TDA9875A Philips Semiconductors, TDA9875A Datasheet - Page 87

• Manufacturer Part Number: TDA9875A
• Description: Digital TV Sound Processor DTVSP
• Manufacturer: Philips Semiconductors

Philips Semiconductors
11 I
The feature interface of the TDA9875A contains two serial
audio inputs and outputs and associated clock signals.
It can be used to supply, for example, audio signals from
received TV programs to a digital audio output device
(AES/EBU format), or import serial audio signals from
other sources for reproduction through the TV set’s
loudspeaker and/or headphone channels. Apart from such
simple data input or output, it is also possible to run audio
signals through an external DSP, which performs some
additional functions, such as room simulation, Dolby
Surround Pro Logic etc. and feed those signals back into
the loudspeaker and/or headphone channels of the
TDA9875A.
Two serial audio formats are supported at the feature
interface, i.e. the I
MSB-aligned format. The difference is illustrated in Fig.9.
In both formats the left audio channel of a stereo sample
pair is output first and is placed on the serial data line (SDI
for input, SDO for output) when the Word Select line (WS)
is LOW. Data is written at the trailing edge of SCK and
read at the leading edge of SCK. The most significant bit
is sent first.
At power-up, the outputs of the feature interface are
3-stated to reduce EMC and allow for combinations with
other ICs. 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 pins SDO1 and SDO2. Depending on the
signal source, switch and matrix positions, the output can
be either mono, stereo or dual language sound on either
output.
The word select output is clocked with the audio sample
frequency at 32 kHz. The serial clock output (SCK) is
clocked at a frequency of 2.048 MHz. This means, that
there are 64 clock pulses per pair of stereo output
samples, or 32 clock pulses per sample. Depending again
on the signal source, the number of significant bits on the
serial data outputs, SDO1 and SDO2, is between
14 and 18.
1999 Dec 20
Digital TV Sound Processor (DTVSP)
2
S-BUS DESCRIPTION
2
C-bus command.
2
S-bus format and a very similar
87
Apart from just feeding a digital audio device, such as a
DAC or an AES/EBU transmitter, the serial data outputs
can be connected directly to the serial inputs (loop-back
connection) or first to an external device, e.g. a feature
DSP such as the SAA7710 and then back to the serial
inputs. In all of these configurations, the SCK and WS
clocks will be generated by the TDA9875A, which then is
the I
The serial data inputs, SDI1 and SDI2, are active at all
times, independent of the serial data outputs being on or
off. When the serial data outputs are off (either after
power-up or via the appropriate I
data and clocks WS and SCK from a separate digital audio
source can be fed into the TDA9875A, be processed and
output in accordance with internal selector positions,
provided that the following criteria are met:
In such cases, the external source is the I
and the TDA9875A is the I
To support synchronization of external devices or as a
master clock for them, a system clock output, SYSCLK, is
available from the TDA9875A. At power-up it is off. It can
be enabled and the output frequency set via an I
command. Available output frequencies are
8.192, 12.288, 16.384 and 24.576 MHz.
32 kHz audio sample frequency
32 clock bits per sample
External timing and data synchronized to TDA9875A.
2
S-bus master.
2
S-bus slave.
2
C-bus command) serial
Product specification
TDA9875A
2
S-bus master
2
C-bus