CS4202
2. GENERAL DESCRIPTION
2.1
AC-Link
The CS4202 is a mixed-signal serial audio codec
with integrated headphone power amplifier com-
pliant with the Intel® Audio Codec ’97 Specifica-
tion, revision 2.2 [6] (referred to as AC ’97). It is
designed to be paired with a digital controller, typ-
ically located on the PCI bus or integrated within
the system core logic chip set. The controller is re-
sponsible for all communications between the
CS4202 and the remainder of the system. The
CS4202 contains two distinct functional sections:
digital and analog. The digital section includes the
AC-link interface, S/PDIF interface, serial data
port, GPIO, power management support, and Sam-
ple Rate Converters (SRCs). The analog section in-
cludes the analog input multiplexer (mux), stereo
input mixer, stereo output mixer, mono output mix-
er, headphone amplifier, stereo Analog-to-Digital
Converters (ADCs), stereo Digital-to-Analog Con-
verters (DACs), and their associated volume con-
trols.
All communication with the CS4202 is established
with a 5-wire digital interface to the controller
called the AC-link. This interface is shown in
Figure 7. All clocking for the serial communication
is synchronous to the BIT_CLK signal. BIT_CLK
is generated by the primary audio codec and is used
to clock the controller and any secondary audio co-
decs. Both input and output AC-link audio frames
are organized as a sequence of 256 serial bits form-
ing 13 groups referred to as ‘slots’. During each au-
dio frame, data is passed bi-directionally between
the CS4202 and the controller. The input frame is
driven from the CS4202 on the SDATA_IN line.
The output frame is driven from the controller on
the SDATA_OUT line. The controller is also re-
sponsible for issuing reset commands via the RE-
SET# signal. Following a Cold Reset, the CS4202
is responsible for notifying the controller that it is
ready for operation after synchronizing its internal
functions. The CS4202 AC-link signals must use
the same digital supply voltage as the controller, ei-
ther +5 V or +3.3 V. See Section 3, AC-Link Frame
Definition, for detailed AC-link information.
AC'97
CODEC
Digital AC'97
Controller
SYNC
BIT_CLK
SDATA_OUT
SDATA_IN
RESET#
Figure 7. AC-link Connections
12
DS549PP1
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