電氣類外文翻譯1

1、<p><b>　　FEATURES </b></p><p><b>　　Computes </b></p><p>　　True rms value </p><p>　　Average rectified value </p><p>　　Absolute value </

2、p><p>　　Provides 200 mV full-scale input range (larger inputs with input attenuator) </p><p>　　High input impedance: 1012 Ω </p><p>　　Low input bias current: 25 pA maximum </p>

3、<p>　　High accuracy: ±0.3 mV ± 0.3% of reading </p><p>　　RMS conversion with signal crest factors up to 5 </p><p>　　Wide power supply range: +2.8 V, ?3.2 V to ±16.5V <

4、;/p><p>　　Low power: 200 mA maximum supply current </p><p>　　Buffered voltage output </p><p>　　No external trims needed for specified accuracy </p><p>　　AD737—an unbuff

5、ered voltage output version with chip power-down also available</p><p>　　GENERAL DESCRIPTION </p><p>　　The AD736 is a low power, precision, monolithic true rms-to-dc converter. It is laser trim

6、med to provide a maximum error of ±0.3 mV ± 0.3% of reading with sine wave inputs. Furthermore, it maintains high accuracy while measuring a wide range of input waveforms, including variable duty-cycle pulses a

7、nd triac (phase)-controlled sine waves. The low cost and small size of this converter make it suitable for upgrading the performance of non-rms precision rectifiers in many applications. Compared to t</p><p>

8、;　　The AD736 can compute the rms value of both ac and dc input voltages. It can also be operated as an ac-coupled device by adding one external capacitor. In this mode, the AD736 can resolve input signal levels of 100 μV

9、 rms or less, despite variations in temperature or supply voltage. High accuracy is also maintained for input waveforms with crest factors of 1 to 3. In addition, crest factors as high as 5 can be measured (introducing

10、only 2.5% additional error) at the 200 mV full-scale input leve</p><p>　　The AD736 has its own output buffer amplifier, thereby pro-viding a great deal of design flexibility. Requiring only 200 μA of power s

11、upply current, the AD736 is optimized for use in portable multimeters and other battery-powered applications. </p><p>　　The AD736 allows the choice of two signal input terminals: a high impedance FET input

12、(1012 Ω) that directly interfaces with High-Z input attenuators and a low impedance input (8 kΩ) that allows the measurement of 300 mV input levels while operating from the minimum power supply voltage of +2.8 V, ?3.2 V.

13、 The two inputs can be used either single ended or differentially. </p><p>　　The AD736 has a 1% reading error bandwidth that exceeds 10 kHz for the input amplitudes from 20 mV rms to 200 mV rms while consum

14、ing only 1 mW. </p><p>　　The AD736 is available in four performance grades. The AD736J and AD736K grades are rated over the 0°C to +70°C and ?20°C to +85°C commercial temperature ranges.

15、 </p><p>　　The AD736A and AD736B grades are rated over the ?40°C to +85°C industrial temperature range. The AD736 is available in three low cost, 8-lead packages: PDIP, SOIC, and CERDIP. </p>

16、;<p>　　PRODUCT HIGHLIGHTS </p><p>　　1. The AD736 is capable of computing the average rectified value, absolute value, or true rms value of various input signals. </p><p>　　2. Only one e

17、xternal component, an averaging capacitor, is required for the AD736 to perform true rms measurement. </p><p>　　3. The low power consumption of 1 mW makes the AD736 suitable for many battery-powered applica

18、tions. </p><p>　　4. A high input impedance of 1012 Ω eliminates the need for an external buffer when interfacing with input attenuators. </p><p>　　5. A low impedance input is available for tho

19、se applications that require an input signal up to 300 mV rms operating from low power supply voltages. </p><p>　　SPECIFICATIONS </p><p>　　At 25°C ± 5 V supplies, ac-coupled with 1 kH

20、z sine wave input applied, unless otherwise noted. Specifications in bold are tested on all production units at final electrical test. Results from those tests are used to calculate outgoing quality levels.</p>&l

21、t;p>　　Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those

22、indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.</p><p>　　THEORY OF OPERATION</

23、p><p>　　As shown by Figure 18, the AD736 has five functional subsections: the input amplifier, full-wave rectifier (FWR), rms core, output amplifier, and bias section. The FET input amplifier allows both a high

24、 impedance, buffered input (Pin 2) and a low impedance, wide dynamic range input (Pin 1). The high impedance input, with its low input bias current, is well suited for use with high impedance input attenuators.</p>

25、;<p>　　The output of the input amplifier drives a full-wave precision rectifier that, in turn, drives the rms core. The essential rms operations of squaring, averaging, and square rooting are performed in the core

26、 using an external averaging capacitor, CAV. Without CAV, the rectified input signal travels through the core unprocessed, as is done with the average responding connection (see Figure 19). </p><p>　　A final

27、 subsection, an output amplifier, buffers the output from the core and allows optional low-pass filtering to be performed via the external capacitor, CF, which is connected across the feedback path of the amplifier. In t

28、he average responding connection, this is where all of the averaging is carried out. In the rms circuit, this additional filtering stage helps reduce any output ripple that was not removed by the averaging capacitor, CA

29、V. </p><p>　　TYPES OF AC MEASUREMENT </p><p>　　The AD736 is capable of measuring ac signals by operating as either an average responding converter or a true rms-to-dc converter. As its name impl

30、ies, an average responding converter computes the average absolute value of an ac (or ac and dc) voltage or current by full-wave rectifying and low-pass filtering the input signal; this approximates the average. The resu

31、lting output, a dc average level, is scaled by adding (or reducing) gain; this scale factor converts the dc average reading to an rms</p><p>　　In contrast to measuring the average value, true rms measurement

32、 is a universal language among waveforms, allowing the magnitudes of all types of voltage (or current) waveforms to be compared to one another and to dc. RMS is a direct measure of the power or heating value of an ac vol

33、tage compared to that of a dc voltage; an ac signal of 1 V rms produces the same amount of heat in a resistor as a 1 V dc signal.</p><p>　　Mathematically, the rms value of a voltage is defined (using a simpl

34、ified equation) as </p><p>　　This involves squaring the signal, taking the average, and then obtaining the square root. True rms converters are smart rectifiers; they provide an accurate rms reading regard

35、less of the type of waveform being measured. However, average responding converters can exhibit very high errors when their input signals deviate from their precalibrated waveform; the magnitude of the error depends on t

36、he type of waveform being measured. For example, if an average responding converter is calibrated to me</p><p>　　CALCULATING SETTLING TIME USING FIGURE 16 </p><p>　　Figure 16 can be used to clos

37、ely approximate the time required for the AD736 to settle when its input level is reduced in amplitude. The net time required for the rms converter to settle is the difference between two times extracted from the graph (

38、the initial time minus the final settling time). As an example, consider the following conditions: a 33 μF averaging capacitor, a 100 mV initial rms input level, and a final (reduced) 1 mV input level. From Figure 16, th

39、e initial settling time (where </p><p>　　The settling time corresponding to the new or final input level of 1 mV is approximately 8 seconds. Therefore, the net time for the circuit to settle to its new value

40、 is 8 seconds minus 80 ms, which is 7.92 seconds. Note that because of the smooth decay characteristic inherent with a capacitor/diode combination, this is the total settling time to the final value (that is, not the set

41、tling time to 1%, 0.1%, and so on, of the final value). In addition, this graph provides the worst-case settling t</p><p>　　RMS MEASUREMENT—CHOOSING THE OPTIMUM VALUE FOR CAV </p><p>　　Because

42、the external averaging capacitor, CAV, holds the rectified input signal during rms computation, its value directly affects the accuracy of the rms measurement, especially at low frequencies. Furthermore, because the aver

43、aging capacitor appears across a diode in the rms core, the averaging time constant increases exponentially as the input signal is reduced. This means that as the input level decreases, errors due to nonideal averaging d

44、ecrease, and the time required for the circuit to se</p><p>　　RAPID SETTLING TIMES VIA THE AVERAGE RESPONDING CONNECTION </p><p>　　Because the average responding connection shown in Figure 19 do

45、es not use the CAV averaging capacitor, its settling time does not vary with the input signal level. It is determined solely by the RC time constant of CF and the internal 8 kΩ resistor in the output amplifier’s feedback

46、 path.</p><p>　　DC ERROR, OUTPUT RIPPLE, AND AVERAGING ERROR </p><p>　　Figure 20 shows the typical output waveform of the AD736 with a sine wave input applied. As with all real-world devices, t

47、he ideal output of VOUT = VIN is never achieved exactly. Instead, the output contains both a dc and an ac error component. As shown in Figure 20, the dc error is the difference between the average of the output signal (

48、when all the ripple in the output is removed by external filtering) and the ideal dc output. The dc error component is therefore set solely by the value of t</p><p>　　As the input frequency increases, both e

49、rror components decrease rapidly; if the input frequency doubles, the dc error and ripple reduce to one quarter and one half of their original values, respectively, and rapidly become insignificant.</p><p>　

50、　AC MEASUREMENT ACCURACY AND CREST FACTOR </p><p>　　The crest factor of the input waveform is often overlooked when determining the accuracy of an ac measurement. Crest factor is defined as the ratio of the

51、peak signal amplitude to the rms amplitude (crest factor = VPEAK/V rms). Many common waveforms, such as sine and triangle waves, have relatively low crest factors (≤2). Other waveforms, such as low duty-cycle pulse train

52、s and SCR waveforms, have high crest factors. These types of waveforms require a long averaging time constant (to average out</p><p>　　APPLICATIONS</p><p>　　CONNECTING THE INPUT </p><

53、p>　　The inputs of the AD736 resemble an op amp, with noninverting and inverting inputs. The input stages are JFETs accessible at Pin 1 and Pin 2. Designated as the high impedance input, Pin 2 is connected directly to

54、a JFET gate. Pin 1 is the low impedance input because of the scaling resistor connected to the gate of the second JFET. This gate-resistor junction is not externally accessible and is servo-ed to the voltage level of the

55、 gate of the first JFET, as in a classic feedback circuit. This act</p><p><b>　　中文翻譯</b></p><p><b>　　運(yùn)算</b></p><p><b>　　真有效值RMS</b></p>&l

56、t;p><b>　　平均整流值</b></p><p><b>　　絕對(duì)值</b></p><p>　　提供滿量程200mV范圍內(nèi)輸入電壓(較大輸入的輸入衰減器)</p><p>　　高輸入阻抗:1012Ω</p><p>　　低的輸入偏置電流:25 pA最大值</p><

57、p>　　精度高:±0.3 mV±0.3%的讀入</p><p>　　波頂因數(shù)的有效值轉(zhuǎn)換提升到5</p><p>　　寬供電范圍:+ 2.8V,?3.2V到16.5 V</p><p>　　低功率:最大200mA就可正常運(yùn)行</p><p><b>　　緩沖輸出電壓</b></p>

58、<p>　　沒(méi)有外部協(xié)議需要規(guī)定準(zhǔn)確性</p><p>　　AD737-是一個(gè)芯片斷電也可使用的非緩沖電壓輸出的版本</p><p><b>　　總體描述</b></p><p>　　AD736是一個(gè)低功率、精密、真有效值單塊集成電路的直流轉(zhuǎn)換器。它是經(jīng)過(guò)激光修正提供一個(gè)最大誤差±0.3 mV±0.3%的讀如與正

59、弦波的輸入。此外,它在很寬的范圍內(nèi)測(cè)量輸入波形仍能確保高精度，輸入波形,包括脈沖占空比可變和相控正弦波。這個(gè)芯片低成本、體積小使它很方便在非有效值精密整流器在許多應(yīng)用里有了很大的提升。比較這些芯片, AD736能提供更高的精確度以相同或更低的成本。</p><p>　　AD736可以計(jì)算交流電和直流電兩種輸入電壓的有效值。它也可以添加一個(gè)外部電容器作為一個(gè)交流耦合的操作設(shè)備。在這種情況下, AD736可以解決輸入

60、信號(hào)有效值等于或少于100uV,即使溫度和電壓變化。高精度也保證輸入的波形在1到3的峰值因子。此外,高達(dá)5波頂因數(shù)可以測(cè)量(引起附加的誤差僅為2.5%)滿量程200mV的水平。</p><p>　　AD736有它自己的輸出緩沖放大器,從而大大提高設(shè)計(jì)的靈活性。只需要200μA供電電流, AD736使便攜式萬(wàn)用表和其他電池驅(qū)動(dòng)的應(yīng)用得到優(yōu)化。</p><p>　　AD736允許兩個(gè)信號(hào)輸入端

61、子可以選擇:一個(gè)高阻抗場(chǎng)效應(yīng)管輸入(1012Ω)直接接口與高Z輸入衰減器和低阻抗輸入(8 kΩ),這樣可以允許測(cè)量300mV輸入值從最低的電源電壓+ 2.8 V,?3.2 V。兩個(gè)輸入可以是使用單端或雙端。</p><p>　　AD736有1%的錯(cuò)誤讀入帶寬，超過(guò)10KHZ的輸入振幅從20 mV有效值到200mV 有效值然而只消耗1 mW。</p><p>　　AD736有四個(gè)性能等級(jí)&l

62、t;/p><p>　　AD736J和AD736K的額定等級(jí)是在0°到+ 70°C 、 20°C到?85°C商業(yè)級(jí)溫度范圍。</p><p>　　AD736A和AD736B的額定等級(jí)在40°到?85°C 工業(yè)級(jí)溫度范圍。</p><p>　　這個(gè)AD736是可利用的在三種低成本、8腳:PDIP,SOIC,CERD

63、IP封裝。</p><p><b>　　產(chǎn)品亮點(diǎn)</b></p><p>　　1.AD736能夠計(jì)算平均矯正值、絕對(duì)值、真有效值等各種輸入信號(hào)。</p><p>　　2. AD736只需一個(gè)外部組件,一個(gè)平均電容、就可以進(jìn)行真有效值的測(cè)量。</p><p>　　3.低功耗1 mW使AD736適合許多電池驅(qū)動(dòng)的應(yīng)用。<

64、;/p><p>　　4.一個(gè)高阻抗1012Ω的輸入，當(dāng)輸入與衰減器連接時(shí)不需要外部的緩沖。</p><p>　　5.一個(gè)低阻抗的輸入可供那些需要一個(gè)輸入信號(hào)達(dá)到300 mV有效值在低電壓下運(yùn)行的應(yīng)用。</p><p><b>　　規(guī)格</b></p><p>　　使用溫度25°C±5 V、交流耦合 1KH

65、Z正弦波輸入,除非另有注明。說(shuō)明書(shū)是在大膽的測(cè)試所有的產(chǎn)品單元后完成的。這些測(cè)試結(jié)果用于計(jì)算出廠質(zhì)量。</p><p>　　超過(guò)最大額定值可能對(duì)設(shè)備造成永久性的損壞。這是額定值僅供參考,在高于額定值或其他的環(huán)境下設(shè)備的功能正常運(yùn)行是不可取的。在最大額定值下使用,可能影響器件的可靠性。</p><p><b>　　工作原理</b></p><p>

66、;　　如圖18所示，AD736有五個(gè)功能分段:輸入放大器,全波整流器(FWR)、有效值的核心、輸出放大器、偏壓部分。若場(chǎng)效應(yīng)管輸入放大器都允許的高阻抗,緩沖輸入(Pin 2)和一個(gè)低阻抗、寬動(dòng)態(tài)范圍輸入(Pin 1)。高阻抗輸入,以其低的輸入偏置電流,很適合使用高阻抗輸入衰減器。</p><p>　　輸入放大器的輸出驅(qū)動(dòng)全波精密整流器,進(jìn)而帶動(dòng)有效值核心?；镜挠行е挡僮骶褪瞧椒?平均值,開(kāi)平方在內(nèi)部核心運(yùn)行，使

67、用一個(gè)外部平均電容器，CAV。沒(méi)有CAV ,整流后的輸入信號(hào)穿越核心未被處理,由于已經(jīng)完成平均響應(yīng)連接 (參見(jiàn)圖19)。</p><p>　　最后一節(jié)、輸出放大器、緩沖器輸出從核心允許可選擇低通濾波通過(guò)外部電容器、CF連接通過(guò)反饋放大器。在平均響應(yīng)的聯(lián)系,在這里所有的平均值運(yùn)算被執(zhí)行。在有效值電路中,該附加濾波階段有助于減少輸出信號(hào)中沒(méi)有被平均電容過(guò)濾掉的脈動(dòng)。</p><p><b

68、>　　交流測(cè)量的類型</b></p><p>　　AD736能夠測(cè)量交流信號(hào)通過(guò)操作要么是平均響應(yīng)整流器或一個(gè)真有效值的直流轉(zhuǎn)換器。正如其名字所示,一個(gè)平均響應(yīng)整流器計(jì)算交流電壓得平均絕對(duì)值(或交流和直流)或者當(dāng)前的全波整流或低通濾波輸入信號(hào)，這個(gè)接近平均值。</p><p>　　輸出結(jié)果,一個(gè)直流平均等級(jí),按增加(或減少)增益來(lái)平衡;這種平衡因素轉(zhuǎn)換的直流平均讀入到一個(gè)

69、真有效值等價(jià)于波形的測(cè)量。例如,一個(gè)正弦波電壓的平均絕對(duì)值是VPEAK 0.636倍,相應(yīng)的有效值是0.707×VPEAK。因此,對(duì)于正弦波電壓,所需的平衡因素是1.11(0.707/0.636)。</p><p>　　與測(cè)量平均值形成對(duì)比,真有效值的波形測(cè)量是一種世界通用方式,允許選擇所有類型的電壓(或電流)波形被比作一個(gè)到另一個(gè)和到直流。</p><p>　　有效值就是在相同

70、的電阻上分別通以直流電流和交流電流，經(jīng)過(guò)一個(gè)交流周期的時(shí)間，它們?cè)陔娮枭纤鶕p失的電能相等。1V的交流與1V的直流在同一電阻上產(chǎn)生相同的熱量。</p><p>　　數(shù)學(xué)的均方根值電壓值的定義(使用一個(gè)簡(jiǎn)化方程)</p><p>　　這包括把信號(hào)平方,做平均值,然后在做平方根的計(jì)算。</p><p>　　真有效值的轉(zhuǎn)換器是靈巧的整流器;他們提供一個(gè)準(zhǔn)確的真有效值讀取無(wú)論

71、是哪類波形的測(cè)量。然而,平均響應(yīng)轉(zhuǎn)換器當(dāng)他們的輸入信號(hào)偏離事先標(biāo)定的波形會(huì)出現(xiàn)誤差;產(chǎn)生誤差的大小取決于波形的被測(cè)形式。例如,如果一個(gè)平均響應(yīng)轉(zhuǎn)換器被校準(zhǔn)去測(cè)量正弦波電壓,然后又用于測(cè)量對(duì)稱方波和直流電壓，轉(zhuǎn)換器就會(huì)產(chǎn)生(讀入)高于真有效值11%的計(jì)算誤差(見(jiàn)表4)。</p><p>　　計(jì)算穩(wěn)定時(shí)間使用圖16</p><p>　　圖16可以用來(lái)得到粗略的估計(jì)AD736解決輸入電平振幅下降

72、所需的時(shí)間。真有效值轉(zhuǎn)換器來(lái)解決兩次提取圖形之間的差別所需的凈時(shí)間 (初始時(shí)間減去最終穩(wěn)定時(shí)間)。例如,考慮以下條件: 一個(gè)33μF平均電容器,一個(gè)初始有效值為100mV的輸入電平,和一個(gè)最終(減少)1 mV輸入電平。從圖16,初步建立時(shí)間(這里的100mV的線與33μF的線相交)大約是80毫秒。</p><p>　　相應(yīng)的到達(dá)新的或最終輸入的1 mV電平所需的穩(wěn)定時(shí)間約為8秒。因此,電路來(lái)解決新值的凈時(shí)間是8秒

73、減80毫秒,即7.92秒。注意到電容器/二極管組合所固有的衰減平滑特性,這是總穩(wěn)定時(shí)間到最終值(即不是穩(wěn)定時(shí)間到1%,0.1%,等等,最終值)。此外,本圖提供了最壞情況的穩(wěn)定時(shí)間，是因?yàn)锳D736處理遞增的輸入電平非常迅速。</p><p>　　CAV有效值(RMS)測(cè)量的最佳選擇</p><p>　　由于外部平均值電容器CAV,在有效值計(jì)算時(shí)保存整流輸入信號(hào) ,其值直接影響有效值的測(cè)量精

74、度,特別對(duì)于低頻來(lái)說(shuō)。此外,因?yàn)槠骄娙萜髟谟行е岛诵拇┻^(guò)一個(gè)二極管。當(dāng)輸入信號(hào)減小時(shí)，平均時(shí)間常數(shù)以指數(shù)形式增加。這意味著只要輸入電壓降低,誤差由于非理想的平均而值減小 ,而電路所需處理新的有效值電壓的時(shí)間增加了。因此,低輸入電平使電路工作的更好(由于平均值增加),增加了測(cè)量操作時(shí)的等待時(shí)間。很明顯,當(dāng)選擇了CAV,精確計(jì)算與需要到達(dá)的穩(wěn)定時(shí)間是一種平衡關(guān)系。</p><p>　　通過(guò)的平均響應(yīng)連接的快速建立時(shí)

75、間</p><p>　　由于在圖19展示出的平均響應(yīng)關(guān)系沒(méi)有使用CAV平均電容器,其穩(wěn)定時(shí)間不隨輸入信號(hào)電平變化。它僅由RC時(shí)間常數(shù)的CF和內(nèi)部8 kΩ電阻在輸出放大器的反饋路徑上而決定。</p><p>　　直流誤差、輸出的波紋,和平均誤差</p><p>　　圖20顯示了典型的AD736正弦輸入的輸出波形應(yīng)用。所有都是真實(shí)的設(shè)備,理想的輸出VOUT = VIN是

76、永遠(yuǎn)不能達(dá)到這樣的。相反,輸出既含有直流輸和交流誤差的組成部分。如圖20時(shí),直流誤差是區(qū)別于平均輸出信號(hào)(當(dāng)所有的輸出脈動(dòng)都被外部濾波掉了)和理想的直流輸出。直流誤差的組成僅僅是平均值由于電容的使用。即使再多的后置濾波(也就是用一個(gè)非常大的CF)允許輸出電壓等于理想值。交流誤差組成,一個(gè)輸出脈動(dòng),能夠被很容易被消除通過(guò)使用一個(gè)足夠大的濾波電容器、CF。在大多數(shù)情況下,直流和交流誤差的成分需要被考慮當(dāng)選擇合適的電容器CAV和電容器CF的值

77、時(shí)。這綜合誤差,代表著最大的不確定度量,是所謂的平均誤差它等于輸出脈動(dòng)的峰值加上直流誤差。</p><p>　　當(dāng)輸入頻率的升高,兩者誤差部分迅速減少;如果輸入頻率加倍,直流誤差和脈動(dòng)減小到四分之一和原始值的一半，迅速成為無(wú)關(guān)緊要的因素。</p><p>　　交流測(cè)量精度和振幅因數(shù)</p><p>　　當(dāng)決定一個(gè)交流測(cè)量的精確度輸入波形的振幅因數(shù)常常被忽視。振幅因數(shù)

78、被定義為最大信號(hào)振幅與有效值振幅之比 (振幅因數(shù)= VPEAK / V rms)。許多常見(jiàn)的波形,如正弦波和三角波,有相對(duì)較低的振幅因數(shù)(≤2)。其他波形,如低頻寬比脈沖序列和可控硅波形,具有高振幅因數(shù)。這些類型的波形需要很長(zhǎng)的平均時(shí)間常數(shù)(在脈沖之間需要很長(zhǎng)的周期達(dá)到最終的平衡)。圖8顯示附加的誤差對(duì)比，對(duì)于各種各樣的CAV值的AD736振幅因數(shù)。</p><p><b>　　應(yīng)用</b>

79、</p><p><b>　　輸入的連接</b></p><p>　　AD736的輸入類似一個(gè)帶著同向和反向的運(yùn)算放大器。輸入級(jí)是結(jié)型場(chǎng)效應(yīng)管(JFET)可以由1腳和2腳輸入。指定為高阻抗輸入、腳2直接連接到結(jié)型場(chǎng)效應(yīng)管（JFET）門(mén)。腳1是低阻抗輸入因?yàn)榭s放電阻連接到第二個(gè)結(jié)型場(chǎng)效應(yīng)管(JFET)門(mén)。門(mén)電阻沒(méi)有在外部連接,是不容易servo-ed外部的電壓水平的門(mén),