Keithley 227 Current Source 1000uA to 1000mA Full Scale in 4 Ranges

The Keithley 227 is a precision bipolar DC current source engineered for laboratory and industrial test applications requiring stable, accurate current output across four selectable ranges. It delivers 1 mA to 1000 mA full scale with exceptional load regulation of ±0.005% and adjustable compliance voltage up to 300 V (50 V on the 1000 mA range). Fine-resolution output control combines a three-digit readout with continuously adjustable least significant digit selection, enabling setability of typically 0.005% of full range in a single rotation.

The output floats up to 500 V above chassis ground with isolation exceeding 10^9 ohms and negligible current drift (less than 5 ppm per volt offset).

Technical Specifications

• Current Ranges: 1 mA, 10 mA, 100 mA, 1000 mA (full scale)


• Compliance Voltage: Up to 300 V on 1 mA, 10 mA, and 100 mA ranges; up to 50 V on 1000 mA range; adjustable limit to 300 V maximum


• Load Regulation: ±0.005% of range (no load to full load)


• Output Float: 500 V above chassis ground; isolation ~10^9 ohms


• Output Stability: Less than 5 ppm per volt offset from ground


• Setability: Approximately 0.005% of full range per 1° rotation


• Operating Temperature: Up to 50°C ambient

Key Features

• Bipolar DC output with continuously adjustable fine current control


• Output modulation capability


• Voltage programming input (standard)


• Optional Model 2271 Programming Option enables remote control of range, magnitude, polarity, and compliance via resistance programming or external power supply closure


• Automatic thermal shutdown on fan failure or abnormal heating


• Replaceable air filter (Keithley Part No. 25791); monthly cleaning recommended in laboratory environments

Typical Applications Precision current sourcing for device characterization, component testing, and automated measurement systems requiring high compliance voltage and fine current resolution across multiple decades.

Compatibility & Integration Voltage programming input standard. Remote programmability available via optional Model 2271 Programming Option for current and compliance resistance programming plus range and compliance maximum selection via external power supply integration.