TDA1400 Tripath Technology, TDA1400 Datasheet - Page 16

• Manufacturer Part Number: TDA1400
• Description: MONO CLASS-T DIGITAL AUDIO AMPLIFIER DRIVER
• Manufacturer: Tripath Technology

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connected directly to the ground star located at the power supply. These precautions will both minimize
audible noise and enhance the crosstalk performance of the TDA1400.
TDA1400 Amplifier Gain
The gain of the TDA1400 is the product of the input stage gain and the modulator gain for the TDA1400.
Please refer to the sections, Input Stage Design, and Modulator Feedback Design, for a complete
explanation of how to determine the external component values.
For example, using a TDA1400 with the following external components,
Input Stage Design
The TDA1400 input stage is configured as an inverting amplifier, allowing the system designer flexibility in
setting the input stage gain and frequency response. Figure 2 shows a typical application where the input
stage is a constant gain inverting amplifier. The input stage gain should be set so that the maximum input
signal level will drive the input stage output to 4Vpp.
The gain of the input stage, above the low frequency high pass filter point, is that of a simple inverting
amplifier:
16
R
R
R
R
R
A
A
A
A
I
F
FBA
FBB
FBC
INPUT1
V
V
= 20kΩ
V
V
= 20kΩ
INPUTSTAGE
TDA1400
TDA1400
TDA1400
= 2.21kΩ
= 1kΩ
= 20kΩ
=
≈
≈
C
I
A
+
−
−
=
V
R
20k Ω
20k Ω
R
−
INPUTSTAGE
R
F
I
I
R
R



R
F
F
R
I
OAOUT_AMP
OAOUT_AUX
FBC



INV_AMP
INV_AUX
Figure 2: TDA1400 Input Stage
20.0k Ω
R
*
*
FBA
(R
A
45
46
BIASCAP
2
1
FBA
*
1.0k Ω
V
R
MODULATOR
*
+
FBB
(1.0k Ω
TDA1400
R
AGND
+
*
AGND
FBB
+
-
-
V5
V5
2.21k Ω
)
+
+
1
2.21k



T r i p a t h T e c h n o l o g y , I n c . - P r e l i m i n a r y I n f o r m a t i o n
Ω
)
+
1



=
-
30.05
T D A 1 4 0 0 – R e v . 0 . 6 5 / K L i / 0 2 . 0 6
V
V