As shown by the vertical portions of the load line, the output voltage may continue to increase in the
positive direction or decrease in the negative direction as current is forced into or pulled out of the
unit. When the output voltage exceeds the over-voltage protection setting, the output will shut down,
the output relays will open, and the OV status bit will be set.
Current Priority
In current priority mode, the output is controlled by a bi-polar constant current feedback loop, which
maintains the output source or sink current at its programmed setting. The output current remains at
its programmed setting, provided the load voltage remains within the voltage limit setting. Current
priority mode is best suited for use with batteries, power supplies, large charged capacitors, and loads
that are sensitive to current overshoots. It minimizes current overshoots during programming, turn-on,
and turn-off transitions and seamlessly transitions between positive and negative currents.
In current priority mode, the output current should be programmed to the desired value. A positive
voltage limit value should also be set. The voltage limit should always be set to a value that is greater
than the actual output voltage requirement of the external load. The following figure shows the current
priority operating locus of the output. The area in the white quadrants shows the output as a source
(sourcing power). The shaded quadrants show the output as a load (sinking power).
The heavy solid line illustrates the locus of possible operating points as a function of the output load.
As shown by the vertical portion of the line, the output current remains regulated at its programmed
setting as long as the output voltage remains within its limit setting. A CC (constant current) status
indicates that the output current is being regulated and the output voltage is within its limit settings.
Note that when the output voltage reaches the voltage limit, the unit no longer operates in constant
current mode and the output current is no longer held constant. Instead, the power supply will now
regulate the output voltage at its voltage limit setting. A LIM+ (positive voltage limit) status is set to
indicate that the voltage limit has been reached. This condition is annunciated by VL+ on the front
panel.
4 Using the Modular Power System
74 Keysight MP4300 Series Operating and Service Guide
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