SAA2520 Datasheet, PDF (23/36 Pages) NXP Semiconductors – Stereo filter and codec for MPEG layer 1 audio applications

Philips Semiconductors
Stereo filter and codec for MPEG layer 1
audio applications
Preliminary specification
SAA2520
INTERNAL SETTINGS (LTCNT1 = LOGIC 1, LTNCT 0 = LOGIC 0)
The operation of the codec is controlled by the bits transferred in this mode.
Table 8 Internal Settings (LTCNT1 = logic 1, LTNCT 0 = logic 0).
msb
S15
...
S11
...
S9
S8
S7
S6
S5
S4
S3
...
S1
...
lsb
name
S12 bit rate index
S10 sample frequency
decode
EXT 256FS
2-channel mono
MUTE
CH1
S2
Tr0 to Tr1
S0
EMPHASIS
function
bit rate indication
44.1, 48 or 32 kHz
indication
1 = decode; 0 = encode
1 = external;
0 = internal 256FS
1 = 2-CH mono;
0 = stereo
1 = mute; 0 = no mute
not used
1 = CH1; 0 = CH2
transparent bits
emphasis indication
valid in
encode
encode
encode/decode
encode/decode
encode
encode/decode
decode
encode
encode
Table 9 Internal Settings (LTCNT1 = logic 1, LTCNT0 = logic 0).
msb
1
1
1
0
0
1
0
1
lsb
bit rate
0
0
384 kbits/s
0
0
256 kbits/s
1
0
192 kbits/s
0
0
128 kbits/s
default value
The bit rate index indicates the bit rate of the encoded
signal and is only effective in the encode mode.
The decode bit determines the operation mode of the
SAA2520. The default value is logic 1 (decoding mode).
EXT 256FS in the encoding mode determines whether or
not the SAA2520 is master or slave of the Filtered-I²S
interface (default is logic 0, master mode).
2CH MONO is used in the encoding mode to determine
whether the sub-band signal is generated as a stereo or
2-channel mono signal. Default value is logic 0.
MUTE is used in both the encoding and decoding modes
to mute the information to or from the Filtered-I²S interface
(the default value is logic 0).
CH1 is utilized in the decoding mode to select one of the
2-channel mono signals to be decoded (default is
I - channel 1). A value of 0 results in channel 2 being
decoded).
The transparent bits are copied in the sub-band signal,
default is 00.
The information from S15 to S10, S7 and S3 to S0 will be
copied into the sub-band signal.
August 1993
23