i ntegrated c ircuits d ivision www.ixysic.com ds-lia120-r03 1 lia120 optically isolated linear error amplifier part # description lia120s 8 pin surface mount (50/tube) lia120str tape and reel (1000/reel) applications features description ordering information block diagram ? power supply feedback ? telecom central office supply ? telecom bricks ? modem transformer replacement ? digital telephone isolation ? optocoupler, precision reference and error amplifier in single package ? low voltage operation 2.7v ? 1.240v 2.5% reference ? ctr matching 15% ? >70db thd ? 70db cmrr ? 3,750v rms isolation ? ul approval pending the lia120 optically isolated reference amplifier combines ixys ic division?s linear optical coupler technology with an industry standard 431 type precision programmable shunt regulator to provide very linear high gain with excellent temperature stability for a total gain error of less than 2db. by using optical feedback, the lia120 essentially eliminates temperature and gain variations due to current transfer ratio (ctr) changes in optocouplers while increasing the bandwidth up to 10x and easing engineering design constraints. the lia120 is very well suited for high gain feedback amplifiers that require excellent linearity and low temperature variation such as isolated power supply feedback stages, modem audio transformer replacement, isolated industrial control signals, and sensor feedback. by using the lia120, system designers can save precious board space and reduce component count. available in an 8 pin surface mount package. 1 2 3 4 5 6 7 8 led (input) fb comp gnd nc k a nc
i ntegrated c ircuits d ivision www.ixysic.com 2 r03 lia120 absolute maximum ratings are stress ratings. stresses in excess of these ratings can cause permanent damage to the device. functional operation of the device at conditions beyond those indicated in the operational sections of this data sheet is not implied. parameter conditions symbol min typ max units input characteristics @ 25oc led forward voltage i led = 5 ma, v comp = v fb (fig.1) v f 0.8 1.2 1.4 v reference voltage i led = 10 ma, v comp = v fb (fig.1) t a = -40 to +85c v ref 1.210 - 1.265 v t a = 25c 1.228 1.24 1.252 deviation of v ref over temperature - see note 1 t a = -40 to +85c v ref (dev) -32 - mv transfer characteristics @ 25oc current transfer ratio in feedback (i ref /i led )i led = 5ma, v ref = 0.5v (fig.2) k 1 1.0 2 3.0 % current transfer ratio (i ka /i led )i led = 5 ma, v comp = v fb , v ka = 5 v (fig. 4) k 2 1.0 2 3.0 % current transfer ratio matching (i ka /i ref )i led = 5ma, v ka = 5.0v k 3 85 100 115 % feedback input current i led = 10 ma, r1 = 10 k (fig.2) i ref - 226 - a deviation of i ref over temperature - see note 1 t a = -40 to +85c i ref (dev) - 110 - a minimum drive current v comp = v fb (fig.1) i led (min) 1- -ma off-state error amplifier current v in = 6 v, v fb = 0 (fig.3) i off - 0.001 0.1 a error amplifier output impedance - see note 2 i led = 0.1 ma to 15 ma, v comp = v fb , f<1 khz (fig.1) iz out i - 0.21 - ? output characteristics @ 25oc cathode dark current v in = open, v ka = 10v (fig. 3) i kao - 0.3 100 na cathode-anode voltage breakdown i ka = 1a bv ka 20 - - v isolation characteristics @ 25oc withstand insulation voltage rh 50%, t a = 25c, t = 1 min (note 3) v iso 3750 - - v rms resistance (input to output) v i-o = 500 v dc (note 3) r i-o -10 12 - ? ac characteristics @ 25oc bandwidth (led) - see note 4 -b w - 100 - khz common mode rejection ratio - see note 5 i led = 1.0 ma, r l =100 k , f=100 hz (fig. 5) cmrr - 70 - db linearity i led = 5 ma, 100 mv pp thd - 70 - db 1. the deviation parameters v ref(dev) and i ref(dev) are defined as the differences between the maximum and minimum values obtained over the rated temperature range. the average full-range temperature coefficient of the reference input voltage, ? v ref , is defined as: | ? v ref | (ppm/c) = {v ref (dev) /v ref (t a 25c)} x 10 6 / ? t a where ? t a is the rated operating free-air temperature range of the device. 2. the dynamic impedance is defined as |z out | = ? v comp / ? i led , for the application circuit in figure 6, |zout| = k 1 r 1 3. 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 to gether. 4. see compensation section for calculating bandwidth of lia120. 5. 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 t he common pulse signal,vcm, to assure that the output will remain low. electrical characteristics: parameter symbol ratings units photodiode cathode-anode voltage v kao 20 v photodiode anode-cathode voltage v ako 0.5 v input voltage v led 9v input dc current i led 20 ma total power dissipation (note 1) p d 145 mw operating temperature t -40 to +85 o c storage temperature t -40 to +125 o c absolute maximum ratings (@ 25oc) 1 derate linearly from 25c at a rate of 2.42 mw/ c.
i ntegrated c ircuits d ivision www.ixysic.com 3 r03 lia120 r1 fig. 1. v ref , v f , i led (min) test circuit fig. 2. i ref test circuit fig. 4. ctr test circuit fig. 3. i off , i kao test circuit v cc = +5v dc v out vcm 10v pp r1 100k + _ fig. 5. cmrr test circuit i led v f 2 3 5 6 7 8 v v ref i led 2 3 5 6 7 8 v v ref i led i ref v ref v ka v in 2 3 5 6 7 8 v 10v i off i kao 2 3 5 6 7 8 v comp 2 3 5 6 7 8 v i led i ka
i ntegrated c ircuits d ivision www.ixysic.com 4 r03 lia120 performance data* *the performance data shown in the graphs above is typical of device performance. for guaranteed parameters not indicated in t he written speci? cations, please contact our application department. led current vs. cathode voltage v comp - cathode voltage (v) i led - supply current (ma) -1.0 15 10 5 0 -5 -10 -15 -0.5 0.0 0.5 1.0 1.5 t a =25 o c v comp =v fb led current vs. cathode voltage v comp - cathode voltage (v) i led - supply current ( p a) -1.0 150 120 90 60 30 0 -30 -60 -90 -120 -150 -0.5 0.0 0.5 1.0 1.5 t a =25 o c v comp =v fb reference voltage vs. ambient temperature v ref - reference voltage (v) -40 1.30 1.37 1.24 1.21 1.18 -20 0 20406080 i led = 10ma t a - ambient temperature (oc) reference current vs. ambient temperature i ref - reference current ( p a) -40 350 300 250 200 150 100 50 -20 0 20406080100 t a - ambient temperature (oc) i led =10ma r 1 =10k : off current vs. ambient temperature i (off) - off current (na) -40 2.5 2.0 1.5 1.0 0.5 0 -20 0 20406080100 v in =10v v fb =0 t a - ambient temperature (oc) led forward current vs. forward voltage i led - forward current (ma) v f - forward-voltage (v) 20 15 10 5 0 1.0 1.1 1.2 1.3 1.4 1.5 85 o c 55 o c 25 o c -5 o c dark current vs. temperature i kao - dark current (na) v ka =10v -40 50 40 30 20 10 0 -10 -20 0 20406080100 t a - ambient temperature (oc) cathode current vs. ambient temperature i k - cathode current ( p a) v ka =5v i led =20ma -40 1400 1200 1000 800 600 400 200 0 -20 0 20406080100 t a - ambient temperature (oc) i led =10ma i led =5ma i led =1ma current transfer ratio vs led current (i ka / i f ) - current transfer ratio (%) i led - forward current (ma) v ka =5v 0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 10 20 30 40 50 t a =-5oc t a =25oc t a =55oc t a =85oc cathode current vs. photodiode voltage i k - cathode current ( p a) v ka (v) 0 500 450 400 350 300 250 200 150 100 50 0 12345678910 i led =20ma i led =10ma i led =5ma i led =1ma t a =25oc bandwidth vs. temperature for high frequency applications frequency (khz) 0 50 40 30 20 10 0 10 20 30 40 50 60 70 80 90 temperature (oc) voltage gain vs. frequency voltage gain, a(v o /v in ) db frequency (khz) 10 60 40 20 0 100 1000 r l =100 :
i ntegrated c ircuits d ivision www.ixysic.com 5 r03 lia120 performance data* *the performance data shown in the graphs above is typical of device performance. for guaranteed parameters not indicated in t he written speci? cations, please contact our application department. output linearity thd for 40db setup -1.00e+02 -9.00e+01 -8.00e+01 -7.00e+01 -6.00e+01 -5.00e+01 -4.00e+01 -3.00e+01 -2.00e+01 -1.00e+01 0.00e+00 1.0e+ 03 2.0e+ 03 3.0e+ 03 4.0e+ 03 5.0e+ 03 6.0e+ 03 7.0e+ 03 8.0e+ 03 9.0e+ 03 frequency (hz) ) b d ( r e w o p noise spectrum for 40db gain setup (220k/2.2k gain) -140 -120 -100 -80 -60 -40 -20 0 1.000e+02 1.000e+03 1.000e+04 1.000e+05 frequency (hz) ) z h / m b d ( n e input spectrum at fb output spectrum
i ntegrated c ircuits d ivision www.ixysic.com 6 r03 lia120 v c v cc v in 100 v out + v out v out r l r 1 r c c c r 2 fig. 6. power supply feedback application circuit fig. 7. non-inverting linear amplifier circuit v i v dd r i r 2 r 1 r c c c r l + C C 100 2 3 5 6 7 8 2 3 5 6 7 8
i ntegrated c ircuits d ivision www.ixysic.com 7 r03 lia120 the lia120 the lia120 is an optically-coupled isolated linear error amplifier. it integrates three of the most fundamental elements necessary to make an isolated power supply: a reference voltage, an error amplifier, and an isolated coupling device. it is functionally equivalent to a 431 type shunt regulator plus a linear optical amplifier. powering the isolated input the isolated input of the lia120 is powered through the led pin (pin 8) via the part to its isolated ground at pin 5. the typical operating current of the device is determined by the output voltage and current requirements as well as the ctr of the linear optocoupler. for figure 7, the led current requirement is set by the following equation. the output voltage is typically constrained by the user to satisfy the design requirements of the application circuit. design considerations must also take into account that r l affects the total gain and that ctr gains vary with process. nominally the led current should be around 1-2ma but can be as high as 10-15ma if the user requires. led current is limited by the resistor in series with pin 8, the led pin, to the supply and is typically 10-100 ohms for operating currents of 1-2ma. the minimum operating voltage of 2.74v for the lia120 from pin 8 to pin 5 is based on the sum of the voltage drop of the led and the operational voltage headroom of the 431. minimum operating voltage for the application circuit is therefore the sum of the lia120 minimum operating voltage plus the voltage drop of the current limiting resistor for a design with 1ma of led current and a current limiting resistor of 100 ohms, the minimum operating voltage is calculated to be 2.74 + (0.001) (100) = 2.84v. feedback setting the gain for the lia120 is accomplished simply by setting two resistors. the application circuit in figure 6 shows a resistor divider feeding the fb pin, so the operating conditions for the gain are governed by: i led = v out,bias r l ? k 1 r 1 r 2 vin vref vref vout r 1 r l 1 k 3 -1 ? = ? - compensation the lia120 is relatively easy to compensate but two factors must be considered when analyzing the circuit. the frequency response of the lia120 can be as high as 40khz, but must be limited because of the closed loop optical feedback to the input signal. in the localized optical feedback there are two poles to consider, the 431 dominant pole and the linear optical coupler pole. the open loop gain of the optical loop (for the application diagram) is: the open loop gain is affected by the selection of r 1 and r 2 , and without any compensation the circuit may oscillate. the addition of a compensation network (c c and r c ) control the maximum bandwidth so that open loop gain is rolling off long before the optical pole causes the circuit to oscillate. the optical pole is at ~180khz so the bandwidth is typically limited to less than 40khz. while there is flexibility in the part to change the compensation technique, the upper limit on frequency response is generally desired to be such that the circuit will not oscillate for a large selection of r 1 and r 2 . therefore the compensation capacitor should not be less than 100pf, which gives adequate bandwidth for most designs. this calculation provides a more accurate gain calculation, but is only necessary when the voltage divider resistor?s impedance is becoming close to the optical output impedance of the shunt regulator. k 3 is taken from the datasheet as 1 nominally. the ac gain of the setup can be represented by: where: ? g m = 1/z out which is ~ 3 siemens ? ctr fb is approximately ctr forward = 0.02 nominally ctr fb = k 1 , ctr forward = k 2 , ctr forward /ctr fb = k 3 a v v out /v in = r l r 1 ? r 2 r 1 g m ctr fb 1 ? g m ctr forward 1 ? a v, optical = gm ctr fb ? ? r 1 r 2
i ntegrated c ircuits d ivision www.ixysic.com 8 r03 lia120 photodiode the bandwidth through the part will be: where: p 1 max is 1khz (6.28krad/s) due to the internal compensation of the 431. ctr is the current transfer ratio of the feedback optocoupler (0.001-0.003). r led is the combined impedance of the limiting resistor and the led resistance (25 ohms) and gm is the transconductance of the 431 (3 siemens). however, since some of these elements vary over operating conditions and temperature, the bandwidth should be practically limited to less than 40khz to avoid oscillations, which is the value computed by 100pf. bw hz = gm ctr fb ? r 1 r 2 ? ? ? ? * p ? 5 led ? & c ? 5 1 r 2 + 1 p 1 < bw hz max the output of the lia120 is a photodiode capable or withstanding high voltages. for the most accurate results, attempt to bias the voltage across the cathode anode the same as v ref . the load resistors can be placed in series with the cathode or anode for desired output polarity.
i ntegrated c ircuits d ivision www.ixysic.com 9 r03 lia120 manufacturing information moisture sensitivity all plastic encapsulated semiconductor packages are susceptible to moisture ingression. ixys integrated circuits division classified all of its plastic encapsulated devices for moisture sensitivity according to the latest version of the joint industry standard, ipc/jedec j-std-020 , in force at the time of product evaluation. we test all of our products to the maximum conditions set forth in the standard, and guarantee proper operation of our devices when handled according to the limitations and information in that standard as well as to any limitations set forth in the information or standards referenced below. failure to adhere to the warnings or limitations as established by the listed specifications could result in reduced product performance, reduction of operable life, and/or reduction of overall reliability. this product carries a moisture sensitivity level (msl) rating as shown below, and should be handled according to the requirements of the latest version of the joint industry standard ipc/jedec j-std-033 . device moisture sensitivity level (msl) rating lia120s msl 1 esd sensitivity this product is esd sensitive , and should be handled according to the industry standard jesd-625 . reflow profile this product has a maximum body temperature and time rating as shown below. all other guidelines of j-std-020 must be observed. device maximum temperature x time lia120s 250oc for 30 seconds board wash ixys integrated circuits division recommends the use of no-clean flux formulations. however, board washing to remove flux residue is acceptable. since ixys integrated circuits division employs the use of silicone coating as an optical waveguide in many of its optically isolated products, the use of a short drying bake could be necessary if a wash is used after solder reflow processes. chlorine- or fluorine-based solvents or fluxes should not be used. cleaning methods that employ ultrasonic energy should not be used. e 3 pb
i ntegrated c ircuits d ivision for additional information please visit our website at: www.ixysic.com lia120 10 ixys integrated circuits division makes no representations or warranties with respect to the accuracy or completeness of the co ntents of this publication and reserves the right to make changes to specifications and product descriptions at any time without notice. neither circuit patent licenses nor indemnity a re expressed or implied. except as set forth in ixys integrated circuits division?s standard terms and conditions of sale, ixys integrated circuits division assumes no liability whatsoever, a nd disclaims any express or implied warranty, relating to its products including, but not limited to, the implied warranty of merchantability, fitness for a particular purpose, or infri ngement of any intellectual property right. the products described in this document are not designed, intended, authorized or warranted for use as components in systems in tended for surgical implant into the body, or in other applications intended to support or sustain life, or where malfunction of ixys integrated circuits division?s product may resul t in direct physical harm, injury, or death to a person or severe property or environmental damage. ixys integrated circuits division reserves the right to discontinue or make changes to its p roducts at any time without notice. specification: ds-lia120-r03 ?copyright 2012, ixys integrated circuits division all rights reserved. printed in usa. 12/22/2012 lia120s lia120str tape & reel dimensions mm (inches) pcb land pattern 2.540 0.127 (0.100 0.005) 9.652 0.381 (0.380 0.015) 6.350 0.127 (0.250 0.005) 9.525 0.254 (0.375 0.010) 0.457 0.076 (0.018 0.003) 0.813 0.102 (0.032 0.004) 4.445 0.127 (0.175 0.005) 7.620 0.254 (0.300 0.010) 0.635 0.127 (0.025 0.005) 0.254 0.0127 (0.010 0.0005) 2.54 (0.10) 8.90 (0.3503) 1.65 (0.0649) 0.65 (0.0255) 3.302 0.051 (0.130 0.002) pin 1 dimensions mm (inches) user direction of feed notes: 1. dimensions carry tolerances of eia standard 481-2 2. tape complies with all notes for constant dimensions listed on page 5 of eia-481-2 embossment embossed carrier top cover tape thickness 0.102 max. (0.004 max.) 330.2 dia. (13.00 dia.) k 1 =4.20 (0.165) 0 k =4.90 (0.193) p=12.00 (0.472) w=16.00 (0.63) bo=10.30 (0.406) ao=10.30 (0.406) mechanical dimensions
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