TDA8948J_1
© NXP B.V. 2008. All rights reserved.
Product data sheet
Rev. 01 — 27 February 2008
5 of 26
NXP Semiconductors
TDA8948J
4-channel audio amplifier
8.
Functional description
8.1 Input configuration
The input cut-off frequency is:
(1)
For SE application R
i
= 60 k
Ω
and C
i
= 220 nF:
(2)
For BTL application R
i
= 30 k
Ω
and C
i
= 470 nF:
(3)
As shown in
Equation 2
and
Equation 3
, large capacitor values for the inputs are not
necessary, so the switch-on delay during charging of the input capacitors can be
minimized. This results in a good low frequency response and good switch-on behavior.
8.2 Power amplifier
The power amplifier is a BTL and/or SE amplifier with an all-NPN output stage, capable of
delivering a peak output current of 4 A.
Using the TDA8948J as a BTL amplifier offers the following advantages:
•
Low peak value of the supply current
•
Ripple frequency on the supply voltage is twice the signal frequency
•
No expensive DC-blocking capacitor
•
Good low frequency performance
GND2
15
ground of channels 3 and 4
V
CC2
16
supply voltage channels 3 and 4
OUT4+
17
non inverted loudspeaker output of channel 4
Table 3.
Pin description
…continued
Symbol
Pin
Description
f
i cut
off
–
(
)
1
2
π
R
i
C
i
×
(
)
-----------------------------
=
f
i cut
off
–
(
)
1
2
π
60
10
3
220
10
9
–
×
×
×
(
)
-----------------------------------------------------------------
12 Hz
=
=
f
i cut
off
–
(
)
1
2
π
30
10
3
470
10
9
–
×
×
×
(
)
-----------------------------------------------------------------
11 Hz
=
=
