GS4911B_09 Datasheet, PDF (89/119 Pages) Gennum Corporation – HD/SD/Graphics Clock and Timing Generator with GENLOCK

Table 3-13: Configuration and Status Registers (Continued)
Register Name
D_v
Constcf_Genlock
RSVD
Address
23h-22h
24h
24h
24h
25h
Bit
31-0
15-8
7-3
2-0
–
Description
R/W
A non-zero number programmed in this register
R/W
defines the denominator for the ratio of the video
clock to the 27MHz reference.
This register can be used for creating custom video
clock frequencies.
NOTE: Once this register is programmed, it must be
updated using bit 6 of register 16h.
The default value of this register will vary
depending on the output video standard selected.
Address 22h = bits 15-0
Address 23h = bits 31-16
Reference: Section 3.9.1 on page 72
Crash_Time - controls the crash lock period of video R/W
PLL locking process. This time contributes to the
total PLL Lock Time given in the AC Characteristics
Table.
The time of the crash process in H reference periods
is determined by [Crash_Time x 4] + 1.
The default value of these bits will vary depending
on the output video standard selected.
Reference: Section 3.6.3 on page 58
Lock_Lost_Threshold - controls the threshold of the R/W
lock indication circuit. A larger value programmed
in this register can increase the stability of the
LOCK_LOST output signal when the input H
reference signal is subject to large amounts of low
frequency jitter. A larger value in this register will
also increase the lock indication time, although not
the actual lock time of the device.
The default value of these bits will vary depending
on the output video standard selected.
Run_Window - controls the output frequency error R/W
in the case of a missing or mis-timed H reference
transition. The default value of this register allows
the device to maintain genlock through one missing
input H pulse.
This feature can be disabled by programming
Run_Window = 000b. In this case, the device will
immediately react to any disturbance of the input H
signal.
The default value of these bits will vary depending
on the output video standard selected.
Reference: Section 3.5.3 on page 47
Reserved.
–
Default
–
–
–
–
–
GS4911B/GS4910B HD/SD/Graphics Clock and Timing
Generator with GENLOCK
Data Sheet
36655 - 5
June 2009
89 of 119