TDA8932B_3
© NXP B.V. 21 June 2007. All rights reserved.
Product data sheet
Rev. 03— 21 June 2007
22 of 48
NXP Semiconductors
TDA8932B
Class-D audio amplifier
14. Application information
14.1 Output power estimation
The output power P
o
at THD+N = 0.5 %, just before clipping, for the SE and BTL
configuration can be estimated using
and
SE configuration:
(2)
BTL configuration:
(3)
Where:
V
P
= supply voltage V
DDP1
−
V
SSP1
(V) or V
DDP2
−
V
SSP2
(V)
R
L
= load impedance (
Ω
)
R
DSon
= on-resistance power switch (
Ω)
R
s
= series resistance output inductor (
Ω)
R
ESR
= equivalent series resistance SE capacitor (
Ω)
t
w(min)
= minimum pulse width (s); 80 ns typical
f
osc
= oscillator frequency (Hz); 320 kHz typical with Rosc = 39 k
Ω
The output power P
o
at THD+N = 10 % can be estimated by:
(4)
show the estimated output power at THD+N = 0.5 % and
THD+N = 10 % as a function of the supply voltage for SE and BTL configurations at
different load impedances. The output power is calculated with: R
DSon
= 0.15
Ω
(at
T
j
= 25
°
C), R
s
= 0.05
Ω
, R
ESR
= 0.05
Ω
and I
O(ocp)
= 4 A (minimum).
P
o 0.5%
(
)
R
L
R
L
R
DSon
R
s
R
ESR
+
+
+
----------------------------------------------------------
1
t
w min
(
)
–
f
osc
×
(
)
×
V
P
×
2
8
R
L
×
-------------------------------------------------------------------------------------------------------------------------------------------
=
P
o 0.5%
(
)
R
L
R
L
2
+
R
DSon
R
s
+
(
)
×
------------------------------------------------------
1
t
w min
(
)
–
f
osc
×
(
)
×
V
P
×
2
2
R
L
×
--------------------------------------------------------------------------------------------------------------------------------------
=
P
o 10%
(
)
1.25
P
o 0.5%
(
)
×
=
