LM1881N-X

更新时间： 2024-01-06 09:28:34

品牌	Logo	应用领域
美国国家半导体 - NSC		/
页数	文件大小	规格书
12页	302K
描述
LM1881 Video Sync Separator

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中文翻译

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技术参数
数据手册

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LM1881N-X 技术参数

是否无铅：	不含铅	是否Rohs认证：	符合
生命周期：	Obsolete	零件包装代码：	DIP
包装说明：	DIP, DIP8,.3	针数：	8
Reach Compliance Code：	compliant	风险等级：	5.66
商用集成电路类型：	SYNC SEPARATOR IC	JESD-30 代码：	R-PDIP-T8
JESD-609代码：	e3	长度：	9.817 mm
湿度敏感等级：	1	功能数量：	1
端子数量：	8	最高工作温度：	70 °C
最低工作温度：		封装主体材料：	PLASTIC/EPOXY
封装代码：	DIP	封装等效代码：	DIP8,.3
封装形状：	RECTANGULAR	封装形式：	IN-LINE
峰值回流温度（摄氏度）：	260	电源：	5/12 V
认证状态：	Not Qualified	座面最大高度：	5.08 mm
子类别：	Other Consumer ICs	最大压摆率：	12 mA
最大供电电压 (Vsup)：	12 V	最小供电电压 (Vsup)：	5 V
表面贴装：	NO	技术：	BIPOLAR
温度等级：	COMMERCIAL	端子面层：	Matte Tin (Sn)
端子形式：	THROUGH-HOLE	端子节距：	2.54 mm
端子位置：	DUAL	处于峰值回流温度下的最长时间：	40
宽度：	7.62 mm	Base Number Matches：	1

LM1881N-X 数据手册

the vertical output pulse will extend beyond the end of the

input vertical sync period. In most systems the end of the

vertical sync period may be very accurate. In this case the

preferred design may be to start the vertical sync pulse at the

end of the vertical sync period, similar to starting the vertical

sync pulse after the first serration pulse. A VGA standard is

to be used as an example to show how this is done. In this

standard a horizontal line is 32 µs long. The vertical sync

period is two horizontal lines long, or 64 µs. The vertical

default sync delay time must be longer than the vertical

sync period of 64 µs. In this case R_SETmust be larger than

680 kΩ. R_SETmust still be small enough for the output of the

integrator to reach V₁before the end of the vertical period of

the input pulse. The first graph can be used to confirm that

R_SETis small enough for the integrator. Instead of using the

vertical serration pulse separation, use the actual pulse

width of the vertical sync period, or 64 µs in this example.

This graph is linear, meaning that a value as large as 2.7 MΩ

can be used for R_SET(twice the value as the maximum at

30 µs). Due to leakage currents it is advisable to keep the

value of R_SETunder 2.0 MΩ. In this example a value of 1.0

MΩ is selected, well above the minimum of 680 kΩ. With this

value for R_SETthe pulse width of the vertical sync output

pulse of the LM1881 is about 340 µs.

Application Notes (Continued)

flip-flop is toggled by the default comparator, starting the

vertical sync pulse at pin 3 of the LM1881. If the default

vertical sync period ends before the end of the input vertical

sync period, then the falling edge of the vertical sync (posi-

tive pulse at the “D” flip-flop) will clock the high output from

the comparator with V₁as a reference input. This will retrig-

ger the oscillator, generating a second vertical sync output

pulse. The “Vertical Default Sync Delay Time vs R_SET” graph

shows the relationship between the R_SETvalue and the

delay time from the start of the vertical sync period before

the default vertical sync pulse is generated. Using the NTSC

example again the smallest resistor for R_SETis 500 kΩ. The

vertical default time delay is about 50 µs, much longer than

the 30 µs serration pulse spacing.

A common question is how can one calculate the required

R_SETwith a video timing standard that has no serration

pulses during the vertical blanking. If the default vertical sync

is to be used this is a very easy task. Use the “Vertical

Default Sync Delay Time vs R_SET” graph to select the nec-

essary R_SETto give the desired delay time for the vertical

sync output signal. If a second pulse is undesirable, then

check the “Vertical Pulse Width vs R_SET” graph to make sure

00915003

FIGURE 1. (a) Composite Video; (b) Composite Sync; (c) Vertical Output Pulse;

(d) Odd/Even Field Index; (e) Burst Gate/Back Porch Clamp

www.national.com

1...3 4 567 8 9...12

中文翻译

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与LM1881N-X相关器件

型号	品牌	获取价格	描述	数据表
LM1881N-X/NOPB	TI	获取价格	SYNC SEPARATOR IC, PDIP8, PLASTIC, DIP-8
LM1881-X	NSC	获取价格	LM1881 Video Sync Separator
LM1882	NSC	获取价格	Programmable Video Sync Generator
LM1882CM	NSC	获取价格	Programmable Video Sync Generator
LM1882CMX	TI	获取价格	SPECIALTY CONSUMER CIRCUIT, PDSO20, SOIC-20
LM1882CN	NSC	获取价格	Programmable Video Sync Generator
LM1882E/883	TI	获取价格	SPECIALTY CONSUMER CIRCUIT, CQCC20, CERAMIC, LCC-20
LM1882EV	TI	获取价格	SPECIALTY CONSUMER CIRCUIT, PQCC20, PLASTIC, LCC-20
LM1882J/883	TI	获取价格	SPECIALTY CONSUMER CIRCUIT, CDIP20, CERAMIC, DIP-20
LM1882L	TI	获取价格	SPECIALTY CONSUMER CIRCUIT, CQCC20, CERAMIC, LCC-20

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