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features ? low nonlinearity: 0.01% ? k 3 (i pd2 /i pd1 ) transfer gain hcnr200: 15% hcnr201: 5% ? low gain temperature coefcient: ?65 ppm/c ? wide bandwidth C dc to >1 mhz ? worldwide safety approval C ul 1577 recognized (5 kv rms/1 min rating) C csa approved C iec/en/din en 60747?5? 2 approved v iorm = 1414 v peak (option #050) ? surface mount option available (option #300) ? 8? pin dip package ? 0.400 spacing ? allows fexible circuit design applications ? low cost analog isolation ? telecom: modem, pbx ? industrial process control: transducer isolator isolator for thermo couples 4 ma to 20 ma loop isola ? tion ? smps feedback loop, smps feedforward ? monitor motor supply voltage ? medical description the hcnr200/201 high ? linearity analog optocoupler consists of a high ? performance algaas led that illumi ? nates two closely matched photodiodes. the input pho ? todiode can be used to monitor, and therefore stabilize, the light output of the led. as a result, the non ? linearity and drift characteristics of the led can be virtually elimi ? nated. the output photodiode produces a photocur rent that is linearly related to the light output of the led. the close matching of the photo ? diodes and advanced de ? sign of the package ensure the high linearity and stable gain characteristics of the opto coupler. the hcnr200/201 can be used to isolate analog signals in a wide variety of applications that require good stabil ? ity, linearity, bandwidth and low cost. the hcnr200/201 is very fexible and, by appro priate design of the appli ? cation circuit, is capable of operating in many diferent modes, includ ing: unipolar/bipolar, ac/dc and inverting/ non? inverting. the hcnr200/201 is an excellent solution for many analog isola tion problems. schematic hcnr200 and hcnr201 high-linearity analog optocouplers data sheet caution: 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. lead (pb) free rohs 6 fully compliant rohs 6 fully compliant options available; -xxxe denotes a lead-free product 3 4 1 2 v f - + i f i pd1 6 5 i pd2 8 7 nc nc pd2 cathode pd2 anode led cathode led anode pd1 cathode pd1 anode
2 ordering information hcnr200/hcnr201 is ul recognized with 5000 vrms for 1 minute per ul1577. option iec/en/din en part rohs non rohs surface gull tape ul 5000 vrms/ 60747-5-2 number compliant compliant package mount wing & reel 1 minute rating v iorm = 1414 v peak quantity ? 000e no option 400 mil x 42 per tube ? 300e #300 widebody x x x 42 per tube hcnr200 ? 500e #500 dip ?8 x x x x 750 per reel hcnr201 ? 050e #050 x x 42 per tube ? 350e #350 x x x x 42 per tube ? 550e #550 x x x x x 750 per reel to order, choose a part number from the part number column and combine with the desired option from the option column to form an order entry. example 1: hcnr200? 550e to order product of gull wing surface mount package in tape and reel packaging with iec/en/ din en 60747?5? 2 v iorm = 1414 v peak safety approval and ul 5000 vrms for 1 minute rating and rohs compliant. example 2: hcnr201 to order product of 8 ? pin widebody dip package in tube packaging with ul 5000 vrms for 1 minute rating and non rohs compliant. option datasheets are available. contact your avago sales representative or authorized distributor for information. remarks: the notation #xxx is used for existing products, while (new) products launched since july 15, 2001 and rohs compliant will use Cxxxe.
3 package outline drawings figure 1a. 8 pin dip 0.40 (0.016) 0.56 (0.022) 1 2 3 4 8 7 6 5 1.70 (0.067) 1.80 (0.071) 2.54 (0.100) typ. 0.51 (0.021) min. 5.10 (0.201) max. 3.10 (0.122) 3.90 (0.154) dimensions in millimeters and (inches). marking : yy - year ww - work week marked with black dot - designates lead free option e xxx = 050 only if option #050,#350,#550 (or -050,-350,-550) ordered (otherwise blank) * - designates pin 1 note: floating lead protrusion is 0.25 mm (10 mils) max. nc pd1 k 1 11.30 (0.445) max. pin one 1.50 (0.059) max. a hcnr200 yyww marking 8 7 6 5 1 2 3 4 9.00 (0.354) typ. 0.20 (0.008) 0.30 (0.012) 0 15 11.00 (0.433) max. 10.16 (0.400) typ. k 2 pd2 nc led ? eee * lot id
4 gull wing surface mount option #300 1.00 0.15 (0.039 0.006) 7 nom. 12.30 0.30 (0.484 0.012) 0.75 0.25 (0.030 0.010) 11.00 (0.433) 5 6 7 8 4 3 2 1 11.15 0.15 (0.442 0.006) 9.00 0.15 (0.354 0.006) 1.3 (0.051) 13.56 (0.534) 2.29 (0.09) land pattern recommendation 1.78 0.15 (0.070 0.006) 4.00 (0.158) max. 1.55 (0.061) max. 2.54 (0.100) bsc dimensions in millimeters (inches). lead coplanarity = 0.10 mm (0.004 inches). note: floating lead protrusion is 0.25 mm (10 mils) max. 0.254 + 0.076 - 0.0051 (0.010 + 0.003) - 0.002) max. figure 1b. 8 pin gull wing surface mount option #300
5 solder refow temperature profle regulatory information the hcnr200/201 optocoupler features a 0.400 wide, eight pin dip package. this package was specifcally designed to meet worldwide regulatory require ments. the hcnr200/201 has been approved by the following organizations: recommended pb-free ir profle 0 time (seconds) temperature (c) 200 100 50 150 100 200 250 300 0 30 sec. 50 sec. 30 sec. 160 c 140 c 150 c peak temp. 245 c peak temp. 240 c peak temp. 230 c soldering time 200 c preheating time 150 c, 90 + 30 sec. 2.5 c 0.5 c/sec. 3 c + 1 c/?0.5 c tight typical loose room temperature preheating rate 3 c + 1 c/?0.5 c/sec. reflow heating rate 2.5 c 0.5 c/sec. no te: non-halide fl ux should be used . 217 c ramp -down 6 c/sec. ma x. ramp -up 3 c/sec. ma x. 150 - 200 c * 245 +0/-5 c t 25 c t o peak 60 t o 150 sec. 15 sec. time within 5 c of a c tu al peak tempera ture t p t s prehea t 60 t o 180 sec. t l t l t smax t smin 25 t p time tempera ture no tes: the time from 25 c t o peak tempera ture = 8 minutes ma x. t smax = 200 c, t smin = 150 c no te: non-halide fl ux should be used . ul recognized under ul 1577, component recognition program, file e55361 csa approved under csa component acceptance notice #5, file ca 88324 iec/en/din en 60747-5-2 approved under iec 60747?5?2:1997 + a1:2002 en 60747?5?2:2001 + a1:2002 din en 60747?5? 2 (vde 0884 teil 2):2003?01 (option 050 only)
6 insulation and safety related specifcations parameter symbol value units conditions min. external clearance l(io1) 9.6 mm measured from input terminals to output (external air gap) terminals, shortest distance through air min. external creepage l(io2) 10.0 mm measured from input terminals to output (external tracking path) terminals, shortest distance path along body min. internal clearance 1.0 mm through insulation distance conductor to (internal plastic gap) conductor, usually the direct distance between the photoemitter and photodetector inside the optocoupler cavity min. internal creepage 4.0 mm the shortest distance around the border (internal tracking path) between two diferent insulating materials measured between the emitter and detector comparative tracking index cti 200 v din iec 112/vde 0303 part 1 isolation group iiia material group (din vde 0110) option 300 C surface mount classifcation is class a in accordance with cecc 00802. iec/en/din en 60747-5-2 insulation characteristics (option #050 only) description symbol characteristic unit installation classifcation per din vde 0110/1.89, table 1 for rated mains voltage 600 v rms i?iv for rated mains voltage 1000 v rms i?iii climatic classifcation (din iec 68 part 1) 55/100/21 pollution degree (din vde 0110 part 1/1.89) 2 maximum working insulation voltage v iorm 1414 v peak input to output test voltage, method b* v pr 2651 v peak v pr = 1.875 x v iorm , 100% production test with t m = 1 sec, partial discharge < 5 pc input to output test voltage, method a* v pr 2121 v peak v pr = 1.5 x v iorm , type and sample test, t m = 60 sec, partial discharge < 5 pc highest allowable overvoltage* v iotm 8000 v peak (transient overvoltage, t ini = 10 sec) safety ? limiting values (maximum values allowed in the event of a failure, also see figure 11) case temperature t s 150 c current (input current i f , p s = 0) i s 400 ma output power p s,output 700 mw insulation resistance at t s , v io = 500 v r s >10 9 *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 and other prod ? uct safety regulations. note: optocouplers providing safe electrical separation per iec/en/din en 60747?5? 2 do so only within the safety ? limiting values to which they are qualifed. protective cut ? out switches must be used to ensure that the safety limits are not exceeded.
7 absolute maximum ratings storage temperature .............................................................................................. ? 55c to +125c operating temperature (t a ) ................................................................................. ? 55c to +100c junction temperature (t j ) ......................................................................................................... 125c refow temperature profle .............................................. see package outline drawings section lead solder temperature ............................................................................................ 260c for 10s (up to seating plane) average input current ? i f ........................................................................................................ 25 ma peak input current ? i f ............................................................................................................... 40 ma (50 ns maximum pulse width) reverse input voltage ? v r ............................................................................................................ 2.5 v (i r = 100 a, pin 1 ?2) input power dissipation .................................................................................... 60 mw @ t a = 85c (derate at 2.2 mw/c for operating temperatures above 85c) reverse output photodiode voltage ........................................................................................ 30 v (pin 6 ?5) reverse input photodiode voltage ............................................................................................ 30 v (pin 3 ?4) recommended operating conditions storage temperature ................................................................................................. ? 40c to +85c operating temperature ............................................................................................ ? 40c to +85c average input current ? i f .................................................................................................. 1 ? 20 ma peak input current ? i f ............................................................................................................... 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)
8 electrical specifcations t a = 25c unless otherwise specifed. parameter symbol device min. typ. max. units test conditions fig. note transfer gain k 3 hcnr200 0.85 1.00 1.15 5 na < i pd < 50 a, 2,3 1 0 v < v pd < 15 v hcnr201 0.95 1.00 1.05 5 na < i pd < 50 a, 1 0 v < v pd < 15 v hcnr201 0.93 1.00 1.07 ? 40c < t a < 85c, 1 5 na < i pd < 50 a, 0 v < v pd < 15 v temperature ?k 3 /?t a ? 65 ppm/c ? 40c < t a < 85c, 2,3 coefcient of 5 na < i pd < 50 a, transfer gain 0 v < v pd < 15 v dc nonlinearity nl bf hcnr200 0.01 0.25 % 5 na < i pd < 50 a, 4,5, 2 (best fit) 0 v < v pd < 15 v 6 hcnr201 0.01 0.05 5 na < i pd < 50 a, 2 0 v < v pd < 15 v hcnr201 0.01 0.07 ? 40c < t a < 85c, 2 5 na < i pd < 50 a, 0 v < v pd < 15 v dc nonlinearity nl ef 0.016 5 na < i pd < 50 a, 3 (ends fit) % 0 v < v pd < 15 v input photo ? k 1 hcnr200 0.25 0.50 0.75 % i f = 10 ma, 7 diode current 0 v < v pd1 < 15 v transfer ratio hcnr201 0.36 0.48 0.72 (i pd1 /i f ) temperature ?k 1 /?t a ? 0.3 %/c ? 40c < t a < 85c, 7 coefcient i f = 10 ma of k 1 0 v < v pd1 < 15 v photodiode i lk 0.5 25 na i f = 0 ma, 8 leakage current 0 v < v pd < 15 v photodiode bv rpd 30 150 v i r = 100 a reverse break ? down voltage photodiode c pd 22 pf v pd = 0 v capacitance led forward v f 1.3 1.6 1.85 v i f = 10 ma 9, voltage 10 1.2 1.6 1.95 i f = 10 ma, ? 40c < t a < 85c led reverse bv r 2.5 9 v i f = 100 a breakdown voltage temperature ?v f /?t a ? 1.7 mv/c i f = 10 ma coefcient of forward voltage led junction c led 80 pf f = 1 mhz, capacitance v f = 0 v
9 ac electrical specifcations t a = 25c unless otherwise specifed. test parameter symbol device min. typ. max. units conditions fig. note led bandwidth f ?3db 9 mhz i f = 10 ma application circuit bandwidth: high speed 1.5 mhz 16 6 high precision 10 khz 17 6 application circuit: imrr high speed 95 db freq = 60 hz 16 6, 7 notes: 1. k 3 is calculated from the slope of the best ft line of i pd2 vs. i pd1 with eleven equally distributed data points from 5 na to 50 a. this is approxi ? mately equal to i pd2 /i pd1 at i f = 10 ma. 2. best fit dc nonlinearity (nl bf ) is the maximum deviation expressed as a percentage of the full scale output of a best ft straight line from a graph of i pd2 vs. i pd1 with eleven equally distrib uted data points from 5 na to 50 a. i pd2 error to best ft line is the deviation below and above the best ft line, expressed as a percentage of the full scale output. 3. ends fit dc nonlinearity (nl ef ) is the maximum deviation expressed as a percentage of full scale output of a straight line from the 5 na to the 50 a data point on the graph of i pd2 vs. i pd1 . 4. device considered a two ? terminal device: pins 1, 2, 3, and 4 shorted together and pins 5, 6, 7, and 8 shorted together. 5. in accordance with ul 1577, each optocoupler is proof tested by applying an insulation test voltage of 6000 v rms for 1 second (leakage detection current limit, i i? o of 5 a max.). this test is performed before the 100% production test for partial discharge (method b) shown in the iec/en/din en 60747?5? 2 insulation characteris? tics table (for option #050 only). 6. specifc performance will depend on circuit topology and components. 7. imrr is defned as the ratio of the signal gain (with signal applied to v in of figure 16) to the isolation mode gain (with v in connected to input common and the signal applied between the input and output commons) at 60 hz, expressed in db. package characteristics t a = 25c unless otherwise specifed. test parameter symbol device min. typ. max. units conditions fig. note input ? output v iso 5000 v rms rh 50%, 4, 5 momentary ? withstand t = 1 min. voltage* resistance r i? o 10 12 10 13 v o = 500 vdc 4 (input ? output) 10 11 t a = 100c, 4 v io = 500 vdc capacitance c i? o 0.4 0.6 pf f = 1 mhz 4 (input ? output) *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), your equipment level safety specifcation, or application note 1074, optocoupler input ? output endurance voltage.
10 figure 5. nl bf vs. temperature. figure 2. normalized k3 vs. input i pd . figure 3. k3 drift vs. temperature. figure 4. i pd2 error vs. input i pd (see note 4). figure 6. nl bf drift vs. temperature. figure 7. input photodiode ctr vs. led input current. figure 8. typical photodiode leakage vs. temperature. figure 9. led input current vs. forward voltage. figure 10. led forward voltage vs. temperature. i lk C photodiode leakage C na 10.0 4.0 0.0 t a C temperature C c 6.0 2.0 cnr200 fig 8 8.0 -25 -55 5 35 65 95 125 v pd = 15 v delta k3 C drift of k3 transfer gain 0.02 -0.005 -0.02 t a C temperature C c 0.01 0.005 -0.01 -0.015 hcnr200 fig 3 = delta k3 mean? = delta k3 mean 2 ? std dev 0.0 0.015 -25 -55 53 56 59 5 125 0 v < v pd < 15 v delta nl bf C drift of best-fit nl C % pts 0.02 -0.005 -0.02 t a C temperature C c 0.01 0.005 -0.01 -0.015 hcnr200 fig 6 = delta nl bf mean? = delta nl bf mean 2 ? std dev 0.0 0.015 -25 -55 53 56 59 5 125 0 v < v pd < 15 v? 5 na < i pd < 50 a normalized k1 C input photodiode ctr 0.0 0.5 0.2 i f C led input current C m a 2.0 6.0 12.0 0.6 0.4 0.3 4.0 8.0 10.0 hcnr200 fig 7 0.7 0.8 0.9 1.0 1.1 1.2 14.0 16.0 -55c 25c -40c 85c 100c normalized to k1 ctr ? at i f = 10 ma, t a = 25c? 0 v < v pd1 < 15 v v f C led forward voltage C v 1.5 1.2 t a C temperature C c 1.8 1.7 1.4 1.3 hcnr200 fig 10 1.6 -25 -55 53 56 59 5 125 i f = 10 ma normalized k3 C transfer gain 0.0 1.06 1.00 0.94 i pd1 C input photodiode current C a 10.0 30.0 60.0 1.04 1.02 0.98 0.96 20.0 40.0 50.0 hcnr200 fig 2 = norm k3 mean? = norm k3 mean 2 ? std dev normalized to best-fit k3 at t a = 25c,? 0 v < v pd < 15 v 0.0 0.03 0.00 -0.03 i pd1 C input photodiode current C a 10.0 30.0 60.0 0.02 0.01 -0.01 -0.02 20.0 40.0 50.0 hcnr200 fig 4 = error mean = error mean 2 ? std dev i pd2 error from best-fit line (% of fs ) t a = 25 c, 0 v < v pd < 15 v nl bf C best-fit non-linearity C % 0.015 0.00 t a C temperature C c 0.03 0.025 0.01 0.005 hcnr200 fig 5 = nl bf 50th percentile ? = nl bf 90th percentile 0.02 0.035 -25 -55 53 56 59 5 125 0 v < v pd < 15 v? 5 na < i pd < 50 a 1.20 100 0.1 0.0001 v f C forward voltage C volts 1.30 1.50 10 1 0.01 0.001 1.40 1.60 cnr200 fig 9 i f C forward current C m a t a = 25c
11 figure 12. basic isolation amplifer. figure 11. thermal derating curve dependence of safety limiting value with case temperature per iec/en/din en 60747-5-2. figure 13. unipolar circuit topologies. 0 800 300 0 t s C case temperature C c 25 75 150 600 500 200 100 50 100 125 cnr200 fig 11 p s output power C m v i s input current C m a 400 700 900 1000 175 - + v in - + v out v in - + - + v out a) positive input cnr200 fig 13 v cc b) positive output c) negative input d) negative output i f led i pd1 pd1 r1 v in a1 + - i pd2 pd2 r2 a2 - + v out pd1 r1 v in a1 - + pd2 pd2 r2 a2 - + v out a) basic topology b) practical circuit cnr200 fig 12 c1 r3 v cc led c2
12 figure 15. loop-powered 4-20 ma current loop circuits. figure 14. bipolar circuit topologies. - + v out +i in - + - + +i out a) receiver cnr200 fig 15 b) transmitter pd2 v in - + v cc -i in r1 r3 pd1 led d1 r2 r1 pd1 led -i out r2 r3 pd2 d1 q1 - + - + v out v in - + - + v out a) single optocoupler cnr200 fig 14 v cc1 b) dual optocoupler v cc1 ios1 v cc2 ios2 v in - + v cc
13 figure 18. bipolar isolation amplifer. figure 16. high-speed low-cost analog isolator. figure 17. precision analog isolation amplifer. - + v mag - + v in oc1 pd1 + - oc2 pd1 r1 50 k d2 c2 10 pf c1 10 pf d1 r4 680 r5 680 oc1 led oc2 led r3 180 k r2 180 k balance c3 10 pf oc1 pd2 r6 180 k r 50 k gain oc2 pd2 v cc1 +15 v v ee1 -15 v cnr200 fig 16 v in v cc1 +5 v r1 68 k pd1 led r3 10 k q1 2n3906 r4 10 q2 2n3904 v cc2 +5 v r2 68 k pd2 r5 10 k q3 2n3906 r6 10 q4 2n3904 r7 470 v out cnr200 fig 17 - + pd1 2 3 a1 7 4 r1 200 k input bnc 1% c3 0.1 v cc1 +15 v c1 47 p lt1097 r6 6.8 k r4 2.2 k r5 270 q1 2n3906 v ee1 -15 v c4 0.1 r3 33 k led d1 1n4150 - + pd2 2 3 a2 7 4 c2 33 p output bnc 174 k lt1097 50 k 1 % v ee2 -15 v c6 0.1 r2 c5 0.1 v cc2 +15 v 6 6
14 figure 20. spice model listing. figure 19. magnitude/sign isolation amplifer. - + v mag - + v in oc1 pd1 + - d4 c2 10 pf c1 10 pf d3 r4 680 oc1 led r1 220 k c3 10 pf oc1 pd2 r5 180 k r6 50 k gain r2 10 k r3 4.7 k d1 - + d2 + - r7 6.8 k v cc r8 2.2 k v ign oc2 6n13 v cc1 +15 v v ee1 -15 v
15 figure 21. 4 to 20 ma hcnr200 receiver circuit. figure 22. 4 to 20 ma hcnr200 transmitter circuit. - + v out - + hcnr200 fig 21 v cc 5.5 v r1 10 k +iloop hcnr200 pd1 -iloop r2 10 k r4 100 2n3906 z1 5.1 v 0.1 f r3 25 0.001 f r5 80 k lm158 hcnr200 pd2 0.001 f 2 hcnr200 led lm158 design equations: vout / iloop = k3 (r5 r3) / r1 + r3) k3 = k2 / k1 = constant = 1 note: the two op ? amps shown are two separate lm158, and not two channels in a single dual package, otherwise the loop side and output side will not be properly isolated. design equations: (iloop/vin)=k3(r5+r3)/(r5r1) k3 = k2/k1 = constant 1 note: the two op ? amps shown are two separate lm158 ics, and not dual channels in a single package, otherwise, the loop side and input side will not be properly isolated; the 5v1 zener should be properly selected to ensure that it conducts at 187a; - + 80k pd1/ic1 lm158 ic2 led/ic1 hcnr200 1nf 150 q1 2n3906 r1 r2 vcc 5.5v vin 0.8v~4v c1 - + lm158 ic3 pd2/ic1 1nf 10k 25 10k 3k2 5v1 100nf 100k 150 q2 q3 q4 2n3904 2n3904 2n3904 r3 r4 r5 r6 r7 r8 c2 c3 +i loop - i loop 12v~40v 4 ~ 20ma 4ma (vin=0.8v) 20ma(vin=4v) ?0? @ 2200hz ?1? @ 1200hz
16 theory of operation figure 1 illustrates how the hcnr200/201 high ? linearity opto coup ler is confgured. the basic optocoupler con ? sists of an led and two photodiodes. the led and one of the photodiodes (pd1) is on the input leadframe and the other photodiode (pd2) is on the output leadframe. the package of the optocoupler is constructed so that each photo diode receives approxi mately the same amount of light from the led. an external feedback amplifer can be used with pd1 to monitor the light output of the led and automatically adjust the led current to compensate for any non ?linear ? ities or changes in light output of the led. the feedback amplifer acts to stabilize and linearize the light output of the led. the output photodiode then converts the stable, linear light output of the led into a current, which can then be converted back into a voltage by another amplifer. figure 12a illustrates the basic circuit topology for implement ing a simple isolation amplifer using the hcnr200/201 optocoupler. besides the optocoupler, two external op ? amps and two resistors are required. this simple circuit is actually a bit too simple to function properly in an actual circuit, but it is quite useful for ex ? plaining how the basic isolation amplifer circuit works (a few more components and a circuit change are required to make a practical circuit, like the one shown in figure 12b). the operation of the basic circuit may not be immedi ? ately obvious just from inspecting figure 12a, particu ? larly the input part of the circuit. stated briefy, amplifer a1 adjusts the led current (i f ), and therefore the current in pd1 (i pd1 ), to maintain its + input terminal at 0 v. for example, increasing the input voltage would tend to in ? crease the voltage of the + input terminal of a1 above 0 v. a1 amplifes that increase, causing i f to increase, as well as i pd1 . because of the way that pd1 is connected, i pd1 will pull the + terminal of the op ? amp back toward ground. a1 will continue to increase i f until its + termi ? nal is back at 0 v. assuming that a1 is a perfect op ? amp, no current fows into the inputs of a1; therefore, all of the current fowing through r1 will fow through pd1. since the + input of a1 is at 0 v, the current through r1, and there fore i pd1 as well, is equal to v in /r1. essentially, amplifer a1 adjusts i f so that i pd1 = v in /r1. notice that i pd1 depends only on the input voltage and the value of r1 and is independent of the light output characteris tics of the led. as the light output of the led changes with temperature, ampli fer a1 adjusts i f to compensate and maintain a constant current in pd1. also notice that i pd1 is exactly proportional to v in , giving a very linear relationship between the input voltage and the photodiode current. the relationship between the input optical power and the output current of a photodiode is very linear. there ? fore, by stabiliz ing and linearizing i pd1 , the light output of the led is also stabilized and linearized. and since light from the led falls on both of the photodiodes, i pd2 will be stabilized as well. the physical construction of the package determines the relative amounts of light that fall on the two photodiodes and, therefore, the ratio of the photodiode currents. this results in very stable operation over time and tempera ? ture. the photodiode current ratio can be expressed as a constant, k, where k = i pd2 /i pd1 . amplifer a2 and resistor r2 form a trans ? resistance am ? plifer that converts i pd2 back into a voltage, v out , where v out = i pd2 *r2. combining the above three equations yields an overall expression relating the output voltage to the input volt ? age, v out /v in = k*(r2/r1). therefore the relationship between v in and v out is con ? stant, linear, and independent of the light output characteris tics of the led. the gain of the basic isola tion amplifer circuit can be adjusted simply by adjusting the ratio of r2 to r1. the parameter k (called k 3 in the electri ? cal specifcations) can be thought of as the gain of the optocoupler and is specifed in the data sheet. remember, the circuit in figure 12a is simplifed in order to explain the basic circuit opera tion. a practical circuit, more like figure 12b, will require a few additional compo ? nents to stabilize the input part of the circuit, to limit the led current, or to optimize circuit performance. example applica tion circuits will be discussed later in the data sheet.
17 to worry about. how ever, the second circuit requires two optocouplers, separate gain adjustments for the posi ? tive and negative portions of the signal, and can exhibit crossover distor tion near zero volts. the correct circuit to choose for an applica tion would depend on the require ? ments of that particular application. as with the basic isolation amplifer circuit in figure 12a, the circuits in fig ? ure 14 are simplifed and would require a few additional compo nents to function properly. two example circuits that operate with bipolar input signals are discussed in the next section. as a fnal example of circuit design fexibility, the simpli ? fed schematics in figure 15 illus trate how to implement 4? 20 ma analog current ? loop transmitter and receiver circuits using the hcnr200/201 optocoupler. an impor ? tant feature of these circuits is that the loop side of the circuit is powered entirely by the loop current, eliminat ? ing the need for an isolated power supply. the input and output circuits in figure 15a are the same as the negative input and positive output circuits shown in figures 13c and 13b, except for the addition of r3 and zener diode d1 on the input side of the circuit. d1 regu ? lates the supply voltage for the input amplifer, while r3 forms a current divider with r1 to scale the loop current down from 20 ma to an appropriate level for the input circuit (<50 a). as in the simpler circuits, the input amplifer adjusts the led current so that both of its input terminals are at the same voltage. the loop current is then divided between r1 and r3. i pd1 is equal to the current in r1 and is given by the following equation: i pd1 = i loop *r3/(r1+r3). combining the above equation with the equations used for figure 12a yields an overall expression relating the output voltage to the loop current, v out /i loop = k*(r2*r3)/(r1+r3). again, you can see that the relationship is constant, lin ? ear, and independent of the charac teristics of the led. the 4 ? 20 ma transmitter circuit in figure 15b is a little dif ? ferent from the previous circuits, partic ularly the output circuit. the output circuit does not directly generate an output voltage which is sensed by r2, it instead uses q1 to generate an output current which fows through r3. this output current generates a voltage across r3, which is then sensed by r2. an analysis similar to the one above yields the following expression relating output current to input voltage: i loop /v in = k*(r2+r3)/(r1*r3). circuit design flexibility circuit design with the hcnr200/201 is very fexible because the led and both photodiodes are acces sible to the designer. this allows the designer to make perf ? ormance trade ? ofs that would otherwise be difcult to make with commercially avail able isolation amplifers (e.g., band width vs. accuracy vs. cost). analog isola tion circuits can be designed for applications that have either unipolar (e.g., 0 ? 10 v) or bipolar (e.g., 10 v) signals, with positive or negative input or output voltages. several simplifed circuit topologies illustrating the design fex ? ibility of the hcnr200/201 are discussed below. the circuit in figure 12a is confgured to be non ? invert ? ing with positive input and output voltages. by simply changing the polarity of one or both of the photodiodes, the led, or the op ? amp inputs, it is possible to imple ment other circuit confgu ra tions as well. figure 13 illustrates how to change the basic circuit to accommodate both positive and negative input and output voltages. the in ? put and output circuits can be matched to achieve any combina tion of positive and negative voltages, allowing for both inverting and non ? inverting circuits. all of the confgurations described above are unipolar (single polar ity); the circuits cannot accom mo date a sig ? nal that might swing both positive and negative. it is pos ? sible, however, to use the hcnr200/201 optocoupler to implement a bipolar isolation amplifer. two topologies that allow for bipolar operation are shown in figure 14. the circuit in figure 14a uses two current sources to ofset the signal so that it appears to be unipolar to the optocoupler. current source i os1 provides enough ofset to ensure that i pd1 is always positive. the second current source, i os2 , provides an ofset of opposite polarity to ob ? tain a net circuit ofset of zero. current sources i os1 and i os2 can be implemented simply as resistors connected to suitable voltage sources. the circuit in figure 14b uses two optocouplers to obtain bipolar operation. the frst optocoupler handles the pos ? itive voltage excursions, while the second optocoupler handles the negative ones. the output photo diodes are connected in an antiparallel confguration so that they produce output signals of opposite polarity. the frst circuit has the obvious advantage of requiring only one optocoupler; however, the ofset performance of the circuit is dependent on the matching of i os1 and i os2 and is also dependent on the gain of the optocoupler. changes in the gain of the opto coupler will directly af ? fect the ofset of the circuit. the ofset performance of the second circuit, on the other hand, is much more stable; it is inde pendent of optocoupler gain and has no matched current sources
18 the preceding circuits were pre sented to illustrate the fexibility in designing analog isolation circuits using the hcnr200/201. the next section presents several com ? plete schematics to illustrate practical applications of the hcnr200/201. example application circuits the circuit shown in figure 16 is a high ? speed low ? cost circuit designed for use in the feedback path of switch ? mode power supplies. this application requires good bandwidth, low cost and stable gain, but does not re ? quire very high accuracy. this circuit is a good example of how a designer can trade of accuracy to achieve improve ments in bandwidth and cost. the circuit has a bandwidth of about 1.5 mhz with stable gain character ? istics and requires few external components. although it may not appear so at frst glance, the circuit in figure 16 is essentially the same as the circuit in fig ? ure 12a. amplifer a1 is comprised of q1, q2, r3 and r4, while amplifer a2 is comprised of q3, q4, r5, r6 and r7. the circuit operates in the same manner as well; the only diference is the performance of amplifers a1 and a2. the lower gains, higher input currents and higher ofset voltages afect the accuracy of the circuit, but not the way it operates. because the basic circuit operation has not changed, the circuit still has good gain stability. the use of discrete transistors instead of op ? amps allowed the design to trade of accuracy to achieve good band ? width and gain stability at low cost. to get into a little more detail about the circuit, r1 is se ? lected to achieve an led current of about 7 ? 10 ma at the nominal input operating voltage according to the fol ? lowing equation: i f = (v in /r1)/k1, where k 1 (i.e., i pd1 /i f ) of the optocoupler is typically about 0.5%. r2 is then selected to achieve the desired output volt age according to the equation, v out /v in = r2/r1. the purpose of r4 and r6 is to improve the dynamic re ? sponse (i.e., stability) of the input and output circuits by lowering the local loop gains. r3 and r5 are selected to provide enough current to drive the bases of q2 and q4. and r7 is selected so that q4 operates at about the same collector current as q2. the next circuit, shown in figure 17, is designed to achieve the highest possible accuracy at a reasonable cost. the high accuracy and wide dynamic range of the circuit is achieved by using low ? cost precision op ? amps with very low input bias currents and ofset voltages and is limited by the performance of the opto coupler. the circuit is de ? signed to operate with input and output voltages from 1 mv to 10 v. the circuit operates in the same way as the others. the only major diferences are the two compensa tion capaci ? tors and additional led drive circuitry. in the high ?speed circuit discussed above, the input and output circuits are stabilized by reducing the local loop gains of the input and output circuits. because reducing the loop gains would decrease the accuracy of the circuit, two compen ? sation capacitors, c1 and c2, are instead used to improve circuit stability. these capacitors also limit the bandwidth of the circuit to about 10 khz and can be used to reduce the output noise of the circuit by reducing its bandwidth even further. the additional led drive circuitry (q1 and r3 through r6) helps to maintain the accuracy and band width of the circuit over the entire range of input voltages. without these components, the transcon duc t ance of the led driver would decrease at low input voltages and led currents. this would reduce the loop gain of the input circuit, reducing circuit accuracy and bandwidth. d1 pre ? vents excessive reverse voltage from being applied to the led when the led turns of completely. no ofset adjustment of the circuit is necessary; the gain can be adjusted to unity by simply adjusting the 50 kohm poten tiometer that is part of r2. any op ? 97 type of op ? amp can be used in the circuit, such as the lt1097 from linear technology or the ad705 from analog devices, both of which ofer pa bias currents, v ofset voltages and are low cost. the input terminals of the op ?amps and the photodiodes are connected in the circuit using kelvin connections to help ensure the accuracy of the circuit. the next two circuits illustrate how the hcnr200/201 can be used with bipolar input signals. the isolation amplifer in figure 18 is a practical implemen tation of the circuit shown in figure 14b. it uses two opto couplers, oc1 and oc2; oc1 handles the positive portions of the input sig ? nal and oc2 handles the negative portions. diodes d1 and d2 help reduce crossover distortion by keeping both amplifers active during both positive and negative portions of the input signal. for example, when the input signal positive, optocoupler oc1 is active while oc2 is turned of. however, the amplifer control ling oc2 is kept active by d2, allowing it to turn on oc2 more rap ? idly when the input signal goes negative, thereby reduc ? ing crossover distortion. balance control r1 adjusts the relative gain for the posi ? tive and negative portions of the input signal, gain con ? trol r7 adjusts the overall gain of the isolation amplifer, and capac i tors c1 ? c3 provide compensa tion to stabilize the amplifers.
for product information and a complete list of distributors, please go to our website: www.avagotech.com avago, avago technologies, and the a logo are trademarks of avago technologies in the united states and other countries. data subject to change. copyright ? 2005-2014 avago technologies. all rights reserved. obsoletes av01-0567en av02-0886en - july 1, 2014 the fnal circuit shown in figure 19 isolates a bipolar analog signal using only one optocoupler and generates two output signals: an analog signal proportional to the magnitude of the input signal and a digital signal cor ? responding to the sign of the input signal. this circuit is especially useful for applica tions where the output of the circuit is going to be applied to an analog ? to ? digital converter. the primary advantages of this circuit are very good linearity and ofset, with only a single gain adjust ? ment and no ofset or balance adjustments. to achieve very high linearity for bipolar signals, the gain should be exactly the same for both positive and negative input polarities. this circuit achieves excellent linearity by using a single optocoupler and a single input resistor, which guarantees identical gain for both posi ? tive and negative polarities of the input signal. this pre ? cise matching of gain for both polari ties is much more difcult to obtain when separate components are used for the diferent input polari ties, such as is the pre vious circuit. the circuit in figure 19 is actually very similar to the pre ? vious circuit. as mentioned above, only one optocoupler is used. because a photodiode can conduct current in only one direction, two diodes (d1 and d2) are used to steer the input current to the appropriate terminal of input photodiode pd1 to allow bipolar input currents. normally the forward voltage drops of the diodes would cause a serious linearity or accuracy problem. however, an additional amplifer is used to provide an appropriate ofset voltage to the other amplifers that exactly cancels the diode voltage drops to maintain circuit accuracy. diodes d3 and d4 perform two diferent functions; the diodes keep their respective amplifers active indepen ? dent of the input signal polarity (as in the previous cir ? cuit), and they also provide the feedback signal to pd1 that cancels the voltage drops of diodes d1 and d2. either a comparator or an extra op ? amp can be used to sense the polarity of the input signal and drive an inex ? pensive digital optocoupler, like a 6n139. it is also possible to convert this circuit into a fully bipolar circuit (with a bipolar output signal) by using the output of the 6n139 to drive some cmos switches to switch the polarity of pd2 depending on the polarity of the input signal, obtaining a bipolar output voltage swing. hcnr200/201 spice model figure 20 is the net list of a spice macro ? model for the hcnr200/201 high? linearity optocoupler. the macro ? model accurately refects the primary characteristics of the hcnr200/201 and should facilitate the design and understanding of circuits using the hcnr200/201 opto ? coupler.

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