CS4207-CNZ Datasheet, PDF (141/148 Pages) Cirrus Logic – Low-power, 4-in / 6-out HD Audio Codec with Headphone Amp

CS4207
For the best ADC performance, fully differential inputs can be connected to the Mic In 1/Line In 2 input pair
only. This topology provides the best common-mode noise rejection and also increases the dynamic range
due to the larger full-scale input voltage. See Figure 13 for the recommended differential input filter.
Left Analog Input + //
(differential trac es )
Left Analog Input - //
Right Analog Input + //
(differential trac es )
Right Analog Input - //
100 k
100  **
1 µF
100 k
100  **
1 µF
100 k
100  **
1 µF
100 k
100  **
1 µF
Note 1
MICIN_L+
* ^{3600 pF}
MICIN_L-
MICIN_R+
* ^{3600 pF}
MICIN_R-
CS4207
+
PGA
-
common mode rejection at input of PGA
reduces external system noise
+
PGA
-
* NPO/C0G dielectric capacitors.
** _{Low ESR, X 7R/X5 R dielectric capacitors.}
AGND
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 13. Differential Input Filter
For all of the input topologies, either input pair can be used with a microphone input by connecting the
MICBIAS pin to the signals as shown in Figure 1. If electrolytic capacitors are used for AC coupling the mi-
crophone inputs, the positive terminal of the capacitor must be connected to the greater bias voltage. The
analog input pins are internally biased at 0.5*VA and the voltage level of the MICBIAS pin can be configured
by setting the VREFE bits in the Mic In 1/Line In 2 Pin Widget Control of the Mic In 1/Line In 2 Pin Widget
(Node ID = 0Dh).
DS880F4
141