Cs4297a – Cirrus Logic CS4297A User Manual
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CS4297A
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Audio I/O
PC_BEEP - Analog Mono Source, Input, Pin 12
The PC_BEEP input is intended to allow the PC system POST (Power On Self-Test) tones to pass
through to the audio subsystem. The PC_BEEP input has two connections: the first connection is to the
analog output mixer, the second connection is directly to the LINE_OUT stereo outputs. While the
RESET# pin is actively being asserted and the BCFG pin is left floating, the PC_BEEP bypass path to
the LINE_OUT outputs is enabled. While the CS4297A is in normal operation mode, with RESET#
deasserted or BCFG grounded, PC_BEEP is a monophonic source to the analog output mixer. The
maximum allowable input is 1 V
RMS
(sinusoidal). This input is internally biased at the Vrefout voltage
reference and requires AC-coupling to external circuitry. If this input is not used, it should be connected
to the Vrefout pin or AC-coupled to analog ground.
PHONE - Analog Mono Source, Input, Pin 13
This analog input is a monophonic source to the analog output mixer. It is intended to be used as a
modem subsystem input to the audio subsystem. The maximum allowable input is 1 V
RMS
(sinusoidal).
This input is internally biased at the Vrefout voltage reference and requires AC-coupling to external
circuitry. If this input is not used, it should be connected to the Vrefout pin or AC-coupled to analog
ground.
MIC1 - Analog Mono Source, Input, Pin 21
This analog input is a monophonic source to the analog output mixer. It is intended to be used as a
desktop microphone connection to the audio subsystem. The CS4297A internal mixer’s microphone
input is MUX selectable with either MIC1 or MIC2 as the input. The maximum allowable input is 1 V
RMS
(sinusoidal). This input is internally biased at the Vrefout voltage reference and requires AC-coupling to
external circuitry. If this input is not used, it should be connected to the Vrefout pin or AC-coupled to
analog ground.
MIC2 - Analog Mono Source, Input, Pin 22
This analog input is a monophonic source to the analog output mixer. It is intended to be used as an
alternate microphone connection to the audio subsystem. The CS4297A internal mixer’s microphone
input is MUX selectable with either MIC1 or MIC2 as the input. The maximum allowable input is 1 V
RMS
(sinusoidal). This input is internally biased at the Vrefout voltage reference and requires AC-coupling to
external circuitry. If this input is not used, it should be connected to the Vrefout pin or AC-coupled to
analog ground.
LINE_IN_L, LINE_IN_R - Analog Line Source, Inputs, Pins 23 and 24
These inputs form a stereo input pair to the CS4297A. The maximum allowable input is 1 V
RMS
(sinusoidal). These inputs are internally biased at the Vrefout voltage reference and require AC-coupling
to external circuitry. If these inputs are not used, they should both be connected to the Vrefout pin or
both AC-coupled, with separate AC-coupling caps, to analog ground.
CD_L, CD_R - Analog CD Source, Inputs, Pins 18 and 20
These inputs form a stereo input pair to the CS4297A. It is intended to be used for the Red Book CD
audio connection to the audio subsystem. The maximum allowable input is 1 V
RMS
(sinusoidal). These
inputs are internally biased at the Vrefout voltage reference and require AC-coupling to external circuitry.
If these inputs are not used, they should both be connected to the Vrefout pin or both AC-coupled, with
separate AC-coupling caps, to analog ground.
CD_GND - Analog CD Common Source, Input, Pin 19
This analog input is used to remove common mode noise from Red Book CD audio signals. The
impedance on the input signal path should be one half the impedance on the CD_L and CD_R input
paths. This pin requires AC-coupling to external circuitry. If this input is not used, it should be connected
to the Vrefout pin or AC-coupled to analog ground.
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DS318PP6
CS4297A