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2 – General Information
20
the HP 6632A, 6633A, and 6634A Series dc power supplies (refer to appendix D in the the
Programming Guide). Dc source status registers allow remote monitoring of a wide variety of dc
source operating conditions.
Output Characteristic
The dc source’s output characteristic is shown in the following figure. The output of the dc
source may be adjusted to any value within the boundaries shown.
Output
Voltage
Output
Current
Imax
Vmax
ISET-ISET
VSET
CC operating line
CV operating line
0
1
2
+
-
-Imax
Figure 2-1. Dc Source Output Characteristic
The dc source can operate in either constant voltage (CV) or constant current (CC) over the rated
output voltage and current. Although the dc source can operate in either mode, it is designed as a
constant voltage source. This means that the unit turns on in constant voltage mode with the
output voltage rising to its Vset value. There is no command for constant current operation. The
only way to turn the unit on in constant current mode is by placing a short across the output and
then enabling or turning the output on.
Note that the dc source cannot be programmed to operate in a specific mode. After initial turn-
on, the operating mode of the unit will be determined by the voltage setting, the current setting,
and the load resistance. In figure 2-1, operating point 1 is defined by the load line traversing the
positive operating quadrant in the constant voltage region. Operating point 2 is defined by the
load line traversing the positive operating quadrant in the constant current region.
Figure 2-1 also shows a single range − two quadrant capability. This means that the dc source is
capable of sourcing as well as sinking current over the output voltage range from zero volts to the
rated maximum. The negative quadrant is identical to the positive quadrant. However, the
negative current cannot be set independently; it tracks the value programmed for the positive
current. Thus, if the positive current is set to 1 A, the negative current is also set to 1 A.
NOTE: If you attempt to operate the dc source beyond its output ratings, the output of
the unit will become unregulated. This is indicated by the UNR annunciator on
the front panel. The output may also become unregulated if the ac input voltage
drops below the minimum rating specified in Appendix A.
Appendix A documents the dc source’s specifications and supplemental characteristics.