真有效值AC-DC转换器AD736及其在RMS仪表电路中的应用

检测系统实习报告题目：基于单片机的工频电压（电流）表的设计姓名：院（系）：专业：指导教师：职称：评阅人：职称：年月摘要在实际中，有效值是应用最广泛的参数，电压表的读数除特殊情况外，几乎都是按正弦波有效值进行定度的。

有效值获得广泛应用的原因，一方面是由于它直接反映出交流信号能量的大小，这对于研究功率、噪声、失真度、频谱纯度、能量转换等是十分重要的；另一方面，它具有十分简单的叠加性质，计算起来极为方便。

本文详细介绍了一个数字工频电压、电流表设计，以AT89S52单片机为控制核心，由电压、电流传感器模块，真有效值测量模块，信号调理模块，AD采集模块及控制、显示模块等构成。

系统采用电压、电流互感器对输入信号进行降压处理，经AD736转换得到原信号的真有效值，由TLC549转换为数字量后送入单片机内进行简要的数据处理并将结果通过LCD实时显示，达到了较好的性能指标。

关键词：工频数字电压（电流）表真有效值AD736 TLC549 AT89S52AbstractIn practice, RMS is the most widely used parameters. Except in special circumstances,voltage meter readings almost all carried out by the RMS of sine wave . The reasons of RMS is widely available, on the one hand, because it directly reflects the size of the exchange of signal energy, which the study of power, noise, distortion, spectrum purity, energy conversion, such as it is very important; On the other hand, it has a very simple superposition of the nature of the calculation will be extremely convenient. The design of single-chip Atmel Corporation AT89S52 as control core, by the current sensor module, True RMS measurement modules, signal conditioning modules, AD acquisition and control module, display module. System uses a current sensor circuit for step-down of the input signal processing, has been converted by the original AD736 True RMS signal by the TLC549 convert into single-chip digital conducted after the brief and the results of data processing in real time through the LCD display, achieve a better performance.Keyword: Digital voltage(current) meter True RMS AD736 TLC549AT89S52目录第一章绪论 (1)§1.1 选题背景及意义 (1)§1.2 系统设计任务 (1)第二章系统总体设计 (2)§2.1 方案论证与比较 (2)2.1.1 电压、电流变换部分 (2)2.1.2 有效值测量部分 (2)§2.2 系统总体设计 (2)第三章硬件设计 (4)§3.1 传感器电路设计 (4)3.1.1 电压互感器 (4)3.1.2 电流互感器 (4)§3.2 真有效值转换电路设计 (5)3.2.1 电压、电流切换电路 (5)3.2.2 真有效值测量电路 (6)§3.3 信号调理电路设计 (7)§3.4 A/D转换电路设计 (7)§3.5 单片机及显示电路设计 (9)第四章软件设计 (10)§4.1 LCD1602液晶显示程序 (10)§4.2 A/D转换程序 (10)§4.3 主程序设计 (12)第五章系统调试及误差分析 (13)§5.1 系统调试及测试结果 (13)5.1.1 AD736测试结果 (13)5.1.2 OP07测试结果 (13)5.1.3 TLC549测试结果 (13)5.1.4 工频电压测量精度 (14)5.1.5 工频电流测量精度 (14)§5.2 误差分析 (14)§5.3 改进方法 (15)结束语 (16)致谢 (17)参考文献 (18)附录 (19)附录一完整电路图 (19)附录二程序清单 (20)第一章绪论§1.1 选题背景及意义在日常的生产、生活和科研中，工频电无处不在，所谓工频就是电力供电系统交流电的频率，我国国家规定工频为50赫兹，即周期为0.02秒，英、美等国规定的工频为60赫兹。

ad736原理
AD736是一款专用于测量电压的集成电路。

它是由ADI（Analog Devices
Inc.）公司生产的一款高性能、精确度较高的电压测量芯片。

下面是AD736的工作原理的简要说明：
AD736是一款True
RMS（有效值）电压转换器。

它的主要功能是测量交流电压的有效值，即以电压的平方平均值作为参考。

AD736的输入是交流电压信号，可以是正弦波、方波或其他复杂波形的交流信号。

它通过内部的精确运算放大器将输入信号放大，并通过整流电路将其转换为直流信号。

在转换过程中，AD736内部使用了一个快速响应的四象限乘法器，它将输入信号与一个参考电平相乘，并输出乘积信号。

这个乘积信号经过低通滤波器进行平均，并通过一个精确的校准电路进行调整，以得到准确的有效值输出。

AD736还提供了一个带有输出缓冲器的电流输出，可用于外部电路的连接。

总之，AD736通过精确的电压放大、整流、乘法和滤波等处理，能够准确测量交流电压信号的有效值，并提供相应的输出。

这使得它在许多需要测量电压的应用中得到广泛使用，如功率监测、音频处理、工业自动化等领域。

REV.CInformation furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.aLow Cost, Low Power,True RMS-to-DC ConverterAD736One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.Tel: 617/329-4700Fax: 617/326-8703FUNCTIONAL BLOCK DIAGRAMFEATURES COMPUTESTrue RMS ValueAverage Rectified Value Absolute ValuePROVIDES200 mV Full-Scale Input Range(Larger Inputs with Input Attenuator)High Input Impedance of 1012 ⍀Low Input Bias Current: 25 pA maxHigh Accuracy: ؎0.3 mV ؎0.3% of ReadingRMS Conversion with Signal Crest Factors Up to 5Wide Power Supply Range: +2.8 V, –3.2 V to ؎16.5 V Low Power: 200 ␮A max Supply Current Buffered Voltage OutputNo External Trims Needed for Specified Accuracy AD737—An Unbuffered Voltage Output Version with Chip Power Down Is Also Available PRODUCT DESCRIPTIONThe AD736 is a low power, precision, monolithic truerms-to-dc converter. It is laser trimmed to provide a maximum error of ±0.3 mV ±0.3% of reading with sine-wave inputs. Fur-thermore, it maintains high accuracy while measuring a wide range of input waveforms, including variable duty cycle pulses and triac (phase) controlled sine waves. The low cost and small physical size of this converter make it suitable for upgrading the performance of non-rms “precision rectifiers” in many applica-tions. Compared to these circuits, the AD736 offers higher ac-curacy at equal or lower cost.The AD736 can compute the rms value of both ac and dc input voltages. It can also be operated ac coupled by adding one ex-ternal capacitor. In this mode, the AD736 can resolve input sig-nal levels of 100 µV rms or less, despite variations intemperature 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 (while introducing only 2.5% additional error) at the 200 mV full-scale input level.The AD736 has its own output buffer amplifier, thereby provid-ing a great deal of design flexibility. Requiring only 200 µA of power supply current, the AD736 is optimized for use in por-table multimeters and other battery powered applications.The AD736 allows the choice of two signal input terminals: a high impedance (1012 Ω) FET input which will directly interface with high Z input attenuators and a low impedance (8 k Ω) inputwhich allows the measurement of 300 mV input levels, while operating from the minimum power supply voltage of +2.8 V,–3.2 V. The two inputs may be used either singly or differentially.The AD736 achieves a 1% of reading error bandwidth exceeding 10 kHz for input amplitudes from 20 mV rms to 200 mV rms while consuming only 1 mW.The AD736 is available in four performance grades. TheAD736J and AD736K grades are rated over the commercial tem-perature range of 0°C to +70°C. The AD736A and AD736B grades are rated over the industrial temperature range of –40°C to +85°C.The AD736 is available in three low-cost, 8-pin packages: plastic mini-DIP, plastic SO and hermetic cerdip.PRODUCT HIGHLIGHTS1.The AD736 is capable of computing the average rectified value, absolute value or true rms value of various input signals.2.Only one external component, an averaging capacitor, is required for the AD736 to perform true rms measurement.3.The low power consumption of 1 mW makes the AD736suitable for many battery powered applications.4.A high input impedance of 1012 Ω eliminates the need for an external buffer when interfacing with input attenuators.5.A low impedance input is available for those applications requiring up to 300 mV rms input signal operating from low power supply voltages.AD736–SPECIFICATIONSREV. C–2–(@ +25؇C ؎5 V supplies, ac coupled with 1 kHz sine-wave input applied unless otherwise noted.)AD736J/A AD736K/BModelConditionsMinTypMaxMinTypMax UnitsTRANSFER FUNCTIONV OUT =Avg .(V IN 2)V OUT =Avg .(V IN 2)CONVERSION ACCURACY 1 kHz Sine Wave Total Error, Internal Trim 1ac Coupled Using C C All Grades0–200 mV rms 0.3/0.30.5/0.50.2/0.20.3/0.3±mV/±% of Reading 200 mV–1 V rms–1.2؎2.0–1.2؎2.0% of Reading T MIN –T MAXA&B Grades @ 200 mV rms 0.7/0.70.5/0.5±mV/±% of Reading J&K Grades @ 200 mV rms 0.0070.007±% of Reading/°C vs. Supply Voltage@ 200 mV rms Input V S = ±5 V to ±16.5 V 0+0.06+0.10+0.06+0.1%/V @ 200 mV rms Input V S = ±5 V to ±3 V 0–0.18–0.30–0.18–0.3%/Vdc Reversal Error, dc Coupled @ 600 mV dc 1.3 2.5 1.3 2.5% of Reading Nonlinearity 2, 0 mV–200 mV @ 100 mV rms 0+0.25+0.35+0.25+0.35% of ReadingTotal Error, External Trim 0–200 mV rms0.1/0.50.1/0.3±mV/±% of Reading ERROR vs. CREST FACTOR 3Crest Factor 1 to 3C AV , C F = 100 µF 0.70.7% Additional Error Crest Factor = 5C AV , C F = 100 µF 2.52.5% Additional ErrorINPUT CHARACTERISTICS High Impedance Input (Pin 2)Signal RangeContinuous rms Level V S = +2.8 V, –3.2 V 200200mV rms Continuous rms Level V S = ±5 V to ±16.5 V 11V rms Peak Transient Input V S = +2.8 V, –3.2 V ؎0.9؎0.9V Peak Transient Input V S = ±5 V ±2.7±2.7V Peak Transient Input V S = ±16.5 V ؎4.0؎4.0V Input Resistance 10121012ΩInput Bias Current V S = ±3 V to ±16.5 V 125125pALow Impedance Input (Pin 1)Signal RangeContinuous rms Level V S = +2.8 V, –3.2 V 300300mV rms Continuous rms Level V S = ±5 V to ±16.5 V llV rms Peak Transient Input V S = +2.8 V, –3.2 V ±1.7±1.7V Peak Transient Input V S = ±5 V ±3.8±3.8V Peak Transient Input V S = ±16.5 V ±11±11V Input Resistance 6.489.6 6.489.6k ΩMaximum Continuous Nondestructive Input All Supply Voltages ±12±12V p-p Input Offset Voltage 4ac Coupled J&K Grades ؎3؎3mV A&B Grades ؎3؎3mV vs. Temperature 830830µV/°C vs. Supply V S = ±5 V to ±16.5 V 5015050150µV/V vs. Supply V S = ±5 V to ±3 V 8080µV/VOUTPUT CHARACTERISTICS Output Offset Voltage J&K Grades ±0.1؎0.5±0.1؎0.3mV A&B Grades ؎0.5؎0.3mV vs.Temperature 120120µV/°C vs. Supply V S = ±5 V to ±16.5 V5013050130µV/V V S = ±5 V to ±3 V5050µV/V Output Voltage Swing 2 k Ω Load V S = +2.8 V, –3.2 V 0 to +1.6+1.70 to +1.6+1.7V 2 k Ω Load V S = ±5 V 0 to +3.6+3.80 to +3.6+3.8V 2 k Ω Load V S = ±16.5 V 0 to +4+50 to +4+5V No Load V S = ±16.5 V 0 to +4+120 to +4+12V Output Current22mA Short-Circuit Current 33mA Output Resistance @ dc 0.20.2ΩFREQUENCY RESPONSE High Impedance Input (Pin 2)For 1% Additional Error Sine-Wave Input V IN = 1 mV rms 11kHz V IN = 10 mV rms 66kHz V IN = 100 mV rms 3737kHz V IN = 200 mV rms3333kHzAD736REV. C –3–AD736J/A AD736K/BModelConditionsMinTypMaxMinTypMaxUnits±3 dB Bandwidth Sine-Wave InputV IN = 1 mV rms 55kHz V IN = 10 mV rms 5555kHz V IN = 100 mV rms 170170kHz V IN = 200 mV rms190190kHzFREQUENCY RESPONSE Low Impedance Input (Pin 1)For 1% Additional Error Sine-Wave Input V IN = 1 mV rms 11kHz V IN = 10 mV rms 66kHz V IN = 100 mV rms 9090kHz V IN = 200 mV rms 9090kHz ±3 dB Bandwidth Sine-Wave Input V IN = l mV rms 55kHz V IN = 10 mV rms 5555kHz V IN = 100 mV rms 350350kHz V IN = 200 mV rms 460460kHz POWER SUPPLYOperatingVoltageRange +2.8, –3.2±5±16.5+2.8, –3.2±5±16.5Volts Quiescent CurrentZero Signal160200160200µA 200 mV rms, No Load Sine-Wave Input230270230270µATEMPERATURE RANGE Operating, Rated Performance Commercial (0°C to +70°C)AD736J AD736K Industrial (–40°C to +85°C)AD736A AD736BNOTES lAccuracy is specified with the AD736 connected as shown in Figure 16 with capacitor C C .2Nonlinearity is defined as the maximum deviation (in percent error) from a straight line connecting the readings at 0 and 200 mV rms. Output offset voltage is adjusted to zero.3Error vs. Crest Factor is specified as additional error for a 200 mV rms signal. C.F. = V PEAK /V rms.4DC offset does not limit ac resolution.Specifications are subject to change without notice.Specifications shown in boldface are tested on all production units at final electrical test.Results from those tests are used to calculate outgoing quality levels.ABSOLUTE MAXIMUM RATINGS 1Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .±16.5 V Internal Power Dissipation 2 . . . . . . . . . . . . . . . . . . . . .200 mW Input Voltage . . . . . . . . . . . . . . . . . . . . . . . ±V S Output Short-Circuit Duration . . . . . . . . . . . . . . . . .Indefinite Differential Input Voltage . . . . . . . . . . . . . . . . .. +V S and –V S Storage Temperature Range (Q) . . . . . . –65°C to +150°C Storage Temperature Range (N, R) . . . . . –65°C to +125°C Operating Temperature RangeAD736J/K . . . . . . . . . . . . . . . . . . . . . . . . . . .0°C to +70°C AD736A/B . . . . . . . . . . . . . . . . . . . . . . . . . .–40°C to +85°CORDERING GUIDETemperature Package Package ModelRange Description Option AD736JN 0°C to +70°C Plastic Mini-DIP N-8AD736KN 0°C to +70°C Plastic Mini-DIP N-8AD736JR 0°C to +70°C Plastic SOIC SO-8AD736KR 0°C to +70°C Plastic SOIC SO-8AD736AQ –40°C to +85°C Cerdip Q-8AD736BQ–40°C to +85°C CerdipQ-8AD736JR-REEL 0°C to +70°C Plastic SOIC SO-8AD736JR-REEL-70°C to +70°C Plastic SOIC SO-8AD736KR-REEL 0°C to +70°C Plastic SOIC SO-8AD736KR-REEL-70°C to +70°CPlastic SOICSO-8PIN CONFIGURATION8-Pin Mini-DIP (N-8), 8-Pin SOIC (R-8),8-Pin Cerdip (Q-8)Lead Temperature Range (Soldering 60 sec) . . . . . . . .+300°C ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .500 VNOTES 1Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability .28-Pin Plastic Package: θJA = 165°C/W 8-Pin Cerdip Package: θJA = 110°C/W8-Pin Small Outline Package: θJA = 155°C/WAD736REV. C–4––Typical CharacteristicsFigure 2.Maximum Input Levelvs. SupplyVoltage Figure 5.Frequency ResponseDriving Pin 2Figure 8.DC Supply Current vs.RMS lnput LevelFigure 1.Additional Error vs.Supply VoltageFigure 4.Frequency ResponseDriving Pin 1Figure 7.Additional Error vs.Temperature Figure 3.Peak Buffer Output vs.Supply VoltageFigure 6.Additional Error vs.Crest Factor vs. CAVFigure 9.–3 dB Frequency vs.RMS Input Level (Pin2)AD736REV. C –5–Typical Characteristics–Figure 10.Error vs. RMS Input Voltage (Pin 2), Output Buffer Off-set Is Adjusted To ZeroFigure 13.Pin 2 Input Bias Current vs. Supply VoltageCALCULATING SETTLING TIME USING FIGURE 14The graph of Figure 14 may be used to closely approximate the time required for the AD736 to settle when its input level is re-duced in amplitude. The net time required for the rms converter to settle will be the difference between two times extracted from the graph – the initial time minus the final settling time. As an example, consider the following conditions: a 33 µF averaging capacitor, an initial rms input level of 100 mV and a final (re-duced) input level of 1 mV. From Figure 14, the initial settling time (where the 100 mV line intersects the 33 µF line) is around 80 ms.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 will be 8 seconds minus 80 ms which is 7.92 seconds. Note that, because of the smooth decay characteristic inherent with a capacitor/diode combina-tion, this is the total settling time to the final value (i.e., not the settling time to 1%, 0.1%, etc., of final value). Also, this graph provides the worst case settling time, since the AD736 will settlevery quickly with increasing input levels.Figure 11. C AV vs. Frequency forSpecified Averaging ErrorFigure 14.Settling Time vs. RMS Input Level for Various Values of CAVFigure 12.RMS Input Level vs.Frequency for Specified Averag-ing ErrorFigure 15.Pin 2 Input Bias Cur-rent vs. TemperatureAD736REV. C–6–Table I. Error Introduced by an Average Responding Circuit When Measuring Common WaveformsWaveform Type Crest Factor True rms ValueAverage Responding % of Reading Error*1 Volt Peak (V PEAK /V rms)Circuit Calibrated to Using Average AmplitudeRead rms Value of Responding CircuitSine Waves Will ReadUndistorted 1.4140.707 V 0.707 V 0%Sine Wave Symmetrical Square Wave 1.00 1.00 V 1.11 V +11.0%Undistorted Triangle Wave 1.730.577 V0.555 V–3.8%GaussianNoise (98% of Peaks <1 V)30.333 V 0.295 V –11.4%Rectangular 20.5 V 0.278 V –44%Pulse Train 100.1 V 0.011 V –89%SCR Waveforms 50% Duty Cycle 20.495 V 0.354 V –28%25% Duty Cycle4.70.212 V0.150 V–30%*%of Reading Error =Average Responding Value –True rmsValueTrue rmsValue×100%TYPES OF AC MEASUREMENTThe AD736 is capable of measuring ac signals by operating as either an average responding or a true rms-to-dc converter. As its name implies, 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 will approximate the average. The resulting output, a dc “average” level, is then scaled by adding (or reducing) gain; this scale factor converts the dc average reading to an rms equivalent value for the waveform being measured. For example, the aver-age absolute value of a sine-wave voltage is 0.636 that of V PEAK ;the corresponding rms value is 0.707 times V PEAK . Therefore,for sine-wave voltages, the required scale factor is 1.11 (0.707divided by 0.636).In contrast to measuring the “average” value, true rms measure-ment 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 voltage compared to that of dc: an ac signal of 1 volt rms will produce the same amount of heat in a resistor as a 1 volt dc signal.Mathematically, the rms value of a voltage is defined (using a simplified equation) as:V rms =Avg .(V 2)This involves squaring the signal, taking the average, and then obtaining the square root. True rms converters are “smart recti-fiers”: they provide an accurate rms reading regardless 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 will depend upon the type of waveform being measured.As an example, if an average responding converter is calibrated to measure the rms value of sine-wave voltages, and then is used to measure either symmetrical square waves or dc voltages, the converter will have a computational error 11% (of reading)higher than the true rms value (see Table I).AD736 THEORY OF OPERATIONAs shown by Figure 16, the AD736 has five functional subsec-tions: input amplifier, full-wave rectifier, rms core, output am-plifier and bias sections. The FET input amplifier allows both a high impedance, buffered input (Pin 2) or a low imped-ance, 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.The output of the input amplifier drives a full wave precision rectifier, which in turn, drives the rms core. It is in the core that the essential rms operations of squaring, averaging and square rooting are performed, using an external averaging capacitor,C AV . Without C AV , the rectified input signal travels through the core unprocessed, as is done with the average responding con-nection (Figure 17).A final subsection, an output amplifier, buffers the output from the core and also allows optional low-pass filtering to be per-formed via external capacitor, C F , connected across the feed-back path of the amplifier. In the average respondingconnection, this is where all of the averaging is carried out. In the rms circuit, this additional filtering stage helps reduce any output ripple which was not removed by the averaging capaci-tor, C AV .Figure 16.AD736 True RMS CircuitAD736REV. C–7–As shown, the dc error is the difference between the average of the output signal (when all the ripple in the output has been removed by external filtering) and the ideal dc output. The dc error component is therefore set solely by the value of averaging capacitor used-no amount of post filtering (i.e., using a very large C F) will allow the output voltage to equal its ideal value. The ac error component, an output ripple, may be easily re-moved by using a large enough post filtering capacitor, C F.In most cases, the combined magnitudes of both the dc and ac error components need to be considered when selecting appro-priate values for capacitors C AV and C F. This combined error, representing the maximum uncertainty of the measurement is termed the “averaging error” and is equal to the peak value of the output ripple plus the dc error.As the input frequency increases, both error components de-crease rapidly: if the input frequency doubles, the dc error and ripple reduce to 1/4 and 1/2 their original values, respectively, and rapidly become insignificant.AC MEASUREMENT ACCURACY AND CREST FACTOR 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 peak signal amplitude to the rms am-plitude (C.F. = V PEAK/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 trains and SCR waveforms, have high crest factors. These types of waveforms require a long averaging time constant (to average out the long time periods between pulses). Figure 6 shows the additional error vs. crest factor of the AD736 for various values of C AV. SELECTING PRACTICAL VALUES FOR INPUT COUPLING (C C), AVERAGING (C AV) AND FILTERING (C F) CAPACITORSTable II provides practical values of C AV and C F for several common applications.Table II. AD737 Capacitor Selection ChartApplication rms Low Max C AV C F SettlingInput Frequency Crest Time*Level Cutoff Factor to 1%(–3dB)General Purpose0–1 V20 Hz5150 µF10 µF360 msrms Computation200 Hz515 µF 1 µF36 ms0–200 mV20 Hz533 µF10 µF360 ms200 Hz5 3.3 µF 1 µF36 msGeneral Purpose0–1 V20 Hz None33 µF 1.2 secAverage200 Hz None 3.3 µF120 msResponding0–200 mV20 Hz None33 µF 1.2 sec200 Hz None 3.3 µF120 msSCR Waveform0–200 mV50 Hz5100 µF33 µF 1.2 secMeasurement60 Hz582 µF27 µF 1.0 sec0–100 mV50 Hz550 µF33 µF 1.2 sec60 Hz547 µF27 µF 1.0 secAudioApplicationsSpeech0–200 mV300 Hz3 1.5 µF0.5 µF18 msMusic0–100 mV20 Hz10100 µF68 µF 2.4 sec*Settling time is specified over the stated rms input level with the input signal increasingfrom zero. Settling times will be greater for decreasing amplitude input signals.RMS MEASUREMENT – CHOOSING THE OPTIMUMVALUE FOR C AVSince the external averaging capacitor, C AV, “holds” the recti-fied input signal during rms computation, its value directly af-fects the accuracy of the rms measurement, especially at lowfrequencies. Furthermore, because the averaging capacitor ap-pears across a diode in the rms core, the averaging time constantwill increase exponentially as the input signal is reduced. Thismeans that as the input level decreases, errors due to nonidealaveraging will reduce while the time it takes for the circuit tosettle to the new rms level will increase. Therefore, lower inputlevels allow the circuit to perform better (due to increased aver-aging) but increase the waiting time between measurements.Obviously, when selecting C AV, a trade-off between computa-tional accuracy and settling time is required.Figure 17.AD736 Average Responding CircuitRAPID SETTLING TIMES VIA THE AVERAGERESPONDING CONNECTION (FIGURE 17)Because the average responding connection does not use theC AV averaging capacitor, its settling time does not vary with in-put signal level; it is determined solely by the RC time constantof C F and the internal 8 kΩ resistor in the output amplifier’sfeedback path.DC ERROR, OUTPUT RIPPLE, AND AVERAGINGERRORFigure 18 shows the typical output waveform of the AD736 witha sine-wave input applied. As with all real-world devices, theideal output of V OUT = V IN is never exactly achieved; instead,the output contains both a dc and an ac error component.Figure 18. Output Waveform for Sine-Wave Input VoltageAD736REV. C–8–C 1174a –10–9/88P R I N T E D I N U .S .A .The input coupling capacitor, C C , in conjunction with the 8 k Ωinternal input scaling resistor, determine the –3 dB low fre-quency rolloff. This frequency, F L , is equal to:F L =12π(8,000)(TheValue of C C in Farads )Note that at F L , the amplitude error will be approximately–30% (–3 dB) of reading. To reduce this error to 0.5% of read-ing, choose a value of C C that sets F L at one tenth the lowest frequency to be measured.In addition, if the input voltage has more than 100 mV of dc offset, than the ac coupling network shown in Figure 21 should be used in addition to capacitor C C .Applications CircuitsFigure 19.AD736 with a High Impedance Input AttenuatorFigure 20.Differential Input ConnectionFigure 21.External Output V OSAdjustmentFigure 22.Battery Powered OptionFigure 23.Low Z, AC Coupled Input ConnectionOUTLINE DIMENSIONSDimensions shown in inches and (mm).。

AD736在机车信号智能监测中的应用
AD736 在机车信号智能监测中的应用
Application of AD936 in Train Signal Intellient Monitoring
铁道科学研究院电子所冯云梅蒋秋华史天运
摘要：对AD736 在机车信号智能监测中的实际应用情况作了详细分析。

关键词：RMS 变换；智能监测；机车信号；轨道感应电压
引言
随着列车运行速度的提升，铁道部规划在未来的列车运行中将逐步取消地面信号机而只使用车上信号系统的重大体制改革，即机车信号系统将是司机操作列车运行的唯一信号引导，而轨道感应电压值的大小直接影响机车信号的正常，所以在对机车信号运行参数的监测中，对轨道感应电压的监测是其中一个很重要的部分。

轨道感应电压是交流小信号，对交流信号有效值的测量主要有以下几种方法：
1）用峰值变换器，通过波峰因数求出有效值；
2）热电偶电桥有效值变换器；
3）用模拟运算组成电子有效值变换器；
4）逐点采样一组数据，求其“均方根”得到其有效值。

以上几种测量方法都存在不同程度的缺点和局限性，为了得到轨道感应电压有效值的精确测量，且实现简单可靠，我们采用真有效值变换器AD736，它通过对输入交流电压进行”平方→求平均值→开平方”的运算而得到交流电压
的有效值。

当我们进行轨道感应电压值的读取时，将变换后的直流信号通过AD 采样器，然后利用单片机进行运算和处理，即可得到感应电压的有效值。

交流有效值—直流变换IC AD736／AD737及应用
王俊省;李兰友
【期刊名称】《电子与电脑》
【年(卷),期】1994(000)003
【摘要】AD736用于交流时,需在引脚①(Cc)外接一电容Cc,这时,低频截上频率f_(CL)为f_(CL)=1/(2π·8KΩ·Cc)。

当Cc=10μF时,f_(CH)=2HZ。

四、AD736实用电路——有效值交流电压表使用AD736构成的交流电压表线路如图10所示。

【总页数】1页(P54)
【作者】王俊省;李兰友
【作者单位】不详;不详
【正文语种】中文
【中图分类】TP335.1
【相关文献】
1.基于交流-直流变换的光电式电流有效值传感器+ [J], 李长胜;李宝树;乔冬
2.MAX610系列交流／直流电源变换器的原理和应用 [J], 宋吉江;牛轶霞
3.交流有效值—直流变换IC AD736／AD737及应用 [J], 王俊省;李兰友
4.一种新型的电源变换电路MAX610及其应用（220伏交流变为5V直流电压）[J], 刘强
5.直流变换器AIC1578原理及应用 [J], 邹士洪
因版权原因，仅展示原文概要，查看原文内容请购买。

真有效值转换器AD736及其应用
崔智勇;李建科
【期刊名称】《河北工业大学学报》
【年(卷),期】2005(034)0z1
【摘要】美国AD公司的AD736是一种真有效值转换器电路,它具有准确性高、灵敏度好、测量速率快、频率特性好、输入阻抗高、输出阻抗低、电源范围宽以及功耗低等特点.本文介绍了AD736的工作原理及特点,给出了以该芯片为核心构成的RMS仪表设计电路.
【总页数】3页(P34-36)
【作者】崔智勇;李建科
【作者单位】河北经贸大学,信息技术学院,河北,石家庄,050061;河北经贸大学,信息技术学院,河北,石家庄,050061
【正文语种】中文
【中图分类】TN6
【相关文献】
1.真有效值直流转换器AD536A及其应用 [J], 梁杰
2.真有效值转换器LTC1966的原理与应用 [J], 王彦朋;任文霞;刘勇
3.真有效值 AC/DC转换器 AD736及其在 RMS仪表电路中的应用 [J], 刘春生
4.单片集成型真有效值转芯片AD736的原理及应用 [J], 纪宗南
5.真有效值转换器LTC 1966在电池巡检仪中的应用 [J], 尤文; 谢荣; 姜磊
因版权原因，仅展示原文概要，查看原文内容请购买。

2012年山东省大学生电子设计竞赛A题低功耗数字多功能表的设计制作低功耗数字多功能表的设计制作摘要：用低功耗单片机为控制核心，设计了低功耗数字多功能表。

本系统包括：直流电压、交流电压、电阻、电容、三极管放大倍数的测量和正弦波信号源电路。

为了提高测量精度，在信号源、电阻、交流电压三个测量电路中，用OPA2111精密仪器放大器芯片，设计了自动较零型仪器放大器。

交流电压信号处理电路中，采用了AD736交流变直流芯片，测量精度较高。

按照题目要求完成了全部功能，并自由发挥增加了晶体管PN结电压的测量功能及温度测量功能。

仿真结果和试验数据表明，本系统具有较高的测量精度，再加后期研发完善，可推广作为数字万用表使用。

关键词：数字多功能表，低功耗，高精度，单片机控制Abstract: With low power consumption single-chip microcomputer as control core, design the low power consumption digital multi-function table. This system includes: dc volts, ac voltage, resistance, capacitance, triode magnification factor measurement and sine wave signal source circuit. In order to improve the measurement precision, the signal source, resistance, ac voltage three in the measurement circuit, with OPA2111 precision instrument amplifier chip, design the automatic a zero type instrument amplifier. In the ac voltage signal processing circuit, adopted AD736 ac variable dc chip, has high accuracy. According to the topic request completed all function, and free play to increase the diode and triode p-n junction voltage measurement function. The simulation results and test data show that this system has high measurement precision, add later research and perfect, can be generalized as digital multimeter use.Keywords: digital multi-function table, low power consumption, high precision, single-chip microcomputer control目录1.方案选择及论证 (3)1.1方案选择 (3)1.2设计方案 (3)2.硬件电路设计及理论分析计算 (3)2.1低功耗供电系统电路 (3)2.2直流电压测量电路 (4)2.3交流电压测量电路 (4)2.4电阻测量电路 (5)2.5电容测量电路 (5)2.6三极管放大倍数测量电路 (6)2.7正弦波信号源电路 (6)3系统软件设计 (7)3.1主程序流程图 (7)3.2系统自动休眠设计 (7)4.测试方案和测试结果分析 (7)4.1直流电压测量方法和测试结果 (7)4.2交流电压测量方法和测试结果 (7)4.3电阻测量方法和测试结果 (8)4.4电容测量方法和测试结果 (8)4.5三极管放大倍数测量方法和测试结果 (8)4.6正弦波信号源测量方法和测试结果 (8)4.7晶体管PN结电压测量方法和测试结果 (9)5自由发挥部分 (9)5.1测晶体管PN结电压电路 (9)5.2温度测量电路 (9)6结论 (9)参考文献 (10)附录1：系统电路原理总图 (11)附录2：部分程序清单 (12)1.方案选择及论证1.1 方案选择方案一：选用MSP430单片机为控制核心。

RMS转DC转换电路的作用1. 引言RMS转DC转换电路是一种用于将交流信号转换为直流信号的电路。

在电子学中，交流信号的幅值往往通过RMS (Root Mean Square)值来表示，而直流信号的幅值则用其本身的数值表示。

因此，需要将交流信号转换为直流信号的情况下，就会用到RMS转DC转换电路。

2. RMS (均方根)值的概念在交流电路中，信号的幅值通常是变化的，因此需要对其进行一种平均化处理，以便更好地描述信号的大小。

RMS值即均方根值，表示交流信号的有效值或等效直流值，是表示交流信号幅值大小的指标。

3. RMS转DC转换电路的原理RMS转DC转换电路将交流信号转换为与其RMS值相等的直流信号。

该电路的主要原理如下：•输入信号放大：交流信号首先通过一个放大器进行放大，以便使得RMS值的幅度能够得到合理的表达。

•方波整流：放大后的交流信号经过一个方波整流器，使得信号的方向不再变化，变成了一个单向的脉冲信号。

•平均化处理：经过整流的信号会通过一个低通滤波器，滤除掉高频分量，将得到一个平均化的信号，即直流信号。

通过以上步骤，RMS转DC转换电路可以将交流信号转换为对应的直流信号。

4. RMS转DC转换电路的应用RMS转DC转换电路在实际中有着广泛的应用，例如：•电能计量：在电能计量中，需要将交流电压和电流转换为直流信号，以便进行电能的测量和计算。

•语音处理：在语音处理中，对于音量的测量通常采用RMS转DC转换电路，以便准确地获取音频信号的幅值信息。

•自动控制系统：在自动控制系统中，RMS转DC转换电路可以对交流信号进行处理，以便进行控制和调节。

5. RMS转DC转换电路的特性RMS转DC转换电路具有以下几个特性：•线性度：良好的RMS转DC转换电路应当具有较好的线性度，即输出直流信号随输入交流信号的变化而变化，一般应保持线性范围较广。

•带宽：RMS转DC转换电路的带宽应足够宽，以便能够处理不同频率范围内的交流信号，兼容不同应用场景。

测量交流信号有效值的一种常用方法是利用平均值响应的AC/DC 转换电路，这种电路采用集成运放和二极管组成精密线性整流电路实现AC/DC 的转换，电路简单、成本低。

这种电路实际反映的是正弦电压的平均值，然后根据电路中平均值与有效值存在的确定关系，来使仪表直接显示出交流电压的有效值。

这种处理方法，当被测正弦电压的失真度超过5%时，测量误差将明显增大。

目前市场上的数字万用表没有特殊说明，都是采用这种方法，因此不能直接测量方波、三角波、锯齿波等非正弦电压的有效值。

在科学实验和工程实际中，会遇到大量的非正弦波。

为了实现对任意交流信号电压有效值的精密测量，而不必考虑被测波形的参数以及失真。

可以采用真有效值转换技术，这种方法是根据真有效值的定义式，通过电路对输入交流电压进行“平方→求平均值→开平方”的运算而得到的，即不通过平均折算而是直接将交流信号的有效值按比例转换为直流信号。

随着集成电路的迅速发展，近年来出现了各种真有效值AC/DC 转换器。

模拟器件公司的AD736是其中非常典型的一种。

AD736采用信号平方后积分的平均技术可以直接测得波形的真实有效值，并且测量灵敏度、精确度也大大改善。

系统总体结构框图如图1所示：基于AD736的真有效值测量电路AD736是一款采用8引脚封装的单片高精度的真RMS-DC 转换器。

输入信号满度值为200mV ，若要测量更大的信号，需要进行信号衰减处理；输入阻抗很高，达到1012Ω；测量信号的最大波峰因数（振幅与有效值之比）达到5；可以测量交流和直流信号的真有效值；最大只需要200µA 的供电电流，供电电压范围宽，且可以单电源或双电源供电，很适合应用于便携式仪表和电池供电的场合。

AD623是AD 公司的一款常用仪表放大器，价格便宜，采用8个引脚封装，可以采用±2.5 V~±6 V 的双电源共电，也可以采用单电源供电，电压范围3V~12V 。

而双电源供电可以达到更好的性能。

《模拟电子技术基础》课程设计目录摘要....................................... .. (1)1.电路方案论证与选择1.1系统基本方案 (2)1.2各模块方案论证与选择1.2.1直流稳压可调电源模块 (2)1.2.2电压衰减模块 (2)1.2.3 AC-DC转换模块 (4)1.2.4数字显示模块 (6)2.电路仿真 (7)3.焊接与调试3.1材料清单 (12)3.2过程描述 (13)4.参数测量及验证 (14)5.心得体会 (15)6.参考文献 (15)7.实物图 (16)课程设计任务书学生姓名：专业班级：电信12级指导教师：刘守军工作单位：信息工程学院题目: 电压交流有效值测量电路设计仿真与实现初始条件：可选元件：集成运算放大器、电阻、电位器、电容若干，直流电源，或自备元器件。

可用仪器：示波器，万用表，直流稳压源，函数发生器要求完成的主要任务:（1）设计任务根据要求，完成电压交流有效值测量电路的仿真设计、装配与调试，鼓励自制正弦信号发生器和稳压电源。

（2）设计要求①输入电压峰值10＜v ，允许误差为±2％，采用LED分段显示，分段区间自定，可加入音响指示；②选择电路方案，完成对确定方案电路的设计。

③利用Proteus或Multisim仿真设计电路原理图，确定电路元件参数、掌握电路工作原理并仿真实现系统功能。

④安装调试并按规范要求格式完成课程设计报告书。

⑤选做：利用仿真软件的PCB设计功能进行PCB设计。

时间安排：1、前半周，完成仿真设计调试；并制作实物。

2、后半周，硬件调试，撰写、提交课程设计报告，进行验收和答辩。

指导教师签名：年月日系主任（或责任教师）签名：年月日摘要模拟电子技术课程设计是继《模拟电子技术基础》理论学习和实验教学之后又一重要的实践性教学环节。

它的任务是在学生掌握和具备电子技术基础知识与单元电路的设计能力之后，让学生综合运用模拟电子技术知识，进行实际模拟电子系统的设计、安装和调测，利用Multisim等相关软件进行电路设计，提高综合应用知识的能力、分析解决问题的能力和电子技术实践技能，让学生了解模拟电子技术在工业生产领域的应用现状和发展趋势。

对H Z正弦交流信有效值的测量单片机公司标准化编码 [QQX96QT-XQQB89Q8-NQQJ6Q8-MQM9N]目录摘要在实际使用中，有效值是应用最广泛的参数，电压表的读数除特殊情况外，几乎都是按正弦波有效值进行定度的。

有效值获得广泛应用的原因，一方面是由于它直接反映出交流信号能量的大小，这对于研究功率、噪声、失真度、频谱纯度、能量转换等是十分重要的；另一方面，它具有十分简单的叠加性质，计算起来极为方便。

本次课程设计以STC89C51单片机为控制核心，利用有效值测量芯片AD736对正弦交流信号的有效值进行测量，测量结果由放大器放大，经TLC549芯片A/D转换后，由单片机控制LCD液晶显示器显示有效值。

关键字：有效值、AD736、TLC549AbstractIn actual use, the RMS is the most widely used parameters, voltage meter in addition to the special situation, almost all is according to the set of sinusoidal RMS. The cause of the valid values being widely applied, on the one hand, because it is directly reflect the size of the ac signal energy, for the study power, noise, distortion, frequency spectrum purity, energy conversion and so on is very important; On the other hand, it has a very simple superposition nature, extremely convenient to calculate.This course design with the STC89C51 microcontroller as the core, using RMS measurement chip AD736 of sinusoidal ac signal effective value measure, the measured results by the amplifier amplification, after eight bits A/D conversion chip, the LCD display RMS was controlled by single chip microcomputer.Keywords: current effective value, AD736, TLC5491.软件介绍Proteus软件是英国Labcenterelectronics公司出版的EDA工具软件（该软件中国总代理为广州风标电子技术有限公司）。

摘要：AD736/AD737是AD公司推出的真有效值直流变换器。

和以往的有效值测量技术不同，真有效值直流变换可以直接测得波形的真实有效值，它不是采用整流加平均测量技术，而是采用信号平方后积分的平均技术。

采用AD736/AD737可以简化仪设计，增加信号测量品种，并且灵敏度、精确度也大大改善。

本文讨论了真RMS测量技术的工作原理，并给出了AD736/AD73典型应用电路。

关键词：AD736/AD737；真RMS-DC；测量；仪表1. 真RMS-DC变换器目前市场上的万用表大多采用简单的整流加平均电路来完成交流信号的测量，因此这些仪表在测量RMS值时要首先校准，而且这种电路组成的万用表只能用于指定的波形如正弦波和三角波等，如果波形一变，测出的读数就不准确了。

真有效值直流变换不同，它可以直接测得输入信号的真实有效值，并和输入波形无关。

一个交变信号的变化情况可用波峰因数C（CrestFactor）来表示，波峰因数定义为信号的峰值和RMS的比值：C =V PEAK/V RMS.不同的交变信号，它的波峰因数也就可能不同，许多常见的波形，如正弦波和三角波，它们的C比较小，一般小于2,而一些占空比的信号和SCR信号，它们的峰值因数就比较大。

要想获得精确的RMS测量结果，如果使用加取平均电路，设计者要事先知道信号的波形，并测得其波峰因数，而RMS-DC变换器测无需知道的波号的开关就能直接测出各种波峰因数的交变信号的有效值。

AD636能外理的信号的最大波峰因数为10,附加误差不超过1%，而AD736/A 能处理的信号波峰因数为5,表1对采用真RMS-DC变换器和加数平均两种技术在各种波形下的性能作了对比。

一个交变信号的有效值的定义为：这时，V RMS为信号的有效值，T为测量时间，V（t）是信号的波形。

V(t)是一个时间的函数，但不一定是周期性的。

对等式的两边进行平方得：右边的积分项可以用一个平均来近似：这样式（2）可以简化为：V RMS2=Avg[V2（t)] (4)等式两边除以V RMS得：V RMS={Avg[]V2(t)]}V RMS（5）这个表达式就是测量一个信号真实有效值的基础、AD公司的真有效值直流变换器也正是采用了这一原理。

基于RMS转换技术的智能毫伏表设计摘要:智能仪表具有数据存储、运算、逻辑判断能力,能根据被测参数的变化自选量程。

本文介绍了以89C51单片机和AD736转换器为核心设计的智能毫伏表,它具有自动量程切换、自动调零、自动报警、准确性高、灵敏度好、测量速率快、频率特性好、电源范围宽以及功耗低等特点。

关键词:真有效值测量毫伏表基于RMS转换技术的智能毫伏表是针对传统测量仪表采用平均值转换法来对遇到大量的非正弦波测量存在着较大的理论误差这一缺陷而设计的。

为了实现对交流信号电压有效值的精密测量,并使之不受被测波形的限制,可以采用RMS转换技术,也就是真有效值转换技术,它不是采用整流加平均的测量技术,而是采用信号平方后积分的平均技术。

真有效值直流变换可以直接测得各种波形的真实有效值。

1 硬件系统设计被测信号首先经过衰减及可编程放大以实现测量量程的自动切换,然后进行真有效值转换,转换得到的真有效值直流电压进行A/D转换变成数字信号后送入单片机系统进行数字处理及显示。

1.1 衰减电路设计真有效值智能毫伏表主要功能是测量不同的电压,而且要求测量的电压值范围很宽,从1mV～300V的直流、正弦交流电压,最大与最小之比达到1000000个数量级。

即使采用6×1/2位A/D芯片也不能满足这样大的动态范围,而且输入电压过高也会烧毁电路元件及系统,因此,要首先对被测电压进行衰减。

本设计的衰减电路采用的是电阻串联分压式的衰减,运用了四个不同阻值的电阻对被测信号实现了1000倍的衰减。

1.2 放大电路的设计由于本系统测量的电压范围是很宽的,可从1mV～300V,而且为了保证电路元器件的正常工作对输入信号进行了1000倍的衰减,因此,为了使系统能对毫伏级输入信号的精确检测,需要对信号进行放大。

而在本系统中利用可编程放大器(PGA)和单片机控制,很容易地实现了自动量程切换与系统的自动测量。

可编程放大器采用了国产的数字可编程增益放大器SFM004。

44河南科技2010.11下电子信息技术一、数字电压表概述1. 数字电压表的发展与应用。

电压表指固定安装在电力、电信、电子设备面板上使用的 仪表，用来测量交、直流电路中的电压。

传统的指针式电压表功能单一、精度低，不能满足数字化时代的需求，并且传统的电压表在测量电压时需要手动切换量程，不仅不方便，而且要求不能超过该量程。

目前，由各种单片A/D转换器构成的数字电压表，已被广泛用于电子及电工测量领域，并且由DVM扩展而成的各种通用及专用数字仪器仪表，也把电量及非电量测量技术提高到崭新水平。

2. 本次设计数字电压表的组成部分。

本设计是由单片机AT89C51作为整个系统控制的核心，整个系统由衰减输入电路、量程自动转换电路、交直流转换电路、模数转换及控制电路以及接口电路五大部分构成。

信号经过衰减电路进行衰减到测量所规范的电压值0～0.5V，直流信号直接经过模数转换及控制电路以及接口电路进行数据处理，交流信号要先经过交直流转换电路转换成直流信号，然后进行处理并由LCD显示。

本设计选取AD736作为交直流转换电路的控制芯片，选取ICL7135作为模数转换的控制芯片。

显示部分选取LCD1601作为显示模块。

二、总体方案设计1. 系统设计方案。

选用单片机AT89C51作为整个系统的核心，用其输入电压的范围控制信号调理电路实现输入量程的自动切换，以达到其既定的高精度性能指标。

分析系统，其关键在于实现电压调理的自动量程控制，而在这一点上，单片机AT89C51就显现出来它的优势——控制简单、方便、快捷、资源丰富、价格低廉等优点，使得在实际制作过程中是一个较为理想的方案。

本设计是由单片机AT89C51、A/D转换器ICL7135、真有效值AC-DC转换器AD736 组成的简易数字电压表，测量交直流电压范围在0～500V，测量正弦波电压的综合误差不超过±3%，使用LCD液晶显示器显示。

2. 系统设计及原理。

整个系统由单片机AT89C51控制电压的输入与输出，模拟电压信号经过挡位切换到不同的分压电路衰减后，经隔离干扰通过转换开关控制，若测量直流电压直接送到A/D 转换，若测量交流电压先把交流转换为直流后送到A/D转换电路进行A/D转换，然后送到单片机中进行数据处理，处理后的数据送到LCD中显示。

真RMS—DC变换器AD736／AD737
熊光宇
【期刊名称】《国外电子元器件》
【年(卷),期】1995(000)006
【摘要】ＡＤ７３６／ＡＤ７３７是ＡＤ公司推出的真有效值直流变换器。

和以
往的有效值测量技术不同，真有效值直流变换可以直接测得各种波形的真实有效值，它不是采用整流加平均的测量技术，而是采用信号平方后积分的平均技术。

采用ＡＤ７３６／ＡＤ７３７可以简化仪器的设计，增加信号测量品种，并且灵敏度、精确度也大大改善。

本文讨论了真ＲＭＳ测量技术的工作原理，并给出了ＡＤ７３６／ＡＤ７３７的典型应用电路。

【总页数】7页(P14-20)
【作者】熊光宇
【作者单位】无
【正文语种】中文
【中图分类】TP335.1
【相关文献】
1.真有效值 AC/DC转换器 AD736及其在 RMS仪表电路中的应用 [J], 刘春生
2.采用△∑技术的实际RMS-DC变换器 [J], Joseph Petrofsky;Glen Brisebois
3.采用Δ∑技术的实际RMS—DC变换器 [J], JosephPetrofsky;京湘;等
4.基于UC2843的DCM模式下反激式DC-DC变换器仿真研究 [J], 王春宁;武浩;陈明会
5.双向全桥DC-DC变换器优化策略的仿真分析 [J], 张丽霞;王洋;杜银景;康伟;康忠健
因版权原因，仅展示原文概要，查看原文内容请购买。

真RMS-DC变换器AD736/AD737AD736/AD737是AD公司推出的真有效值直流变换器。

和以往的有效值测量技术不同,真有效值直流变换可以直接测得各种波形的真实有效值,它不是采用整流加平均测量技术,而是采用信号平方后积分的平均技术。

采用AD736/AD737可以简化仪器的设计,增加信号测量品种,并且灵敏度、精确度也大大改善。

本文讨论了真RMS测量技术的工作原理,并给出了AD736/AD737的典型应用电路。

AD736/AD737；真RMS-DC；测量；仪表;AD737JN；The AD737* is a low power, precision, monolithic true rms-to-dc converter. It is laser trimmed to provide a maximum error of ±0.2 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 and triac (phase) controlled sine waves. The low cost and small physical size of this converter make it suitable for upgrading the performance of non-rms precision rectifiers in many applications. Compared to these circuits, the AD737 offers higher accuracy at equal or lower cost.The AD737 can compute the rms value of both ac and dc input voltages. It can also be operated ac-coupled by adding one external capacitor. In this mode, the AD737 can resolve input signal levels of 100 μV 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 (while introducing only 2.5% additional error) at the 200 mV full-scale input level.The AD737 has no output buffer amplifier, thereby significantly reducing dc offset errors occurring at the output, which makes the device highly compatible with high input impedance ADCs.Requiring only 160 μA of power supply current, the AD737 is optimized for use in portable multimeters and other battery-powered applications. This converter also provides a power-down feature that reduces the power-supply standby current to less than 30 μA.T wo signal input terminals are provided in the AD737. A high impedance (1012 Ω) FET input interfaces directly with high R input attenuators, and a low impedance (8 kΩ) input accepts rms voltages to 0.9 V while operating from the minimum power supply voltage of ±2.5 V. The two inputs can be used either single ended or differentially.The AD737 achieves 1% of reading error bandwidth, exceeding 10 kHz for input amplitudes from 20 mV rms to 200 mV rms, while consuming only 0.72 mW.The AD737 is available in four performance grades. The AD737J and AD737K grades are rated over the commercial temperature range of 0°C to 70°C. The AD737JR-5 is tested with supply voltages of ±2.5 V dc. The AD737A and AD737B grades are rated over the industrial temperature range of −40°C to +85°C. The AD737 is available in three low cost, 8lead packages: PDIP, SOIC_N, and CERDIP.Product Highlights1. Capable of computing the average rectified value, absolute value, or true rms value of variousinput signals.2. Only one external component, an averaging capacitor, is required for the AD737 to perform true rms measurement.3. The low power consumption of 0.72 mW makes the AD737 suitable for battery-powered applications. 1. 真RMS-DC变换器目前市场上的万用表大多采用简单的整流加平均电路来完成交流信号的测量,因此这些仪表在测量RMS值时要首先校准,而且用这种电路组成的万用表只能用于指定的波形如正弦波和三角波等,如果波形一变,测出的读数就不准确了。

rms转dc转换电路作用RMS转DC转换电路是一种电路，它的作用是将交流信号转换为直流信号。

在许多电子设备中，需要将交流信号转换为直流信号，以便进行后续的处理和分析。

RMS转DC转换电路是一种非常常见的电路，它可以将交流信号的有效值转换为直流信号的平均值。

RMS转DC转换电路的原理是利用了交流信号的平方平均值和直流信号的平均值之间的关系。

交流信号的平方平均值是指信号的平方值的平均值，而直流信号的平均值是指信号的平均值。

因此，如果我们可以测量交流信号的平方平均值，并将其与直流信号的平均值进行比较，就可以得到一个有效的RMS转DC转换电路。

RMS转DC转换电路通常由一个电容和一个电阻组成。

电容用于滤除交流信号的高频成分，而电阻用于将交流信号转换为直流信号。

当交流信号通过电容时，它会被滤除掉高频成分，只剩下直流信号。

然后，直流信号通过电阻，产生一个电压降，这个电压降就是交流信号的平方平均值。

最后，我们可以通过测量电阻两端的电压来得到交流信号的平方平均值，并将其与直流信号的平均值进行比较，从而得到一个有效的RMS转DC转换电路。

RMS转DC转换电路在许多电子设备中都有广泛的应用。

例如，在音频设备中，需要将音频信号转换为直流信号，以便进行后续的放大和处理。

在电力系统中，需要将电压和电流信号转换为直流信号，以便进行功率计算和负载分析。

在工业自动化中，需要将传感器信号转换为直流信号，以便进行控制和监测。

RMS转DC转换电路是一种非常重要的电路，它可以将交流信号转换为直流信号，从而方便后续的处理和分析。

在实际应用中，我们需要根据具体的需求选择合适的电容和电阻，以确保电路的性能和稳定性。

自动量程转换数字电压表摘要：采用集成芯片MC14433作为数字电压表的A/D转换及分压电路、译码驱动电路和数字显示模块。

通过多路模拟开关与电阻设置了多个电压量程，应用MC14433的超欠量程信息控制移位寄存器的左移或右移，自动识别输入电压的范围，选择相应的衰减，实现量程的自动转换功能。

译码驱动电路与数码管完成被测电压的数字显示。

该电压表具有测量精确高、操作方便、性能稳定、扩展功能强及显示清晰度高等特点。

关键词：数字电压表，A/D转换，数字显示，多路模拟开关，自动切换Abstract: Integrated chips used in digital voltmeter MC14433 A / D conversion and partial pressure circuit, drive circuit and decoding digital display module. Through a multi-channel analog switches and resistors to set the number of voltage range, the application of ultra MC14433 range of information control due to the left or right shift register, automatically identify the input voltage range, select the appropriate attenuation, to achieve automatic conversion range . Drive circuit and the digital decoder to complete the measured voltage figures. The voltage meter has a measuring accuracy, easy operation, stable performance, high extensions and display high-definition features.Keywords:Digital voltmeter, A / D conversion, digital display, multi-channel analog switch, auto switch目录1 前言 (1)2 整体方案设计 (2)2.1方案论证 (2)2.2方案比较 (3)3 单元模块设计 (5)3.1分压电路模块 (5)3.1.1 CC4066 (5)3.2自动量程切换电路模块 (6)3.2.1 CC40194 (6)3.2.2 CC4013 (7)3.3A/D转换电路模块 (8)3.3.1 MC14433 (8)3.4数字显示电路 (10)3.4.1 CD4511 (11)4 系统设计 (13)5 系统技术指标及精度和误差分析 (14)6 设计总结 (15)7 参考文献 (16)附录1：电路总原理图 (17)附录2：元器件清单 (18)附录3：系统设计相关软件 (19)1 前言进入21世纪以来，随着计算机技术和软件技术的发展，电子测量仪器领域发生了一场革命性的变革，传统的测试仪器逐步被与PC机相配合使用的模块仪器所取代，形成了所谓的“虚拟仪器”，自动测试系统结构也从传统的机架层迭式结构发展成为模块化结构，当通用硬件平台确定后，决定仪器功能的将是软件，而不是硬件，现代测试技术逐步向标准化、规模化、网络化方向发展。