adv7171a-dbrd Analog Devices, Inc., adv7171a-dbrd Datasheet - Page 39

• Manufacturer Part Number: adv7171a-dbrd
• Description: Digital Pal/ntsc Video Encoder With 10-bit Ssaf ?nd Advanced Power Management
• Manufacturer: Analog Devices, Inc.

The circuit in Figure 55 can be used to generate a 13.5 MHz waveform using the 27 MHz clock and the HSYNC pulse. This waveform is
guaranteed to produce the 13.5 MHz clock in synchronization with the 27 MHz clock. This 13.5 MHz clock can be used if a 13.5 MHz
clock is required by the MPEG decoder. This guarantees that the Cr and Cb pixel information is input to the ADV7170/ADV7171 in the
correct sequence.
RESET
TELETEXT PULL-UP AND
PULL-DOWN RESISTORS
SHOULD ONLY BE USED
IF THESE PINS ARE NOT
CONNECTED
TTX
TTXREQ
5V (V
5V (V
AA
CC
4kΩ
100kΩ
100kΩ
100nF
)
)
(SAME CLOCK AS USED BY
MPEG2 DECODER)
27MHz CLOCK
CLOCK
HSYNC
SHOULD BE
GROUNDED
5V (V
UNUSED
INPUTS
AA
0.1µF
)
5V (V
5V (V
2–9, 12–14
AA
AA
10kΩ
38–42,
0.1µF
)
)
D
CK
25
33
35
15
16
17
22
37
36
44
Figure 54. Recommended Analog Circuit Layout
COMP
V
P15–P0
SCRESET/RTC
HSYNC
FIELD/VSYNC
BLANK
RESET
TTX
TTXREQ
CLOCK
REF
Q
Figure 55. Circuit to Generate 13.5 MHz
ALSB
18
ADV7170/
ADV7171
Rev. B | Page 39 of 64
V
POWER SUPPLY DECOUPLING
FOR EACH POWER SUPPLY GROUP
AA
1, 11, 20, 28, 30
GND
SCLOCK
10, 19, 21,
29, 43
SDATA
DAC D
DAC C
DAC B
DAC A
R
0.1µF
SET
27
26
31
32
23
24
34
0.01µF
75Ω
75Ω
75Ω
75Ω
150Ω
D
CK
100Ω
100Ω
5V (V
Q
5V (V
AA
10µF
)
CC
5kΩ
)
(FERRITE BEAD)
13.5MHz
5V (V
S-VIDEO
L1
CC
ADV7170/ADV7171
5kΩ
)
MPU BUS
33µF
5V
V
GND
CC