Cirrus Logic AN168 - Manual (Page 33)

AN168
AN168REV2 33
2.3 Example 3: TDA1905 -- 2.5 Watts into 4
Ω
The schematic for the TDA1905 speaker driver is
shown in Figure 24. The TDA1905, from ST, is
capable of supplying 2.5 Watts of RMS power into
a 4
Ω load with less than 2% THD. The gain
required to achieve 2.5 Watts is +10 dB, which is
implemented with an attenuation stage of -30 dB
followed by the TDA1905 gain implemented as
+40 dB.
The high-pass corner frequency near 300 Hz is
given by:
The low-pass corner frequency near 4 kHz is given
by:
Gain
R2
R1 R2 +
--------------------
⎝ ⎠
⎛ ⎞
1
R3
R4
------- +
⎝ ⎠
⎛ ⎞
×
=
Fhp
1
2
πC1 R1 R2
+
( )
----------------------------------------
≈
+40dB
-30dB
2.5 Watts into 4 ohms
Gain = +10dB
Gain = [R2/(R1+R2)]*[1+R3/R4]
CS6422_A0
+14V
R4
121
LS?
4 Ohm SPEAKER
+
-
U1
TDA1905
8
6
9-16 7
1
3 2
C1
1500pF
R2
12.1K
R1
374K
+
C3
10uF
C5
0.1uF
C2
3300pF
+
C7
2.2uF
+
C4
100uF
+ C6
10uF
+
C8
1000uF
C9
0.22uF
+
C10
47uF
R5
1ohm R3
12.1K
Figure 24. TDA 1905 Schematic