User manual

Model 6220/6221 User’s Manual DC Current Source Operation 3-3
Return to Section 3 topics
Compliance
The compliance setting limits the output voltage of the Model 622x. The voltage
compliance limit can be set from 0.1V to 105V in 10mV steps. The output will not
exceed the programmed compliance level.
Make sure to set compliance to a voltage level that is greater than the voltage
requirements for the load. For example, if sourcing 10mA to a 1kΩ load, the volt-
age compliance setting must be >10V (10mA x 1kΩ = 10V). If it is not, the Model
622x goes into compliance and the magnitude of the current output will be less
than the programmed setting. For example, if compliance is set to 9V and current
output is set to 10mA, only 9mA will be sourced to a 1kΩ load (9V/1kΩ = 9mA).
The OUTPUT indicator light blinks when the current source is in compliance.
Either there is a fault condition in the test circuit, or the source and/or compliance
levels are not properly set.
Compliance overshoot
Depending on range and load impedance, step changes in current could cause
the output voltage to briefly overshoot its normal expected level by as much as 2V.
During normal “out of compliance” operation, this voltage “glitch” will settle to the
expected output voltage within the settling time specification for the selected
range (see “Output response” on page 3-5).
If the compliance voltage is set too close to the expected output voltage, the over-
shoot could place the Model 622x in compliance. Due to the compliance circuitry,
it could take several microseconds for the overshoot to settle and return the cur-
rent source to the “out of compliance” state. This slower response to overshoot
could damage a voltage sensitive DUT (Device Under Test).
One way to avoid compliance overshoot is to set a compliance that is at least 2V
above the expected static output voltage. For example, if the normal operating
voltage across the load is 10V, set the compliance to at least 12V.
Additional details on compliance overshoot and prevention are provided in
Appendix E of the Reference Manual.
Output power (source or sink)
The maximum power output of the Model 622x is 11W. The bipolar current source
provides four quadrant source or sink operation. When connected to a passive
DUT, the Model 622x operates as a source. When connected to an active load
(e.g., external source, capacitor), the Model 622x can operate as a source or sink.
When operating as a source, current is delivered to a test circuit. The polarity of
the current and the voltage seen at the output are the same (both positive or both
negative).