tda9874h NXP Semiconductors, tda9874h Datasheet - Page 27

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

Philips Semiconductors
7.3.11
The default setting at power-up is 0000 0000.
Table 33 NICAM configuration register (subaddress 14)
Table 34 Description of the NICAM configuration register bits
7.3.11.1
The decision of whether auto-muting is permitted shall be taken by the controlling microprocessor based on information
contained in the TDA9874H status registers. Thus, it depends on the strategy implemented in the software whether the
auto-mute function is in accordance with “NICAM 728 ETS Revised for Data Applications” or any other preference.
The NICAM de-emphasis gain is 0 dB at 40 Hz.
Bit AMSEL has only an effect on the analog sound outputs OUTL and OUTR. With regard to the digital sound output
(I
When carrier 2 is in FM mode, bit TIMPOL should be set to logic 1, to achieve the best S/N performance with the current
oscillator application proposal (see Chapter 12).
2000 Jun 26
2
S), the auto-mute will only switch between NICAM and the first sound carrier.
Digital TV sound demodulator/decoder
BIT
7
7
6
5
4
3
2
1
0
NICAM
Notes
CONFIGURATION REGISTER
SYMBOL
DOUTEN
TIMPOL
NDEEM
AMUTE
AMSEL
6
these bits are not used and should be set to logic 0
Timing loop polarity: bit TIMPOL = 1 inverts the polarity. This feature can be used to
compensate for the phase shift that is introduced by an external inverting amplifier at the
pin V
the VCXO. Bit TIMPOL = 0 sets the NICAM timing loop to normal polarity.
Data output enable: bit DOUTEN = 1 enables the output of the NICAM serial data
stream from the DQPSK demodulator and of the associated clock, PCLK.
If bit DOUTEN = 0 both outputs will be 3-stated.
this bit is not used and should be set to logic 0
Auto-mute select: bit AMSEL = 1 will switch the auto-mute between NICAM sound and
the analog mono input. This bit has only an effect if the auto-mute function is enabled
and if the DAC has been selected in the Analog Output Select Register
(see Section 7.3.17). If bit AMSEL = 0 the auto-mute will switch between NICAM sound
and the sound on the first sound carrier (i.e. FM mono or AM).
De-emphasis on/off: bit NDEEM = 1 switches the NICAM J17 de-emphasis off.
Bit NDEEM = 0 switches the NICAM J17 de-emphasis on.
Auto-muting on/off: bit AMUTE = 1 automatic muting is disabled. This bit has only an
effect, if the second sound carrier is set to NICAM. Bit AMUTE = 0 enables the
automatic switching between NICAM and the program on the first sound carrier
(i.e. FM mono or AM), dependent on the NICAM bit error rate.
TIMPOL
tune
5
. Such an amplifier could be used to provide a larger tuning voltage swing for
DOUTEN
4
27
3
DESCRIPTION
AMSEL
2
NDEEM
1
Product specification
TDA9874H
AMUTE
0