AD9980PCB datasheet(17/44 Pages) AD

номер детали	AD9980PCB

подробное описание детали	High Performance 8-Bit Display Interface

PDF	44 Pages

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производитель	AD [Analog Devices]

домашняя страница	http://www.analog.com

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17 / 44 page

AD9980

Rev. 0 | Page 17 of 44

HSYNCOUT

VSYNC

FILTER

WINDOW

EXPECTED

EDGE

FILTER

WINDOW

EQUALIZATION

PULSES

HSYNCIN

Figure 10. Sync Processing Filter

Vsync Filter and Odd/Even Fields

The Vsync filter is used to eliminate spurious Vsyncs, maintain

a stable timing relationship between the Vsync and Hsync

output signals, and generate the odd/even field output.

The filter works by examining the placement of Vsync with

respect to Hsync, and if necessary, slightly shifting it in time.

The goal is to keep the Vsync and Hsync leading edges from

switching at the same time, eliminating confusion as to when

the first line of a frame occurs. Enable the Vsync filter with

all cases, including interlaced video, and is required when using

the Hsync per Vsync counter. Figure 12 illustrates even/odd

field determination in two situations.

FIELD 1

FIELD 0

SYNC SEPARATOR THRESHOLD

FIELD 1

FIELD 0

HSYNCIN

VSYNCIN

VSYNCOUT

O/E FIELD

ODD FIELD

QUADRANT

Figure 11.

AD9980PCB датащи(PDF) 17 Page - Analog Devices