công cụ tìm kiếm bảng dữ liệu linh kiện điện tử
  Vietnamese  ▼
ALLDATASHEET.VN

X  

LM1881 bảng dữ liệu(PDF) 7 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor. Click here to check the latest version.
tên linh kiện LM1881
Giải thích chi tiết về linh kiện  Video Sync Separator
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
nhà sản xuất  NSC [National Semiconductor (TI)]
Trang chủ  http://www.national.com
Logo NSC - National Semiconductor (TI)

LM1881 bảng dữ liệu(HTML) 7 Page - National Semiconductor (TI)

Back Button LM1881 Datasheet HTML 3Page - National Semiconductor (TI) LM1881 Datasheet HTML 4Page - National Semiconductor (TI) LM1881 Datasheet HTML 5Page - National Semiconductor (TI) LM1881 Datasheet HTML 6Page - National Semiconductor (TI) LM1881 Datasheet HTML 7Page - National Semiconductor (TI) LM1881 Datasheet HTML 8Page - National Semiconductor (TI) LM1881 Datasheet HTML 9Page - National Semiconductor (TI) LM1881 Datasheet HTML 10Page - National Semiconductor (TI) LM1881 Datasheet HTML 11Page - National Semiconductor (TI) Next Button
Zoom Inzoom in Zoom Outzoom out
 7 / 12 page
background image
Application Notes (Continued)
ODD/EVEN FIELD PULSE
An unusual feature of LM1881 is an output level from Pin 7
that identifies the video field present at the input to the
LM1881. This can be useful in frame memory storage appli-
cations or in extracting test signals that occur in alternate
fields. For a composite video signal that is interlaced, one of
the two fields that make up each video frame or picture must
have a half horizontal scan line period at the end of the
vertical scan — i.e., at the bottom of the picture. This is called
the “odd field” or “even field”. The “even field” or “field 2” has
a complete horizontal scan line at the end of the field. An odd
field starts on the leading edge of the first equalizing pulse,
whereas the even field starts on the leading edge of the
second equalizing pulse of the vertical retrace interval. Fig-
ure 1(a) shows the end of the even field and the start of the
odd field.
To detect the odd/even fields the LM1881 again integrates
the composite sync waveform (Figure 2). A capacitor is
charged during the period between sync pulses and dis-
charged when the sync pulse is present. The period between
normal horizontal sync pulses is enough to allow the capaci-
tor voltage to reach a threshold level of a comparator that
clears a flip-flop which is also being clocked by the sync
waveform. When the vertical interval is reached, the shorter
integration time between equalizing pulses prevents this
threshold from being reached and the Q output of the flip-flop
is toggled with each equalizing pulse. Since the half line
period at the end of the odd field will have the same effect as
an equalizing pulse period, the Q output will have a different
polarity on successive fields. Thus by comparing the Q
polarity with the vertical output pulse, an odd/even field index
is generated. Pin 7 remains low during the even field and
high during the odd field.
BURST/BACKPORCH OUTPUT PULSE
In a composite video signal, the chroma burst is located on
the backporch of the horizontal blanking period. This period,
approximately 4.8 µs long, is also the black level reference
for the subsequent video scan line. The LM1881 generates a
pulse at Pin 5 that can be used either to retrieve the chroma
burst from the composite video signal (thus providing a
subcarrier synchronizing signal) or as a clamp for the DC
restoration of the video waveform. This output is obtained
simply by charging an internal capacitor starting on the
trailing edge of the horizontal sync pulses. Simultaneously
the output of Pin 5 is pulled low and held until the capacitor
charge circuit times out — 4 µs later. A shorter output burst
gate pulse can be derived by differentiating the burst output
00915004
*Components Optional, See Text
FIGURE 2.
www.national.com
7


Số phần tương tự - LM1881

nhà sản xuấttên linh kiệnbảng dữ liệuGiải thích chi tiết về linh kiện
logo
National Semiconductor ...
LM1881 NSC-LM1881 Datasheet
303Kb / 12P
   LM1881 Video Sync Separator
logo
Texas Instruments
LM1881 TI-LM1881 Datasheet
1Mb / 18P
[Old version datasheet]   AC Coupled Composite input Signal
logo
National Semiconductor ...
LM1881-X NSC-LM1881-X Datasheet
303Kb / 12P
   LM1881 Video Sync Separator
LM1881M NSC-LM1881M Datasheet
303Kb / 12P
   LM1881 Video Sync Separator
logo
Texas Instruments
LM1881M TI1-LM1881M Datasheet
1Mb / 18P
[Old version datasheet]   Video Sync Separator
More results

Mô tả tương tự - LM1881

nhà sản xuấttên linh kiệnbảng dữ liệuGiải thích chi tiết về linh kiện
logo
Texas Instruments
LM1881MX TI1-LM1881MX Datasheet
1Mb / 18P
[Old version datasheet]   Video Sync Separator
logo
National Semiconductor ...
LM1881 NSC-LM1881 Datasheet
303Kb / 12P
   LM1881 Video Sync Separator
LMH1981 NSC-LMH1981_07 Datasheet
1Mb / 16P
   Multi-Format Video Sync Separator
LMH1981 NSC-LMH1981 Datasheet
679Kb / 13P
   Multi-Format Video Sync Separator
logo
Texas Instruments
LMH1981 TI1-LMH1981 Datasheet
1Mb / 24P
[Old version datasheet]   Multi-Format Video Sync Separator
logo
Intersil Corporation
ISL59450 INTERSIL-ISL59450 Datasheet
2Mb / 37P
   Multiformat Video Crosspoint with Integrated Sync Separator
logo
Renesas Technology Corp
ISL59450 RENESAS-ISL59450 Datasheet
2Mb / 37P
   Multiformat Video Crosspoint with Integrated Sync Separator
logo
Intersil Corporation
EL4511 INTERSIL-EL4511_10 Datasheet
645Kb / 24P
   Super Sync Separator
logo
National Semiconductor ...
LMH1980 NSC-LMH1980 Datasheet
746Kb / 14P
   Auto-Detecting SD/HD/PC Video Sync Separator
logo
Intersil Corporation
EL4511 INTERSIL-EL4511 Datasheet
453Kb / 24P
   Super Sync Separator
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12


bảng dữ liệu tải về

Go To PDF Page


Link URL




Chính sách bảo mật
ALLDATASHEET.VN
Cho đến nay ALLDATASHEET có giúp ích cho doanh nghiệp của bạn hay không?  [ DONATE ] 

Alldatasheet là   |   Quảng cáo   |   Liên lạc với chúng tôi   |   Chính sách bảo mật   |   Trao đổi link   |   Tìm kiếm theo nhà sản xuất
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com