Tektronix PS 5010

Operating Mode (cont)
@ POSITIVE supply output terminal
@ LOGIC supply ground (chassis ground) terminal
Operating Instructions-PS 50 1 0
Entry Mode (cont)
@ LOGIC supply positive output terminal
@ Ground binding post
@ Plug-in release latch
OPERATING CONSIDERATIONS
Auto Crossover
The floating supplies are the automatic crossover type.
Under normal conditions,
!hi3 supply operates in one of two
modes: constant voltage or constant current. In the con-
stant voltage mode, decreasing the load impedance in-
creases the output current until the programmed current
,
limit is reached. Further reduction in load impedance puts
the supply in constant current mode. As the load impedance
continues to decrease, the output current remains constant
and the output voltage decreases.
The opposite is true with increasing load impedance. The
supply provides constant current until the voltage reaches
the programmed voltage limit. Further increase in load im-
pedance puts the supply in the constant voltage mode. See
Fig. 2-4.
Logic Supply Foldback Current Limit
The logic supply regulator employs foldback current limit-
ing. This term refers to current limit which is a function of the
output voltage. The specified output voltage range of the
logic supply is 4.5 V to
5.5 V. As long as the output voltage
remains in the specified range, the supply operates in a con-
stant voltage, constant current automatic crossover mode.
For voltages under approximately 4 V, the maximum current
limit becomes a linearly proportional function of output volt-
age. The current limit folds back to approximately
1 A with
Decreasing
Load
Increasing
Voltage
Crossover
Point
Fig.
2-4. Load lines for individual load impedances.
zero output voltage (short circuit). When the logic supply is
in foldback mode, neither the current loop nor the voltage
loop are balanced. The front panel will display this (blank in
operating mode). See Fig. 2-5.