Application information

TS4974

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4

Application information

4.1

Differential configuration principle

The TS4974 is a monolithic full-differential input/ output power amplifier with a digital volume

control. It has an internal gain range of -33 dB up to +12 dB, by steps of 3dB (see

Section 4.9: Volume setting on page 20), which offers better performance in terms of noise

immunity and PSRR.

The advantages of a full-differential amplifier are:

●

Very high PSRR (power supply rejection ratio).

●

High common mode noise rejection.

●

Virtually zero pop without additional circuitry, giving a faster start-up time compared to

conventional single-ended input amplifiers.

●

Easier interfacing with differential output audio DAC.

In theory, the filtering of the internal bias by an external bypass capacitor is not necessary.

But, to reach maximum performance in all tolerance situations, it is better to keep this

option.

4.2

Low frequency response

The input coupling capacitors block the DC part of the input signal at the amplifier inputs.

cut-off frequency.

Note:

Differential input impedance of 60 k

value.

-3 dB.

Figure 39.

-3dB lower cut-off frequency vs. input capacitance

)

Hz

(

C

R

2

1

F

in

in

CL

×

×

π

×

=

0.5

1

10

100

Typical Input

Impedance

Maximum Input

Impedance

Minimum Input

Impedance

All gain setting

Tamb=25

Input Capacitor Cin (

0.1