tda9870ah NXP Semiconductors, tda9870ah Datasheet - Page 15

• Manufacturer Part Number: tda9870ah
• Description: Digital Tv Sound Processor Dtvsp
• Manufacturer: NXP Semiconductors

Philips Semiconductors
Balance can be realized by independent control of the left
and right channel volume settings.
Bass is adjustable between +15 and 12 dB with 1 dB
resolution and treble is adjustable between
+12 and 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 and 93 dB with 3 dB 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.
6.2.6
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 range from +15 to 15 dB with 1 dB
resolution. Outputs can be disabled to improve EMC
performance.
The I
forced mono, stereo, channel swap, channel 1 and
channel 2.
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.
6.2.7
The signal level at the output of the ADC can be adjusted
in a range from +15 to 15 dB with 1 dB resolution.
The audio ADC itself is scaled to a gain of 6 dB.
1999 Dec 20
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
2
S-bus serial data outputs and the four processed
S-bus output matrix provides the following functions:
F
C
EATURE INTERFACE
HANNEL FROM THE AUDIO
ADC
2
2
C-bus data byte +8
S-bus input/output
2
2
S-bus serial data
S-bus port is
2
S-bus ports.
15
6.2.8
Level adjust with control positions 0, +3, +6 and +9 dB.
6.2.9
Input channels to the crossbar switch are from the audio
ADC, I
channel path after matrix and AVL (see Fig.6).
Output channels comprise loudspeaker, headphone, I
I
The I
the loudspeaker and headphone channels, but without the
beeper signals.
6.2.10
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.
6.2.11
The TDA9870A provides a special expert mode that gives
direct write access to the internal Coefficient RAM (CRAM)
of the DSP. It can be used to create user-defined
characteristics, such as a tone control with different corner
frequencies or special boost/cut characteristics to correct
the low-frequency loudspeaker and/or cabinet frequency
responses by means of the bass boost filter. However, this
mode must be used with great care.
More information on the functions of this device, such as
the number of coefficients per function, their default
values, memory addresses etc., can be made available on
request.
2
S2 and the audio DACs for line output and SCART.
2
S1 and I
2
S1, I
C
D
S
E
IGNAL GAIN
XPERT MODE
HANNEL TO THE ANALOG CROSSBAR PATH
IGITAL CROSSBAR SWITCH
2
S2, FM path and from the loudspeaker
2
S2 outputs also provide digital outputs from
2
Product specification
C-bus will not cause
TDA9870A
2
S1,