1) All of the graphs listed in the Spec. Sheet were taken using an 8ohm resistor in series with an inductor as the load? Should I not be taking any measurements using only an 8ohm resistor as the load?

1) All of the graphs listed in the Spec. Sheet were taken using an 8ohm resistor in series with an inductor as the load? Should I not be taking any measurements using only an 8ohm resistor as the load?

Hello bill,

The test inductance simulates what one might find in a loudspeaker coil. For example, consider the 33uH placed in series with 8 ohms as a test load. At 20 KHz this inductor has a reactance of 4.2 ohms, resulting in a total load impedance of sqrt (8^2 + 4.2^2) = 9 ohms. Thus the inductor has little effect on the overall load impedance, but is necessary for the SSM3302's normal operation. Page 16 of the data sheet says, "The SSM3302 does not require an output filter;

*it relies on the inherent inductance of the speaker coil*and the natural filtering of the speaker and the human ear to recover the audio component of the square wave output." Thus the test loads ADI employed for their graphs reflect how the part is typically used.Best regards,

Bob

Hello bill,

The test inductance simulates what one might find in a loudspeaker coil. For example, consider the 33uH placed in series with 8 ohms as a test load. At 20 KHz this inductor has a reactance of 4.2 ohms, resulting in a total load impedance of sqrt (8^2 + 4.2^2) = 9 ohms. Thus the inductor has little effect on the overall load impedance, but is necessary for the SSM3302's normal operation. Page 16 of the data sheet says, "The SSM3302 does not require an output filter;

it relies on the inherent inductance of the speaker coiland the natural filtering of the speaker and the human ear to recover the audio component of the square wave output." Thus the test loads ADI employed for their graphs reflect how the part is typically used.Best regards,

Bob