APPENDIX 1 - POWER CONSUMPTION MEASUREMENTS
PROCEDURE
USound MEMS speakers have a frequency dependent impedance (showing a capacitance behaviour),
so the power consumption is strongly dependent on the frequency of the signal. Therefore, only power
consumption measurements such as the quiescent current from a certain power supply can be taken
from a static DC current measurement instrument (i.e. Multimeter).
In order to provide a more accurate power consumption measurement within the context of the
application (i.e. audio playback), various measurement signals (i.e. IEC Noise 60268-1) are used and
the average of the power consumption over time must be taken.
HARDWARE MEASUREMENT SETUP
Power consumption measurements with audio playback can be carried out with the appropriate
instrumentation (with enough sampling frequency, low enough noise floor, enough sensitivity and
range, etc.). Instrumentation used for measuring audio signals (for example: Audio Precision
instrumentation) usually provide the means necessary to also perform such power consumption
measurements. Therefore, an Audio Precision instrument is used in this section to set a reference
example on how to measure power consumption with a frequency and amplitude changing signal,
such as audio songs or IEC Noise.
For performing a power consumption measurement at a certain dBSPL with Tarvos evaluation
board 1.0 UC-E3010 and any kind of signal, the following devices are needed:
•Power Supply (i.e. HMC 8043)
•APX measurement system (i.e. 525 or 515)
•1Ωshunt
Figure 3 displays how the different elements must be connected.
Figure 3. Power consumption measurement setup with UC-E3010
