CS4231A Datasheet, PDF (12/76 Pages) List of Unclassifed Manufacturers – PARALLEL INTERFACE MULTIMEDIA AUDIO CODEC

CS4231A
GENERAL DESCRIPTION
The CS4231A is a monolithic integrated circuit
that provides audio in personal computers or
other parallel interface environments. The func-
tions include stereo Analog-to-Digital and
Digital-to-Analog converters (ADCs and DACs),
analog mixing, anti-aliasing and reconstruction
filters, line and microphone level inputs, optional
A-Law / µ-Law coding, simultaneous capture
and playback and a parallel bus interface. Five
analog inputs are provided and three can be mul-
tiplexed to the ADC. The line input, two
auxiliary inputs and a mono input can be mixed
with the output of the DAC with full volume
control. Several data modes are supported in-
cluding 8- and 16-bit linear as well as 8-bit
companded, 4-bit ADPCM compressed, and 16-
bit Big Endian. The CS4231A is packaged in a
68-pin PLCC or a 100-pin TQFP.
Enhanced Functions (MODE 2)
The CS4231A’s initial state is labeled MODE 1
and forces the CS4231A to appear as a CS4248.
Enhanced functionality is provided by a second
mode on the CS4231A. To switch from
MODE 1 to MODE 2, the MODE2 bit should be
set to one in the MODE and ID register (I12).
When MODE 2 is selected, the bit IA4 in the
Index Address register (R0) will be decoded as a
valid index pointer, providing 16 additional reg-
isters and increased functionality over the
CS4248.
To reverse the procedure, clear the MODE2 bit
and the CS4231A will resume operation in
MODE 1. Since previous code writes a zero to
bit IA4 of the Index Address register (R0), the
CS4231A is backwards compatible with the
CS4248 and the AD1848.
12
Mixer Attenuation Control on Line Input
The CS4231A adds mixer attenuation control for
the LINE inputs which are then summed into the
output mixer. This fourth input to the mixer
completes the recommended mixer configuration
for MPC Level-2 compliance. The LINE mix
register provides 32 volume adjustments in 1.5
dB steps. In addition, there is a one bit mute
control.
The additional MODE 2 functions are:
1. Full-Duplex DMA support
2. A programmable timer
3. Mono output with mute control
4. Mono input with mixer volume control
5. ADPCM and Big Endian audio data formats
6. Independent selection of capture and
playback audio data formats
7. Selectable serial audio data port.
ANALOG HARDWARE DESCRIPTION
The analog hardware consists of an MPC
Level 2-compatible mixer (four stereo mix
sources), three line-level stereo inputs, a stereo
microphone input, a mono input, a mono output,
and a stereo line output. This section describes
the analog hardware needed to interface with
these pins.
Analog Inputs
The analog inputs consist of four stereo analog
inputs, and one mono input. As shown on this
data sheet cover, the input to the ADCs comes
from a multiplexer that selects between two ana-
log line-level inputs (LINE, AUX1), a
microphone level input (MIC), and the output
from the MPC-compatible mixer. The LINE and
AUX1 lines also feed the MPC mixer and in-
clude individual volume controls. Unused analog
inputs should be connected together and then
connected through a capacitor to analog ground.
DS139PP2