Measurements

UM0984

16/25

Doc ID 17812 Rev 2

Figure 7.

Efficiency at full load (1 A) vs. input voltage

The output voltage efficiency depending on the output current of the 12 V output is displayed

in Figure 6. The 3.3 V output was not loaded for this measurement.

Figure 7 shows the efficiency of the SMPS at full load applied on the 12 V output (1 A, 3.3 V

output not loaded) depending on the different input voltages. A drop of efficiency at low input

voltage is mainly caused by an increase of the losses of the input inrush resistor and CMC.

The efficiency was calculated as the ratio between the output power and input power. The

input power was directly measured by power analyzer NORMA 4000. The output power was

calculated as the product of the output current and output voltage. The output voltage was

measured on the output connector by multimeter KEITHLEY 2000 and the current was

measured by multimeter FLUKE 189.