TDA7350A Datasheet, PDF (19/22 Pages) STMicroelectronics – 22W BRIDGE-STEREO AMPLIFIER FOR CAR RADIO

Figure 44
BALANCE INPUT IN BRIDGE CONFIGURATION
A helpful characteristic of the TDA7350A is that,in
bridge configuration, a signal present on both the
input capacitors is amplified by the same amount
Figure 45
TDA7350A
and it is present in phase at the outputs,so this
signal does not produce effects on the load.The
typical value of CMRR is 46 dB.
Looking at fig 45, we can see that a noise signal
from the ground of the power amplifier to the
ground of the hypothetical preamplifier is ampli-
fied of a factor equal to the gain of the amplifier
(2 • Gv).
Using a configuration of fig. 46 the same ground
noise is present at the output multiplied by the
factor 2 • Gv/200.
This means less distortion,less noise (e.g. motor
cassette noise ) and/or a simplification of the lay-
out of PC board.
The only limitation of this balanced input is the
maximum amplitude of common mode signals
(few tens of millivolt) to avoid a loss of output
power due to the common mode signal on the
output, but in a large number of cases this signal
is within this range.
HIGH GAIN ,LOW NOISE APPLICATION
The following section describes a flexible pream-
plifier having the purpose to increase the gain of
the TDA7350A.
Figure 46
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