CS4207-CNZ Datasheet, PDF (140/148 Pages) Cirrus Logic – Low-power, 4-in / 6-out HD Audio Codec with Headphone Amp

CS4207
For an improvement from using the single-ended circuitry, both analog stereo input pairs may be configured
in a pseudo-differential topology. This provides common-mode noise rejection for single-ended inputs by
differentially routing LINEIN_C-, MICIN_L-, and/or MICIN_R- with the signal traces. See Figure 12 for the
recommended pseudo-differential input filter.
Left Analog Input 1 //
(differential trac es )
GND
//
(differential trac es )
Right Analog Input 1 //
Left Analog Input 2 ^//
(differential trac es )
GND
//
GND
//
(differential trac es )
Right Analog Input 2 //
100 k
100 k
100  **
100  ^{1 µF} **
100  ^{** 1 µF}
1 µF
Note 1
* ^{1800 pF}
*
1800 pF
LINEIN_L+
LINEIN_C-
LINEIN_R+
100 k
100 k
100  **
100  ^{1 µF} **
100 
1 µF
**
1 µF
100  **
1 µF
* ^{1800 pF}
MICIN_L+
MICIN_L-
*
1800 pF
MICIN_R-
MICIN_R+
CS4207
+
PGA
-
-
PGA
+
common mode rejection at input of PGA
reduces external system noise
+
PGA
-
-
PGA
+
* NPO/C0G dielectric capacitors.
** _{Low ESR, X7R/X5R dielectric capacitors.}
Note:
1. These capacitors serve as a charge reservoir for the internal switched capacitor ADC
modulators and should be placed as close as possible to the inputs.
Figure 12. Pseudo-Differential Input Filter
AGND
140
DS880F4