TS4974_07 Datasheet, PDF (17/25 Pages) STMicroelectronics – 1W differential audio power amplifier with up/down digital volume control pins

TS4974
4.3
Power dissipation and efficiency
Assumptions:
● Load voltage and current are sinusoidal (V_out and I_out)
● Supply voltage is a pure DC source (V_CC)
The output voltage is:
V_out = Vpeak sinωt (V)
and
Application information
I_out
=
V_{-----o---u---t -}
R_L
(A)
and
P_out
=
V_{-----p---e---a---k--}²_----
2R_L
(W)
Therefore, the average current delivered by the supply voltage is:
Equation 1
I_{CC AVG} =
2
-^V----^p---^e---^a---^k--
πR_L
(A)
The power delivered by the supply voltage is:
P_supply = V_CC I_{CC AVG} (W)
Therefore, the power dissipated by each amplifier is:
P_diss = P_supply - P_out (W)
Equation 2
P_diss
=
2_--------2_----V_----C----C--
π R_L
P_out–P_out
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