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12/9/04 optically isolated error amplifier page 1 of 13 fod2742a fod2742b fod2742c ?2003 fairchild semiconductor corporation description the fod2742 optically isolated ampli?r consists of the popular ka431 precision programmable shunt reference and an optocoupler. the optocoupler is a gallium arsenide (gaas) light emitting diode optically coupled to a silicon phototransistor. it comes in 3 grades of reference voltage tolerance = 2%, 1%, and 0.5%. the current transfer ratio (ctr) ranges from 100% to 200%. it also has an outstanding temperature coef?ient of 50 ppm/?. it is primarily intended for use as the error ampli?r/ reference voltage/optocoupler function in isolated ac to dc power supplies and dc/dc con- verters. when using the fod2742, power supply designers can reduce the component count and save space in tightly packaged designs. the tight tolerance reference eliminates the need for adjustments in many applications. the device comes in a 8-pin small outline package. features optocoupler, precision reference and error ampli?r in single package 2.5v reference ctr 100% to 200% 2,500v rms isolation ul approval e90700, volume 2 bsi approval 8661, 8662 vde approval 136616 csa approval 1113643 low temperature coef?ient 50 ppm/? max fod2742a: tolerance 0.5% fod2742b: tolerance 1% fod2742c: tolerance 2% applications power supplies regulation dc to dc converters * the compensation network must be attached between pins 6 and 7. pin definitions pin number pin name pin function description 1 nc not connected 2 c phototransistor collector 3 e phototransistor emitter 4 nc not connected 5 gnd ground 6 comp error ampli?r compensation. this pin is the output of the error ampli?r. * 7 fb voltage feedback. this pin is the inverting input to the error ampli?r 8 led anode led. this pin is the input to the light emitting diode. functional block diagram 1 2 3 4 5 6 7 8 led fb comp gnd nc c e nc
12/9/04 page 2 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c typical application v o v 1 r1 r2 2 3 8 6 7 5 pwm control fan4803 fod2742 notes 1. derate linearly from 25 c at a rate of 2.42 mw/ c 2. derate linearly from 25 c at a rate of 1.42 mw/ c. 3. derate linearly from 25 c at a rate of 2.42 mw/ c. 4. functional operation under these conditions is not implied. permanent damage may occur if the device is subjected to conditio ns outside these ratings. absolute maximum ratings (t a = 25 c unless otherwise speci ed.) parameter symbol value units storage temperature t stg -40 to +125 c operating temperature t opr -25 to +85 c re ow temperature pro le (refer to g. 21) input voltage v led 37 v input dc current i led 20 ma collector-emitter voltage v ceo 70 v emitter-collector voltage v eco 7v collector current i c 50 ma input power dissipation (note 1) pd1 145 mw transistor power dissipation (note 2) pd2 85 mw total power dissipation (note 3) pd3 145 mw
12/9/04 page 3 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c 1. the deviation parameters v ref(dev) and i ref(dev) are de ned as the differences between the maximum and minimum values obtained over the rated temperature range. the average full-range temperature coef cient of the reference input voltage, ? v ref , is de ned as: where ? t a is the rated operating free-air temperature range of the device. 2. the dynamic impedance is de ned as |z out | = ? v comp / ? i led . when the device is operating with two external resistors (see figure 2), the total dynamic impedance of the circuit is given by: electrical characteristics (t a = 25 c unless otherwise speci ed.) input characteristics parameter test conditions symbol device min. typ. max. unit led forward voltage (i led = 10 ma, v comp = v fb ) ( g. 1) v f all 1.20 1.5 v reference voltage i led = 10 ma, v comp = v fb ( g. 1) v ref a 2.482 2.495 2.508 v b 2.470 2.495 2.520 v c 2.450 2.500 2.550 v deviation of v ref over temperature t a = -25 c to +85 c ( g. 1) v ref (dev) all 3.5 17 mv ratio of v ref variation to the output of the error ampli er i led = 10 ma ( g. 2) ? v comp = 10v to v ref ? v ref / ? v comp all -0.5 -2.7 mv/ v ? v comp = 36v to 10v -0.3 -2.0 feedback input current i led = 10ma, r 1 = 10k ? ( g. 3) i ref all 2.2 4 a deviation of i ref over temperature t a = -25 c to +85 c ( g. 3) i ref (dev) all 1.0 1.2 a minimum drive current v comp = v fb ( g. 1) i led (min) all 0.45 1.0 ma off-state error ampli er current v led = 37v, v fb = 0 ( g. 4) i (off) all 0.01 1.0 a error ampli er output impedance (see note 2) v comp = v ref , i led = 1ma to 20ma, f 1.0 khz |z out | all 0.15 0.5 ? ? v ref ppm/ c () v ref dev () /v ref t a 25 c = () {} 10 6 ? t a ---------------------------------------------------------------------------------------------------- - = z out, tot = ? v ? i ------- -z out 1 r1 r2 ------- - +
12/9/04 page 4 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c notes 1. device is considered as a two terminal device: pins 1,2 3 and 4 are shorted together and pins 5,6,7 and 8 are shorted togethe r. 2. common mode transient immunity at output high is the maximum tolerable (positive) dvcm/dt on the leading edge of the common mode impulse signal, vcm, to assure that the output will remain high. common mode transient immunity at output low is the maximum tolerable (negative) dvcm/dt on the trailing edge of the common pulse signal,vcm, to assure that the output will remain low. output characteristics (t a = 25 c unless otherwise speci ed.) parameter test conditions symbol min typ max unit collector dark current (v ce = 10 v) (fig. 5) i ceo 150na emitter-collector voltage breakdown (i e = 100 a) bv eco 710 v collector-emitter voltage breakdown (i c = 1.0ma) bv ceo 70 120 v transfer characteristics (t a = 25 c unless otherwise speci ed.) parameter test conditions symbol min typ max unit current transfer ratio (i led = 10 ma, v comp = v fb , v ce = 5 v) (fig. 6) ctr 100 140 200 % collector-emitter saturation voltage (i led = 10 ma, v comp = v fb, i c = 2.5 ma) (fig. 6) v ce (sat) 0.16 0.4 v isolation characteristics (t a = 25 c unless otherwise speci ed.) parameter test conditions symbol min typ max unit input-output insulation leakage current (rh = 45%, t a = 25 c, t = 5s, v i-o = 3000 vdc) (note. 1) i i-o 1.0 a withstand insulation voltage (rh <= 50%, t a = 25 c, t = 1 min) (note 1) v iso 2500 vrms resistance (input to output) v i-o = 500 vdc (note 1) r i-o 10 12 ohm switching characteristics (t a = 25 c unless otherwise speci ed.) parameter test conditions symbol min typ max unit bandwidth (fig. 7) bw 50 khz common mode transient immunity at output high (i led = 0 ma, ? vcm ? = 10 v pp rl = 2.2 kv (fig. 8) (note 2) ? cmh ? 1.0 kv/s common mode transient immunity at output low (i led = 10 ma, ? vcm ? = 10 v pp rl = 2.2 kv (fig. 8) (note 2) ? cml ? 1.0 kv/s
12/9/04 page 5 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c i (led) v (led) v comp v comp i ceo v ce v ref v ce i (led) v f v ref v ref 82 3 2 3 v v v 6 7 5 i (led) i (led) i (c) i (off) i ref 8 6 2 3 2 3 2 3 v v 7 5 8 6 7 5 8 6 7 5 8 6 2 3 7 5 r1 8 6 r1 r2 7 5 fig. 1. v ref , v f, i led (min) test circuit fig. 3. i ref test circuit fig. 5. i ceo test circuit fig. 6. ctr, v ce(sat) test circuit fig. 4. i (off) test circuit fig. 2. ? v ref/ ? v comp test circuit
12/9/04 page 6 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c 3 2 1 4 8 7 6 a b 5 3 4 2 1 6 5 7 8 v cc = +5v dc v cc = +5v dc i f = 10 ma i f = 0 ma (a) i f = 10 ma (b) v in 0.47v 0.1 v pp 47 ? v out v out vcm 10v p-p r1 2.2k ? r l 1 f + _ fig. 7 frequency response test circuit fig. 8 cmh and cml test circuit
12/9/04 page 7 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c typical performance curves fig. 10 ? reference voltage vs. ambient temperature i off - off-state current (na) v led = 37v t a = 25 c v comp = v fb t a - ambient temperature ( c) -40 -20 0 20 40 60 80 100 t a - ambient temperature ( c) -40 -20 0 20 40 60 80 100 fig. 9a ? led current vs. cathode voltage i led - supply current (ma) i led - supply current (ma) i ref - reference current ( a) -15 -10 -5 0 5 10 15 -1 0 1 2 v comp - cathode voltage (v) 3 fig. 9b ? led current vs. cathode voltage fig. 11 ? reference current vs ambient temperature -1.0 -0.5 0.0 0.5 1.0 -1 0 1 2 v comp - cathode voltage (v) 3 1 10 100 2 3 t a = 25 c v comp = v fb i led = 10ma r1 = 10k ? fig. 12 ? off-state current vs. ambient temperature v f - forward voltage (v) i f - forward current (ma) 5 0.9 1.0 1.1 1.2 70 c 25 c 0 c 1.3 1.4 10 15 20 fig. 13 ? forward current vs. forward voltage v ref - reference voltage (v) i led = 10ma t a - ambient temperature ( c) -40 -20 0 20 40 60 80 100 2.490 2.492 2.494 2.496 2.498 2.500 2.502 2.504 2.506 2.508 2.510
12/9/04 page 8 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c typical performance curves t a - ambient temperature ( c) t a - ambient temperature ( c) v ce - collector-emitter voltage (v) i led - forward current (ma) 110 100 (i c /i f ) - current transfer ratio (%) 40 60 80 100 120 140 160 0 102030405060708090 100 ic - collector current (ma) 0 5 10 15 20 25 30 -40 -20 0 20 40 60 80 100 i ceo - dark current (na) 0.1 1 10 100 1000 0123456789 10 i c - collector current (ma) 0 5 10 15 20 25 30 35 fig. 15 ? collector current vs. ambient temperature fig. 14 ? dark current vs. ambient temperature fig. 18 ? collector current vs. collector voltage fig. 16 ? current transfer ratio vs. led current v ce = 5v i led = 10ma i c = 2.5ma 0 c 25 c 70 c i led = 20ma v ce = 5v i led = 10ma i led = 5ma i led = 1ma v ce = 10v t a = 25 c i led = 20ma i led = 10ma i led = 5ma i led = 1ma fig. 17 ? saturation voltage vs. ambient temperature v ce(sat) - saturation voltage (v) 0.10 0.12 0.14 0.16 0.18 0.20 0.22 -40 -20 0 20 40 t a - ambient temperature ( c) 60 80 100 0.24 0.26 temperature - c delta vref / delta vout ( mv/v) -0.32 -0.30 -0.28 -0.26 -0.24 -0.22 -0.34 -0.36 -0.38 -0.40 -0.42 -0.44 -40 -20 0 20 40 60 80 100 fig. 19 ? rate of change vref to vout vs. temperature
12/9/04 page 9 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c typical performance curves 1 10 100 1000 fig. 20 ? voltage gain vs. frequency frequency - khz voltage gain - db -15 -10 -5 0 5 vcc=10v if=10ma rl = 100 ? rl = 1k ? rl = 500 ?
12/9/04 page 10 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c the fod2742 the fod2742 is an optically isolated error ampli er. it incorpo- rates three of the most common elements necessary to make an isolated power supply, a reference voltage, an error ampli- er, and an optocoupler. it is functionally equivalent to the popular ka431 shunt voltage regulator plus the cny17f-x optocoupler. powering the secondary side the led pin in the fod2742 powers the secondary side, and in particular provides the current to run the led. the actual structure of the fod2742 dictates the minimum voltage that can be applied to the led pin: the error ampli er output has a minimum of the reference voltage, and the led is in series with that. minimum voltage applied to the led pin is thus 2.5v + 1.5v = 4.0v. this voltage can be generated either directly from the output of the converter, or else from a slaved second- ary winding. the secondary winding will not affect regulation, as the input to the fb pin may still be taken from the output winding. the led pin needs to be fed through a current limiting resistor. the value of the resistor sets the amount of current through the led, and thus must be carefully selected in conjunction with the selection of the primary side resistor. feedback output voltage of a converter is determined by selecting a resistor divider from the regulated output to the fb pin. the fod2742 attempts to regulate its fb pin to the reference voltage, 2.5v. the ratio of the two resistors should thus be: the absolute value of the top resistor is set by the input offset current of 5.2a. to achieve 0.5% accuracy, the resistance of r top should be: compensation the compensation pin of the fod2742 provides the opportu- nity for the designer to design the frequency response of the converter. a compensation network may be placed between the comp pin and the fb pin. in typical low-bandwidth systems, a 0.1f capacitor may be used. for converters with more stringent requirements, a network should be designed based on measurements of the system s loop. an excellent reference for this process may be found in practical design of power supplies by ron lenk, ieee press, 1998. secondary ground the gnd pin should be connected to the secondary ground of the converter. no connect pins the nc pins have no internal connection. they should not have any connection to the secondary side, as this may compromise the isolation structure. photo-transistor the photo-transistor is the output of the fod2742. in a normal con guration the collector will be attached to a pull-up resistor and the emitter grounded. there is no base connection neces- sary. the value of the pull-up resistor, and the current limiting resis- tor feeding the led, must be carefully selected to account for voltage range accepted by the pwm ic, and for the variation in current transfer ratio (ctr) of the opto-isolator itself. example: the voltage feeding the led pins is +12v, the volt- age feeding the collector pull-up is +10v, and the pwm ic is the fairchild ka1h0680, which has a 5v reference. if we select a 10kv resistor for the led, the maximum current the led can see is (12v-4v) /10k ? = 800a. the ctr of the opto-isolator is a minimum of 100%, so the minimum collector current of the photo-transistor when the diode is full on is also 800a. the collector resistor must thus be such that: select 12k ? to allow some margin. r top r bottom ------------------------- - v out v ref -------------- 1 = v out 2.5 r top ---------------------------- - 1040 a > 10v 5v r collector ----------------------------------- -800 a or r collector 6.25k ? ; > <
12/9/04 page 11 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c package dimensions lead coplanarity : 0.004 (0.10) max 0.202 (5.13) 1 0.182 (4.63) 0.021 (0.53) 0.011 (0.28) 0.050 (1.27) typ 0.244 (6.19) 0.224 (5.69) 0.143 (3.63) 0.123 (3.13) 0.008 (0.20) 0.003 (0.08) 0.010 (0.25) 0.006 (0.16) sea ti ng plane 0.164 (4.16) 0.144 (3.66) footprint drawing 0.024 (0.61) 0.050 (1.27) 0.155 (3.94) 0.275 (6.99) 0.060 (1.52) ordering information marking information option order entry identi ? er description r1 r1 tape and reel (500 units per reel) r1v r1v vde0884, tape and reel (500 units per reel) r2 r2 tape and reel (2,500 units per reel) r2v r2v vde0884, tape and reel (2,500 units per reel) 1 2 6 4 3 5 2742a s yy x v de ? nitions 1 fairchild logo 2 device number 3 vde mark (note: only appears on parts ordered with vde option see order entry table) 4 one digit year code 5 two digit work week ranging from 01 to 53 6 assembly package code
12/9/04 page 12 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c carrier tape speci ? cations re ? ow pro ? le 4.0 0.10 1.5 min user direction of feed 2.0 0.05 1.75 0.10 5.5 0.05 12.0 0.3 8.0 0.10 0.30 max 8.3 0.10 3.50 0.20 0.1 max 6.40 0.20 5.20 0.20 1.5 0.1/-0 ramp up = 2 10 c/sec peak reflow temperature: 245 c (package surface temperature) time of temperature higher than 183 c for 120 180 seconds one time soldering reflow is recommended 230 c, 10 30 s time (minute) 0 300 250 200 150 100 50 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 temperature ( c) time above 183 c, 120 180 sec 245 c peak
12/9/04 life support policy fairchild s products are not authorized for use as critical components in life support devices or systems without the express written approval of the president of fairchild semiconductor corporation. as used herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. 2. a critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. disclaimer fairchild semiconductor reserves the right to make changes without further notice to any products herein to improve reliability, function or design. fairchild does not assume any liability arising out of the application or use of any product or circuit described herein; neither does it convey any license under its patent rights, nor the rights of others. page 13 of 13 ? 2003 fairchild semiconductor corporation optically isolated error amplifier fod2742a fod2742b fod2742c
careers | sitema go datasheets, samples, buy technical information applications design center support company investors my f a home >> find products >> fod2742c 8-pin soic error am plifier optocoupler general description back to top features contents ? general description ? features ? applications ? ordering information ? product status/pricing/packaging ? order samples ? safety agency certificates ? qualification support the fod2742 optically isolated amplifier consists of the popular ka431 precision programmable shunt reference and an optocoupler. the optocoupler is a gallium arsenide (gaa s) light emitting diode optically coupled to a silicon phototransistor. it comes in 3 grades of reference voltage tolerance = 2%, 1%, and 0.5%. the current transfer ratio (ctr) ranges from 100% to 200%. it also has an outstanding temperature coefficient of 50 ppm/c. it is primarily intended for use as the error amplifier/reference voltage/optocoupler function in isolated ac to dc power supplies and dc/dc converters. when using the fod2742, power supply designers can reduce the component count and save space in tightly packaged de signs. the tight tolerance reference eliminates the need for adjustments in many applications. the device comes in a 8-pin small outline package. z optocoupler, precision reference and error amplifier in single package z 2.5v reference z ctr 100% to 200% z 2,500v rms isolation datasheet download this datasheet e - mail this datasheet this page print version related links request samples how to order products product change notices (pcns) support sales support quality and reliability design cente r pa g e 1 of 4 product folder - fairchild p/n fod2742c - 8-pin soic error am p lifier o p tocou p le r 17-au g -2007 mhtml:file://c:\temp\FOD2742CV.mht
back to top product status/pricing/packaging back to top applications back to top z ul approval e90700 z bsi approval 8661, 8662 z vde approval 136616 z csa approval 1113643 z low temperature coefficient 50 ppm/c max z fod2742a: tolerance 0.5%; fod2742b: tolerance 1%; fod2742c: tolerance 2% z power supplies regulation z dc to dc converters ordering information the following options can be ordered with this part: packaging option description r1 tape and reel (500 units per reel) r1v vde0884, tape and reel (500 units per reel) r2 tape and reel (2,500 units per reel) r2v vde0884, tape and reel (2,500 units per reel) product product status pb-free status pricing* package type leads packing method fod2742c full production $0.329 soic-w 8 box fod2742cr1 full production $0.357 soic-w 8 tape reel pa g e 2 of 4 product folder - fairchild p/n fod2742c - 8-pin soic error am p lifier o p tocou p le r 17-au g -2007 mhtml:file://c:\temp\FOD2742CV.mht
back to top safety agency certificates back to top qualification support click on a product for detailed qualification data fod2742cr1v full production $0.357 soic-w 8 tape reel fod2742cr2 full production $0.357 soic-w 8 tape reel fod2742cr2v full production $0.357 soic-w 8 tape reel FOD2742CV full production $0.329 soic-w 8 box * fairchild 1,000 piece budgetary pricing ** a sample button will appear if the part is available through fa irchild's on-line samples program. if there is no sample butt on, please contact a fairchild distributor to obtain samples indicates product with pb -free second-level interconne ct. for more information click here. certificate agency fi 21495 (801 k) fimko fimko e90700, vol. 2 (1188 k) ul (1577) underwriters laboratories inc. 1113643 (221 k) csa canadian standa rds association 136616 (2536 k) vde vde pruf-und zertifizierungsinstitut product fod2742c pa g e 3 of 4 product folder - fairchild p/n fod2742c - 8-pin soic error am p lifier o p tocou p le r 17-au g -2007 mhtml:file://c:\temp\FOD2742CV.mht
back to top fod2742cr1 fod2742cr1v fod2742cr2 fod2742cr2v FOD2742CV ? 2007 fairchild semiconductor products | design center | support | company news | investors | my fairchild | contact us | site index | privacy policy | site terms & conditions | standard terms & conditions o pa g e 4 of 4 product folder - fairchild p/n fod2742c - 8-pin soic error am p lifier o p tocou p le r 17-au g -2007 mhtml:file://c:\temp\FOD2742CV.mht

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