光电隔离线性放大器HCPL_7510及其应用
线性隔离放大器,频率电压转换,电压频率转换
•
4、输出纹波不大于50mV。
• 降低系统成本和功耗。
• 其它。
方案设计与论证
• 1、电压-频率转换模块
方案一：积分器和555定时器电路。 方案二：由普通低噪声运放构建一个积分器，再由另一
片构建一个比较器，辅之以N沟道场效应管和稳压二极 管等分立元件构成的电压-频率转换器。 方案三：采用CD4046内部锁相环中的压控振荡器。 方案四：由AD公司生产的专用高精度电压/频率转换器 AD650
输出即应可得随输入线性变化的方波频率信号。
2、利用AD650设计V/F转换模块
复位周期由单稳态触发器的定时器决定：
•
复位周期1脚电位上升幅度的大小：
当复位周期结束时，单稳态触发器输出回到低电平状 态，电流开关重新打向集成运放输出 端。开始下一个 积分周期，形成自振荡。记分周期:
单稳态触发器每触发一次的时间间隔为，晶体管的输 出受单稳控制，因此输出频率为:
电路图：
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光耦隔离电路
• 光耦隔离芯片电路简单，只是要注意两端不能共 地。
AD650 F/V转换电路
• 该转换电路结束之后还要通过实验算出输出的电压与最初 输入电压的关系，建立相应的函数关系，作进一步的调理， 比如加放大或功放电路，必要时还需要加入软件。因为现 在还没有作这一部分的实验，暂时还不能确定这个关系， 也就无法设计这个电路。
• 方案二：由AD公司生产的专门频率/电压转换芯片AD650。 • 方案三：利用低功耗Msp430单片机检测输入的频率值，
光耦隔离运放HCPL-7800 在电机电流采样中的应用 电子技术
光耦隔离运放HCPL-7800 在电机电流采样中的应用电子技术欢迎到访我的豆丁主页:(文档精灵)本文格式为WORD，能编辑和复制，感谢您的阅读。
光耦隔离运放HCPL-7800 在电机电流采样中的应用隔离运放电机驱动旁路电容">摘要:本文介绍了一种专门适用于隔离运放HCPL-7800的结构和特点，并重点介绍了此隔离运放的应用。
关键词:隔离运放，电流采样1. 概述HCPL-7800隔离运放是专门为电机驱动电流的检测设计的。
电机电流通过一个外部采样。
电阻得到模拟电压，进入芯片。
在隔离侧的另一边得到一个微分的输出电压。
这个微分的输出电压正比与电机电流，通过一个光耦放大器转换成单端信号。
由于在现代开关逆变器电机驱动中电压的共模干扰一般都有几百伏每微秒，而HCPL-7800能够抗至少10kv/us的共模干扰。
正是基于这一点,HCPL-7800隔离运放为在很嘈杂的环境中，电机电流的检测提供了更高的准确性和稳定性，也为各种各样的电机控制提供了平滑控制的可能。
它也能被用于在严重的噪声干扰的环境中需要很高的准确性，稳定性和线性的的模拟信号的隔离。
HCPL-7800的增益为+/-3%，HCPL-7800(A)适用于比较精确的场合，因为它的增益为+/-1%，它应用了先进的( Sigma;-Delta;)的模数转换技术，斩波放大器和全微分电路拓扑。
它的具体的原理图如图1所示:图1 HCPL-7800的结构简图HCPL-7800(A)隔离运放广泛应用于电机的相电流检测，逆变器的电流检测，开关电源的脉冲信号的隔离，一般的电流检测和监测，一般的模拟信号的隔离等方面。
跟LEM比较，它更加适用于电机电流的检测，抗共模抑制比的能力较强，同时具有很高的性价比。
2. 典型应用图2是HCPL-7800对电机电流采样的应用电路，从图中可以看出HCPL-7800(A)的电源欢迎到访我的豆丁主页:(文档精灵)本文格式为WORD，能编辑和复制，感谢您的阅读。
光耦培训_原理及应用
Avago Technologies - Isolation Product Division
Avago Technologies - Isolation Product Division
输出-传输延时,脉宽失真比和延时偏差
Input Signal
Output Signal
PWD
tPLH
tPHL
VCM
• • • • •
Insulation - 绝缘耐压 Viorm (VDE)IEC, Viso UL Signal Isolation – 共模抑制比 CMR = V/µs @VCM Gain – 电流传输比 CTR = (IO / IF) ´ 100% Speed – 传输延时 tpLH，tpHL , 脉宽失真 PWD =tpLH − tpHL LED Drive Current - LED 驱动电流 IF
PWD = tPLH - tPHL
最大数据率受到 传输延时的限制
通道1
IF VO IF VO
50 % 50 % 1.5 V
1.5 V
通道2
tPSK
Tpsk (传输延时偏 差)对隔离并行数 据和电机驱动死区 时间控制非常重要
Avago Technologies - Isolation Product Division
传输延时和温度,负载都有一定关系,设计中需要考虑最恶劣情况
Avago Technologies - Isolation Product Division
增益 – 电流转换比CTR
VCC
光电二极管
IF
+ VF −
IP
LED
IO
CTR = IO / IF ´ 100%
隔离放大器及其应用
坏， 要求 测试 设备 和被 测产 品在 电气上 完全 隔 离 ， 得 使 它们 只 能通过 磁或 光 的 耦 合进 行 信 息 的传 输 ， 没 有 而 电气 上 的连接 。又 比如 ， 电力测 试 系统 中 ， 某 被测 的电
压、 电流均 很 大 ， 过分 压 、 流衰 减 后 如 果 直 接 接 入 经 分 测控 计算 机 ， 然会 对测 试设 备造 成很 大 的危害 ， 仍 为此
１ 隔 离方 式 简 介
隔离 是 指 电气 上 的隔 离 ， 信 号通 过 其 他 渠 道 进 让
行传 输 ， 免 电气 上 的 直 接相 连 。隔 离放 大 的 基 本要 避 求 是保 证信 号不 失真 ， 具 有 较 高 的 隔 离 电压 和 一 定 并 的频率 范 围 。常用 的 隔离 方 式有 变压 器 耦 合 、 电耦 光
Ｖｏ． ８ Ｎｏ ６ Ｊ ｎ ２ ｌ １２ ． ｕ ． ０ ｌ
仪 器 设 备 研 制 与应 用
隔离放大器及其应用
徐 志 跃
（ 京 航 空 航 天 大 学 电 工 电子 中 心 ，北 京 １ ０ ９ ） 北 ０ １１
～一一 一一 一～ 一 ～
一～ 一 ｓ ． 唧ｓ 一ａ 一ｋ ｓ 一 一～ 一 删 ¨ ｒ ～
１ ２ 光 电耦 合 ．
纹波 电压 峰峰 值为 ２ ０ｍＶ； 增益 为 固定值 为 １ ０ 信 号 ．；
隔离 放 大器 的技 术 特 点 、 内部 结 构 、 作 原 理 、 用 中 的 注 意 事 项 、 试 技 巧 和 应 用 实 例 。隔 离 放 大 器 经 过 实 工 使 调
际 测试 达 到 了很 好 的 效 果 。
关 键 词 ： 离 放 大 器 ；变 压 器耦 合 ； 电耦 合 ； 容 耦 合 隔 光 电
隔离放大器及其应用
隔离放大器及其应用徐志跃【摘要】使用隔离放大器可以提高共模拟制比,能保护测试设备、被测产品和操作人员的人身安全.简要地介绍了常用的变压器耦合、光电耦合、电容耦合的隔离放大器的结构形式和技术特点.重点介绍了ISO-l24P隔离放大器的技术特点、内部结构、工作原理、使用中的注意事项、调试技巧和应用实例.隔离放大器经过实际测试达到了很好的效果.【期刊名称】《实验技术与管理》【年(卷),期】2011(028)006【总页数】4页(P53-56)【关键词】隔离放大器;变压器耦合;光电耦合;电容耦合【作者】徐志跃【作者单位】北京航空航天大学电工电子中心,北京100191【正文语种】中文【中图分类】TP211Abstract:Making use of isolated amplifiers can improve the common mode rejection ratio,protect test equipment and units under test and ensure the safety of operators.The structures and technical specifications for several common used isolated amplifiers,such as transformer coupler,optical coupler and capacitor coupler,are discussed briefly.Especially,the isolatedamplifier ISO-124P is introduced.The relative affairs,for example,its features,internal structure,operational principle,usage considerations and skills for adjustment are described.By practical tests,the isolated amplifier has excellent specifications.Key words:isolated amplifier;transformer coupler;optical coupler;capacitor coupler在工业控制的信号调理电路中经常需要对信号进行放大处理。
一种基于光耦HCPL0601的光电隔离型功率MOSFET驱动电路
一种基于光耦HCPL0601的光电隔离型功率MOSFET驱动电路姬弘扬【摘要】本文首先介绍了光耦HCPL0601的工作特性及其应用。
并提出了一种应用HCPL0601实现光电隔离的功率MOSFET驱动电路的设计方案。
该驱动电路同时适用于驱动上、下管的导通与关断。
实验结果表明，该驱动电路可以得到有效的驱动信号。
【期刊名称】《数字技术与应用》【年(卷),期】2014(000)010【总页数】1页(P81-81)【关键词】HCPL0601;光电隔离;功率MOSFET;驱动电路【作者】姬弘扬【作者单位】西安工程大学电子信息学院陕西西安 710048【正文语种】中文【中图分类】TH702MOSFET由于其开关速度快、输入阻抗高、驱动功率小、热稳定性好等优点,在诸多领域中获得了广泛的应用。
为了适应不同场合的使用要求,各种类型的驱动电路也相继出现[1]。
MOSFET的驱动方式一般分为:直接驱动、光耦隔离驱动、专用集成驱动器驱动等[2]。
而在电机交流调速系统中,其驱动电路需要提供频率变化范围较宽的驱动信号,因此多采用光耦隔离驱动[3]。
采用光耦隔离可很好的实现高频信号隔离,具有较低的输入输出电容,隔离效果好,可以有效的消除电路中产生的EMI,没有辐射也不易受周围电磁场的干扰[4]。
本文提出了一种基于HCPL0601的功率MOSFET驱动电路设计方案,实现光电隔离,并由实验结果可知,该方案可得到理想的驱动输出波形。
光耦HCPL0601是安华高科技公司生产的一种高速光电隔离接口芯片。
下降沿延时和上升沿延时的典型值分别是10ns和24ns,保证了驱动信号的快速性。
检测器芯片输出为集电极开路肖特基箝位晶体管,内置屏蔽可以保证瞬时共模抑制比(CMR)达10kV/us。
光电耦合器的交流和直流参数可以在-40°C到85°C的温度范围得到保证,带来无障碍的系统性能。
并查手册可知,HCPL0601实现输入输出反逻辑。
HCPL-7510
Agilent HCPL-7510Isolated Linear Sensing ICData SheetDescriptionThe HCPL-7510 isolated linear current sensing IC family is designed for current sensing in low-power electronic motor drives. In a typicalimplementation, motor current flows through an external resistor and the resultinganalog voltage drop is sensed by the HCPL-7510. An output voltage is created on the other side of the HCPL-7510 optical isolation barrier. This single-ended output voltage is proportional to the motor current. Since common-mode voltage swings of several hundred volts in tens of nanoseconds are common in modern switching inverter motor drives, the HCPL-7510was designed to ignore very high common-mode transient slew rates (of at least 10kV/µs).The high CMR capability of the HCPL-7510 isolation amplifier provides the precision and stability needed to accurately monitor motor current in high noise motor control environ-ments, providing for smoother control (less “torque ripple”)in various types of motor control applications.Features•15 kV/µs common-mode rejection at Vcm = 1000 V•Compact, auto-insertable 8-pin DIP package•60 ppm/°C gain drift vs.temperature•–0.6 mV input offset voltage •8 µV/°C input offset voltage vs.temperature•100 kHz bandwidth•0.06% nonlinearity, single-ended amplifier output for low power application.•Worldwide safety approval:UL 1577 (3750 Vrms/1 min.), CSA and IEC/EN/DIN EN 60747-5-2(Option 060 only)•Advanced sigma-delta (Σ-∆)A/D converter technology Applications•Low-power inverter current sensing•Motor phase and rail current sensing•Switched mode power supply signal isolation•General purpose low-power current sensing and monitoring •General purpose analog signal isolationCAUTION: It is advised that normal static precautions be taken in handling and assembly of this component to prevent damage and /or degradation which may be induced by ESD.Functional DiagramThe product can also be used for general analog signal isolation applications. For general applications, we recommend the HCPL-7510(gain tolerance of ±5%). The HCPL-7510 utilizes sigma delta (S-D) analog-to-digital converter technology to delivery offset and gain accuracy and stability over time and temperature. This performance is delivered in a compact, auto-insert, 8-pin DIP package that meets world-wide regulatory safety standards. (A gull-wingsurface mount option #300 is also available).V DD1V IN+V IN–GND1V DD2V OUT V REF GND2Ordering InformationSpecify part number followed by option number (if desired).Example:HCPL-7510-XXXXNo option = Standard DIP package, 50 per tube.300 = Gull Wing Surface Mount Option, 50 per tube.500 = Tape and Reel Packaging Option.060 = IEC/EN/DIN EN 60747-5-2 Option.XXXE = Lead Free OptionPackage Outline DrawingsHCPL-7510 Standard DIP PackageDIMENSIONS IN MILLIMETERS AND (INCHES).NOTE: FLOATING LEAD PROTUSION IS 0.5 mm (20 mils) MAX.0.20 (0.008)3.56 ± 0.13 (0.140 ± 0.005)HCPL-7510 Gull Wing Surface Mount Option 300 Outline Drawing1.080 ± 0.320(0.043 ± 0.013)BSCDIMENSIONS IN MILLIMETERS (INCHES).TOLERANCES (UNLESS OTHERWISE SPECIFIED):xx.xx = 0.01xx.xxx = 0.005LEAD COPLANARITYMAXIMUM: 0.102 (0.004) NOTE: FLOATING LEAD PROTUSION IS 0.5 mm (20 mils) MAX.Solder Reflow Temperature ProfileRecommended Pb-Free IR ProfileT L T smax T smin25T pTIME (SECONDS)T E M P E R A T U R E (˚C )NOTES:THE TIME FROM 25 ˚C to PEAK TEMPERATURE = 8 MINUTES MAX.T smax = 200 ˚C, T smin = 150 ˚CIEC/EN/DIN EN 60747-5-2Approved under:IEC 60747-5-2:1997 + A1:2002EN 60747-5-2:2001 + A1:2002DIN EN 60747-5-2 (VDE 0884 Teil 2):2003-01.IEC/EN/DIN EN 60747-5-2 Insulation Characteristics [1]DescriptionSymbol Characteristic Unit Installation classification per DIN EN 0110-1/1997-04, Table 1for rated mains voltage - 150 V rms I – IV for rated mains voltage - 300 V rms I – III for rated mains voltage - 600 V rms I – II Climatic Classification55/100/21Pollution Degree (DIN EN 0110-1/1997-04)2Maximum Working Insulation VoltageV IORM 891V peak Input to Output Test Voltage, Method b [2]V IORM x 1.875 = V PR , 100% production test with t m = 1 sec, partial discharge <5 pC V PR 1670V peak Input to Output Test Voltage, Method a [2]V IORM x 1.5 = V PR , type and sample test, t m = 60 sec, partial discharge <5 pC V PR 1336V peak Highest Allowable Overvoltage (transient overvoltage t ini = 10 sec)V IOTM6000V peak Safety-limiting values – maximum values allowed in the event of a failure.Case Temperature T S 175°C Input Current [3]I S, INPUT 400mA Output Power [3]P S, OUTPUT 600mW Insulation Resistance at T S , V IO = 500 VR S>109ΩNotes:1. Insulation characteristics are guaranteed only within the safety maximum ratings which must be ensured by protective circuits within the application. Surface Mount Classifications is Class A in accordance with CECC00802.2. Refer to the optocoupler section of the Isolation and Control Components Designer’s Catalog,under Product Safety Regulations section,(IEC/EN/DIN EN 60747-5-2) for a detailed description of Method a and Method b partial discharge test profiles.3. Refer to the following figure for dependence of P S and I S on ambient temperature.Regulatory InformationThe HCPL-7510 has been approved by the following organizations:ULApproved under UL 1577, component recognition program up to V ISO = 3750 V RMS . File E55361.CSAApproved under CSA Component Acceptance Notice #5, File CA 88324.O U T P U T P O W E R – P S , I N P U T C U R R E N T – I S0T S – CASE TEMPERATURE – C600400800200100300500700Insulation and Safety Related SpecificationsParameter Symbol Value Unit ConditionsMinimum External Air Gap L(101)7.4mm Measured from input terminals to output terminals, (clearance)shortest distance through air.Minimum External Tracking L(102)8.0mm Measured from input terminals to output terminals, (creepage)shortest distance path along body.Minimum Internal Plastic Gap0.5mm Through insulation distance conductor to conductor, (internal clearance)usually the straight line distance thickness between theemitter and detector.Tracking Resistance CTI>175V DIN IEC 112 Part 1(comparative tracking index)Isolation Group IIIa Material Group (DIN EN 0110-1/1997-04)Absolute Maximum RatingsParameter Symbol Min.Max.Units Note Storage Temperature T S–55125°COperating Temperature T A–40100°CSupply Voltage V DD1_max, V DD1_max06VSteady-State Input Voltage V IN+, V IN-–2.0V DD1 + 0.5-VTwo Second Transient Input Voltage V IN+, V IN-–6.0V DD1 + 0.5-VOutput Voltage V OUT–0.5V DD2 + 0.5-VReference Input Voltage V REF0.0V DD2 + 0.5-VReference Input Current I REF20-mALead Solder Temperature260°C for 10 sec., 1.6 mm below seating planeSolder Reflow Temperature Profile See Package Outline Drawings sectionRecommended Operating ConditionsParameter Symbol Min.Max.Units Note Operating Temperature T A–4085°CSupply Voltage V DD1, V DD2 4.5 5.5VInput Voltage (accurate and linear)V IN+, V IN-–200200mVInput Voltage (functional)V IN+, V IN-–2.0 2.0VReference Input Voltage V REF 4.0V DD2VUnless otherwise noted, all typicals and figures are at the nominal operation conditions of V IN+ = 0V, V IN- = 0V,V REF = 4.0V, V DD1 = V DD2 = 5.0 V and T A = 25°C; all Minimum/Maximum specifications are within the Recommended Operating Conditions.TestParameter Symbol Min.Typ.Max.Units Conditions Fig.NoteChange vs. TemperatureGain G V REF/0.512V REF/0.512V/V-0.2 V < V IN+82– 3%+ 3%< 0.2 VT A = 25°CIN+vs. Temperature< 0.2 VV OUT 200 mV Nonlinearity NL2000.060.55%-0.2 V < V IN+103,4OUT200IN+ Nonlinearity Change< 0.2 VOUT100IN+< 0.1 VInput Supply Current I DD111.716mA1,2,3 Output Supply Current I DD29.916mA1,2,3 Reference Voltage Input I REF0.261mACurrentINCurrent vs. TermperatureCoefficientMaximum Input Voltage|V IN+|MAX256mV5before V OUT ClippingEquivalent Input Impedance R IN700kΩV OUT Output Impedance R OUT15ΩInput DC Common-Mode CMRR IN63dB7 Rejection RatioOver recommended operating conditions unless otherwise specified.Parameter Symbol Min.Typ.Max.Units Test Conditions Fig.Note V IN to V OUT Signal Delay (50 – 10%)t PD10 2.24µs V IN+ = 0 mV to 200 mV step13V IN to V OUT Signal Delay (50 – 50%)t PD50 3.45µsV IN to V OUT Signal Delay (50 – 90%)t PD90 5.29.9µsV OUT Rise Time (10 – 90%)t R 3.07µsV OUT Fall Time (10 – 90%)t F 3.27µsV OUT Bandwidth (-3 dB)BW50100kHz V IN+ = 200 mV pk-pk14V OUT Noise N OUT31.5mVrms V IN+ = 0 VCommon Mode Transient CMTI1015kV/µs T A = 25°C, V CM = 1000 V15 ImmunityPackage CharacteristicsParameter Symbol Min.Typ.Max.Units Test Conditions Fig.Note Input-Output Momentary V ISO3750V rms T A = 25°C, RH < 50%6 Withstand VoltageInput-Output Resistance R I-O>109ΩV I-O = 500 VInput-Output Capacitance C I-O 1.4pF Freq = 1 MHzNotes:General Note: Typical values were taken from a sample of nominal units operating at nominal conditions (V DD1 = V DD2 = 5 V, V REF = 4.0 V, Temperature = 25°C) unless otherwise stated. Nominal plots shown from Figure 1 to 11 represented the drift of these nominal units from their nominal operating conditions.1.Input Offset Voltage is defined as the DC Input Voltage required to obtain an output voltage of V REF/2.2.Gain is defined as the slope of the best-fit line of the output voltage vs. the differential input voltage (V IN+ - V IN-) over the specified input range. Gainis derived from V REF/512 mV; e.g. V REF = 5.0, gain will be 9.77 V/V.3.Nonlinearity is defined as half of the peak-to-peak output deviation from the best-fit gain line, expressed as a percentage of the full-scale outputvoltage range.4.NL200 is the nonlinearity specified over an input voltage range of ±200 mV.5.NL100 is the nonlinearity specified over an input voltage range of ±100 mV.6.In accordance with UL1577, each optocoupler is proof tested by applying an insulation test voltage •4500 Vrms for 1 second (leakage detection currentlimit, I I-O < 5 µA). This test is performed before the 100% production test for the partial discharge (method b) shown inIEC/EN/DIN EN 60747-5-2 Insulation Characteristic Table, if applicable.7. CMRR is defined as the ratio of the differential signal gain (signal applied differentially between pins 2 and 3) to the common-mode gain (input pinstied together and the signal applied to both inputs at the same time), expressed in dB.Figure 1. Supply current vs. supply voltage.Figure 6. Input offset change vs. supply voltage.Figure 5. Output voltage vs. input voltage.Figure 4. Input current vs. input voltage.Figure 3. Supply current vs. input voltage.Figure 2. Supply current vs. temperature.Figure 9. Gain change vs. temperature.Figure 8. Gain change vs. supply voltage.Figure 7. Input offset change vs. temperature.I D D – S U P P L Y C U R R E N T – m AV DD – SUPPLY VOLTAGE – V1113812109T A – TEMPERATURE – C9.59.07.511.07.010.58.5I D D – S U P P L Y C U R R E N T – m A8.010.09.08.05.012.04.011.07.0I D D – S U P P L Y C U R R E N T – m A6.010.0V IN – INPUT VOLTAGE – V-0.4-0.6-1.2-0.20.200.2-1.40-0.30.3-0.8-0.1I I N – I N P U T C U R R E N T –µA0.1-1.0-0.2V IN – INPUT VOLTAGE – V2.52.00.54.003.51.5V O – O U T P U T V O L T A G E – V1.03.0V IN – INPUT VOLTAGE – VD V OS – I N P U T O F F S E T C H A N G E – µVV DD – SUPPLY VOLTAGE – V∆V O S – I N P U T O F F S E T C H A N G E – m VT A – TEMPERATURE – C∆G A I N – G A I N C H A N G E – %V DD – SUPPLY VOLTAGE – V 0.0100.020-0.0100.0150.005-0.0050T A – TEMPERATURE – C0.30.2-0.2-200.72080-0.30.6-401000.1040∆G A I N – G A I N C H A N G E – %60-0.10.400.5Figure 15. CMTI test circuit.Figure 14. Bandwidth.Figure 13. Propagation delay vs. temperature.Figure 12. Propagation delay test circuit.Figure 11. Nonlinearity vs. temperature.Figure 10. Nonlinearity vs. supply voltage.T A – TEMPERATURE – C0.070.090.05N L – N O N L I N E A R I T Y – %0.060.08N L – N O N L I N E A R I T Y – %V DD – SUPPLY VOLTAGE – V 0.0460.0500.0400.0480.0440.042V OUTREFV V INT A – TEMPERATURE – C360T P D – P R O P A G A T I O N D E L A Y – µs2541FREQUENCY – kHzG A I N – d BV V OUTCMV REFApplication InformationPower Supplies and BypassingThe recommended supply connections are shown in Figure 16. A floating power supply (which in many applications could be the same supply that is used to drive the high-side power transistor) is regulated to 5 V using a simple zener diode (D1); the value of resistor R4 should be chosen to supply sufficient current from the existing floating supply. The voltage from the current sensing resistor (Rsense) is applied to the input of the HCPL-7510through an RC anti-aliasingfilter (R2 and C2). Althoughthe application circuit isrelatively simple, a fewrecommendations should befollowed to ensure optimalperformance.The power supply for theHCPL-7510 is most oftenobtained from the same supplyused to power the powertransistor gate drive circuit. Ifa dedicated supply is required,in many cases it is possible toadd an additional winding onan existing transformer.Otherwise, some sort of simpleisolated supply can be used,such as a line poweredtransformer or a high-frequency DC-DC converter.An inexpensive 78L05 three-terminal regulator can also beused to reduce the floatingsupply voltage to 5 V. To helpattenuate high- frequencypower supply noise or ripple,a resistor or inductor can beused in series with the inputof the regulator to form alow-pass filter with theregulator’s input bypasscapacitor.Figure 16. Recommended supply and sense resistor connections.As shown in Figure 17, 0.1 µF bypass capacitors (C1, C2)should be located as close as possible to the pins of the HCPL-7510. The bypass capacitors are required because of the high-speed digital nature of the signals inside the HCPL-7510. A 0.01µF bypass capacitor (C2) is also recommended at the input due to the switched-capacitor nature of the input circuit. The input bypass capacitor also forms part of the anti-aliasing filter, which is recommended to prevent high frequency noise from aliasing down to lowerfrequencies and interfering with the input signal. The input filter also performs an important reliability function—it reduces transient spikes from ESD events flowing through the current sensing resistor.PC Board LayoutThe design of the printed circuit board (PCB) should follow good layout practices,such as keeping bypasscapacitors close to the supply pins, keeping output signals away from input signals, the use of ground and power planes, etc. In addition, the layout of the PCB can alsoaffect the isolation transient immunity (CMTI) of theHCPL-7510, due primarily to stray capacitive coupling between the input and the output circuits. To obtainoptimal CMTI performance, the layout of the PC board should minimize any stray coupling by maintaining the maximum possible distance between the input and output sides of the circuit and ensuring that any ground or power plane on the PC board does not passdirectly below or extend much wider than the body of the HCPL-7510.Figure 17. Recommended HCPL-7510 application circuit.FLOATING POSITIVECurrent Sensing ResistorsThe current sensing resistor should have low resistance (to minimize power dissipation), low inductance (to minimizedi/dt induced voltage spikes which could adversely affect operation), and reasonable tolerance (to maintain overall circuit accuracy). Choosing a particular value for the resistor is usually a compromise between minimizing power dissipation and maximizing accuracy. Smaller sense resistance decreases power dissipation, while larger sense resistance can improve circuit accuracy by utilizing the full input range of the HCPL-7510.The first step in selecting a sense resistor is determining how much current the resistor will be sensing. The graph in Figure 18 shows the RMS current in each phase of a three-phase induction motor as a function of average motor output power (in horsepower, hp) and motor drive supply voltage. The maximum valueof the sense resistor is determined by the current being measured and the maximum recommended input voltage of the isolation amplifier. The maximum sense resistance can be calculated by taking the maximum recommended input voltage and dividing by the peak current that the sense resistor should see during normal operation. For example, if a motor will have a maximum RMS current of 10 A and can experience up to 50% overloads during normal operation, then the peak current is 21.1 A (=10 x 1.414 x 1.5). Assuming a maximum input voltage of 200 mV, the maximum value of sense resistance in this case wouldbe about 10 mΩ. Themaximum average powerdissipation in the senseresistor can also be easilycalculated by multiplying thesense resistance times thesquare of the maximum RMScurrent, which is about 1 W inthe previous example. If thepower dissipation in the senseresistor is too high, theresistance can be decreasedbelow the maximum value todecrease power dissipation.The minimum value of thesense resistor is limited byprecision and accuracyrequirements of the design. Asthe resistance value isreduced, the output voltageacross the resistor is alsoreduced, which means that theoffset and noise, which arefixed, become a largerpercentage of the signalamplitude. The selected valueof the sense resistor will fallsomewhere between theminimum and maximumvalues, depending on theparticular requirements of aspecific design.When sensing currents largeenough to cause significantheating of the sense resistor,the temperature coefficient(tempco) of the resistor canintroduce nonlinearity due tothe signal dependenttemperature rise of theresistor. The effect increasesas the resistor-to-ambientthermal resistance increases.This effect can be minimizedby reducing the thermalresistance of the currentsensing resistor or by using aresistor with a lower tempco.Lowering the thermalresistance can be accomplishedby repositioning the currentsensing resistor on the PCboard, by using larger PCboard traces to carry awaymore heat, or by using a heatsink. For a two-terminalcurrent sensing resistor, as thevalue of resistance decreases,the resistance of the leadsbecome a significantpercentage of the totalresistance. This has twoprimary effects on resistoraccuracy. First, the effectiveresistance of the sense resistorcan become dependent onfactors such as how long theleads are, how they are bent,how far they are inserted intothe board, and how far solderwicks up the leads duringassembly (these issues will bediscussed in more detailshortly). Second, the leads aretypically made from amaterial, such as copper,which has a much highertempco than the material fromwhich the resistive elementitself is made, resulting in ahigher tempco overall. Both ofthese effects are eliminatedwhen a four-terminal currentsensing resistor is used. Afour-terminal resistor has twoadditional terminals that areK elvin-connected directlyacross the resistive elementitself; these two terminals areused to monitor the voltageacross the resistive elementwhile the other two terminalsare used to carry the loadcurrent. Because of the Kelvinconnection, any voltage dropsacross the leads carrying theload current should have noimpact on the measuredvoltage.When laying out a PC board for the current sensingresistors, a couple of points should be kept in mind. The Kelvin connections to the resistor should be broughttogether under the body of the resistor and then run very close to each other to the input of the HCPL-7510; this minimizes the loop area of the connection and reduces the possibility of stray magnetic fields from interfering with the measured signal. If the sense resistor is not located on the same PC board as the HCPL-7510 circuit, a tightly twisted pair of wires can accomplish the same thing. Also, multiple layers of the PC board can beused to increase current carrying capacity. Numerous plated-through vias should surround each non-Kelvin terminal of the sense resistor to help distribute the current between the layers of the PC board. The PC board should use 2 or 4 oz. copper for the layers, resulting in a current carrying capacity in excess of 20 A. Making the current carrying traces on the PC board fairly large can also improve the sense resistor’s power dissipation capability by acting as a heat sink. Liberal use of vias where the load current enters and exits the PC board is also recommended.Sense Resistor ConnectionsThe recommended method for connecting the HCPL-7510 to the current sensing resistor is shown in Figure 17. VIN+ (pin 2 of the HPCL-7510) is connected to the positiveterminal of the sense resistor,while VIN- (pin 3) is shorted to GND1 (pin 4), with the powersupply return path functioning as the sense line to the negative terminal of the current sense resistor. This allows a single pair of wires or PC board traces to connectthe HCPL-7510 circuit to the sense resistor. By referencing the input circuit to the negative side of the sense resistor, any load current induced noise transients on the resistor are seen as acommon- mode signal and will not interfere with the current-sense signal. This is important because the large loadcurrents flowing through the motor drive, along with the parasitic inductances inherent in the wiring of the circuit,can generate both noise spikes and offsets that are relatively large compared to the small voltages that are beingmeasured across the current sensing resistor. If the same power supply is used both for the gate drive circuit and for the current sensing circuit, it is very important that the connection from GND1 of the HCPL-7510 to the sense resistor be the only return path for supply current to the gate drive power supply in order to eliminate potential ground loop problems. Theonly direct connection between the HCPL-7510 circuit and the gate drive circuit should be the positive power supply line.Figure 18. Motor output horsepower vs. motor phase current and supply voltage.1554025MOTOR PHASE CURRENT – A (rms)30M O T O R O U T P U T P O W E R – H O R S E P O W E R0102035FREQUENTLY ASKED QUESTIONS ABOUT THE HCPL-75101. THE BASICS1.1: Why should I use the HCPL-7510 for sensing current when Hall-effect sensors are available which don’t need an isolated supply voltage?Available in an auto-insertable, 8-pin DIP package, the HCPL-7510 is smaller than and has better linearity, offset vs. temperature and Common Mode Rejection (CMR) performance than most Hall-effect sensors. Additionally, often the required input-side power supply can be derived from the same supply that powers the gate-drive optocoupler.2. SENSE RESISTOR AND INPUT FILTER2.1: Where do I get 10 mΩ resistors? I have never seen one that low.Although less common than values above 10 Ω, there are quite a few manufacturers of resistors suitable for measuring currents up to 50 A when combined with the HCPL-7510. Example product information may be found at Dale’s web site (/vishay/dale) and Isotek’s web site () and Iwaki Musen Kenkyusho’s website (http://www.iwakimusen.co.jp) and Micron Electric’s website (http://www.micron-e.co.jp).2.2: Should I connect both inputs across the sense resistor instead of grounding VIN- directly to pin 4?This is not necessary, but it will work. If you do, be sure to use an RC filter on both pin 2 (VIN+) and pin 3 (VIN-) to limit the input voltage at both pads.2.3: Do I really need an RC filter on the input? What is it for? Are other values of R and C okay?The input anti-aliasing filter (R=39 Ω, C=0.01 µF) shown in the typical application circuit is recommended for filtering fast switching voltage transients from the input signal.(This helps to attenuate higher signal frequencies which could otherwise alias with the input sampling rate and cause higher input offset voltage.)Some issues to keep in mind using different filter resistors or capacitors are:1. (Filter resistor:) The equivalent input resistance for HCPL-7510 is around 700 kΩ. It istherefore best to ensure that the filter resistance is not a significant percentage of this value;otherwise the offset voltage will be increased through the resistor divider effect. [As anexample, if Rfilt = 5.5 kΩ, then VOS = (Vin * 1%) = 2 mV for a maximum 200 mV input and VOS will vary with respect to Vin.]2. The input bandwidth is changed as a result of this different R-C filter configuration. In fact thisis one of the main reasons for changing the input-filter R-C time constant.3. (Filter capacitance:) The input capacitance of the HCPL-7510 is approximately 1.5 pF. Forproper operation the switching input-side sampling capacitors must be charged from a relatively fixed (low impedance) voltage source. Therefore, if a filter capacitor is used it is best for this capacitor to be a few orders of magnitude greater than the CINPUT (A value of at least 100 pF works well.)2.4: How do I ensure that the HCPL-7510 is not destroyed as a result of short circuit conditions which cause voltage drops across the sense resistor that exceed the ratings of the HCPL-7510’s inputs?Select the sense resistor so that it will have less than 5 V drop when short circuits occur. The only other requirement is to shut down the drive before the sense resistor is damaged or its solder joints melt. This ensures that the input of the HCPL-7510 can not be damaged by sense resistors going open-circuit.3. ISOLATION AND INSULATION3.1: How many volts will the HCPL-7510 withstand?The momentary (1 minute) withstand voltage is 3750 V rms per UL 1577 and CSA Component Acceptance Notice #5.4. ACCURACY4.1: Does the gain change if the internal LED light output degrades with time?No. The LED is used only to transmit a digital pattern. Agilent has accounted for LED degradation in the design of the product to ensure long life.5. MISCELLANEOUS5.1: How does the HCPL-7510 measure negative signals with only a +5 V supply?The inputs have a series resistor for protection against large negative inputs. Normal signals are no more than 200 mV in amplitude. Such signals do not forward bias any junctions sufficiently to interfere with accurate operation of the switched capacitor input circuit./semiconductorsFor product information and a complete listof distributors, please go to our web site.For technical assistance call:Americas/Canada: +1 (800) 235-0312or (916) 788-6763Europe: +49 (0) 6441 92460China: 10800 650 0017Hong Kong: (+65) 6756 2394India, Australia, New Zealand: (+65) 6755 1939Japan: (+81 3) 3335-8152(Domestic/Inter-national), or 0120-61-1280(Domestic Only)Korea: (+65) 6755 1989Singapore, Malaysia, Vietnam, Thailand,Philippines, Indonesia: (+65) 6755 2044Taiwan: (+65) 6755 1843Data subject to change.Copyright © 2005 Agilent Technologies, Inc.February 2, 2005obsoletes 5989-0317EN5989-2162EN。
隔离放大器及其应用
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２００６年４月 地 质 装 备
光电隔离线性放大器ＨＣＰＬ－７５１０及其应用
赵毅１ 陈晓东１，２
（１中国地质科学院物化探研究所 河北廊坊 ０６５０００）
（２中国地质大学 北京 １０００８３）
１ 功能简述
ＨＣＰＬ－７５１０是美国安捷伦公司生产的对电流敏感的隔离放大器，主要应用于马达电流的检测，也
可应用于一般的模拟信号检测。
它的工作电压为隔离的双＋５伏，工作电流为１６ｍＡ，输入电压为：－２５６～＋２５６ｍＶ，线性度为０．０６％，带宽为１００ｋＨｚ，它有表贴和双列直插两种封装型式，图１是它的原理框图。
值为：４～５．１２Ｖ，故增益最大为１０倍。
当输入电压在－２５６～＋２５６ｍＶ之间时，其线性度为０．０６％。
图２ 为线性度曲线，图中参考电压为４Ｖ，由图２ 可看出当输入电压不在－２５６～＋２５６ｍＶ之间时，输出将为一固定值。
图２ ＨＣＰＬ－７５１０线性度曲线
４ 典型应用电路
２５
图 ３典型应用电路
２ 器件主要指标
共模抑制：15kV/uS (在Vcm=1000V) 增益温漂：60ppm/℃ 输入偏置电压：-0.6mV 输入偏置电压温漂：8uV/℃ 带宽：１００ｋＨｚ 线性度：0.06% 输入阻抗：700k
输出阻抗：15 输出噪声：３１．５ｍＶｒｍｓ
３ 增益设定及线性度
ＨＣＰＬ－７５１０的增益由参考电压ＶＲＥＦ决定，其增益公式为：Ｇ＝ＶＲＥＦ／０．５１２， 其中ＶＲＥＦ为参考电压，其
Ω
Ω本文简要介绍了光电隔离线性放大器ＨＣＰＬ－７５１０的功能及性能指标，并给出应用实例。
并且对其优缺点进行了分析并给出了解决办法。
光电隔离 线性放大器
摘 要：关 键 词：
图１ 原理框
图
第７卷 第２期
５ 应用实例
ＨＣＰＬ－７５１０可以用来在模拟电路和数字电路之间进行模拟信号的隔离，在一些模拟电路和数字电路混用的电路中，如果模拟信号对噪声要求较
高，则必须加以隔离，否则数字电路将影响到模拟电路的正常工作。
由图２可看出，当输入为－２５６～＋２５６ｍＶ时，输出在０～４Ｖ之间。
这就需要根据其增益对输出进行电平转换，它可以采用模拟电路进行硬件电平转换，也可以采用软件进行数字电平转换。
图４ 是ＨＣＰＬ－７５１０在三分量ＳＱＵＩＤ磁强计控制系统中应用。
由于ＳＱＵＩＤ检测的信号比较微弱，最小为微伏级，所以，数字电路的引入必然会对其有一定的影响。
这就要求数字电路部分不能影响到模拟电路部分，最好是数字部分与模拟部分完全隔
图３为其典型应用电路，其中参考电压ＶＲＥＦ可
用典型的参考电压电路供给，如果ＨＣＰＬ－７５１０输出接Ａ／Ｄ采样，也可由Ａ／Ｄ的参考电压供给。
由图３可以看出，如果输入端噪声较大，可以在输入端加低通滤波电路。
同样如果输出端噪声较大，也可以在输出端加低通滤波电路。
赵毅等：光电隔离线性放大器HCPL-7510及其应用
２６
离。
这里我们采用ＨＣＰＬ－７５１０光电隔离放大器把模
拟部分和数字部分完全隔离，这样就做到了数字电路对ＳＱＵＩＤ模拟电路没有什么影响。
图４ 中ＲＥＦ０２ＡＰ为基准电压集成电路，它提供一个５．１２Ｖ的基准电压给ＨＣＰＬ－７５１０的参考电压输入端Ｖｒｅｆ，根据ＨＣＰＬ－７５１０的增益公式 Ｇ ＝ＶＲＥＦ／０．５１２可知，其放大倍数为１０倍。
ＨＣＰＬ－７５１０的输出经过ＬＣ滤波后再经跟随器送到Ａ／Ｄ采样器的输入端进行采样，其电平转换采用软件进行数字电平转换。
６ 小结
ＨＣＰＬ－７５１０线性光电隔离放大器的出现，为我们解决模拟信号和数字电路的隔离提供了一种途径。
它的电源为双单＋５Ｖ，这也为我们使用带来了便利。
因为大多数隔离放大器都使用正负两种隔离电源，使用起来不是非常方便。
同时它还可以输入正负两种信号，这就满足了大多数的应用。
它的唯一缺点是输出噪声偏大，如果允许可以在输出端加低通滤波器加以解决。
（收稿日期：２００５年９月５日）
图４ ＨＣＰＬ－７５１０
应用实例线路图。