Output Characteristic - Agilent Technologies 6631B User Manual

2 – General Information
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.
-
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.
20
Output
Voltage
Vmax
VSET
-Imax
0
-ISET
Figure 2-1. Dc Source Output Characteristic
CV operating line
1
CC operating line
2
+
ISET Imax
Output
Current