Figure 20. Standby and mute circuits

STBY

MUTE

0 V

3.3 V

C7

2.2 µF

R2

30 kΩ

Standby

0 V

3.3 V

C15

2.2 µF

R4

30 kΩ

Mute

TDA7498

Figure 21. Turn on/off sequence for minimizing speaker “pop”

5.3

Gain setting

The gain of the TDA7498 is set by the two inputs, GAIN0 (pin 30) and GAIN1 (pin31). Internally, the gain is set by

changing the feedback resistors of the amplifier.

Table 7. Gain settings

GAIN0

GAIN1

Nominal gain, Gv (dB)

L

L

25.6

L

H

31.6

H

L

35.6

H

H

37.6

5.4

Input resistance and capacitance

The input impedance is set by an internal resistor Ri = 60 kΩ (typical). An input capacitor (Ci) is required to couple

the AC input signal.

The equivalent circuit and frequency response of the input components are shown in Figure 22. Input circuit and

frequency response. For Ci = 470 nF the high-pass filter cutoff frequency is below 20 Hz:

fC = 1 / (2 * π * Ri * Ci)

TDA7498

Gain setting

DS6437 - Rev 10

page 12/22