1998 Jun 23

7

Philips Semiconductors

Product specification

negative video modulation and FM sound

TDA8722

Table 1

Data format; notes 1 and 2

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

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.

Table 3

Dividing number N for programming channel 21 (471.25 MHz)

Notes

1. Bits b1 and b0 are not programmable.

Table 4

Content of the data bytes to program channel 21 (471.25 MHz)

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.

BYTE

BIT 7

MSB

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

LSB

ACKNOWLEDGE BIT

Address byte C8

1

1

0

0

1

0

0

0

ACK

Data byte 1

0

b11

b10

b9

b8

b7

b6

b5

ACK

Data byte 2

1

b4

b3

b2

ACK

RESULT

b11

b10

b9

b8

b7

b6

b5

b4

b3

b2

512

256

128

64

32

16

8421

0.5

0.25

RESULT

BITS

b11

b10

b9

b8

b7

b6

b5

b4

b3

b2

Value

011101011101

0

256

128

64

0

16

04210

0.25

BYTE

BIT 7

MSB

BIT 6

BIT 5

BIT 4

BIT 3

BIT 2

BIT 1

BIT 0

LSB

ACKNOWLEDGE BIT

Address byte C8

1

1

0

0

1

0

0

0

ACK

Data byte 1

0

0

1

1

1

0

1

0

ACK

Data byte 2

1

0

0

0

0

1

1

1

ACK