tda9874h NXP Semiconductors, tda9874h Datasheet - Page 40

• Manufacturer Part Number: tda9874h
• Description: Digital Tv Sound Demodulator/decoder
• Manufacturer: NXP Semiconductors

Philips Semiconductors
8
The digital audio interface of the TDA9874H consists of a
serial audio output and associated clock signals. It can be
used to supply digital audio signals from received
TV programs to a suitable output device, e.g. a DAC or an
AES/EBU transmitter.
Two serial audio formats are supported at the digital audio
interface, i.e. the I
MSB-aligned format. The difference is illustrated in Fig.6.
In both formats the left audio channel of a stereo sample
pair is output first, and is placed on the Serial Data Output
(SDO) line when the Word Select line (WS) is at LOW
level. Data is written at the trailing edge of the Serial Clock
(SCK) output and read at the leading edge of SCK. The
most significant bit is sent first.
At power-up, the outputs of the digital audio interface are
3-stated to reduce EMC and allow for combinations with
other ICs.
2000 Jun 26
handbook, full pagewidth
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Digital TV sound demodulator/decoder
I
2
S-BUS DESCRIPTION
SCK
WS
SDO
SCK
WS
SDO
2
S-bus format and a very similar
LSB
LSB
MSB
MSB
Fig.6 Serial audio interface formats.
one sample
one sample
b. MSB-alignment format.
a. I
2
S-bus format.
40
If output is desired, it has to be activated by means of an
I
When the output is enabled, the serial audio data can be
taken from pin SDO. Depending on the signal source,
switch and matrix positions, the output can be either mono,
stereo or dual language.
The Word Select output (WS) is clocked with the audio
sample frequency of 32 kHz. The serial clock output is
clocked at a frequency of 2048 MHz. This means, that
there are 64 clock pulses per pair of stereo output
samples, or 32 clock pulses per sample. There are
18 significant bits used on the serial data output.
A symmetrical system clock output (SYSCLK) is available
from the TDA9874H as a master clock for external digital
audio devices. At power-up, the clock is off. It can be
enabled and the output frequency set via an I
command. Available output frequencies are 8192, 12288,
16384 and 24576 MHz.
2
C-bus command.
LSB
LSB
MSB
MSB
Product specification
TDA9874H
2
MGK758
MGK759
C-bus