Advanced Energy Monitor - Silicon Laboratories EFM8BB3-SLSTK2022A User Manual

UG125: EFM8BB3-SLSTK2022A User's Guide

Advanced Energy Monitor

7. Advanced Energy Monitor
7.1 Usage
The AEM data is collected by the board controller and can be displayed by the energyAware Profiler, available through Simplicity Stu-
dio. By using the energyAware Profiler, current consumption and voltage can be measured in realtime.
7.2 Theory of Operation
To accurately measure current ranging from 0.1 µA to 50 mA (114 dB dynamic range), a current sense amplifier is utilized together with
a dual gain stage. The current sense amplifier measures the voltage drop over a small series resistor, and the gain stage further ampli-
fies this voltage with two different gain settings to obtain two current ranges. The transition between these two ranges occurs around
250 µA. Digital filtering and averaging is done within the Board Controller before the samples are exported to the Energy Profiler appli-
cation.
During startup of the kit, an automatic calibration of the AEM is performed. This calibration compensates for the offset error in the sense
amplifiers.
Figure 7.1. Advanced Energy Monitor
7.3 Accuracy and Performance
The AEM is capable of measuring currents in the range of 0.1 µA to 47 mA. For currents above 250 µA, the AEM is accurate within 0.1
mA. When measuring currents below 250 µA, the accuracy increases to 1 µA. Although the absolute accuracy is 1 µA in the sub 250
µA range, the AEM is able to detect changes in the current consumption as small as 100 nA. The AEM produces 6250 current samples
per second.
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