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3位半数字表头芯片ICL7107中文资料

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3位半数字表头芯片ICL7107中文资料3位半数字表头芯片ICL7107中文资料 (1) 31/2位双积分型A/D转换器ICL7107功能与特点 ? ICL7107是31/2位双积分型A/D转换器,属于CMoS大规模集成电路,它的最大显示值为士1999,最小分辨率为100uV,转换精度为0.05士1 个字。 ? 能直接驱动共阳极LED数码管,不需要另加驱动器件,使整机线路简化,采用士5V两组电源供电,并将第21脚的GND接第30脚的IN 。 ? 在芯片内部从V+与COM之间有一个稳定性很高的2.8V基准电源,通过电阻分压器可获得所需的基准电压VREF 。 ...
3位半数字表头芯片ICL7107中文资料
3位半数字头芯片ICL7107中文资料 (1) 31/2位双积分型A/D转换器ICL7107功能与特点 ? ICL7107是31/2位双积分型A/D转换器,属于CMoS大规模集成,它的最大显示值为士1999,最小分辨率为100uV,转换精度为0.05士1 个字。 ? 能直接驱动共阳极LED数码管,不需要另加驱动器件,使整机线路简化,采用士5V两组电源供电,并将第21脚的GND接第30脚的IN 。 ? 在芯片内部从V+与COM之间有一个稳定性很高的2.8V基准电源,通过电阻分压器可获得所需的基准电压VREF 。 ? 能通过内部的模拟开关实现自动调零和自动极性显示功能。 ? 输入阻抗高,对输入信号无衰减作用。 ? 整机组装方便,无需外加有源器件,配上电阻、电容和LED共阳极数码管,就能构成一只直流数字电压表头。 ? 噪音低,温漂小,具有良好的可靠性,寿命长。 ? 芯片本身功耗小于15mw(不包括LED)。 ? 不设有一专门的小数点驱动信号。使用时可将LED共阳极数数码管公共阳极接V+. ? 可以方便的进行功能检查。 (2) ICL7107引脚功能及主要电气参数 V,和V-分别为电源的正极和负极, au-gu,aT-gT,aH-gH:分别为个位、十位、百位笔画的驱动信号,依次接个位、十位、百位LED显示器的相应笔画电极。 Bck:千位笔画驱动信号。接千位LEO显示器的相应的笔画电极。 PM:液晶显示器背面公共电极的驱动端,简称背电极。 of vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading development of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical Oscl-OSc3 :时钟振荡器的引出端,外接阻容或石英晶体组成的振荡器。第38脚至第40脚电容量的选择是根据下列公式来决定: Fosl = 0.45/RC COM :模拟信号公共端,简称“模拟地”,使 用时一般与输入信号的负端以及基准电压的负极相连。 TEST :测试端,该端经过500欧姆电阻接至逻辑电路的公共地,故也称“逻辑地”或“数字地”。 VREF, VREF- :基准电压正负端。 CREF:外接基准电容端。 INT:27是一个积分电容器,必须选择温度系数小不致使积分器的输入电压产生漂移现象的元件 IN,和IN- :模拟量输入端,分别接输入信号的正端和负端。 AZ:积分器和比较器的反向输入端,接自动调零电容CAz 。如果应用在200mV满刻度的场合是使用0.47μF,而2V满刻度是0.047μF。 BUF:缓冲放大器输出端,接积分电阻Rint。其输出级的无功电流( idling current )是100μA,而缓冲器与积分器能够供给20μA的驱动电流,从此脚接一个Rint至积分电容器,其值在满刻度200mV时选用47K,而2V满刻度则使用470K。 ICL7107主要参数: 电源电压 ICL7107 V+ to GND 6V 温度范围 0? to 70? ICL7107 V- to GND -9V 热电阻 PDIP封装 qJA(?/W) 50 MQFP封装 80 模拟输入电压 V+ to V- 最大结温 150? of vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading development of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical 参考输入电压 V+ to V- 最高储存温度范围 -65? to 150? 时钟输入 GND to V+ 其振荡周期Tc=2RCIn1.5=2.2RC 图2 ICL7107A/D转换器原理 计数器对反向积分过程的时钟脉冲进行计数。控制逻辑包括分频器、译码器、相位驱动器、控制器和锁存器。 分频器用来对时钟脉冲逐渐分频,得到所需的计数脉冲fc和共阳极LED数码管公共电极所需的方波信号fc。 译码器为BCD-7段译码器,将计数器的BCD码译成LED数码管七段笔画组成数字的相应编码。 驱动器是将译码器输出对应于共阳极数码管七段笔画的逻辑电平变成驱动相应笔画的方波。 控制器的作用有三个:第一,识别积分器的工作状态,适时发出控制信号,使各模拟开关接通或断开,A/D转换器能循环进行。第二,识别输入电压极性,控制LED数码管的负号显示。第二,当输入电压超量限时发出溢出信号,使千位显示“1" ,其余码全部熄灭。 钓锁存器用来存放A/D转换的结果,锁存器的输出经译码器后驱动LED 。它的每个测量周期自动调零(AZ)、信号积分(INT)和反向积分(DE)三个阶段。 第一阶段:自动调零阶段AZ 转换开始前(转换控制信号VL=0) ,先将计时器清零,并接通开关S0 ,使积分电容C完全放电。 第二阶段:信号积分INT of vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading development of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical 令开关S1合到输入信号V1一侧,积分器对V1进行固定时间Tl的积分,积分结果为: 上式说明,在Tl固定条件下V0与Vl成正比。 第三阶段:反向积分DE 令开关S1转至参考电压VREF一侧,积分器反向积分。如果积分器的输出电压上升至必零时,所经过的积分时间T2则可得, 可见,反向积分到V0=0这段时间T2与Vl成正比。令时钟脉冲CD的周期为Tc,计数扔器在T2时间内计数值为N得:T2=NTc 代入上式得: 分析可知:T1,Tc,VREF固定不变,计数值N仅与VIN成正比,实现了模拟量到数字量的转变。 下面介绍A/D转化过程的时间分配。假设时钟脉冲频率为40KHz,每个周期为4000Tc, 如图3所示,每个测量周期中三个阶段工作自动循环。 图3 双积分型A/D转换器的电压波形图 of vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading development of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical 各阶段时间分配如下 ?信号积分时间Tl用1000Tc 。 ?信号反向积分时间T2用0一2000Tc ,这段时间的长短是由VIN的大小决定的。 ?自动调零时间T0用1000,3000Tc 。 从上面的分析可知,Tl 侍定不变的,但T2随VIN的大小而改变。因为, 选基准电压VRFF = 100.0mv , 由: 得:VIN=0.1N 满量程时N=2000,同样由上式可导出满量程时VIN与基准电压的关系为:VIN=2VREF 。为了提高仪表的抗干扰能力,通常选定的采样时间Tl 为工频周期的整数倍。我国采用50Hz交流电网,其周期为20ms,应选T1=n×20ms。n= l,2,3„„n越大,对串模干扰的抑制能力越强,但n越大,A/D转换的时间越长。因此,一般取Tl=100ms,即f0,40KHz 。 由T0=2RC105=2.2RC,得 式中T0为振荡周期。 由上式可知,当f0=40KHz时,阻容元件的选取并不唯一,只要满足要求即可。 of vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading development of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical (3) ICL7107的工作原理 双积分型A/D转换器ICL7107是一种间接A/D转换器。它通过对输入模拟电压和参考电压分别进行两次积分,将输入电压平均值变换成与之成正比的时间间隔,然后利用脉冲时间间隔,进而得出相应的数字性输出。 它的原理性框图如图2所示,它包括积分器、比较器、计数器,控制逻辑和时钟信号源。积分器是A/D转换器的心脏,在一个测量周期内,积分器先后对输入信号电压和基准电压进行两次积分。比较器将积分器的输出信号与零电平进行比较,比较的结果作为数字电路的控制信一号。时钟信号源的周期Tc作为测量时间间隔的标准时间。它是由内部的两个反向器以及外部的RC组成的。 of vision Yibin formation in the Center surrounded by, organic dispersion band of bead-space layout structure, as leading development of the city to the East along the Yangtze River. Shi Gu area, lingang new vision to expand, Naxi district to the North, the East open places to expand, Jiang an eastward connection, Ping Shan, radiation to the West; the South Bank area, the minjiang River area, Golden Sands area on a long-term basis in a reasonable space to develop, perfect urban district along the Yangtze River in Yibin "Ribbon multi-center" strategic vision of space frame. Yibin Center City development construction steering extension type extended and connotation type upgrade simultaneously of mode, in Metro construction of while is committed to old city transformation and built district of perfect, through live and industry with to of reasonable layout optimization city structure, improve city traffic operation efficiency; vigorously improved city environment, shaping city features, upgrade city quality, play city of service function, formed has perfect modern service capacity of big city. Construction of urban green space system, promoting the construction of peripheral green space and protection of historical
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