TDA7491LP Datasheet, PDF (26/37 Pages) STMicroelectronics – 2 x 5-watt dual BTL class-D audio amplifier

Applications information
TDA7491LP
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.
Table 7. Gain settings
Voltage level on pin GAIN0
L⁽¹⁾
Voltage level on pin GAIN1
H⁽¹⁾
Nominal gain, G_v (dB)
20
L
H
26
H
L
30
H
H
32
1. Refer to V_inL and V_inH in Table 5: Electrical specifications on page 10 for the drive levels for L and H
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
Rf
Input
signal
Ci
Input _Ri
pin
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Doc ID 13541 Rev 5