AMETEK SLH Series RevC - Manual (Page 60)

Applications Sorensen SLH-Series DC High Power Electronic Load
4-6 M540074-01 Rev C
4.5
CONSTANT RESISTANCE (CR) MODE APPLICATION
Major applications:
Voltage source testing, current source testing, power supply power-up
sequence
CR mode can be used in conjunction with CC mode when testing switching power supplies, to
avoid shutdown.
For example, if CC mode alone were used in test set up, a 5V/50A output power supply cannot
deliver 50A over its start-up range of 0-5 volts. In many cases, the power supply short circuit or
over current protection circuit will shut the power supply down because it can’t deliver enough
current at low voltage. This is due to the power supply trying to deliver 50A at 2V because the
load is in CC mode.
Therefore, when testing a power supply, the CR mode can be used to allow the power supply
voltage and current to ramp up together. After ramp-up the CC mode should be used to
complete testing. The need for manually switching from the CR to the CC mode is eliminated
with SLH-series DC electronic loads. They can be programmed with proper current and slew
rate in the CC mode, which allows a power supply to reach its specified output condition in the
CC load mode.
Note:
Vsense input should be connected when running in CR mode to avoid resistance
variation due to the cable resistance.
CURRENT
SOURCE
+
-
ELECTRONIC LOLAD
CR MODE
VOLTAGE
SOURCE
ELECTRONIC LOLAD
CR MODE
V
INPUT
VOLTAGE
LOAD RESISTANCE
SETTING
I
LOAD CURRENT
- +
DC
OUTPUT
Figure 4-6 Constant Resistance ode Application