CS4201 Datasheet, PDF (52/68 Pages) Cirrus Logic – CrystalClear Audio Codec 97 with headphone Amplifier

CS4201
10.2 Analog Outputs
10.2.2 Mono Output
The analog output section provides a stereo, a
headphone, and a mono output. The MONO_OUT,
LINE_OUT_L, and LINE_OUT_R pins require
680 pF to 1000 pF NPO dielectric capacitors be-
tween the corresponding pin and analog ground.
Each analog output is DC-biased up to the Vrefout
voltage signal reference, nominally 2.4 V. This re-
quires the outputs be AC-coupled to external cir-
cuitry (AC loads must be greater than 10 kΩ for the
line output or 32 Ω for the headphone output). The
headphone coupling capacitors should be 220 µF
or greater to minimize low frequency roll-off.
10.2.1 Stereo Outputs
The LINE_OUT and HP_OUT stereo outputs de-
pend on the configuration of the HPCFG pin. As
shown in Figure 24, if the HPCFG pin is left float-
ing, the part behaves as specified in AC ’97. As
shown in Figure 25, if the HPCFG pin is grounded,
the part behaves as if HP_OUT was the only out-
put. In this case, LINE_OUT will be muted, the
Master Volume Register (Index 02h) will control
HP_OUT and PC_BEEP will be routed to
HP_OUT during RESET.
The mono output, MONO_OUT, can be either a
sum of the left and right output channels, attenuat-
ed by 6 dB to prevent clipping at full scale, or the
selected Mic signal. The mono out channel can
drive the PC internal mono speaker using an appro-
priate buffer circuit
10.3 Miscellaneous Analog Signals
The AFLT1 and AFLT2 pins must have a 1000 pF
NPO capacitor to analog ground. These capacitors
provide a single-pole low-pass filter at the inputs to
the ADCs. This makes low-pass filters at each ana-
log input pin unnecessary.
The REFFLT pin must have a short, wide trace to a
2.2 µF and a 0.1 µF capacitor connected to analog
ground (see Figure 27 in Section 11, Grounding
and Layout, for an example). The 2.2 µF capacitor
must not be replaced by any other value and must
be ceramic with low leakage current. Electrolytic
capacitors should not be used. No other connection
should be made, as any coupling onto this pin will
degrade the analog performance of the CS4201.
Likewise, digital signals should be kept away from
REFFLT for similar reasons.
LINE_OUT_R
LINE_OUT_L
10 µ F
+ ELEC
10 µ F
+ ELEC
220 k Ω
1000 pF 1000 pF
220 k Ω
Line Out
Jack
HP_OUT_R
HP_OUT_L
HP_OUT_C
HPCFG
AGND
220 µ F
+ ELEC
220 µ F
+ ELEC
1 µF
+ ELEC
AGND AGND _Headphone
Jack
10 k Ω 10 k Ω
AGND AGND
Figure 24. Line Out and Headphone Out Setup
52
LINE_OUT_R
LINE_OUT_L
HP_OUT_R
HP_OUT_L
HP_OUT_C
HPCFG
220 µ F
+ ELEC
220 µ F
+ ELEC
1 µF
+ ELEC
10 k Ω
10 k Ω
Line Out/
Headphone
Jack
AGND
AGND AGND
Figure 25. Line Out/Headphone Out Setup
DS483PP3