ML6431CH MICRO-LINEAR [Micro Linear Corporation], ML6431CH Datasheet - Page 13

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

FUNCTIONAL DESCRIPTION
VGA CLOCKS
For VGA applications the ML6431 is recommended.
Table 6 provides a list of the VGA clocks that can be
generated using the ML6431. To use the information in
Locked (ML6431): The ML6431 must be line
(horizontal) locked to an input video source for at
least two fields and also be vertically locked before
the locked detect signal goes high. When a video
source is removed, the ML6431 will lose horizontal
lock after two entire fields with no video present.
However, vertical lock may be lost before horizontal
lock. Because the locked pin is the logical AND of
the internal horizontal locked and vertical locked
signals the locked pin may go low before the internal
horizontal locked signal.
"LOW" (TYPICAL)
FREERUN PIN
ML6431 W/
POWER UP
INPUT VIDEO
WITHIN ±6%
RANGE
HORIZONTAL
HORIZONTAL
UNLOCKED
PRESENT
PRESENT
LOCKED
SIGNAL
SIGNAL
2
1
Figure 4a. ML6431 Freerun Mode State Diagram
OUTSIDE ±6%
INPUT VIDEO
FOR > 1 FRAME
FOR > 1 FRAME
IF INPUT VIDEO
IF INPUT VIDEO
FOR > 1 FRAME
RANGE
IF NO VIDEO
FOR > 1 FRAME
IF NO VIDEO
(Continued)
FREERUN PIN
FREERUN PIN
TOGGLE
TOGGLE
"HIGH"
"HIGH"
HORIZONTAL
HORIZONTAL
UNLOCKED
NO SIGNAL
NO SIGNAL
PRESENT
PRESENT
LOCKED
4
3
Table 6 first find the resolution and refresh rate required.
Determine which crystal, PAL or NTSC is needed. Change
the crystal to the proper frequency if necessary. Over the
serial-bus, program the registers as indicated in Table 6.
Supply to pin 6 an horizontal sync signal at TTL or CMOS
levels and at the specified frequency. Trigger an
oscilloscope on the falling edge of the horizontal input to
view the outputs. The VGA pixel clock will be found on
pin 18. Other useful signals are noted in table 6. External
logic may be needed to produce usable vertical sync
pulses.
AUDIO CLOCKS
The audio modes can be activated via serial bus (Register
7). When this mode is activated an audio clock
frequency can be selected via serial bus (Register 8). See
Table 9.
FOR > 2 FRAMES
IF NO VIDEO
FREERUN PIN
FREERUN PIN
FREERUN PIN
FREERUN PIN
TOGGLE
TOGGLE
"HIGH"
"HIGH"
"LOW"
"LOW"
ML6430/ML6431
MODE #1
MODE #2
FREERUN
FREERUN
5
6
"HIGH" (TYPICAL)
FREERUN PIN
ML6431 W/
POWER UP
13