TFA9812 Datasheet, PDF (50/66 Pages) NXP Semiconductors – BTL stereo Class-D audio amplifier with I2S input

NXP Semiconductors
TFA9812
BTL stereo Class-D audio amplifier with I²S input
R_S = Series resistance output inductor (Ω).
δ_max = Maximum duty factor (0.96).
The output power at 10 % THD can be estimated using Equation 11:
P_O(10%) = 1.25 ⋅ P_O(0.5%)
(11)
Figure 11 and Figure 12 show the estimated output power at THD = 0.5 % and
THD = 10 % as a function of BTL supply voltage for different load impedances.
30
P_O (0.5 %)
(W/channel)
20
010aaa347
(1)
(2)
45
P_O (10 %)
W/channel
30
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(1)
(2)
10
15
(3)
(3)
0
8
12
16
20
24
V_P (V)
(1) 6 Ω
(2) 8 Ω
(3) 16 Ω
Fig 11. BTL P_O (0.5 %) as a function of V_P
0
8
12
16
20
24
V_P (V)
(1) 6 Ω
(2) 8 Ω
(3) 16 Ω
Fig 12. BTL P_O (10 %) as a function of V_P
14.2 Output current limiting
The peak output current is internally limited above a level of 3 A minimum. During normal
operation the output current should not exceed this threshold level of 3 A otherwise the
output signal will be distorted. The peak output current in BTL can be estimated using
Equation 12:
I_O(max) ≤ -_R----_L----₊----₂-----_â‹----_〈--^VR----^PD----_S---_o--_n----₊-----_R----_S--_〉-
(12)
Where:
V_P= supply voltage (V) (V_DDP-V_SSP)
R_L= load impedance (Ω)
R_DSon= 'On' resistance power switch (Ω)
R_S= series resistance output inductor (Ω)
TFA9812_1
Preliminary data sheet
Rev. 01 — 30 October 2008
© NXP B.V. 2008. All rights reserved.
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