The 228A is a Current Source from Keithley. A current source is a type of electronic test equipment in circuit form that can deliver or absorb electrical current that’s independent of the voltage across its terminals. There are two types of current sources: dependent and independent. A dependent current source delivers an electric current that is proportional to another voltage in the circuit. An independent current source delivers a constant current.
100 Watt source or sink
<1ms transient recovery
Built-in voltage/current monitors
Smooth range changes
Rechargeable battery backup
The Keithley 228A is a precision programmable source with the capacity to sink or source up to 100 watts. Six ranges accurately regulate voltage or current as determined by the load. The 228A is two programmable sources in one (with built-in monitors), giving you the flexibility for a broader range of test setups, without having to buy separate sources.
The 228A is capable of bipolar source or sink up to a full 100 watts without derating, permitting it to act as a voltage or current supply or as an active load. Operating status is continuously shown on front panel LEDs.
The 228A's modulation input allows voltage programming. DC to 600 Hz inputs can be used to vary the output within the full scale range of the source, simulate variable load conditions in sink, provide a power boost, or test power supply rejection.
Load transient recovery time is less than 1ms, without overshoot or oscillation.
Voltage and Current Monitor
The output voltage and current are continuously monitored and displayed. These values can also be read back over the IEEE-488 bus, eliminating the need for separate measurement instruments.
Remote sensing assures the full rated voltage under test, even when delivering high currents. The unique safety disconnect design eliminates external terminal blocks and barrier strips.
The IEEE-488 interface is standard with the 228A, and all front panel controls and capabilities are available over the bus. TRIGGER IN/OUT enables synchronization with other components in your test setup, and the programmable dwell time allows settling before TRIGGER OUT is issued.
The 228A checks its own operation and provides diagnostic error messages. An SRQ can be programmed to alert the system of many operating conditions. The internal 100-point memory retains programmed data through power down, brownout, or even a month or more in storage, and allows you to step through repetitive test sequences with minimal bus activity.