3 Test Results

The demo hardware was tested for SPL performance using the setup shown in Figure 3-1. A Radio Shack SPL meter evaluated the sound values at the distance of 1 meter from piezoelectric sounder.

Figure 3-1 SPL Test Setup Performed with Radio Shack SPL Meter

Within the SPL measurement, the frequency was swept between 100Hz and 4.1kHz for evaluation. The results are shown in Figure 3-2. As can be seen, the SPL range of this demo over the described frequency range is 80 to 100dB. More importantly, the SPL at frequencies ≥ 520Hz is at least 88dB. These results show the ability of this demo to produce a wide range of sound frequencies at acceptable SPL levels for playback of audio and different alarm tones with a single piezo speaker element and fixed circuit design.

Figure 3-2 SPL Measurement Test Results on the Smoke Alarm Demo With the DRV8220 and MSPM0G Performed With Radio Shack SPL Meter at the Distance of 1m From the Piezo Sounder