Keithley 225 Current Source

The Keithley 225 Current Source is a precision DC current generator delivering stable, accurate output across seven decade ranges from 10⁻⁷ A to 10⁻¹ A. Built for component testing, sensor excitation, and calibration applications, the Model 225 combines low noise, high resolution, and programmable current levels with remote control capabilities for seamless integration into automated test systems.

– Technical Specifications

Output Current
• Ranges: 10⁻⁷ A to 10⁻¹ A (seven decade ranges)
• Resolution: 0.02% of full scale with three significant figures; trim potentiometer provides 0.02% of full-range resolution or better
• Accuracy: ±0.5% of setting + 0.12% of range; ±0.5% of reading, ±0.05% of full range
• Stability: Within 0.02%; regulated to ±0.005% of full range (10⁻⁷ to 10⁻⁶ A ranges, no load to full load) and ±0.05% on 10⁻¹ A range
• Noise: Less than 0.01% of full range; less than 0.01% RMS of full range above 5 Hz

Voltage Compliance
• Maximum: 100 V
• Adjustable limit: 3 V to 100 V; variable from 10 V to 100 V
• Output regulation maintained over ±10 to ±100 V compliance limits

Output Control
• Polarity: Positive or negative
• Floating: 1500 V maximum off chassis ground; less than 5 ppm of full-range change per volt off ground
• Voltage programming: DC-coupled 0 to +11 V input with 10 kΩ input resistance
• Modulation: 50 Hz to 500 Hz via transformer input (approximately 500 Ω input impedance)

Filtering & Loading
• Operates with inductive loads up to 100 mH (greater than 10% L/R ratio)
• Output shunt impedance: 1 µF shunted by greater than 10¹⁰ ohms

– Key Features

• BNC connectors on front and rear panels
• Selectable AC input: 105–125 VAC or 210–250 VAC, 50–60 Hz
• Low power consumption: 25 watts
• Compact bench format: 155 mm H × 225 mm W × 310 mm D; half-rack variant available at 133 mm H
• Weight: 4.2 kg net

– Typical Applications

• Resistor, diode, and transistor characterization
• Precision sensor excitation
• Calibration procedures requiring stable DC current sources

– Compatibility & Integration

Designed for manual operation and integration into automated measurement systems via voltage programming input. Operating environment: 50% relative humidity limit at 25°C.