AMETEK SLD Series - Manual (Page 52)

Applications Sorensen SLD-Series DC Load
4-6 M540075-01 Rev C
4.5 Constant Resistance (CR) Mode Application
Major application: voltage source testing, current source testing, power supply power-up
sequence
CR mode is used in conjunction with CC mode for testing switching power supplies.
Caution must be exercised when using the CC mode in test set up; for example, 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.
This is due to the power supply trying to deliver 50A at 2V because the load tester is in the CC
mode. The power supply is designed not to do this.
Therefore, when testing a power supply, the CR mode should 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 SLD-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.
Figure 4-6 Constant Resistance Mode Application