TDA9875 Philips Semiconductors, TDA9875 Datasheet - Page 11

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

Philips Semiconductors
6.1.8
This function is enabled by setting bit AMUTE LOW
subaddress 14 (see Section 10.3.11). Upper and lower
error limits may be defined by writing appropriate values to
two registers in the I
17; see Sections 10.3.13 and 10.3.14). When the number
of errors in a 128 ms period exceeds the upper error limit
the auto-mute function will switch the output sound from
NICAM to whatever sound is on the first sound carrier
(FM or AM). When the error count is smaller than the lower
error limit the NICAM sound is restored.
The auto-mute function can be disabled by setting bit
AMUTE HIGH. In this condition clicks become audible
when the error count increases; the user will hear a signal
of degrading quality.
A decision to enable/disable the auto-muting is taken by
the microcontroller based on an interpretation of the
application control bits C1, C2, C3 and C4 and, possibly,
any additional strategy implemented by the set maker in
the microcontroller software.
1998 Feb 13
Digital TV Sound Processor (DTVSP)
NICAM
AUTO
2
C-bus section (subaddresses 16 and
-
MUTE
11
When the AM sound in NICAM L systems is demodulated
in the 1st sound IF and the audio signal connected to the
mono input of the TDA9875, the controlling microcontroller
must implement the switching from NICAM reception to
mono input, if auto-muting is desired.
6.1.9
A circuit diagram of the external components of the
voltage-controlled crystal oscillator is illustrated in Fig.8
(see Chapter 12).
6.1.10
Both test pins are active HIGH, in normal operation of the
device they are wired to V
manufacturing tests only and are not available to
customers. Without external circuitry these pads are pulled
down to LOW level with internal resistors.
C
T
EST PINS
RYSTAL OSCILLATOR
SSD1
. Test functions are for
Preliminary specification
TDA9875