TDA9875 Philips Semiconductors, TDA9875 Datasheet - Page 14

• Manufacturer Part Number: TDA9875
• Description: Digital TV Sound Processor DTVSP
• Manufacturer: Philips Semiconductors

Philips Semiconductors
Soft-mute provides a mute ability in addition to volume
control with a well defined time (32 ms) after which the
soft-mute is completed. A smooth fading is achieved by a
cosine masking.
6.2.7
The matrix provides the following functions; forced mono,
stereo, channel swap, channel 1 and channel 2
(or C and S in Dolby Surround Pro Logic mode).
Volume is controlled individually for each channel in a
range from +24 to 83 dB with 1 dB resolution. There is
also a mute position. For the purpose of a simple control
software in the microcontroller, the decimal number that is
sent as an I
to the volume setting in dBs (e.g. the I
byte +10 sets the new volume value to +10 dB).
Balance can be realized by independent control of the left
and right channel volume settings.
Bass is adjustable between +15 dB and 12 dB with 1 dB
resolution and treble is adjustable between 12 dB with
1 dB resolution.
For the purpose of a simple control software in the
microcontroller, the decimal number that is sent as an
I
bass or treble setting in dB (e.g. the I
sets the new value to +8 dB).
The beeper provides tones in a range from approximately
400 Hz to 30 kHz. The frequency can be selected via the
I
loudspeaker and headphone channel signals. The beeper
volume is adjustable with respect to full-scale between
0 dB and 93 dB with a 3 dB step resolution. The beeper
is not effected by mute.
Soft-mute provides a mute ability in addition to volume
control with a well defined time (32 ms) after which the
soft-mute is completed. A smooth fading is achieved by a
cosine masking.
6.2.8
The feature interface comprises two I
ports and a system clock output. Each I
equipped with level adjust facilities that can change the
signal level in a 15 dB range in 1 dB steps. Outputs can
be disabled to improve EMC performance.
The I
forced mono, stereo, channel swap, channel 1 and
channel 2.
1998 Feb 13
2
2
C-bus data byte for bass or treble is identical to the new
C-bus. The beeper output signal is added to the
Digital TV Sound Processor (DTVSP)
2
S-bus output matrix provides the following functions;
H
F
EATURE INTERFACE
EADPHONE
2
C-bus data byte for volume control is identical
(A
UXILIARY
)
CHANNEL
2
2
2
C-bus data byte +8
S-bus input/output
C-bus data
2
S-bus port is
14
One example of how the feature interface can be used in
a TV set is to connect an external Dolby Surround Pro
Logic DSP, such as the SAA7710, to the I
Outputs must be enabled and a suitable master clock
signal for the DSP can be taken from pin SYSCLK.
A stereo signal from any source will be output on one of
the I
signal channels will be entered at both I
inputs. Left and right could then be output to the power
amplifiers via the Main channel, centre and surround via
the Auxiliary channel.
6.2.9
The signal level at the output of the ADC can be adjusted
in a range of 15 dB with a 1 dB step resolution. The audio
ADC itself is scaled to a gain of 6 dB.
6.2.10
Level adjust with control positions 0 dB, +3 dB, +6 dB
and +9 dB.
6.2.11
Input channels to the crossbar switch are from the audio
ADC, I
loudspeaker channel path after matrix and AVL.
Output channels comprise loudspeaker, headphone, I
I
The I
the loudspeaker and headphone channels, but without the
beeper signals.
6.2.12
There are a number of functions that can provide signal
gain, e.g. volume, bass and treble control. Great care has
to be taken when using gain with large input signals in
order not to exceed the maximum possible signal swing,
which would cause severe signal distortion. The nominal
signal level of the various signal sources to the digital
crossbar switch should be 15 dB below digital full-scale
( 15 dB full-scale). This means that a volume setting of,
say, +15 dB would just produce a full-scale output signal
and not cause clipping, if the signal level is nominal.
Sending illegal data patterns via the I
any changes of the current setting for the volume, bass,
treble, bass boost and level adjust functions.
2
S2 and the audio DACs for line output and SCART.
2
2
S-bus serial data outputs and the four processed
S1 and I
2
S1, I
CONVERTER
C
C
D
G
HANNEL FROM THE AUDIO ANALOG
HANNEL TO THE ANALOG CROSSBAR PATH
IGITAL CROSSBAR SWITCH
ENERAL
2
S2, FM path, NICAM path and from the
2
S2 outputs also provide digital outputs from
Preliminary specification
(
SEE
2
C-bus will not cause
2
S-bus serial data
Fig.6)
TDA9875
2
S-bus ports.
-
TO
-
DIGITAL
2
S1,