安捷伦线性光电耦合器HCNR200 201

HCNR200HCNR201

Features

• Low Nonlinearity: 0.01%• K3 (IPD2/IPD1) Transfer GainHCNR200: ±15%HCNR201: ±5%

• Low Gain TemperatureCoefficient: -65ppm/°C• Wide Bandwidth – DC to>1 MHz

• Worldwide Safety Approval

-UL 1577 Recognized(5 kV rms/1 min Rating)-CSA Approved

-IEC/EN/DIN EN 60747-5-2 Approved

VIORM = 1414 V peak(Option #050)

• Surface Mount OptionAvailable

(Option #300)

• 8-Pin DIP Package - 0.400\"Spacing

• Allows Flexible CircuitDesign

• Special Selection for

HCNR201: Tighter K1, K3and Lower NonlinearityAvailable

Applications

• Low Cost Analog Isolation• Telecom: Modem, PBX

• Industrial Process Control:Transducer Isolator

Isolator for Thermocouples4mA to 20 mA Loop Isolation• SMPS Feedback Loop, SMPSFeedforward

• Monitor Motor SupplyVoltage• Medical

characteristics of the LED can bevirtually eliminated. The outputphotodiode produces a photocur-rent that is linearly related to thelight output of the LED. The closematching of the photodiodes andadvanced design of the packageensure the high linearity andstable gain characteristics of theoptocoupler.

The HCNR200/201 can be used toisolate analog signals in a widevariety of applications thatrequire good stability, linearity,bandwidth and low cost. TheHCNR200/201 is very flexibleand, by appropriate design of theapplication circuit, is capable ofoperating in many differentmodes, including: unipolar/

bipolar, ac/dc and inverting/non-inverting. The HCNR200/201 isan excellent solution for manyanalog isolation problems.

Description

The HCNR200/201 high-linearityanalog optocoupler consists of ahigh-performance AlGaAs LEDthat illuminates two closely

matched photodiodes. The inputphotodiode can be used to

monitor, and therefore stabilize,the light output of the LED. As aresult, the nonlinearity and drift

Schematic

1LED CATHODE–VFLED ANODE2+IF7NC8NC3PD1 CATHODEIPD1IPD26PD2 CATHODEPD1 ANODE45PD2 ANODECAUTION: It is advised that normal static precautions be taken in handling and assembly of this component toprevent damage and/or degradation which may be induced by ESD.

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Ordering Information:

HCNR20x

0 = ±15% Transfer Gain, 0.25% Maximum Nonlinearity1 = ±5% Transfer Gain, 0.05% Maximum Nonlinearity

Option yyyy

050 = IEC/EN/DIN EN 60747-5-2 VIORM = 1414 V peak Option300 = Gull Wing Surface Mount Lead Option500 = Tape/Reel Package Option (1 k min.)XXXE = Lead Free Option

Option data sheets available. Contact your Agilent Technologies sales representative or authorized distributorfor information.

Remarks: The notation “#” is used for existing products, while (new) products launched since 15th July2001 and lead free option will use “-”

Package Outline Drawings

11.30 (0.445)MAX.87650.20 (0.008)0.30 (0.012)OPTION CODE*A HCNR200Z YYWWDATECODE9.00(0.354)TYP.11.00(0.433)MAX.10.16(0.400)TYP.0°15°PINONE12341.50(0.059)MAX.5.10 (0.201) MAX.12LEDNC8NCK1K270.51 (0.021) MIN.33.10 (0.122)3.90 (0.154)0.40 (0.016)0.56 (0.022)2.54 (0.100) TYP.4651.70 (0.067)1.80 (0.071)PD1PD2DIMENSIONS IN MILLIMETERS AND (INCHES).* MARKING CODE LETTER FOR OPTION NUMBERS.\"V\" = OPTION 050OPTION NUMBERS 300 AND 500 NOT MARKED.NOTE: FLOATING LEAD PROTRUSION IS 0.25 mm (10 mils) MAX.Figure 1.

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Gull Wing Surface Mount Option #300

11.15 ± 0.15(0.442 ± 0.006)8765LAND PATTERN RECOMMENDATION9.00 ± 0.15(0.354 ± 0.006)13.56(0.534)12341.3(0.051)1.55(0.061)MAX.12.30 ± 0.30(0.484 ± 0.012)11.00MAX.(0.433)2.29(0.09)4.00MAX.(0.158)1.78 ± 0.15(0.070 ± 0.006)2.54(0.100)BSC0.75 ± 0.25(0.030 ± 0.010)1.00 ± 0.15(0.039 ± 0.006)+ 0.0760.254- 0.0051+ 0.003)(0.010- 0.002)7° NOM.DIMENSIONS IN MILLIMETERS (INCHES).LEAD COPLANARITY = 0.10 mm (0.004 INCHES).NOTE: FLOATING LEAD PROTRUSION IS 0.25 mm (10 mils) MAX.4

Solder Reflow Temperature Profile

300PREHEATING RATE 3°C + 1°C/–0.5°C/SEC.REFLOW HEATING RATE 2.5°C ± 0.5°C/SEC.PEAKTEMP.245°CPEAKTEMP.240°CTEMPERATURE (°C)200160°C150°C140°CPEAKTEMP.230°C2.5°C ± 0.5°C/SEC.30SEC.30SEC.SOLDERINGTIME200°C3°C + 1°C/–0.5°C100PREHEATING TIME150°C, 90 + 30 SEC.50 SEC.TIGHTTYPICALLOOSEROOMTEMPERATURE0050100150200250TIME (SECONDS)Recommended Pb-Free IR Profile

tpTpTL260 +0/-5 °C217 °CRAMP-UP3 °C/SEC. MAX.150 - 200 °CRAMP-DOWN6 °C/SEC. MAX.TIME WITHIN 5 °C of ACTUALPEAK TEMPERATURE20-40 SEC.TEMPERATURETsmaxTsmintsPREHEAT60 to 180 SEC.25t 25 °C to PEAKTIMEtL60 to 150 SEC.NOTES:THE TIME FROM 25 °C to PEAK TEMPERATURE = 8 MINUTES MAX.Tsmax = 200 °C, Tsmin = 150 °CRegulatory Information

The HCNR200/201 optocouplerfeatures a 0.400\" wide, eight pinDIP package. This package wasspecifically designed to meetworldwide regulatory require-ments. The HCNR200/201 hasbeen approved by the followingorganizations:

UL

Recognized under UL 1577,

Component Recognition Program,FILE E55361

CSA

Approved under CSA ComponentAcceptance Notice #5, File CA88324

IEC/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(Option 050 only)

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Insulation and Safety Related Specifications

Parameter

Min. External Clearance(External Air Gap)Min. External Creepage(External Tracking Path)Min. Internal Clearance(Internal Plastic Gap)

SymbolL(IO1)L(IO2)

Value9.610.01.0

Unitsmmmmmm

Conditions

Measured from input terminals to outputterminals, shortest distance through airMeasured from input terminals to outputterminals, shortest distance path along bodyThrough insulation distance conductor toconductor, usually the direct distance

between the photoemitter and photodetectorinside the optocoupler cavity

The shortest distance around the borderbetween two different insulating materialsmeasured between the emitter and detectorDIN IEC 112/VDE 0303 PART 1Material group (DIN VDE 0110)

Min. Internal Creepage(Internal Tracking Path)Comparative Tracking IndexIsolation Group

CTI

4.0mm

200IIIa

V

Option 300 – surface mount classification is Class A in accordance with CECC 00802.

IEC/EN/DIN EN 60747-5-2 Insulation Characteristics (Option #050 Only)

Description

Installation classification per DIN VDE 0110/1.89, Table 1For rated mains voltage ≤600 V rmsFor rated mains voltage ≤1000 V rmsClimatic Classification (DIN IEC 68 part 1)Pollution Degree (DIN VDE 0110 Part 1/1.89)

Maximum Working Insulation VoltageInput to Output Test Voltage, Method b*

VPR = 1.875 x VIORM, 100% Production Test with tm = 1 sec, Partial Discharge < 5 pCInput to Output Test Voltage, Method a*

VPR = 1.5 x VIORM, Type and sample test, tm = 60 sec,Partial Discharge < 5 pCHighest Allowable Overvoltage*

(Transient Overvoltage, tini = 10 sec)Safety-Limiting Values

(Maximum values allowed in the event of a failure,also see Figure 11)Case Temperature

Current (Input Current IF, PS = 0)Output PowerInsulation Resistance at TS, VIO = 500 V

VIORMVPRSymbol

Characteristic

I-IVI-III55/100/21

214142651

V peakV peakUnit

VPR

2121V peak

VIOTM

8000V peak

PS,OUTPUT

RS

TSIS

150400700>109

°CmAmWΩ

*Refer to the front of the Optocoupler section of the current catalog for a more detailed description of IEC/EN/DIN EN 60747-5-2 andother product safety regulations.

Note: Optocouplers providing safe electrical separation per IEC/EN/DIN EN 60747-5-2 do so only within the safety-limiting values towhich they are qualified. Protective cut-out switches must be used to ensure that the safety limits are not exceeded.

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Absolute Maximum Ratings

Storage Temperature..................................................-55°C to +125°COperating Temperature (TA)........................................-55°C to +100°CJunction Temperature (TJ)............................................................125°CReflow Temperature Profile...See Package Outline Drawings SectionLead Solder Temperature..................................................260°C for 10s(up to seating plane)

Average Input Current - IF............................................................25 mAPeak Input Current - IF.................................................................40 mA(50 ns maximum pulse width)

Reverse Input Voltage - VR..............................................................2.5 V(IR = 100 µA, Pin 1-2)

Input Power Dissipation.........................................60 mW @ TA = 85°C(Derate at 2.2 mW/°C for operating temperatures above 85°C)

Reverse Output Photodiode Voltage................................................30 V(Pin 6-5)

Reverse Input Photodiode Voltage...................................................30 V(Pin 3-4)

Recommended Operating Conditions

Storage Temperature....................................................-40°C to +85°COperating Temperature.................................................-40°C to +85°CAverage Input Current - IF.......................................................1 - 20 mAPeak Input Current - IF.................................................................35 mA(50% duty cycle, 1 ms pulse width)

Reverse Output Photodiode Voltage...........................................0 - 15 V(Pin 6-5)

Reverse Input Photodiode Voltage..............................................0 - 15 V(Pin 3-4)

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Electrical Specifications

TA = 25°C unless otherwise specified. ParameterSymbolDeviceTransfer GainK3Min.Typ.Max.1.001.001.001.151.051.07Units Test ConditionsFig.Note11,21,2HCNR2000.85HCNR2010.95HCNR2010.93TemperatureCoefficient ofTransfer GainDC NonLinearity(Best Fit)∆K3/∆TA -65ppm/°CNLBFHCNR200HCNR201HCNR2010.010.010.010.250.050.07%DC Nonlinearity(Ends Fit)Input Photo-diode CurrentTransfer Ratio(IPD1/IF)TemperatureCoefficientof K1PhotodiodeLeakage CurrentPhotodiodeReverse Break-down VoltagePhotodiodeCapacitanceLED ForwardVoltageNLEFK1HCNR2000.25HCNR2010.36∆K1/∆TA0.0160.500.48-0.30.750.72%/°C%5 nA < IPD < 50 µA,2,30 V < VPD < 15 V5 nA < IPD < 50 µA,0 V < VPD < 15 V-40°C < TA < 85°C,5 nA < IPD < 50 µA,0 V < VPD < 15 V-40°C < TA < 85°C,2,35 nA < IPD < 50 µA,0 V < VPD < 15 V5 nA < IPD < 50 µA,4,5,0 V < VPD < 15 V65 nA < IPD < 50 µA,0 V < VPD < 15 V-40°C < TA < 85°C,5 nA < IPD < 50 µA,0 V < VPD < 15 V5 nA < IPD < 50 µA,0 V < VPD < 15 VIF = 10 mA,70 V < VPD1 < 15 V32,32,342ILKBVRPD300.515025nA V-40°C < TA < 85°C,IF = 10 mA0 V < VPD1 < 15 VIF = 0 mA,0 V < VPD < 15 VIR = 100 µA78CPDVF1.31.2221.61.691.851.95pFVVPD = 0 VIF = 10 mAIF = 10 mA,-40°C < TA < 85°CIF = 100 µA9,10LED ReverseBreakdownVoltageTemperatureCoefficient ofForward VoltageLED JunctionCapacitanceBVR2.5V∆VF/∆TA-1.7mV/°CIF = 10 mACLED80pFf = 1 MHz,VF = 0 V8

AC Electrical Specifications

TA = 25°C unless otherwise specified.

Parameter

LED Bandwidth

Application Circuit Bandwidth:High SpeedHigh PrecisionApplication Circuit: IMRRHigh Speed

SymbolDeviceMin.Typ.Max.Unitsf -3dB

91.51095

MHzMHzkHzdB

freq = 60 Hz TestConditionsIF = 10 mA

161716

777, 8Fig.Note

Package Characteristics

TA = 25°C unless otherwise specified.

ParameterInput-OutputMomentary-WithstandVoltage*Resistance(Input-Output)SymbolDeviceVISOMin.5000Typ.Max.UnitsV rms TestConditionsRH ≤50%,t = 1 min.VO = 500 VDCTA = 100°C,VIO = 500 VDC0.40.6pFf = 1 MHzFig.Note5, 6RI-O101210111013Ω555Capacitance(Input-Output)CI-O*The Input-Output Momentary Withstand Voltage is a dielectric voltage rating that should not be interpreted as an input-output

continuous voltage rating. For the continuous voltage rating refer to the VDE 0884 Insulation Characteristics Table (if applicable), yourequipment level safety specification, or Application Note 1074, “Optocoupler Input-Output Endurance Voltage.”

Notes:

1. K3 is calculated from the slope of thebest fit line of IPD2 vs. IPD1 with elevenequally distributed data points from5nA to 50 µA. This is approximatelyequal to IPD2/IPD1 at IF = 10 mA.

2. Special selection for tighter K1, K3 andlower Nonlinearity available.

3. BEST FIT DC NONLINEARITY (NLBF) isthe maximum deviation expressed as apercentage of the full scale output of a“best fit” straight line from a graph ofIPD2 vs. IPD1 with eleven equally distrib-uted data points from 5 nA to 50µA.IPD2 error to best fit line is the deviation

below and above the best fit line,expressed as a percentage of the fullscale output.

4. ENDS FIT DC NONLINEARITY (NLEF)is the maximum deviation expressed asa percentage of full scale output of astraight line from the 5 nA to the 50 µAdata point on the graph of IPD2 vs. IPD1.5. Device considered a two-terminaldevice: Pins 1, 2, 3, and 4 shorted

together and pins 5, 6, 7, and 8 shortedtogether.

6. In accordance with UL 1577, each

optocoupler is proof tested by applyingan insulation test voltage of ≥6000 Vrms for ≥1 second (leakage detection

current limit, II-O of 5 µA max.). Thistest is performed before the 100%production test for partial discharge(method b) shown in the IEC/EN/DINEN 60747-5-2 Insulation Characteris-tics Table (for Option #050 only).7. Specific performance will depend oncircuit topology and components.8. IMRR is defined as the ratio of the

signal gain (with signal applied to VIN ofFigure 16) to the isolation mode gain(with VIN connected to input commonand the signal applied between theinput and output commons) at 60 Hz,expressed in dB.

1.06= NORM K3 MEANN= NORM K3 MEAN ± 2 • STD DEVIAG1.04 REFS1.02NART –1.00 3K DEZ0.98ILAMRO0.96NNORMALIZED TO BEST-FIT K3 AT T < 15 VA = 25°C,0 V < V0.94PD0.010.020.030.040.050.060.0IPD1 – INPUT PHOTODIODE CURRENT – µAFigure 2. Normalized K3 vs. Input IPD.

0.035= NLBF 50TH PERCENTILE%= NL BF 90TH PERCENTILE–0.03 YTIRA0.025ENIL-N0.02ON TI0.015F-TSEB0.01 – FBL0.0050 V < VPD < 15 VN5 nA < IPD < 50 µA0.00-55-255356595125TA – TEMPERATURE – °CFigure 5. NLBF vs. Temperature.10.0AVPD = 15 Vn – 8.0EGAKAE6.0L EDOIDO4.0TOHP – 2.0KLI0.0-55-255356595125TA – TEMPERATURE – °CFigure 8. Typical Photodiode Leakagevs. Temperature.0.02NIAG0.015 RE0 V < VPD < 15 VFS0.01NART0.005 3K F0.0O TFI-0.005RD – 3-0.01K AT-0.015= DELTA K3 MEANL= DELTA K3 MEAN ± 2 • STD DEVED-0.02-55-255356595125TA – TEMPERATURE – °CFigure 3. K3 Drift vs. Temperature.

ST0.02P %0 V < V –0.0155 nA < IPD < 15 V PD < 50 µALN T0.01IF-TS0.005EB FO0.0 TFIR-0.005D – F-0.01BLN A-0.015T= DELTA NLLBF MEANED-0.02= DELTA NLBF MEAN ± 2 • STD DEV-55-255356595125TA – TEMPERATURE – °CFigure 6. NLBF Drift vs. Temperature.

100TA = 25°CA10m – TNE1RRUC D0.1RAWR0.01OF – FI0.0010.00011.201.301.401.501.60VF – FORWARD VOLTAGE – VOLTSFigure 9. LED Input Current vs.Forward Voltage.9

)0.03SF= ERROR MEAN F= ERROR MEAN ± 2 • STD DEVO %0.02( ENIL 0.01TIF-TSE0.00B MOR-0.01F RORR-0.02E 2DTA = 25 °C, 0 V < VPD < 15 VPI-0.030.010.020.030.040.050.060.0IPD1 – INPUT PHOTODIODE CURRENT – µAFigure 4. INote 4).

PD2 Error vs. Input IPD (SeeR1.2T-55°CC E1.1-40°CDOI1.025°CDOT0.985°COHP0.8100°C TUP0.7NI – 0.61K D0.5EZIL0.4NORMALIZED TO K1 CTRAAT IF = 10 mA, TA = 25°CMR0.30 V < VPD1 < 15 VON0.20.02.04.06.08.010.012.014.016.0IF – LED INPUT CURRENT – mAFigure 7. Input Photodiode CTR vs.LED Input Current.

1.8IVF = 10 mA –1.7 EGATL1.6OV DRA1.5WROF 1.4DEL – F1.3V1.2-55-255356595125TA – TEMPERATURE – °CFigure 10. LED Forward Voltage vs.Temperature.

1000900PS OUTPUT POWER – mVIS INPUT CURRENT – mA80070060050040030020010000255075100125150175TS – CASE TEMPERATURE – °CFigure 11. Thermal Derating CurveDependence of Safety Limiting Valuewith Case Temperature per IEC/EN/DIN EN 60747-5-2.

VCCVIN-+A) POSITIVE INPUT VIN-+C) NEGATIVE INPUTFigure 13. Unipolar Circuit Topologies.

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R2R1VIN+-IPD1PD1A1IPD2A2VOUT-PD2+LEDIFA) BASIC TOPOLOGYVCCR2R1C1C2VINLED-R3-PD1A1PD2PD2A2VOUT++B) PRACTICAL CIRCUITFigure 12. Basic Isolation Amplifier.

-VOUT+B) POSITIVE OUTPUT-VOUT+D) NEGATIVE OUTPUT11

VCC1VCC1VCC2IOS1VIN-+IOS2-VOUT+A) SINGLE OPTOCOUPLERVCC-VIN+-VOUT+-+B) DUAL OPTOCOUPLERFigure 14. Bipolar Circuit Topologies.

+IINR1D1-PD1+-IINR3A) RECEIVERVCCVINR1-PD1+D1-Q1+LEDLEDPD2R2-VOUT++IOUTR2PD2 R3-IOUTB) TRANSMITTERFigure 15. Loop-Powered 4-20 mA Current Loop Circuits.

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VCC2 +5 VVCC1 +5 VR510 KR7470VOUTQ42N3904Q32N3906PD2R610R310 KR168 KLEDR268 KQ22N3904Q12N3906R410VINPD1Figure 16. High-Speed Low-Cost Analog Isolator.

VCC1 +15 VC30.1µR42.2 KR5270Q12N3906R1200 K1%PD1C147 P72-6A13LT1097+4C40.1µR333 KD11N4150R66.8 KVCC2 +15 VC50.1µINPUTBNCC233 P76LT1097-2A23+4C60.1µR2174 K1 %PD250 KOUTPUTBNCVEE1 -15 VLEDVEE2 -15 VFigure 17. Precision Analog Isolation Amplifier.

C3 10 pfC1 10 pfR6180 KR2180 KD1-+R4680OC1LEDOC1PD2-VMAG+OC2PD1OC2LEDR5680OC2PD2R750 KGAINOC1PD1VINR150 KBALANCE+-D2R3180 KC2 10 pfFigure 18. Bipolar Isolation Amplifier.

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C3 10 pfC1 10 pfR5180 KD1-+VINR1220 KR4680 K OC1PD1D2R210 KR34.7 K+--+C2 10 pf+-R76.8 KD4VCCOC1LEDOC1PD2-VMAG+D3GAINR650 KR82.2 KVSIGNOC26N139Figure 19. Magnitude/Sign Isolation Amplifier.

H.SUBCKT HCNR200Figure 20. SPICE Model Listing.

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0.001 µF+ILOOPHCNR200LEDR110 kΩR4180 Ω+-R210 kΩ0.001 µF-ILOOPR325 ΩDESIGN EQUATIONS:VOUT / ILOOP = K3 (R5 R3) / R1 + R3)K3 = K2 / K1 = CONSTANT = 1NOTE: THE TWO OP-AMPS SHOWN ARE TWO SEPARATE LM158, AND NOT TWO CHANNELS IN A SINGLEDUAL PACKAGE, OTHERWISE THE LOOP SIDE AND OUTPUT SIDE WILL NOT BE PROPERLY ISOLATED.2LM1582N3906HCNR200PD 2Z15.1 V0.1 µFR580 kΩVCC5.5 V+HCNR200-PD 1-+-+LM158VOUTFigure 21. 4 to 20 mA HCNR200 Receiver Circuit.

VCC5.5 V0.001 µFR8100 kΩ2N3904Z15.1 V2N39042N39040.1 µFR73.2 kΩ1DESIGN EQUATIONS:(ILOOP / VIN) = K3 (R5 + R3) / R5 R1)K3 = K2 / K1 = CONSTANT = 1NOTE: THE TWO OP-AMPS SHOWN ARE TWO SEPARATE LM158, AND NOT TWO CHANNELS IN A SINGLEDUAL PACKAGE, OTHERWISE THE LOOP SIDE AND OUTPUT SIDE WILL NOT BE PROPERLY ISOLATED.R525 ΩR6140 Ω0.001 µFR410 kΩR310 kΩ+ILOOPR2150 ΩHCNR200LED2N3906VINR180 kΩVCCLM158HCNR200PD 2LM158HCNR200PD 1-ILOOPFigure 22. 4 to 20 mA HCNR200 Transmitter Circuit.

Theory of Operation

Figure 1 illustrates how theHCNR200/201 high-linearityoptocoupler is configured. Thebasic optocoupler consists of anLED and two photodiodes. TheLED and one of the photodiodes(PD1) is on the input leadframeand the other photodiode (PD2) ison the output leadframe. Thepackage of the optocoupler isconstructed so that each photo-diode receives approximately thesame amount of light from theLED.

An external feedback amplifiercan be used with PD1 to monitorthe light output of the LED andautomatically adjust the LEDcurrent to compensate for anynon-linearities or changes in lightoutput of the LED. The feedbackamplifier acts to stabilize andlinearize the light output of theLED. The output photodiode thenconverts the stable, linear lightoutput of the LED into a current,which can then be converted backinto a voltage by anotheramplifier.

Figure 12a illustrates the basiccircuit topology for implementinga simple isolation amplifier usingthe HCNR200/201 optocoupler.Besides the optocoupler, twoexternal op-amps and two

resistors are required. This simplecircuit is actually a bit too simpleto function properly in an actualcircuit, but it is quite useful forexplaining how the basic isolationamplifier circuit works (a fewmore components and a circuitchange are required to make apractical circuit, like the oneshown in Figure 12b).

The operation of the basic circuitmay not be immediately obviousjust from inspecting Figure 12a,

particularly the input part of thecircuit. Stated briefly, amplifierA1 adjusts the LED current (IF),and therefore the current in PD1(IPD1), to maintain its “+” inputterminal at 0 V. For example,

increasing the input voltage wouldtend to increase the voltage of the“+” input terminal of A1 above 0V. A1 amplifies that increase,causing IF to increase, as well asIPD1. Because of the way that PD1is connected, IPD1 will pull the “+”terminal of the op-amp backtoward ground. A1 will continueto increase IF until its “+”

terminal is back at 0 V. Assumingthat A1 is a perfect op-amp, nocurrent flows into the inputs ofA1; therefore, all of the currentflowing through R1 will flow

through PD1. Since the “+” inputof A1 is at 0 V, the current

through R1, and therefore IPD1 aswell, is equal to VIN/R1.

Essentially, amplifier A1 adjusts IFso that

IPD1 = VIN/R1.

Notice that IPD1 depends ONLY onthe input voltage and the value ofR1 and is independent of the lightoutput characteristics of the LED.As the light output of the LEDchanges with temperature, ampli-fier A1 adjusts IF to compensateand maintain a constant currentin PD1. Also notice that IPD1 isexactly proportional to VIN, givinga very linear relationship betweenthe input voltage and thephotodiode current.

The relationship between the inputoptical power and the outputcurrent of a photodiode is verylinear. Therefore, by stabilizingand linearizing IPD1, the lightoutput of the LED is alsostabilized and linearized. And

15

since light from the LED falls onboth of the photodiodes, IPD2 willbe stabilized as well.

The physical construction of thepackage determines the relativeamounts of light that fall on thetwo photodiodes and, therefore,the ratio of the photodiodecurrents. This results in verystable operation over time andtemperature. The photodiodecurrent ratio can be expressed asa constant, K, where

K = IPD2/IPD1.

Amplifier A2 and resistor R2 forma trans-resistance amplifier thatconverts IPD2 back into a voltage,VOUT, where

VOUT = IPD2*R2.

Combining the above threeequations yields an overallexpression relating the outputvoltage to the input voltage,

VOUT/VIN = K*(R2/R1).Therefore the relationship

between VIN and VOUT is constant,linear, and independent of thelight output characteristics of theLED. The gain of the basic isola-tion amplifier circuit can beadjusted simply by adjusting theratio of R2 to R1. The parameterK (called K3 in the electrical

specifications) can be thought ofas the gain of the optocoupler andis specified in the data sheet.Remember, the circuit in

Figure12a is simplified in orderto explain the basic circuit opera-tion. A practical circuit, more likeFigure12b, will require a few

additional components to stabilizethe input part of the circuit, tolimit the LED current, or to

optimize circuit performance.Example application circuits willbe discussed later in the datasheet.

Circuit Design Flexibility

Circuit design with the HCNR200/201 is very flexible because theLED and both photodiodes areaccessible to the designer. Thisallows the designer to make perf-ormance trade-offs that wouldotherwise be difficult to make withcommercially available isolationamplifiers (e.g., bandwidth vs.accuracy vs. cost). Analog isola-tion circuits can be designed forapplications that have eitherunipolar (e.g., 0-10 V) or bipolar(e.g., ±10 V) signals, withpositive or negative input or

output voltages. Several simplifiedcircuit topologies illustrating thedesign flexibility of the HCNR200/201 are discussed below.The circuit in Figure 12a isconfigured to be non-invertingwith positive input and outputvoltages. By simply changing thepolarity of one or both of thephotodiodes, the LED, or the op-amp inputs, it is possible to

implement other circuit configu-rations as well. Figure 13illustrates how to change thebasic circuit to accommodateboth positive and negative inputand output voltages. The inputand output circuits can be

matched to achieve any combina-tion of positive and negativevoltages, allowing for bothinverting and non-invertingcircuits.

All of the configurations describedabove are unipolar (single polar-ity); the circuits cannot accommo-date a signal that might swingboth positive and negative. It is

possible, however, to use theHCNR200/201 optocoupler toimplement a bipolar isolationamplifier. Two topologies thatallow for bipolar operation areshown in Figure 14.

The circuit in Figure14a uses twocurrent sources to offset thesignal so that it appears to beunipolar to the optocoupler.Current source IOS1 providesenough offset to ensure that IPD1is always positive. The secondcurrent source, IOS2, provides anoffset of opposite polarity to

obtain a net circuit offset of zero.Current sources IOS1 and IOS2 canbe implemented simply asresistors connected to suitablevoltage sources.

The circuit in Figure14b uses twooptocouplers to obtain bipolaroperation. The first optocouplerhandles the positive voltageexcursions, while the secondoptocoupler handles the negativeones. The output photodiodes areconnected in an antiparallelconfiguration so that theyproduce output signals ofopposite polarity.

The first circuit has the obviousadvantage of requiring only oneoptocoupler; however, the offsetperformance of the circuit is

dependent on the matching of IOS1and IOS2 and is also dependent onthe gain of the optocoupler.Changes in the gain of the opto-coupler will directly affect theoffset of the circuit.

The offset performance of thesecond circuit, on the other hand,is much more stable; it is inde-pendent of optocoupler gain andhas no matched current sourcesto worry about. However, the

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second circuit requires twooptocouplers, separate gainadjustments for the positive andnegative portions of the signal,and can exhibit crossover distor-tion near zero volts. The correctcircuit to choose for an applica-tion would depend on the

requirements of that particularapplication. As with the basicisolation amplifier circuit in

Figure12a, the circuits in Figure14 are simplified and wouldrequire a few additional compo-nents to function properly. Twoexample circuits that operate withbipolar input signals are

discussed in the next section.As a final example of circuitdesign flexibility, the simplifiedschematics in Figure 15 illustratehow to implement 4-20 mAanalog current-loop transmitterand receiver circuits using theHCNR200/201 optocoupler. Animportant feature of these circuitsis that the loop side of the circuitis powered entirely by the loopcurrent, eliminating the need foran isolated power supply.The input and output circuits inFigure 15a are the same as thenegative input and positive outputcircuits shown in Figures 13c and13b, except for the addition of R3and zener diode D1 on the inputside of the circuit. D1 regulatesthe supply voltage for the inputamplifier, while R3 forms acurrent divider with R1 to scalethe loop current down from 20mA to an appropriate level for theinput circuit (<50 µA).

As in the simpler circuits, theinput amplifier adjusts the LEDcurrent so that both of its inputterminals are at the same voltage.The loop current is then divided

between R1 and R3. IPD1 is equalto the current in R1 and is givenby the following equation:IPD1 = ILOOP*R3/(R1+R3).Combining the above equationwith the equations used for Figure12a yields an overall expressionrelating the output voltage to theloop current,

VOUT/ILOOP = K*(R2*R3)/(R1+R3).Again, you can see that therelationship is constant, linear,and independent of the charac-teristics of the LED.

The 4-20 mA transmitter circuit inFigure15b is a little differentfrom the previous circuits, partic-ularly the output circuit. Theoutput circuit does not directlygenerate an output voltage whichis sensed by R2, it instead usesQ1 to generate an output currentwhich flows through R3. Thisoutput current generates a

voltage across R3, which is thensensed by R2. An analysis similarto the one above yields thefollowing expression relatingoutput current to input voltage:ILOOP/VIN = K*(R2+R3)/(R1*R3).The preceding circuits were pre-sented to illustrate the flexibilityin designing analog isolationcircuits using the HCNR200/201.The next section presents severalcomplete schematics to illustratepractical applications of theHCNR200/201.

Example ApplicationCircuits

The circuit shown in Figure 16 isa high-speed low-cost circuitdesigned for use in the feedbackpath of switch-mode power

supplies. This application requiresgood bandwidth, low cost andstable gain, but does not requirevery high accuracy. This circuit isa good example of how a designercan trade off accuracy to achieveimprovements in bandwidth andcost. The circuit has a bandwidthof about 1.5 MHz with stable gaincharacteristics and requires fewexternal components.

Although it may not appear so atfirst glance, the circuit in Figure16 is essentially the same as thecircuit in Figure 12a. Amplifier A1is comprised of Q1, Q2, R3 andR4, while amplifier A2 is

comprised of Q3, Q4, R5, R6 andR7. The circuit operates in thesame manner as well; the onlydifference is the performance ofamplifiers A1 and A2. The lowergains, higher input currents andhigher offset voltages affect theaccuracy of the circuit, but notthe way it operates. Because thebasic circuit operation has notchanged, the circuit still has goodgain stability. The use of discretetransistors instead of op-ampsallowed the design to trade offaccuracy to achieve good

bandwidth and gain stability atlow cost.

To get into a little more detailabout the circuit, R1 is selected toachieve an LED current of about7-10 mA at the nominal input

operating voltage according to thefollowing equation:

IF = (VIN/R1)/K1,

where K1 (i.e., IPD1/IF) of theoptocoupler is typically about0.5%. R2 is then selected to

achieve the desired output voltageaccording to the equation,

VOUT/VIN = R2/R1.

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The purpose of R4 and R6 is toimprove the dynamic response(i.e., stability) of the input andoutput circuits by lowering thelocal loop gains. R3 and R5 areselected to provide enough

current to drive the bases of Q2and Q4. And R7 is selected so thatQ4 operates at about the samecollector current as Q2.

The next circuit, shown in

Figure17, is designed to achievethe highest possible accuracy at areasonable cost. The high

accuracy and wide dynamic rangeof the circuit is achieved by usinglow-cost precision op-amps withvery low input bias currents andoffset voltages and is limited bythe performance of the opto-coupler. The circuit is designed tooperate with input and outputvoltages from 1 mV to 10 V.The circuit operates in the sameway as the others. The only majordifferences are the two compensa-tion capacitors and additionalLED drive circuitry. In the high-speed circuit discussed above, theinput and output circuits arestabilized by reducing the localloop gains of the input and outputcircuits. Because reducing theloop gains would decrease theaccuracy of the circuit, two

compensation capacitors, C1 andC2, are instead used to improvecircuit stability. These capacitorsalso limit the bandwidth of thecircuit to about 10 kHz and canbe used to reduce the output

noise of the circuit by reducing itsbandwidth even further.

The additional LED drive circuitry(Q1 and R3 through R6) helps tomaintain the accuracy and band-width of the circuit over the entirerange of input voltages. Withoutthese components, the transcon-ductance of the LED driver would

decrease at low input voltagesand LED currents. This wouldreduce the loop gain of the inputcircuit, reducing circuit accuracyand bandwidth. D1 preventsexcessive reverse voltage frombeing applied to the LED whenthe LED turns off completely.No offset adjustment of the circuitis necessary; the gain can beadjusted to unity by simplyadjusting the 50kohm poten-tiometer that is part of R2. AnyOP-97 type of op-amp can beused in the circuit, such as theLT1097 from Linear Technologyor the AD705 from Analog

Devices, both of which offer pAbias currents, µV offset voltagesand are low cost. The input

terminals of the op-amps and thephotodiodes are connected in thecircuit using Kelvin connectionsto help ensure the accuracy of thecircuit.

The next two circuits illustratehow the HCNR200/201 can beused with bipolar input signals.The isolation amplifier in

Figure18 is a practical implemen-tation of the circuit shown inFigure14b. It uses two opto-couplers, OC1 and OC2; OC1handles the positive portions ofthe input signal and OC2 handlesthe negative portions.

Diodes D1 and D2 help reducecrossover distortion by keepingboth amplifiers active during bothpositive and negative portions ofthe input signal. For example,when the input signal positive,optocoupler OC1 is active whileOC2 is turned off. However, theamplifier controlling OC2 is keptactive by D2, allowing it to turnon OC2 more rapidly when theinput signal goes negative,thereby reducing crossoverdistortion.

Balance control R1 adjusts therelative gain for the positive andnegative portions of the inputsignal, gain control R7 adjusts theoverall gain of the isolation

amplifier, and capacitors C1-C3provide compensation to stabilizethe amplifiers.

The final circuit shown inFigure19 isolates a bipolaranalog signal using only oneoptocoupler and generates twooutput signals: an analog signalproportional to the magnitude ofthe input signal and a digitalsignal corresponding to the signof the input signal. This circuit isespecially useful for applicationswhere the output of the circuit isgoing to be applied to an analog-to-digital converter. The primaryadvantages of this circuit are verygood linearity and offset, withonly a single gain adjustment andno offset or balance adjustments.To achieve very high linearity forbipolar signals, the gain should beexactly the same for both positiveand negative input polarities. Thiscircuit achieves excellent linearityby using a single optocoupler anda single input resistor, which

guarantees identical gain for bothpositive and negative polarities ofthe input signal. This precisematching of gain for both polari-ties is much more difficult to

obtain when separate componentsare used for the different inputpolarities, such as is the previouscircuit.

The circuit in Figure19 is actuallyvery similar to the previous

circuit. As mentioned above, onlyone optocoupler is used. Becausea photodiode can conduct currentin only one direction, two diodes(D1 and D2) are used to steer theinput current to the appropriateterminal of input photodiode PD1

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to allow bipolar input currents.Normally the forward voltage

drops of the diodes would cause aserious linearity or accuracyproblem. However, an additionalamplifier is used to provide anappropriate offset voltage to theother amplifiers that exactly

cancels the diode voltage drops tomaintain circuit accuracy.Diodes D3 and D4 perform twodifferent functions; the diodeskeep their respective amplifiersactive independent of the inputsignal polarity (as in the previouscircuit), and they also provide thefeedback signal to PD1 thatcancels the voltage drops ofdiodes D1 and D2.

Either a comparator or an extraop-amp can be used to sense thepolarity of the input signal anddrive an inexpensive digitaloptocoupler, like a 6N139.It is also possible to convert thiscircuit into a fully bipolar circuit(with a bipolar output signal) byusing the output of the 6N139 todrive some CMOS switches toswitch the polarity of PD2

depending on the polarity of theinput signal, obtaining a bipolaroutput voltage swing.

HCNR200/201 SPICEModel

Figure 20 is the net list of aSPICE macro-model for theHCNR200/201 high-linearityoptocoupler. The macro-modelaccurately reflects the primarycharacteristics of the HCNR200/201 and should facilitate thedesign and understanding ofcircuits using the HCNR200/201optocoupler.

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