ML6431CH MICRO-LINEAR [Micro Linear Corporation], ML6431CH Datasheet - Page 12

• Manufacturer Part Number: ML6431CH
• Description: Genlocking Sync Generator with Digital Audio Clock for NTSC, PAL & VGA
• Manufacturer: MICRO-LINEAR [Micro Linear Corporation]

ML6430/ML6431
FUNCTIONAL DESCRIPTION
FREERUN MODE
Both the ML6430 and ML6431 can be used in Freerun
mode. The ML6431 is recommended for applications
requiring a more robust Freerun mode of operations.
Figure 4 and Figure 4a describe the state diagrams for
both the ML6430 and ML6431. Note that the ML6431
includes a faster path to go from FREERUN MODE #1 to
FREERUN MODE #2.
12
Freerun mode: FREERUN MODE #1 is entered when
the freerun pin is toggled high while the ML6430/
ML6431 is horizontally locked (i.e. internal horizontal
locked signal is present). In this mode, the digital
frequency value stored in the line-locked PLL is held
and the ML6430/ML6431 will freerun at a frequency
very close to that of the last locked video source.
Freerun mode #1 is best used by physically tying the
NoSignal pin to the freerun pin as shown in Figures 9
or 10. FREERUN MODE #2 is entered when the
freerun pin is toggled high while the ML6430/Ml6431
"LOW" (TYPICAL)
FREERUN PIN
ML6430 W/
POWER UP
INPUT VIDEO
WITHIN ±6%
RANGE
HORIZONTAL
HORIZONTAL
UNLOCKED
PRESENT
PRESENT
LOCKED
SIGNAL
SIGNAL
2
1
OUTSIDE ±6%
INPUT VIDEO
Figure 4. ML6430 Freerun Mode State Diagram
FOR > 1 FRAME
FOR > 1 FRAME
IF INPUT VIDEO
FOR > 1 FRAME
IF INPUT VIDEO
IF NO VIDEO
RANGE
FOR > 1 FRAME
IF NO VIDEO
(Continued)
FREERUN PIN
FREERUN PIN
TOGGLE
TOGGLE
"HIGH"
"HIGH"
HORIZONTAL
HORIZONTAL
UNLOCKED
NO SIGNAL
NO SIGNAL
PRESENT
LOCKED
PRESENT
4
3
is not horizontally locked to a video source. In this
mode, a ROM lookup table is used to set the freerun
frequency of the ML6430/ML6431. In this mode the
output frequency is as accurate as the Crystal plus the
accuracy of the look up table. See Figures 4 and 4a
for the NoSignal-Locked-Freerun state machine
diagram.
NoSignal: NoSignal will go low if video is present for
one entire field. NoSignal will be high if video is not
present for one entire field.
Locked (ML6430): The ML6430 must be line
(horizontal) locked to an input video source and also
be vertically locked before the locked detect signal
goes high. When a video source is removed, the
locked signal may be high or low. Please note that the
locked pin is the logical AND of the internal
horizontal locked and vertical locked signals. For
example, the internal horizontal locked signal may be
high even though the locked pin is asserted low.
FREERUN PIN
FREERUN PIN
FREERUN PIN
FREERUN PIN
TOGGLE
TOGGLE
"HIGH"
"HIGH"
"LOW"
"LOW"
FREERUN
MODE #1
FREERUN
MODE #2
5
6
"HIGH" (TYPICAL)
FREERUN PIN
POWER UP
ML6430 W/