The Keithley 228A is a programmable bipolar voltage and current source and sink, designed to deliver up to 100W of power. Operating in all four quadrants, the 228A can function as a high-precision constant voltage or constant current source, as well as an active electronic load. It features standard GPIB connectivity, dual 4.5-digit LED displays for simultaneous output readback, remote 4-wire sensing, and an internal 100-step program memory for sequencing.
Specifications
General
| Parameter | Value |
|---|---|
| Interfaces | GPIB (IEEE-488) |
| Display | Dual 4.5-digit red LED displays for voltage and current |
| Maximum Common Mode Voltage | 100 V peak (chassis to output common) |
| Warm-up Time | 1 hour to rated accuracy |
Physical
| Parameter | Value |
|---|---|
| Power Supply | 100V / 120V / 220V / 240V AC (switch-selectable), 50/60 Hz, 350 VA max |
| Operating Temperature | 0°C to 50°C |
| Dimensions (W×H×D) | 133 mm × 435 mm × 448 mm |
| Weight | 9.8 |
Voltage Source Specifications
| Parameter | Value |
|---|---|
| Voltage Output Ranges | ±1.0100 V, ±10.100 V, ±101.00 V |
| Voltage Programming Resolution | 100 µV (1 V range), 1 mV (10 V range), 10 mV (100 V range) |
Current Source Specifications
| Parameter | Value |
|---|---|
| Current Output Ranges | ±101.00 mA, ±1.0100 A, ±10.100 A |
| Current Programming Resolution | 10 µA (100 mA range), 100 µA (1 A range), 1 mA (10 A range) |
System & Channel Configuration
| Parameter | Value |
|---|---|
| Operating Modes | Constant Voltage (CV) or Constant Current (CC) |
| Four-Quadrant Operation | Full 4-quadrant sourcing and sinking up to 100 W |
| Number of Channels | 1 |
| Sensing Modes | 2-wire local or 4-wire remote sensing |
| Output Terminals | Rear panel quick-disconnect terminal block |
Measurement Specifications
| Parameter | Value |
|---|---|
| Readback Monitor | Simultaneous measurement and display of actual output voltage and current |
| Readback Display Resolution | 4.5 digits |
Triggering and Memory Buffer
| Parameter | Value |
|---|---|
| Memory Capacity | 100-step internal program memory |
| External Modulation Input | Rear panel input for external analog programming/modulation |
Control and Connectivity
| Parameter | Value |
|---|---|
| GPIB Interface | Standard IEEE-488 compliance |
Power Specifications
| Parameter | Value |
|---|---|
| AC Input Voltage Options | 100V, 120V, 220V, or 240V AC (rear-panel switch selectable) |
| AC Input Line Frequency | 50 Hz or 60 Hz |
| Maximum Power Consumption | 350 VA |
Physical and Environmental
| Parameter | Value |
|---|---|
| Form Factor | Full-rack width, 3U height |
| Storage Temperature Range | -25°C to 65°C |
| Operating Humidity Range | 0% to 80% RH up to 35°C (non-condensing) |
Performance
| Parameter | Value |
|---|---|
| Maximum Output Power | 100 W (source or sink) |
| Voltage Programming Accuracy | ±(0.05% + 10 mV) on 10V range, ±(0.05% + 100 mV) on 100V range |
| Current Programming Accuracy | ±(0.1% + 1 mA) on 1A range, ±(0.1% + 10 mA) on 10A range |
| Voltage Load Regulation | ±(0.01% + 1 mV) for 0 to full load change |
| Current Load Regulation | ±(0.01% + 100 µA) on 1A range, ±(0.01% + 1 mA) on 10A range for 0 to max voltage change |
| Voltage Line Regulation | ±(0.01% + 1 mV) for 10% line voltage change |
| Current Line Regulation | ±(0.01% + 100 µA) on 1A range, ±(0.01% + 1 mA) on 10A range for 10% line voltage change |
| Voltage Ripple and Noise | <10 mV RMS, <50 mV peak-to-peak (0.1 Hz to 20 MHz) |
| Current Ripple and Noise | <500 µA RMS on 1A range, <5 mA RMS on 10A range |
| Voltage Slew Rate (100V Range) | 0.01 V/ms to 100 V/ms (in 1-2-5 sequence) |
| Voltage Slew Rate (10V Range) | 0.001 V/ms to 10 V/ms (in 1-2-5 sequence) |
| Current Slew Rate (10A Range) | 0.001 A/ms to 10 A/ms (in 1-2-5 sequence) |
| Current Slew Rate (1A Range) | 0.0001 A/ms to 1 A/ms (in 1-2-5 sequence) |
| Temperature Coefficient | ±(0.1 × specified accuracy) per °C (0°C to 18°C & 28°C to 50°C) |
| Maximum Sink Power | 100 W |
| Load Transient Recovery Time | < 1 ms to settle within 100 mV (or 10 mA) of programmed value for a step change of 50% to 100% of full scale load |
Modulation Input
| Parameter | Value |
|---|---|
| Modulation Input Impedance | 10 kΩ |
| Modulation Sensitivity | 10 V for 100% modulation of range |
| Modulation Bandwidth | DC to 1.2 kHz (3 dB bandwidth) |
External Trigger
| Parameter | Value |
|---|---|
| Trigger Input Level | TTL compatible, active on negative-going edge |
| Minimum Trigger Input Pulse Width | 10 µs |
| Trigger Output Level | TTL compatible, negative-going pulse |
| Trigger Output Pulse Width | 20 µs |
Remote Sensing
| Parameter | Value |
|---|---|
| Maximum Sense Lead Resistance | 10 Ω per lead |
| Maximum Voltage Drop in Output Leads | 0.5 V |
Output Characteristics
| Parameter | Value |
|---|---|
| Voltage Source Mode Output Resistance | < 20 mΩ |
| Common Mode Impedance | > 10^9 Ω in parallel with < 0.05 µF |
GPIB Interface
| Parameter | Value |
|---|---|
| GPIB Interface Functions | SH1, AH1, T6, L4, SR1, RL1, PP0, DC1, DT1, C0, E1 |
Technology
Linear Power Supply / Source Measure Unit (SMU) precursor
Applications
Precision semiconductor testing, battery charging/discharging simulation, and active load testing