I have a circuit designed around the TPA2006D1 amplifier driving a 4 ohm speaker. The amplifier is sources by a 5V supply. It has been run in development intermittently for several months without issue. I am not using the full power output of the amplifier - in fact, I am probably only at about 200 mW of power output.
However, I just noticed today that I have a problem. In the datasheet, there is mention in the max settings section that the minimum load resistance above a 4.2V supply is 6.4 ohms. I assume this is due to the fact that there is not enough resistance to the output FETs and it could weaken them with a lower load resistance so even though I am not using the full power of the device, I would still have problems.
I can't find an 8 ohm speaker that meets our needs. Is there anything that can be done to allow the use of the 4 ohm speaker? I have thought of putting a diode in the power supply path to drop .7V to get it closer to the 4.2V. I thought of adding an inductor in series with the speaker to bump it's effective impedance. Would either of these work? Is there a better way? (Or any way?)
Thanks,
Brent
