ad725-eb Analog Devices, Inc., ad725-eb Datasheet - Page 10

• Manufacturer Part Number: ad725-eb
• Description: Low Cost Rgb To Ntsc/pal Encoder With Luma Trap Port
• Manufacturer: Analog Devices, Inc.

AD725
Symbol
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NOTES
1
2
Input clock = 14.318180 MHz, STND pin = logic high.
Input cock = 17.734475 MHz, STND pin = logic low.
SW
SB
SM
MW
SR
RW
SD
DW
SS
BY
SC
BC
Name
Sync Width
Sync to Blanking
End
Sync to Modulator
Restore
Modulator Restore
Width
Sync to RGB DC
Restore
DC Restore Width
Sync to Delay Line
Reset
Delay Line Reset
Width
Sync Input to Luma
Sync Output
Blanking End to
LUMA Start
Sync to Colorburst
Blanking End to
CRMA Start
DELAY LINE RESET
(USER INPUTS)
(USER INPUTS)
HSYNC/VSYNC
BURST FLAG/
MODULATOR
RIN/GIN BIN
RESTORE
CLAMPS
INPUT
CRMA
LUMA
Description
Input valid sync width for burst
insertion (user-controlled).
Minimum sync to color delay
(user-controlled).
Delay to modulator clamp start.
Length of modulator offset clamp
(no chroma during this period).
Delay to input clamping start.
Length of input clamp (no RGB
response during this period).
Delay to start of delay line
clock reset.
Length of delay line clock reset
(no luma response during this
period), also burst gate.
Delay from sync input assertion
to sync in LUMA output.
Delay from RGB input assertion
to LUMA output response.
Delay from valid horizontal sync
start to CRMA colorburst output.
Delay from RGB input assertion
to CRMA output response.
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Table I. Timing Description (See Figure 18)
t
SM
SS
Figure 18. Timing Diagram (Not to Scale)
SW
t
MW
t
t
SR
SD
t
SC
t
SB
t
t
DW
RW
–10–
Min
Max
Min
typ
typ
typ
typ
t
BC
NTSC
t
BY
1
2.8 s
5.3 s
8.2 s
392 ns
140 ns
5.4 s
2.5 s
5.7 s
2.5 s
310 ns
340 ns
5.8 s
360 ns
typ
typ
Min
Max
Min
typ
typ
PAL
2
REV. 0
3.3 s
5.4 s
8.1 s
298 ns
113 ns
5.6 s
2.3 s
5.8 s
2.3 s
265 ns
280 ns
5.9 s
300 ns