TS4984 Datasheet, PDF (21/29 Pages) STMicroelectronics – 2 x 1W Stereo audio power amplifier with active low standby mode

Application Information
TS4984
Then, the power dissipated by each amplifier is:
Pdiss = Psupply – P_out
(W)
Pdiss
=
-2--------2---V-----^C----^C-- ⋅
π R_L
P_out – P_out
(W)
and the maximum value is obtained when:
∂_----∂P---P-d---_{o-i--s-u--s-t--- = 0}
and its value is:
P_dissmax
=
-2---^V----^c-²--^c-
π²R_L
(W)
Note: This maximum value is only depending on power supply voltage and load values.
The efficiency, η, is the ratio between the output power and the power supply:
η = _P-----s^P---_u-^o--_p--^u-_p--^t--_l-_y- = ---^π--4--V--V--^P---_C-^E---_C-^A----^K--
The maximum theoretical value is reached when V_PEAK = V_CC, so that:
π_{---- = 78.5%}
4
The TS4984 has two independent power amplifiers, and each amplifier produces heat due to its power
dissipation. Therefore, the maximum die temperature is the sum of the each amplifier’s maximum power
dissipation. It is calculated as follows:
P_{diss L} = Power dissipation due to the left channel power amplifier.
P_{diss R} = Power dissipation due to the right channel power amplifier.
Total P_diss = P_{diss L} + P_{diss R} (W)
In most cases, P_{diss L} = P_{diss R}, giving:
Total Pd _iss = 2PdissL (W)
or, stated differently:
Total
P_diss
=
4---------2---V-----_C----C--
π R_L
P_out – 2P_out
(W)
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