I need a very small and highly efficient audio DAC, capable of driving a 0.15Watt 20mm mini speaker.
Power source: 3V lithium coin cell.
20mm speakers are available with 8ohm, 32ohm and 100ohm impedance.
How about putting a LC filter on the PWM output of the Mega48 and drive a 100ohm speaker directly. Would this be the smallest and most efficient ADC possible?
I'am open to other suggestions.