Datasheet

Applications information TDA7493
12/30 Doc ID 14570 Rev 6
5.3 Input resistance and capacitance
The input impedance is set by an internal resistor, Ri, of value 60 kΩ. An input coupling
capacitor (Ci) is required on each input line. These two components together form a
high-pass filter whose cutoff frequency is:
f
C
= 1 / (2 * π * Ri * Ci)
Figure 4. Input high-pass RC filter
The value of Ci is chosen depending on the application and the speaker system. For a
cut-off frequency less than 20 Hz, the input capacitors could be 470 nF each.
If a polarized capacitor is used, it is important to connect the positive side of the capacitor to
the terminal with higher DC voltage. The DC voltage on the input pins is V
CC
/ 2.
Figure 5. Device input structure
Ri
Rf
Rf
Ri
Ci
Ci
Input signal
+
-