Datasheet

Applications information TDA7491LP
26/37 Doc ID 13541 Rev 5
5.3 Gain setting
The gain of the TDA7491LP is set by the two inputs, GAIN0 (pin 30) and GAIN1 (pin 31).
Internally, the gain is set by changing the feedback resistors of the amplifier.
5.4 Input resistance and capacitance
The input impedance is set by an internal resistor Ri = 68 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 29. For Ci = 220 nF the high-pass filter cut-off frequency is below 20 Hz:
fc = 1 / (2 * π * Ri * Ci)
Figure 29. Device input circuit and frequency response
Table 7. Gain settings
Voltage level on pin GAIN0 Voltage level on pin GAIN1 Nominal gain, G
v
(dB)
L
(1)
1. Refer to V
inL
and V
inH
in Table 5: Electrical specifications on page 10 for the drive levels for L and H
H
(1)
20
LH26
HL 30
HH32
Ri
Input
Ci
Rf
Input
pin
signal