TDA7350A datasheet(19/22 Pages) STMICROELECTRONICS

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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

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

• 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 45

Figure 46

Figure 44

TDA7350A

19/22

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