TDA75610SLV
8
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8.1
Inputs impedance matching
Figure 37. Inputs impedance matching circuit
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The above is a simplified input stage where it is visible that the AC-GND impedance (60 kΩ)
is the same as the input one.
During battery variations the SVR voltage is moved and VIN and VAC-GND tracks it through
the two R-C networks.
Any differences of this two time constants can produce a differential input voltage, which can
produce a noise.
Consequently, any additional passive components at the inputs (other than the input
capacitors) such as series resistance or R dividers must be compensated for at AC-GND
level by connecting the same equivalent resistance in series to CAC-GND.
A good 1:1 matching (ZAC-GND = ZIN) is therefore recommended to minimize pop. This rule
applies to both "4-CH operation" and "2-CH operation", as any unused input has be AC-
grounded (through the same CIN value).
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