If the audio output power (Pout) of the MAX97220 audio amplifier is known, the input power (Pin) can be calculated as :
Pin = Pout + Pd
where,
Pin = Power supplied to the audio amp
Pout = Output power of the audio amp
Pd = Power Dissipation of the audio amp
Power Dissipation can be determined from the datasheet typical operating characteristic Power Dissipation vs. Output Power (toc22).
For example, for an output power of 125mW per channel, the power dissipation is 350 mW.
Pd = 350mW
Since 125mW is output power per channel, Pout = 2x125mW = 250mW
Pin = 250mW + 350mW = 600 mW
If Vin = 5V (supply voltage) , since Pin = Vin x Iin,
Iin = 600/5 = 120mA (supply current) .