CS4294 Datasheet, PDF (34/42 Pages) Cirrus Logic – SoundFusion Audio/Docking Codec 97 (AMC 97)

CS4294
BIT_CLK - AC-link Serial Port Master Clock, Input/Output
This input/output signal controls the master clock timing for the AC-link. In codec primary
mode, this signal is an output 12.288 MHz clock signal which is divided down by two from the
XTL_IN input clock pin. In codec secondary mode, this signal is an input which controls the
AC-link serial interface. In BIT_CLK mode, this signal generates all internal clocking
including the AC-link serial interface timing. A series terminating resistor of 47 Ω should be
connected on this signal close to the CS4294 in primary mode or close to the BIT_CLK source
if in secondary mode.
SDATA_OUT - AC-link Serial Data Input Stream to AC ‘97, Input
This input signal transmits the control information and digital audio output streams to be sent
to the DACs. The data is clocked into the CS4294 on the falling edge of BIT_CLK. A series
terminating resistor of 47 Ω should be connected on this signal close to the device driving the
input.
SDATA_IN - AC-link Serial Data Output Stream from AC ‘97, Output
This output signal transmits the status information and digital audio input streams from the
ADCs. The data is clocked out of the CS4294 on the rising edge of BIT_CLK. A series
terminating resistor of 47 Ω should be connected on this signal as close to the CS4294 as
possible.
XTL_IN - Crystal Input
This pin accepts either a crystal, with the other pin attached to XTL_OUT, or an external
CMOS clock. XTL_IN must have a crystal or clock source attached for proper operation except
when operating in BIT_CLK mode. The crystal frequency must be 24.576 MHz and designed
for fundamental mode, parallel resonance operation.
XTL_OUT - Crystal Output
This pin is used for a crystal placed between this pin and XLT_IN. If an external clock is used
on XTL_IN or the codec is in BIT_CLK mode, this pin must be left floating with no traces or
components connected to it.
ID1#, ID0# - Codec ID, Inputs
These pins select the codec ID and mode of operation for the CS4294. They are sampled after
the rising edge of RESET# and not used after. These inputs have internal 100 kΩ pull-ups and
should be left floating for a logic 0 or tied to analog ground for a logic 1. The pins utilize
inverted logic, so the condition of both pins floating sets the codec to primary mode while any
other combination sets the codec to a secondary mode. In primary mode, the codec is always
clocked from an external crystal or an external oscillator connected to the XTL_IN and/or
XTL_OUT pins with BIT_CLK as an output. In secondary mode, the clocking mechanism is
determined by the state of the BCM# pin with BIT_CLK always being an input.
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