CS4294 Datasheet, PDF (35/42 Pages) Cirrus Logic – SoundFusion Audio/Docking Codec 97 (AMC 97)

CS4294
BCM# - BIT_CLK Mode, Input
This pin selects the secondary mode clocking mechanism. BCM# is sampled after the rising
edge of RESET# and not used after. In codec secondary mode (ID1# and or ID0# grounded),
grounding this input will select BIT_CLK mode. In this mode, BIT_CLK is defined as an input
and all internal timing will be derived from the BIT_CLK signal and no connections should be
made to XTAL_IN and XTAL_OUT. When BCM# is floating, all timing will be derived from
the XTAL_IN pin. In this case, XTAL_IN must be synchronous to BIT_CLK. In primary mode,
BCM# must be left floating.
GPIO[8:3] - General Purpose Input/Output
These GPIO pins are used to control discrete digital functions. When a GPIO pin is configured
as an input, it behaves as a Schmitt trigger input with 350 mV of hysteresis at 5 V and 220 mV
of hysteresis at 3.3 V. When a GPIO pin in configured as an output, it may function as a
normal CMOS output (4 mA drive) or as an open drain output. GPIO pins power up in the high
impedance state (tri-state).
8.2 Analog I/O Pins
MIC1 - Analog Mono Source, Input
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 maximum allowable input is
1 V_RMS (sinusoidal). If the 20 dB internal boost is enabled, the maximum allowable input is
100 mV_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 AC coupled to
analog ground.
LINE_IN_L and LINE_IN_R- Analog Line Source, Inputs
These inputs form a stereo input pair to the CS4294. The maximum allowable input is
1 V_RMS (sinusoidal). These inputs are internally biased at the Vrefout voltage reference. AC
coupling to external circuitry is required. 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 and CD_R - Analog CD Source, Inputs
These inputs form a stereo input pair to the CS4294. 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. AC coupling to
external circuitry is required. 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
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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