Teledyne LeCroy T3PS Series, User Manual

Page: 21 / 159

When the power supply is operating in constant
current mode (CC) a constant current will be
supplied to the load. When in constant current
mode the voltage output can vary, whilst the
current remains constant. When the load
resistance increases to the point where the set
current limit (I
SET
) can no longer be sustained the
power supply switches to CV mode. The point
where the power supply switches modes is the
crossover point.
When the power supply is operating in CV mode,
a constant voltage will be supplied to the load,
whilst the current will vary as the load varies. At
the point that the load resistance is too low to
maintain a constant voltage, the power supply will
switch to CC mode and maintain the set current
limit.
The conditions that determine whether the power
supply operates in CC or CV mode depends on
the set current (I
SET
), the set voltage (V
SET
), the load
resistance (R
L
) and the critical resistance (R
C
). The
critical resistance is determined by V
SET
/I
SET
. The
power supply will operate in CV mode when the
load resistance is greater than the critical
resistance. This means that the voltage output will
be equal to the V
SET
voltage but the current will be
less than I
SET
. If the load resistance is reduced to
the point that the current output reaches the I
SET
level, the power supply switches to CC mode.
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