To measure the efficiency of the AEM simply connect an SMU to the input of the converter and another to the output. By dividing the output power by the input power, the efficiency of the converter can be determined.
For example, for measuring the system efficiency between STO and LOAD of the AEM10920, the input of the converter will be the STO pin, and the output will be the LOAD pin.
This efficiency measurement will include the quiescent current of the AEM and the power converter efficiency.