TDA8722 Datasheet, PDF (7/28 Pages) NXP Semiconductors – I2C-bus programmable modulator for negative video modulation and FM sound

Philips Semiconductors
I²C-bus programmable modulator for
negative video modulation and FM sound
Product specification
TDA8722
Table 1 Data format; notes 1 and 2
BYTE
Address byte C8
Data byte 1
Data byte 2
BIT 7
MSB
1
0
1
BIT 6
1
b11
T0⁽³⁾
BIT 5
0
b10
T1⁽³⁾
BIT 4
0
b9
T2⁽³⁾
BIT 3
1
b8
P0⁽⁴⁾
BIT 2
0
b7
b4
BIT 1
0
b6
b3
BIT 0
LSB
0
b5
b2
ACKNOWLEDGE BIT
ACK
ACK
ACK
Notes
1. The 10 programmable bits of N are: b2 to b11.
2. Internal hardware sets: b1 = 0 and b0 = 1.
3. T0, T1 and T2 are bits used for test purposes (see Table 5).
4. P0 is a bit used for controlling the state of the output Port (see Table 6).
Table 2 Structure of the dividing number N
RESULT
BITS⁽¹⁾
b11 b10 b9
b8
b7
b6
b5
b4
b3
b2 b1⁽²⁾ b0⁽²⁾
Frequency (MHz)⁽³⁾ 512 256 128 64 32 16
8
4
2
1 0.5 0.25
Notes
1. Bits b2 to b11 are programmable and represent the integer part of the frequency in MHz. Bits b1 and b0 are fixed
internally to b1 = 0 and b0 = 1 to get the added 0.25 MHz, common for most TV channels.
2. Bits b1 and b0 are not programmable.
3. f_osc = 512b11 + 256b10 + 128b9 + 64b8 + 32b7 + 16b6 + 8b5 + 4b4 + 2b3 + b2 + 0.25 (MHz).
Table 3 Dividing number N for programming channel 21 (471.25 MHz)
RESULT
BITS
b11 b10 b9
b8
b7
b6
b5
b4
b3
b2 b1⁽¹⁾ b0⁽¹⁾
Value
0
1
1
1
0
1
0
1
1
1
0
1
Frequency (MHz)⁽²⁾ 0
256 128 64
0
16
0
4
2
1
0 0.25
Notes
1. Bits b1 and b0 are not programmable.
2. f_osc = 0 + 256 + 128 + 64 + 0 + 16 + 0 + 4 + 2 + 1 + 0.25 (MHz) = 471.25 MHz.
Table 4 Content of the data bytes to program channel 21 (471.25 MHz)
BYTE
Address byte C8
Data byte 1
Data byte 2
BIT 7
MSB
1
0
1
BIT 6
1
0
0
BIT 5
0
1
0
BIT 4
0
1
0
BIT 3
1
1
0
BIT 2
0
0
1
BIT 1
0
1
1
BIT 0
LSB
0
0
1
ACKNOWLEDGE BIT
ACK
ACK
ACK
It is possible to change only one data byte. The circuit will recognize which one is received with the value of MSB
(0 for data byte 1 and 1 for data byte 2). It is possible to change the frequency by 1 MHz with data byte 2. It is easy to
increment the channel frequency when its frequency width is 8 MHz by simply incrementing data byte 1.
1998 Jun 23
7