This is 1.5 W audio power amplifier circuit based on low distortion power IC SSM2211.
The SSM22111 is a high performance audio amplifier that delivers 1 W rms of low distortion audio power into a bridge-connected 8 Ω speaker load (or 1.5 W rms into a 4 Ω load).
The SSM2211 operates over a wide temperature range and is specified for single-supply voltages between 2.7 V and 5.5 V. When operating from batteries, it continues to operate down to 1.75 V. This makes the SSM2211 the best choice for unregulated applications, such as toys and games.
Featuring a 4 MHz bandwidth and distortion below 0.2% THD + N @ 1 W, superior performance is delivered at higher power or lower speaker load impedance than competitive units. Furthermore, when the ambient temperature is at 25°C, THD + N < 1%, and VS = 5 V on a four-layer PCB, the SSM2211 delivers a 1.5 W output.
The low differential dc output voltage results in negligible losses in the speaker winding and makes high value dc blocking capacitors unnecessary. The battery life is extended by using shutdown mode, which typically reduces quiescent current drain to 100 nA.
Download SSM2211 datasheet
I think that is an interesting point, it made me think a bit. Thanks for sparking my thinking cap. Sometimes I get so much in a rut that I just feel like a record.