise rejection
• Four 32-bit counter channels for frequency and event counting
– Typical Applications
• Automated test equipment (ATE) control and data acquisition
• Industrial process monitoring and relay switching
• Multi-channel sensor interfacing and instrumentation
• High-speed digital stimulus and response capture
– Compatibility & Integration
• Compatible with Tektronix/Keithley 3700A series mainframes
• Slot-card form factor for expandable system configuration
