TFA9815 NXP Semiconductors, TFA9815 Datasheet - Page 15

• Manufacturer Part Number: TFA9815
• Description: The TFA9815 is a 2-channel power comparator for high-efficiency class D audio amplifiersystems
• Manufacturer: NXP Semiconductors

NXP Semiconductors
13. Application information
TFA9815_1
Preliminary data sheet
13.1 Output power estimation
For BTL configuration the output power can be estimated using
Where,
The output power at 10% THD can be estimated by using
Figure 5
THD = 10 % as a function of the BLT supply voltage for different load impedances.
P
P
Fig 5.
•
•
•
•
o
o
1%
10%
V
R
R
R
P
L
DSon
S
=
=
= supply voltage [V]
= load impedance [ ]
(W)
= series resistance output inductor [ ]
P
1.25 P
---------------------------------------------------------------------------------
o
and
THD+N = 0.5 %
f = 1 kHz
(1) 4
(2) 6
(3) 8
BTL output power as function of supply voltage: THD = 1 %
40
30
20
10
= on resistance power switch [ ]
0
----------------------------------------------------- -
R
8
L
Figure 6
+
2
o
0.5%
R
R
Rev. 01 — 16 December 2008
2
L
DSon
below show the estimated output power at THD = 0.5 % and
10
R
L
+
R
S
12
V
P
2
14
16
Equation 2
Audio amplifier 2 x 17 W
Equation
18
V
010aaa449
© NXP B.V. 2008. All rights reserved.
TFA9815
P
(V)
1:
2
3
1
20
15 of 26
(1)
(2)