Cirrus Logic CS4297A - Manual (Page 45)

CS4297A
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AC-Link
RESET# - AC ’97 Chip Reset, Input, Pin 11
This active low signal is the asynchronous Cold Reset input to the CS4297A. The CS4297A must be
reset before it can enter normal operating mode.
SYNC - AC-Link Serial Port Sync pulse, Input, Pin 10
This signal is the serial port timing signal for the AC-link. Its period is the reciprocal of the maximum
sample rate, 48 kHz. The signal is generated by the controller, synchronous to BIT_CLK. SYNC is an
asynchronous input when the CS4297A is configured as a primary audio codec and is in a PR4
powerdown state. A series terminating resistor of 47
Ω should be connected on the signal near the
SYNC source.
BIT_CLK - AC-Link Serial Port Master Clock, Input/Output, Pin 6
This input/output signal controls the master clock timing for the AC-link. In primary mode, this signal is a
12.288 MHz output clock derived from a 24.576 MHz crystal on the XTL_IN input clock. When the
CS4297A is in secondary mode, this signal is an input which controls the AC-link serial interface and
generates all internal clocking including the AC-link serial interface timing and the analog sampling
clocks. A series terminating resistor of 47
Ω should be connected on this signal close to the CS4297A in
primary mode or close to the BIT_CLK source in secondary mode.
SDATA_OUT - AC-Link Serial Data Input Stream to AC ’97, Input, Pin 5
This input signal receives the control information and digital audio output streams. The data is clocked
into the CS4297A on the falling edge of BIT_CLK. A series terminating resistor of 47
Ω should be
connected on this signal near the controller.
SDATA_IN - AC-Link Serial Data Output Stream from AC ’97, Output, Pin 8
This output signal transmits the status information and digital audio input streams from the ADCs. The
data is clocked out of the CS4297A on the rising edge of BIT_CLK. A series terminating resistor of 47
Ω
should be connected on this signal as close to the CS4297A as possible.
Power Supplies
DVdd1, DVdd2 - Digital Supply Voltage, Pins 1 and 9
Digital supply voltage for the AC-link section of the CS4297A. These pins can be tied to +5 V digital or
to +3.3 V digital. The CS4297A and controller AC-link should share a common digital supply
DVss1, DVss2 - Digital Ground, Pins 4 and 7
Digital ground connection for the AC-link section of the CS4297A. These pins should be isolated from
analog ground currents.
AVdd1, AVdd2 - Analog Supply Voltage, Pins 25 and 38
Analog supply voltage for the analog and mixed signal sections of the CS4297A. These pins must be
tied to the analog +5 V power supply. It is strongly recommended that +5 V be generated from a voltage
regulator to ensure proper supply currents and noise immunity from the rest of the system.
AVss1, AVss2 - Analog Ground, Pins 26 and 42
Ground connection for the analog, mixed signal, and substrate sections of the CS4297A. These pins
should be isolated from digital ground currents.
DS318PP6 45
CS4297A