ML6430 datasheet(13/33 Pages) MICRO-LINEAR

13 / 33 page

ML6430/ML6431

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.

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

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.

FUNCTIONAL DESCRIPTION (Continued)

Figure 4a. ML6431 Freerun Mode State Diagram

INPUT VIDEO

WITHIN ±6%

RANGE

POWER UP

ML6431 W/

FREERUN PIN

"LOW" (TYPICAL)

POWER UP

ML6431 W/

FREERUN PIN

"HIGH" (TYPICAL)

IF NO VIDEO

FOR > 1 FRAME

TOGGLE

FREERUN PIN

"HIGH"

TOGGLE

FREERUN PIN

"HIGH"

TOGGLE

FREERUN PIN

"HIGH"

IF INPUT VIDEO

FOR > 1 FRAME

FREERUN PIN

"LOW"

IF NO VIDEO

FOR > 1 FRAME

FREERUN PIN

"LOW"

IF INPUT VIDEO

FOR > 1 FRAME

TOGGLE

FREERUN PIN

"HIGH"

INPUT VIDEO

OUTSIDE ±6%

RANGE

IF NO VIDEO

FOR > 2 FRAMES

HORIZONTAL

LOCKED

NO SIGNAL

PRESENT

FREERUN

MODE #1

HORIZONTAL

LOCKED

SIGNAL

PRESENT

HORIZONTAL

UNLOCKED

NO SIGNAL

PRESENT

FREERUN

MODE #2

HORIZONTAL

UNLOCKED

SIGNAL

PRESENT

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