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參數(shù)資料
| 型號(hào)： | AD9981 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | High Performance 10-Bit Display Interface |
| 中文描述： | 高性能10位顯示接口 |
| 文件頁數(shù)： | 17/44頁 |
| 文件大小： | 506K |
| 代理商： | AD9981 |
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AD9981
Rev. 0 | Page 17 of 44
0
SOG INPUT
SOGOUT OUTPUT
CONNECTED TO
HSYNCIN
NEGATIVE PULSE WIDTH = 40 SAMPLE CLOCKS
COMPOSITE
SYNC
AT HSYNCIN
VSYNCOUT
FROM SYNC
SEPARATOR
–300mV
–300mV
0mV
700mV MAXIMUM
Figure 9. Sync Slicer and Sync Separator Output
Sync Separator
As part of sync processing, the sync separator’s task is to extract
Vsync from the composite sync signal. It works on the idea that
the Vsync signal stays active for a much longer time than the
Hsync signal. By using a digital low-pass filter and a digital
comparator, it rejects pulses with small durations (such as
Hsyncs and equalization pulses) and only passes pulses with
large durations, such as Vsync (see Figure 9).
The threshold of the digital comparator is programmable for
maximum flexibility. To program the threshold duration, write a
value (N) to Register 0x11. The resulting pulse width is N ×
200 ns. So, if N = 5 the digital comparator threshold is 1 μs. Any
pulse less than 1 μs is rejected, while any pulse greater than 1 μs
passes through.
There are two things to keep in mind when using the sync
separator. First, the resulting clean Vsync output is delayed from
the original Vsync by a duration equal to the digital comparator
threshold (N × 200 ns). Second, there is some variability to the
200 ns multiplier value. The maximum variability over all
operating conditions is ±20% (160 ns to 240 ns). Since normal
Vsync and Hsync pulse widths differ by a factor of about 500 or
more, the 20% variability is not an issue.
Hsync Filter and Regenerator
The Hsync filter is used to eliminate any extraneous pulses from
the Hsync or SOGIN inputs, outputting a clean, low-jitter signal
that is appropriate for mode detection and clock generation.
The Hsync regenerator is used to recreate a clean, although not
low jitter, Hsync signal that can be used for mode detection and
counting Hsyncs per Vsync. The Hsync regenerator has a high
degree of tolerance to extraneous and missing pulses on the
Hsync input, but is not appropriate for use by the PLL in
creating the pixel clock due to jitter.
The Hsync regenerator runs automatically and requires no
setup to operate. The Hsync filter requires the setting up of a
filter window. The filter window sets a periodic window of time
around the regenerated Hsync leading edge where valid Hsyncs
are allowed to occur. The general idea is that extraneous pulses
on the sync input occur outside of this filter window and thus
are filtered out. In order to set the filter window timing, pro-
gram a value (
x
) into Register 0x23. The resulting filter window
time is ±
x
times 25 ns around the regenerated Hsync leading
edge. Just as for the sync separator threshold multiplier, allow a
±20% variance in the 25 ns multiplier to account for all oper-
ating conditions (20 ns to 30 ns range).
A second output from the Hsync filter is a status bit (0x25,
Bit 1) that tells whether extraneous pulses were present on the
incoming sync signal or not. Many times extraneous pulses are
included for copy protection purposes, so this status bit can be
used to detect that.
The filtered Hsync (rather than the raw Hsync/SOGIN signal)
for pixel clock generation by the PLL is controlled by
Register 0x20, Bit 2. The regenerated Hsync (rather than
the raw Hsync/ SOGIN signal) for the sync processing is
controlled by Register 0x20, Bit 1. Use of the filtered Hsync
and regenerated Hsync is recommended. See Figure 10 for an
illustration of a filtered Hsync.
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PDF描述 |
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| AD9981KSTZ-80 | High Performance 10-Bit Display Interface |
| AD9981KSTZ-95 | High Performance 10-Bit Display Interface |
| AD9983AKSTZ-140 | High Performance 8-Bit Display Interface |
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD9981/PCB | 制造商:AD 制造商全稱:Analog Devices 功能描述:High Performance 10-Bit Display Interface |
| AD9981/PCBZ | 制造商:Analog Devices 功能描述:Evaluation Board For The High Performance 10-Bit Display Interface 制造商:Analog Devices 功能描述:EVAL BD FOR THE HI-PERF 10-BIT DISPLAY INTRFC - Bulk |
| AD9981KST-80 | 制造商:Analog Devices 功能描述:HIGH PERFORMANCE 10-BIT DISPLAY INTERFACE - Bulk |
| AD9981KSTZ-80 | 功能描述:IC INTERFACE 10BIT ANALOG 80LQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 專用 系列:- 特色產(chǎn)品:NXP - I2C Interface 標(biāo)準(zhǔn)包裝:1 系列:- 應(yīng)用:2 通道 I²C 多路復(fù)用器 接口:I²C，SM 總線 電源電壓:2.3 V ~ 5.5 V 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:剪切帶 (CT) 安裝類型:表面貼裝 產(chǎn)品目錄頁面:825 (CN2011-ZH PDF) 其它名稱:568-1854-1 |
| AD9981KSTZ-95 | 功能描述:IC INTERFACE 10BIT ANALOG 80LQFP RoHS:是 類別:集成電路 (IC) >> 接口 - 專用 系列:- 特色產(chǎn)品:NXP - I2C Interface 標(biāo)準(zhǔn)包裝:1 系列:- 應(yīng)用:2 通道 I²C 多路復(fù)用器 接口:I²C，SM 總線 電源電壓:2.3 V ~ 5.5 V 封裝/外殼:16-TSSOP（0.173"，4.40mm 寬） 供應(yīng)商設(shè)備封裝:16-TSSOP 包裝:剪切帶 (CT) 安裝類型:表面貼裝 產(chǎn)品目錄頁面:825 (CN2011-ZH PDF) 其它名稱:568-1854-1 |
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