视频分离器LM1881资料[图]

demon · 发表于 2007-7-5 20:34:58

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><IMG src="http://www.intelligentcar.cn/up/l1881.jpg">TL H 9150 LM1881VideoSyncSeparator February 1995 LM1881 Video Sync Separator General Description The LM1881 Video sync separator extracts timing informa- tion including composite and vertical sync burst back porch timing and odd even field information from standard nega- tive going sync NTSC PAL and SECAM video signals with amplitude from 0 5V to 2V p-p The integrated circuit is also capable of providing sync separation for non-standard fast- er horizontal rate video signals The vertical output is pro- duced on the rising edge of the first serration in the vertical sync period A default vertical output is produced after a time delay if the rising edge mentioned above does not oc- cur within the externally set delay period such as might be the case for a non-standard video signal F eatures Y AC coupled composite input signal Y l10 kX input resistance Y k10 mA power supply drain current Y Composite sync and vertical outputs Y Odd even field output Y Burst gate back porch output Y Horizontal scan rates to 150 kHz Y Edge triggered vertical output Y Default triggered vertical output for non-standard video signal (video games-home computers) Connection Diagram LM1881N TL H 9150–1 Order Number LM1881M or LM1881N See NS Package Number M08A or N08E PAL in this datasheet refers to European broadcast TV standard ""Phase Alternating Line"" and not to Programmable Array LogicC 1995 National Semiconductor Corporation RRD-B30M115 Printed in U S A Absolute Maximum Ratings If Military Aerospace specified devices are requiredp lease contact the National Semiconductor Sales Office Distributors for availability and specificationsS upply Voltage 13 2V Input Voltage 3 Vpp (VCC e 5V) 6 Vpp (VCC t 8V) Output Sink Currents Pins 1 3 5 5 mA Output Sink Current Pin 7 2 mA Package Dissipation (Note 1) 1100 mW Operating Temperature Range 0 C b 70 C Storage Temperature Range b65 C to a150 C ESD Susceptibility (Note 2) 2 kV Soldering Information Dual-In-Line Package (10 sec ) 260 C Small Outline Package Vapor Phase (60 sec ) 215 C Infrared (15 sec ) 220 C See AN-450 ""Surface Mounting Methods and their Effect on Product Reliability"" for other methods of soldering surface mount devicesE lectrical Characteristics VCC e 5V Rset e 680 kX TA e 25 C Unless otherwise specified Parameter Conditions Typ Tested Design Units Limit (Note 3) Limit (Note 4) (Limits) Supply Current Outputs at Logic 1 VCC e 5V 5 2 10 mAmax VCC e 12V 5 5 12 mAmax DC Input Voltage Pin 2 1 5 1 3 Vmin 1 8 Vmax Input Threshold Voltage Note 5 70 55 mVmin 85 mVmax Input Discharge Current Pin 2 VIN e 2V 11 6 mAmin 16 mAmax Input Clamp Charge Current Pin 2 VIN e 1V 0 8 0 2 mAmin RSET Pin Reference Voltage Pin 6 Note 6 1 22 1 10 Vmin 1 35 Vmax Composite Sync Vertical IOUT e 40 mA VCC e 5V 4 5 4 0 Vmin Outputs Logic 1 VCC e 12V 11 0 Vmin IOUT e 1 6 mA VCC e 5V 3 6 2 4 Vmin Logic 1 VCC e 12V 10 0 Vmin Burst Gate Odd Even IOUT e 40 mA VCC e 5V 4 5 4 0 Vmin Outputs Logic 1 VCC e 12V 11 0 Vmin Composite Sync Output IOUT e b1 6 mA Logic 0 Pin 1 0 2 0 8 Vmax Vertical Sync Output IOUT e b1 6 mA Logic 0 Pin 3 0 2 0 8 Vmax Burst Gate Output IOUT e b1 6 mA Logic 0 Pin 5 0 2 0 8 Vmax Odd Even Output IOUT e b1 6 mA Logic 0 Pin 7 0 2 0 8 Vmax Vertical Sync Width 230 190 msmin 300 msmax Burst Gate Width 2 7 kX from Pin 5 to VCC 4 2 5 msmin 4 7 msmax Vertical Default Time Note 7 65 32 msmin 90 msmax Note 1 For operation in ambient temperatures above 25 C the device must be derated based on a 150 C maximum junction temperature and a package thermal resistance of 110 C W junction to ambientN ote 2 ESD susceptibility test uses the ""human body model 100 pF discharged through a 1 5 kX resistor""N ote 3 Typicals are at TJ e 25 C and represent the most likely parametric normN ote 4 Tested Limits are guaranteed to National"s AOQL (Average Outgoing Quality Level)N ote 5 Relative difference between the input clamp voltage and the minimum input voltage which produces a horizontal output pulseN ote 6 Careful attention should be made to prevent parasitic capacitance coupling from any output pin (Pins 1 3 5 and 7) to the RSET pin (Pin 6)N ote 7 Delay time between the start of vertical sync (at input) and the vertical output pulse2 Typical Performance Characteristics Pulse Separation vs Vertical Serration Rset Value Selection vs Rset Sync Delay Time Vertical Default Gate Time vs Rset Burst Black Level Width vs Rset Vertical Pulse Width vs Temperature Vertical Pulse Supply Voltage Supply Current vs TL H 9150–2 3 Application Notes The LM1881 is designed to strip the synchronization signals from composite video sources that are in or similar to the N T S C format Input signals with positive polarity video (in- creasing signal voltage signifies increasing scene bright- ness) from 0 5V (p-p) to 2V (p-p) can be accommodatedT he LM1881 operates from a single supply voltage between 5V DC and 12V DC The only required external components beside power supply and set current decoupling are the in- put coupling capacitor and a single resistor that sets internal current levels allowing the LM1881 to be adjusted for source signals with line scan frequencies differing from 15 734 kHz Four major sync signals are available from the I C composite sync including both horizontal and vertical scan timing information a vertical sync pulse a burst gate or back porch clamp pulse and an odd even output The odd even output level identifies which video field of an inter- laced video source is present at the input The outputs from the LM1881 can be used to gen-lock video camera VTR signals with graphics sources provide identification of video fields for memory storage recover suppressed or contami- nated sync signals and provide timing references for the extraction of coded or uncoded data on specific video scan linesT o better understand the LM1881 timing information and the type of signals that are used refer to Figure 2(a–e) which shows a portion of the composite video signal from the end of one field through the beginning of the next fieldC OMPOSITE SYNC OUTPUT The composite sync output Figure 2(b) is simply a repro- duction of the signal waveform below the composite video black level with the video completely removed This is ob- tained by clamping the video signal sync tips to 1 5V DC at Pin 2 and using a comparator threshold set just above this voltage to strip the sync signal which is then buffered out to Pin 1 The threshold separation from the clamped sync tip is nominally 70 mV which means that for the minimum input level of 0 5V (p-p) the clipping level is close to the halfway point on the sync pulse amplitude (shown by the dashed line on Figure 2(a) ) This threshold separation is indepen- dent of the signal amplitude therefore for a 2V (p-p) input the clipping level occurs at 11% of the sync pulse ampli- tude The charging current for the input coupling capacitor is 0 8 mA whereas the discharge current is only 11 mA typi- cally This allows relatively small capacitor values to be used 0 1 mF is generally recommendedN ormally the signal source for the LM1881 is assumed to be clean and relatively noise-free but some sources may have excessive video peaking causing high frequency video and chroma components to extend below the black level refer- ence Some video discs keep the chroma burst pulse pres- ent throughout the vertical blanking period so that the burst actually appears on the sync tips for three line periods in- stead of at black level A clean composite sync signal can be generated from these sources by filtering the input sig- nal When the source impedance is low typically 75X a 620X resistor in series with the source and a 510 pF capaci- tor to ground will form a low pass filter with a corner fre- quency of 500 kHz This bandwidth is more than sufficient to pass the sync pulse portion of the waveform however any subcarrier content in the signal will be attenuated by almost 18 dB effectively taking it below the comparator thresholdF iltering will also help if the source is contaminated with thermal noise The output waveforms will become delayed from between 40 ns to as much as 200 ns due to this filterT his much delay will not usually be significant but it does contribute to the sync delay produced by any additional sig- nal processing Since the original video may also undergo processing the need for time delay correction will depend on the total system not just the sync stripperV ERTICAL SYNC OUTPUT A vertical sync output is derived by internally integrating the composite sync waveform (Figure 3) To understand the generation of the vertical sync pulse refer to the lower left hand section Figure 3 Note that there are two comparators in the section One comparator has an internally generated voltage reference called V1 going to one of its inputs The other comparator has an internally generated voltage refer- ance called V2 going to one of its inputs Both comparators have a common input at their noninverting input coming from the internal integrator The internal integrator is used for integrating the composite sync signal This signal comes from the input side of the composite sync buffer and are positive going sync pulses The capacitor to the integrator is internal to the LM1881 The capacitor charge current is set by the value of the external resistor Rset The output of the integrator is going to be at a low voltage during the normal horizontal lines because the integrator has a very short time to charge the capacitor which is during the hori- zontal sync period The equalization pulses will keep the output voltage of the integrator at about the same levelb elow the V1 During the vertical sync period the narrow going positive pulses shown in Figure 2 is called the serra- tion pulse The wide negative portion of the vertical sync

闫红宇 · 发表于 2007-8-23 04:06:02

能把CCD ,LM1881和单片机的连接电路贴出来啊?

demon · 发表于 2007-8-24 05:21:13

<

><IMG src="http://www.intelligentcar.cn/up/l1881.jpg">其中的摄像头供电电压以你的为准<A target=_blank href="http://www.freescalecar.cn/up/l1881.jpg" target=_blank></A>

demon · 发表于 2007-8-24 05:22:19

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>也有别的接法这个只供参考

随风飘帆 · 发表于 2007-10-5 19:27:03

<A target=_blank href="http://www1.demonstudio.cn/ShowPost.asp?ThreadID=35">视频分离器LM1881</A>，懂了。

0500320321 · 发表于 2007-12-11 03:54:37

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>资料全是英文的??有中文的吗?

liantianfeixue · 发表于 2009-2-10 23:17:00

虽然是英文还是谢了

飞思卡尔123 · 发表于 2009-11-3 20:41:46

有中文的吗

Neozoic · 发表于 2013-3-22 18:23:26

为什么是一大屏的代码啊

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