TS4984FC Datasheet, PDF (20/30 Pages) STMicroelectronics – 1.2W Stereo Audio Power Amplifier with Active Low Standby Mode

Application Information
The following graph (Figure 63) shows an example of C_in and C_feed influence.
Figure 63. Frequency response gain versus C_in & C_feed
10
5
0
-5
-10
-15
-20
-25
10
Cfeed = 330pF
Cfeed = 680pF
Cin = 470nF ^{Cfeed = 2.2nF}
Cin = 22nF
Cin = 82nF
Rin = Rfeed = 22kΩ
Tamb = 25°C
100
1000
Frequency (Hz)
10000
TS4984FC
4.4
Power dissipation and efficiency
Hypotheses:
● Voltage and current in the load are sinusoidal (V_out and I_out).
● Supply voltage is a pure DC source (V_CC).
Regarding the load we have:
V_out = V_PEAK sinωt (V)
and
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:
I_CCAVG =
2
V_{-----P---E----A---K--}
πR_L
(A)
The power delivered by the supply voltage is:
P_supply = V_CC ⋅ I_CCAVG
(W)
Then, the power dissipated by each amplifier is:
P_diss = P_supply – P_out
(W)
P_diss
=
2_--------2_----V_{----C----C-- â‹}
π R_L
P_out – P_out
(W)
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