back data format and the capture data format is
independently selectable in the Capture Data
Format register (I28).
The CS4231A always orders the left channel
data before the right channel. Note that these
definitions apply regardless of the specific for-
mat of the data. For example, 8-bit linear data
streams look exactly like 8-bit companded data
streams. Also, the left sample always comes first
in the data stream regardless of whether the sam-
ple is 16- or 8-bit in size.
There are four data formats supported by the
CS4231A during MODE 1 operation: 16-bit
signed (little endian), 8-bit unsigned, 8-bit com-
panded
µ
-Law, and 8-bit companded A-Law.
See Figures 12 through 15.
Additional data formats are supported in
MODE 2 operation: 4-bit ADPCM, and 16-bit
signed big endian. See Figures 16 through 19.
With the addition of the Big Endian and
ADPCM audio data formats, the CS4231A is
compliant with the IMA recommendations for
digital audio data formats (and sample frequen-
cies).
16-bit Signed
The 16-bit signed format (also called 16-bit 2’s
complement) is the standard method of repre-
senting 16-bit digital audio. This format gives
96 dB theoretical dynamic range and is the
standard for compact disk audio players. This
format uses the value -32768 (8000h) to repre-
sent maximum negative analog amplitude while
32767 (7FFFh) represents maximum positive
analog amplitude.
8-bit Unsigned
The 8-bit unsigned format is commonly used in
the personal computer industry. This format de-
livers a theoretical dynamic range of 48 dB. This
format uses the value 0 (00h) to represent maxi-
mum negative analog amplitude while 255 (FFh)
represents maximum positive analog amplitude.
The 16-bit signed and 8-bit unsigned transfer
functions are shown in Figure 10.
8-bit Companded
The 8-bit companded formats (A-Law and
µ
-
Law) come from the telephone industry.
µ
-Law
is the standard for the United States/Japan while
A-Law is used in Europe. Companded audio al-
lows either 64 dB or 72 dB of dynamic range
0
+FS
-FS
A
NAL
O
G
V
A
LU
E
0
65
128
191
255
DIGITAL CODE
8-bit
unsigned:
16-bit
2’s comp:
-32768
-16384
0
16384
32767
Figure 10. Linear Transfer Functions
0
+FS
-FS
DIGITAL CODE
ANA
L
O
G
V
A
L
U
E
A-Law: 2Ah
15h
95h
AAh
7Fh/FFh
55h/D5h
00h
3Fh
BFh
80h
u-Law:
Figure 11. Companded Transfer Functions
CS4231A
22
DS139PP2
Summary of Contents for CS4231A
Page 63: ...Figure 1 CS4231 Aux1 In CDB4231 4248 DS111DB7 63 ...
Page 64: ...Figure 2 Microphone In Figure 3 Mono Speaker Out CDB4231 4248 64 DS111DB7 ...
Page 65: ...Figure 4 Line In CDROM In Aux2 CDB4231 4248 DS111DB7 65 ...
Page 66: ...Figure 5 Line Headphone Out CDB4231 4248 66 DS111DB7 ...
Page 67: ...Figure 6 Address Decode and Board ID CDB4231 4248 DS111DB7 67 ...
Page 68: ...Figure 7 Analog Power Buffer CDB4231 4248 68 DS111DB7 ...
Page 72: ...Figure 8 Silk Screen CDB4231 4248 72 DS111DB7 ...
Page 73: ...Figure 9 Component Side Top 1st Layer CDB4231 4248 DS111DB7 73 ...
Page 74: ...Figure 10 Solder Side Bottom 4th Layer CDB4231 4248 74 DS111DB7 ...
Page 75: ...Figure 11 Ground 2nd Layer Inverse CDB4231 4248 DS111DB7 75 ...
Page 76: ...Figure 12 Power 3rd Layer Inverse CDB4231 4248 76 DS111DB7 ...