TDA9874A Philips Semiconductors, TDA9874A Datasheet - Page 33

• Manufacturer Part Number: TDA9874A
• Description: Digital TV sound demodulator/decoder
• Manufacturer: Philips Semiconductors

Philips Semiconductors
10.3.5
This register should not be used when applying ESP.
Three bytes are required to define a 24-bit frequency
control word to represent the sound carrier (i.e. mixer)
frequency. These three bytes are stored at
subaddresses 3 to 5; subaddress 3 being the high byte.
Execution of the command starts only after all bytes have
been received. If an error occurs, e.g. a premature STOP
condition, partial data for this function is ignored. The
sound carrier frequency can be calculated in accordance
with the following formula:
Table 23 Carrier 1 frequency register high byte (subaddress 3)
Table 24 Carrier 1 frequency register middle byte (subaddress 4)
Table 25 Carrier 1 frequency register low byte (subaddress 5)
10.3.6
This register should not be used when applying ESP. The format is the same as for sound carrier 1, except
subaddresses 6 to 8 are used. Subaddress 6 holds the high byte.
If the C2FR is used, it will be for either the second FM sound carrier of a terrestrial or satellite FM program or the NICAM
sound carrier.
1999 Dec 03
data
Digital TV sound demodulator/decoder
=
B7
B7
B7
7
7
7
f
--------
f
C
mix
C
clk
ARRIER
ARRIER
2
24
1 F
2 F
B6
B6
B6
REQUENCY
REQUENCY
6
6
6
R
R
EGISTER
EGISTER
B5
B5
B5
5
5
5
(C1FR)
(C2FR)
B4
B4
B4
4
4
4
33
where:
Example: A 5.5 MHz sound carrier frequency will be
generated by sending the following sequence of data
bytes to the TDA9874A (data = 7509333 in decimal
notation or 729555 in hexadecimal notation):
01110010 10010101 01010101.
The default setting after power-on reset is ‘0000 0000’ for
all three bytes.
data = 24-bit frequency control word
f
f
2
mix
clk
24
B3
B3
B3
3
3
3
= 12.288 MHz (clock frequency of mixer)
= 16777216 (number of steps in a 24-bit word size).
= desired sound carrier frequency
B2
B2
B2
2
2
2
Preliminary specification
B1
B1
B1
1
1
1
TDA9874A
B0
B0
B0
0
0
0