19/23

TDA7350A

Figure 47.

5.5 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 48, we can see that a noise signal from the ground of the power amplifier to the ground of

the hypothetical preamplifier is amplified of a factor equal to the gain of the amplifier (2 · Gv). Using a con-

figuration of fig. 49 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 layout 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 num-

ber of cases this signal is within this range.

5.6 High Gain, Low Noise Application

The following section describes a flexible preamplifier having the purpose to increase the gain of the

TDA7350A.

Figure 48.

Figure 49.