
Usin
g
your Pro
g
rammable Power Supply 5 - 13
5.5.3 Constant volta
g
e or constant current source
Your power supply has been desi
g
ned accordin
g
to the automatic crossover
principle. This means that each output channel will operate in the Constant
Volta
g
e (CV) mode or in the Constant Current CC mode, dependin
g
on:
• the pro
g
rammed output volta
g
e Vset and current Iset
• the resistance (impedance) of the load Rload, connected to the output channel
For a
g
iven Vset and Iset, an output channel is either:
in the CV mode if or in the CC mode if .
In the CV mode the output is a constant volta
g
e, so the current throu
g
h the load
depends on the load resistance (Rload).
In the CC mode the output is a constant current, so the volta
g
e across the load
depends on the load resistance (Rload).
The followin
g
picture shows when the output channel
g
oes into the CV or into the
CC mode of operation, when connected to a variable resistor Rload.
If Rload increases (Rload > Rc), the output channel
g
oes into the CV mode,
reducin
g
the current throu
g
h the load.
If Rload decreases (Rload < Rc), the output channel
g
oes into the CC mode,
reducin
g
the volta
g
e across the load.
Rload
Vset
Iset
>
R
load
V
set
I
set
<
Rload >Rc
R=∞(open circuit)
Voltage
V(set)
Rc= Vset
Iset (crossover point)
Rload <Rc
CC
CV
I(set) Current ST5848
R=0(short circuit)
Fi
g