ML6430/ML6431
FUNCTIONAL DESCRIPTION
(Continued)
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
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
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.
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.
TOGGLE
FREERUN PIN
"HIGH"
IF NO VIDEO
FOR > 1 FRAME
HORIZONTAL
LOCKED
POWER UP
ML6431 W/
FREERUN PIN
"LOW" (TYPICAL)
SIGNAL
PRESENT
2
HORIZONTAL
LOCKED
NO SIGNAL
PRESENT
IF INPUT VIDEO
FOR > 1 FRAME
3
TOGGLE
FREERUN PIN
"HIGH"
FREERUN PIN
"LOW"
FREERUN
MODE #1
5
INPUT VIDEO
WITHIN ±6%
RANGE
INPUT VIDEO
OUTSIDE ±6%
RANGE
IF NO VIDEO
FOR > 2 FRAMES
IF NO VIDEO
FOR > 1 FRAME
HORIZONTAL
UNLOCKED
SIGNAL
PRESENT
1
IF INPUT VIDEO
FOR > 1 FRAME
TOGGLE
FREERUN PIN
"HIGH"
HORIZONTAL
UNLOCKED
NO SIGNAL
PRESENT
4
FREERUN PIN
"LOW"
TOGGLE
FREERUN PIN
"HIGH"
FREERUN
MODE #2
6
POWER UP
ML6431 W/
FREERUN PIN
"HIGH" (TYPICAL)
Figure 4a. ML6431 Freerun Mode State Diagram
13
MICRO-LINEAR [ MICRO LINEAR CORPORATION ]
