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1 ? fn6378.3 caution: these devices are sensitive to electrosta tic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | intersil (and design) is a registered trademark of intersil americas inc. copyright ? intersil americas inc. 2007, 2008. all rights reserved. all other trademarks mentioned are the property of their respective owners. isl28168, isl28268 34a micro-power single and dual rail-to-rail input-output (rrio) low input bias current op amps the isl28168 and isl28268 are micro-power operational amplifiers optimized for single supply operation over a power supply range of 2.4vdc to 5. 5vdc. these devices draw minimal supply current and operate rail-to-rail at the input and output, while providing excellent dc-accuracy, noise and output drive specifications. competing devices seriously degrade these parameters to achieve micro-power supply current. the parts feature an input range enhancement circuit (irec), which enables them to maintain cmrr performance for input voltages greater than the positive supply. the input signal is capable of swinging 0.25v above the positive supply and to 100mv below the negative supply with only a slight degradation of the cmrr performance. the output operation is rail-to-rail. the 1/f corner of the voltage noise spectrum is at 100hz. this results in low frequency noise performance, which can only be found on devices with an order of magnitude higher supply current. isl28168 and isl28268 can be operated from one lithium cell or two ni-cd batteries. the isl28168 contains an enable pin feature that allows the device to be shutdown when not in use. features ? 34a typical supply current ? 10pa typical input bias current ? 200khz gain bandwidth product ? 2.4v to 5.5v single supply voltage range ? rail-to-rail input and output ? enable pin (isl28168 only) ? pb-free (rohs compliant) applications ? battery- or solar-powered systems ? 4ma to 20ma current loops ? handheld consumer products ? medical devices ? sensor amplifiers ? adc buffers ? dac output amplifiers pinouts ordering information part number (note) part marking package (pb-free) pkg. dwg. # isl28168fhz-t7* gaca 6 ld sot-23 mdp0038 isl28168fhz-t7a* gaca 6 ld sot-23 mdp0038 isl28268fbz 28268 fbz 8 ld soic mdp0027 isl28268fbz-t7* 28268 fbz 8 ld soic mdp0027 ISL28268FUZ 8268z 8 ld msop mdp0043 ISL28268FUZ-t7* 8268z 8 ld msop mdp0043 isl28168eval1z evaluation board - 6 ld sot-23 isl28268soiceval1z evaluation board - 8 ld soic isl28268msopeval1z evaluation board - 8 ld msop *please refer to tb347 for detai ls on reel specifications. note: these intersil pb-free pl astic packaged products employ special pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus anneal (e3 termination finish, which is rohs compliant and compatible with both snpb and pb-free soldering operations). intersil pb-free products are msl classified at pb-free peak reflow te mperatures that meet or exceed the pb-free requirements of ipc/jedec j std-020. isl28168 (6 ld sot-23) top view isl28268 (8 ld soic) top view isl28268 (8 ld msop) top view 1 2 3 6 4 5 +- out v- in+ v+ en in- 1 2 3 4 8 7 6 5 out_a in-_a in+_a v+ out_b in-_b v- in+_b + - +- 1 2 3 4 8 7 6 5 out_a in-_a in+_a v+ out_b in-_b v- in+_b + - +- data sheet june 30, 2008
2 fn6378.3 june 30, 2008 absolute maxi mum ratings (t a = +25c) thermal information supply voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5.75v supply turn-on voltage slew rate . . . . . . . . . . . . . . . . . . . . . 1v/s differential input current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5ma differential input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.5v input voltage . . . . . . . . . . . . . . . . . . . . . . . . . v- - 0.5v to v+ + 0.5v esd rating human body model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3kv machine model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .300v charge device model. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1500v thermal resistance ja (c/w) 6 ld sot-23 package . . . . . . . . . . . . . . . . . . . . . . . 230 8 ld soic package . . . . . . . . . . . . . . . . . . . . . . . . 120 8 ld msop package . . . . . . . . . . . . . . . . . . . . . . . . 160 output short-circuit duration . . . . . . . . . . . . . . . . . . . . . . .indefinite ambient operating temperature range . . . . . . . . .-40c to +125c storage temperature range . . . . . . . . . . . . . . . . . .-65c to +150c operating junction temperature . . . . . . . . . . . . . . . . . . . . . +125c pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/pb-freereflow.asp caution: do not operate at or near the maximum ratings listed fo r extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty.. important note: all parameters having min/max specifications are guaranteed. typical values are for information purposes only. u nless otherwise noted, all tests are at the specified temperature and are pulsed tests, therefore: t j = t c = t a electrical specifications v + = 5v, v - = 0v, v cm = 2.5v, r l = open , t a = +25c unless otherwise specified. boldface limits apply over the operating temperature range, -40c to +125c. temperature data established by c haracterization. parameter description conditions min (note 1) typ max (note 1) unit dc specifications v os input offset voltage isl28168 -1.6 -1.8 0.09 1.6 1.8 mv isl28268 -2.4 -2.6 0.09 2.4 2.6 mv input offset voltage vs temperature 0.3 v/c i os input offset current t a = -40c to +85c -35 -80 5 35 80 pa i b input bias current t a = -40c to +85c -30 -80 10 30 80 pa cmir common-mode voltage range guaranteed by cmrr 0 5 v cmrr common-mode rejection ratio v cm = 0v to 5v 75 70 98 db psrr power supply rejection ratio v + = 2.4v to 5.5v 80 75 98 db a vol large signal voltage gain v o = 0.5v to 4.5v, r l = 100k to v cm 100 75 220 v/mv v o = 0.5v to 4.5v, r l = 1k to v cm 45 v/mv v out maximum output voltage swing output low, r l = 100k to v cm 5.5 6 20 mv output low, r l = 1k to v cm 135 150 250 mv output high, r l = 100k to v cm 4.992 4.990 4.995 v output high, r l = 1k to v cm 4.84 4.77 4.874 v i s,on quiescent supply current, enabled per amp 34 43 55 a i s,off quiescent supply current, disabled (isl28168) 10 14 19 a v os t --------------- - isl28168, isl28268
3 fn6378.3 june 30, 2008 i o + short-circuit output source current r l = 10 to v cm 27 15 30 ma i o - short-circuit output sink current r l = 10 to v cm -25 -22 -15 ma v supply supply operating range v + to v - 2.4 5.5 v v inh en pin high level (isl28168) 2 v v inl en pin low level (isl28168) 0.8 v i enh en pin input high current (isl28168) v en = v + 11.5 1.6 a i enl en pin input low current (isl28168) v en = v - 12 25 30 na ac specifications gbw gain bandwidth product a v = 100, r f = 100k , r g = 1k , r l = 10k to v cm 200 khz unity gain bandwidth -3db bandwidth a v =1, r f = 0 , v out = 10mv p-p , r l = 10k to v cm 420 khz e n input noise voltage peak-to-peak f = 0.1hz to 10hz 1.4 v p-p input noise voltage density f o = 1khz 64 nv/ hz i n input noise current density f o = 10khz 0.19 pa/ hz cmrr @ 60hz input common mode rejection ratio v cm = 1v p-p , r l = 10k to v cm -70 db psrr+ @ 120hz power supply rejection ratio - +v v + , v - = 1.2v and 2.5v, v source = 1v p-p , r l = 10k to v cm -64 db psrr- @ 120hz power supply rejection ratio - -v v + , v - = 1.2v and 2.5v v source = 1v p-p , r l = 10k to v cm -85 db transient response sr slew rate 0.1 v/s t r , t f , large signal rise time, 10% to 90%, v out a v = +2 , v out = 1v p-p , r g = r f = 10k r l = 10k to v cm 10 s fall time, 90% to 10%, v out a v = +2 , v out = 1v p-p , r g = r f = 10k r l = 10k to v cm 9s t r , t f , small signal rise time, 10% to 90%, v out a v = +2 , v out = 10mv p-p , r g = r f = r l = 10k to v cm 650 ns fall time, 90% to 10%, v out a v = +2 , v out = 10mv p-p , r g = r f = r l = 10k to v cm 640 ns t en enable to output turn-on delay time, 10% en to 10% v out , (isl28168) v en = 5v to 0v, a v = +2, r g = r f = r l = 1k to v cm 15 s enable to output turn-off delay time, 10% en to 10% v out , (isl28168) v en = 0v to 5v, a v = +2, r g = r f = r l = 1k to v cm 0.5 s note: 1. parameters with min and/or max limits are 100% tested at +25 c, unless otherwise specified. te mperature limits established by characterization and are not production tested. electrical specifications v + = 5v, v - = 0v, v cm = 2.5v, r l = open , t a = +25c unless otherwise specified. boldface limits apply over the operating temperature range, -40c to +125c. temperature data established by c haracterization. (continued) parameter description conditions min (note 1) typ max (note 1) unit isl28168, isl28268
4 fn6378.3 june 30, 2008 typical performance curves v + = 5v, v - = 0v, v cm = 2.5v, r l = open figure 1. gain vs frequency vs feedback resistor values r f /r g figure 2. gain vs frequency vs v out, r l = 1k figure 3. gain vs frequency vs v out , r l = 10k figure 4. gain vs frequency vs v out , r l = 100k figure 5. gain vs frequency vs r l figure 6. frequency resp onse vs closed loop gain -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 r f = r g = 10k 100 1k 10k 100k 1m frequency (hz) 10 r f = r g = 499 r f = r g = 1k r f = r g = 4.99k v + = 5v r l = 1k a v = +2 v out = 10mv p-p c l = 16.3pf normalized gain (db) -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 1k 10k 100k 1m frequency (hz) v out = 100mv v out = 10mv v out = 50mv normalized gain (db) v + = 5v r l = 1k a v = +1 v out = 10mv p-p c l = 16.3pf v out = 1v -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 1k 10k 100k 1m frequency (hz) v out = 100mv v out = 50mv v out = 10mv v + = 5v r l = 10k a v = +1 v out = 10mv p-p c l = 16.3pf normalized gain (db) v out = 1v -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 1k 10k 100k 1m frequency (hz) v out = 100mv v out = 50mv v out = 10mv normalized gain (db) v + = 5v r l = 100k a v = +1 v out = 10mv p-p c l = 16.3pf v out = 1v -6 -5 -4 -3 -2 -1 0 1 2 3 4 1k 10k 100k 1m frequency (hz) r l = 10k r l = 1k r l = 100k normalized gain (db) v + = 5v a v = +1 v out = 10mv p-p c l = 16.3pf 10 100 1k 10k 100k 1m frequency (hz) -10 0 10 20 30 40 50 60 70 av = 1, r g = inf, r f = 0 av = 10, r g = 1k, r f = 9.09k av = 101, r g = 1k, r f = 100k av = 1001, r g = 1k, r f = 1m a v = 1001 a v = 101 a v = 10 a v = 1 gain (db) v + = 5v v out = 10mv p-p c l = 16.3pf r l = 10k isl28168, isl28268
5 fn6378.3 june 30, 2008 figure 7. gain vs frequency vs supply vo ltage figure 8. gain vs frequency vs c l figure 9. cmrr vs frequency, v + = 2.4v and 5v figure 10. psrr vs frequency, v + , v - = 1.2v figure 11. psrr vs frequency, v + , v - = 1.2v figure 12. input voltage noise density vs frequency typical performance curves v + = 5v, v - = 0v, v cm = 2.5v, r l = open (continued) -8 -7 -6 -5 -4 -3 -2 -1 0 1 v + = 2.4v 1k 10k 100k 1m frequency (hz) r l = 10k a v = +1 v out = 10mv p-p c l = 16.3pf normalized gain (db) v + = 5v -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 1k 10k 100k 1m frequency (hz) c l = 98.3pf c l = 72.3pf c l = 55.3pf c l = 43.3pf c l = 34.3pf c l = 16.3pf normalized gain (db) v + = 5v r l = 10k a v = +1 v out = 10mv p-p -90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 10 100 1k 10k 100k 1m frequency (hz) v + = 2.4v, 5v r l = 10k a v = +1 v cm = 1v p-p c l = 16.3pf cmrr (db) -100 -80 -60 -40 -20 0 -90 -70 -50 -30 -10 10 10 100 1k 10k 100k 1m frequency (hz) v + = 2.4v r l = 10k a v = +1 v cm = 1v p-p c l = 16.3pf psrr- psrr+ psrr (db) -100 -80 -60 -40 -20 0 -90 -70 -50 -30 -10 10 10 100 1k 10k 100k 1m frequency (hz) v + = 5v r l = 10k a v = +1 v cm = 1v p-p c l = 16.3pf psrr- psrr+ psrr (db) 10 100 1000 1 10 100 1k 10k 100k frequency (hz) v + = 5v r l = 10k a v = +1 c l = 16.3pf input voltage noise (nv hz) isl28168, isl28268
6 fn6378.3 june 30, 2008 figure 13. input current noise density vs freque ncy figure 14. input voltage noise 0.1hz to 10hz figure 15. large signal step respons e figure 16. small signal step response figure 17. isl28168 enable to output response fig ure 18. input offset vo ltage vs common mode input voltage typical performance curves v + = 5v, v - = 0v, v cm = 2.5v, r l = open (continued) 0.1 1 10 1 10 100 1k 10k 100k frequency (hz) v + = 5v r l = 10k a v = +1 c l = 16.3pf input current noise (pa hz) -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0 012345678910 time (s) v + = 5v r l = 10k r g = 100, r f = 100k a v = 1000 c l = 16.3pf input noise (v) -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0 50 100 150 200 250 300 350 400 time (s) v + , v - = 2.5v r l = 10k r g = r f = 10k a v = 2 c l = 16.3pf v out = 1v p-p large signal (v) 0.006 0.008 0.010 0.012 0.014 0.016 0.018 0.020 0 50 100 150 200 250 300 350 400 time (s) v + , v - = 2.5v r l = 10k r g = r f = 10k a v = 2 c l = 16.3pf v out = 10mv p-p small signal (v) -1 0 1 2 3 4 5 6 0 50 100 150 200 250 300 350 400 time (s) -0.2 0 0.2 0.4 0.6 0.8 1.0 1.2 v + = 5v r g = r f = 10k a v = +2 v out = 1v p-p c l = 16.3pf v-enable v-out r l = 10k v-enable (v) output (v) -500 -400 -300 -200 -100 0 100 200 300 400 500 0123456 v cm (v) -1 v + = 5v r l = open a v = +1000 r f = 100k, r g = 100 v os (v) isl28168, isl28268
7 fn6378.3 june 30, 2008 figure 19. input bias current vs common mode input voltage figure 20. supply current enabled vs temperature, v + , v - = 2.5v figure 21. supply current disabled vs temperature, v + , v - = 2.5v figure 22. v os (sot pkg) vs temperature, v in = 0v, v + , v - = 2.75v figure 23. v os (sot pkg) vs temperature, v in = 0v, v + , v - = 2.5v figure 24. v os (sot pkg) vs temperature, v in = 0v, v + , v - = 1.2v typical performance curves v + = 5v, v - = 0v, v cm = 2.5v, r l = open (continued) -100 -80 -60 -40 -20 0 20 40 60 80 100 -10123456 vcm (v) v + = 5v r l = open a v = +1000 r f = 100k, r g = 100 i bias (pa) 20 25 30 35 40 45 50 -40 -20 0 20 40 60 80 100 120 temperature (c) current (a) median max n = 1000 min 5 6 7 8 9 10 11 12 13 14 -40 -20 0 20 40 60 80 100 120 temperature (c) current (a) median max n = 1000 min -1.5 -1.0 -0.5 0 0.5 1.0 1.5 -40-200 20406080100120 temperature (c) v os (v) median max n = 1000 min -1.5 -1.0 -0.5 0 0.5 1.0 1.5 -40 -20 0 20 40 60 80 100 120 temperature (c) v os (v) median max n = 1000 min -1.5 -1.0 -0.5 0 0.5 1.0 1.5 -40 -20 0 20 40 60 80 100 120 temperature (c) v os (v) median max n = 1000 min isl28168, isl28268
8 fn6378.3 june 30, 2008 figure 25. i bias + vs temperature, v + , v - = 2.5v figure 26. i bias - vs temperature, v + , v - = 2.5v figure 27. i bias + vs temperature, v + , v - = 1.2v figure 28. i bias - vs temperature, v + , v - = 1.2v figure 29. i os vs temperature, v + , v - = 2.5 figure 30. i os vs temperature, v + , v - = 1.2v typical performance curves v + = 5v, v - = 0v, v cm = 2.5v, r l = open (continued) -50 0 50 100 150 200 250 -40-200 20406080100120 temperature (c) i bias + (pa) max median min n = 1000 -50 0 50 100 150 200 250 300 350 400 450 500 -40 -20 0 20 40 60 80 100 120 temperature (c) i bias - (pa) max median min n = 1000 -50 0 50 100 150 200 250 300 350 -40 -20 0 20 40 60 80 100 120 temperature (c) i bias + (pa) max median min n = 1000 -50 0 50 100 150 200 250 300 350 400 450 -40 -20 0 20 40 60 80 100 120 temperature (c) i bias - (pa) max median min n = 1000 -160 -140 -120 -100 -80 -60 -40 -20 0 20 -40-200 20406080100120 temperature (c) i os (pa) max median min n = 1000 -150 -130 -110 -90 -70 -50 -30 -10 10 30 -40 -20 0 20 40 60 80 100 120 temperature (c) max median min i os (pa) n = 1000 isl28168, isl28268
9 fn6378.3 june 30, 2008 figure 31. cmrr vs temperature, v cm = -2.5v to +2.5v, v +, v - = 2.5v figure 32. psrr vs temperature, v +, v - = 1.2v to 2.75v figure 33. a vol vs temperature, v +, v - = 2.5v, v o = -2v to +2v, r l = 100k figure 34. a vol vs temperature, v +, v - = 2.5v, v o = -2v to +2v, r l = 1k figure 35. v out high vs temperature, v +, v - = 2.5v, r l = 1k figure 36. v out high vs temperature, v +, v - = 2.5v, r l = 100k typical performance curves v + = 5v, v - = 0v, v cm = 2.5v, r l = open (continued) 70 80 90 100 110 120 130 140 -40-200 20406080100120 temperature (c) cmrr (db) median max n = 1000 min 80 90 100 110 120 130 140 -40-200 20406080100120 temperature (c) psrr (db) 80 90 100 110 120 130 140 -40-200 20406080100120 median max n = 1000 min 100 150 200 250 300 350 400 450 -40 -20 0 20 40 60 80 100 120 temperature (c) median min a vol (v/mv) n = 1000 max 20 25 30 35 40 45 50 55 60 65 70 -40 -20 0 20 40 60 80 100 120 temperature (c) median a vol (v/mv) max min n = 1000 4.84 4.85 4.86 4.87 4.88 4.89 4.90 4.91 4.92 -40 -20 0 20 40 60 80 100 120 temperature (c) v out (v) max n = 1000 min median 4.9955 4.9960 4.9965 4.9970 4.9975 4.9980 -40 -20 0 20 40 60 80 100 120 temperature (c) v out (v) max n = 1000 min median isl28168, isl28268
10 fn6378.3 june 30, 2008 figure 37. v out low vs temperature, v +, v - = 2.5v, r l = 1k figure 38. v out low vs temperature, v +, v - = 2.5v, r l = 100k figure 39. i o + short circuit output current vs temperature, v in = -2.55v, r l = 10k, v +, v - = 2.5v figure 40. i o - short circuit output current vs temperature, v in = +2.55v, r l = 10k, v +, v - = 2.5v typical performance curves v + = 5v, v - = 0v, v cm = 2.5v, r l = open (continued) 100 110 120 130 140 150 160 170 180 190 -40-200 20406080100120 temperature (c) max n = 1000 min median v out (mv) 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 -40 -20 0 20 40 60 80 100 120 temperature (c) v out (mv) median max n = 1000 min 20 25 30 35 40 45 -40 -20 0 20 40 60 80 100 120 temperature (c) i o + short circuit current (ma) median max n = 1000 min -32 -30 -28 -26 -24 -22 -20 -40 -20 0 20 40 60 80 100 120 temperature (c) i o - short circuit current (ma) median max n = 1000 min isl28168, isl28268
11 fn6378.3 june 30, 2008 applications information introduction the isl28168 is a single cmos rail-to-rail input, output (rrio) operational amplifier with an enable feature. the isl28268 is a dual version wit hout the enable feature. both devices are designed to operate from single supply (2.4v to 5.5v) or dual supplies (1.2v to 2.75v). rail-to-rail input/output many rail-to-rail input stages us e two differential input pairs, a long-tail pnp (or pfet) and an npn (or nfet). severe penalties have to be paid for this circuit topology. as the input signal moves from one supply rail to another, the operational amplifier switches from one input pair to the other causing drastic changes in input offset voltage and an undesired change in magnitude and polarity of input offset current. the isl28168 and isl28268 achieve input rail-to-rail operation without sacrific ing important precision specifications and degrading distortion performance. the devices? input offset voltage exhibits a smooth behavior throughout the entire common-mode input range. the input bias current versus the common-mode voltage range gives us an undistorted behavior from typically 100mv below the negative rail, and 0.25v higher than the v+ rail. the cmos output stage features excellent drive capability, typically swinging to within 6mv of either rail with a 100k load. pin descriptions isl28168 (6 ld sot-23) isl28268 (8 ld soic) (8 ld msop) pin name function equivalent circuit 4 2 (a) 6 (b) in- in-_a in-_b inverting input circuit 1 3 3 (a) 5 (b) in+ in+_a in+_b non-inverting input see circuit 1 2 4 v- negative supply circuit 2 1 1 (a) 7 (b) out out_a out_b output circuit 3 6 8 v+ positive supply see circuit 2 5en chip enable circuit 3 in+ in- v+ v- v+ v- capacitively coupled esd clamp v+ v- out logic pin v+ v- isl28168, isl28268
12 fn6378.3 june 30, 2008 results of over-driving the output caution should be used when over-driving the output for long periods of time. over-driving the output can occur in two ways. 1. the input voltage times the gain of the amplifier exceeds the supply voltage by a large value 2. the output current required is higher than the output stage can deliver. these conditions can result in a shift in the input offset voltage (v os ) as much as 1v/hr. of exposure under these conditions. in+ and in- input protection all input terminals have internal esd protection diodes to both positive and negative supply rails, limiting the input voltage to within one diode beyond the supply rails. they also contain back-to-back diodes across the input terminals (see ?pin descriptions? on page 11 - circuit 1 ) . for applications where the input differential voltage is expected to exceed 0.5v, an external series resistor mu st be used to ensure the input currents never exceed 5ma (see figure 41). enable/disab le feature the isl28168 offers an en pin that disables the device when pulled up to at least 2.0v. in the disabled state (output in a high impedance state), the part consumes typically 10a at room temperature. by disabling the part, multiple isl28168 parts can be connected together as a mux. in this configuration, the outputs are ti ed together in parallel and a channel can be selected by the en pin. the loading effects of the feedback resistors of the disabled amplifier must be considered when multiple amp lifier outputs are connected together. note that feed through from the in+ to in- pins occurs on any mux amp disabled channel where the input differential voltage exceeds 0.5v (e.g., active channel v out = 1v, while disabled channel v in = gnd), so the mux implementation is best suited for small signal applications. if large signals are required, use series in+ resistors, or large value r f , to keep the feed through current low enough to minimize the impact on the acti ve channel. see ?limitations of the differential input protection? on page 12 for more details.the en pin also has an internal pull-down. if left open, the en pin will pull to the negative rail and the device will be enabled by default. the en pin should never be left floating. the en pin should be connected directly to the -v pin when not used. limitations of the differential input protection if the input differential voltage is expected to exceed 0.5v, an external current limiting resistor must be used to ensure the input current never exceeds 5ma. for non inverting unity gain applications, the current limiting can be via a series in+ resistor, or via a feedback resistor of appropriate value. for other gain configurations, the se ries in+ resistor is the best choice, unless the feedback (r f ) and gain setting (r g ) resistors are both sufficiently lar ge to limit the input current to 5ma. large differential input voltages can arise from several sources: 1. during open loop (comparator) operation. used this way, the in+ and in- voltages don?t track, so differentials arise. 2. when the amplifier is disabled but an input signal is still present. an r l or r g to gnd keeps the in- at gnd, while the varying in+ signal creates a differential voltage. mux amp applications are similar, except that the active channel v out determines the voltage on the in- terminal. 3. when the slew rate of the input pulse is considerably faster than the op amp?s slew rate. if the v out can?t keep up with the in+ signal, a differential voltage results, and visible distortion occurs on t he input and output signals. to avoid this issue, keep the input slew rate below 0.1v/s, or use appropriate current limiting resistors. large (>2v) differential input voltages can also cause an increase in disabled i cc . using only one channel the isl28268 is a dual op amp. if the application only requires one channel, the us er must configure the unused channel to prevent it from o scillating. the unused channel will oscillate if the input and output pins are floating. this will result in higher than expected supply currents and possible noise injection into the channel being used. the proper way to prevent this oscillation is to short the output to the negative input and ground the positive input (as shown in figure 42). proper layout maximizes performance to achieve the maximum performance of the high input impedance and low offset voltage, care should be taken in the circuit board layout. the pc board surface must remain clean and free of moisture to avoid leakage currents between adjacent traces. surface coating of the circuit board will reduce surface moisture and provide a humidity barrier, reducing parasitic resistance on the board. when input leakage current is a concern, the use of guard rings around the amplifier inputs will further reduce leakage currents. figure 41. input current limiting - + r in r l v in v out figure 42. preventing oscillations in unused channels - + isl28168, isl28268
13 fn6378.3 june 30, 2008 figure 43 shows a guard ring example for a unity gain amplifier that uses the low imp edance amplifier output at the same voltage as the high impedance input to eliminate surface leakage. the guard ring does not need to be a specific width, but it should form a continuous loop around both inputs. for further reduction of leakage currents, components can be mounted to the pc board using teflon standoff insulators. current limiting these devices have no internal current-limiting circuitry. if the output is shorted, it is possible to exceed the absolute maximum rating for output current or power dissipation, potentially resulting in the destruction of the device. power dissipation it is possible to exceed the +125c maximum junction temperatures under certain load and power-supply conditions. it is therefore important to calculate the maximum junction temperature (t jmax ) for all applications to determine if power supply voltages, load conditions, or package type need to be modified to remain in the safe operating area. these paramete rs are related in equation 1: where: ?p dmaxtotal is the sum of the maximum power dissipation of each amplifier in the package (pd max ) ?pd max for each amplifier can be calculated using equation 2: where: ?t max = maximum ambient temperature ? ja = thermal resistance of the package ?pd max = maximum power dissipation of 1 amplifier ?v s = supply voltage (magnitude of v + and v - ) ?i max = maximum supply current of 1 amplifier ?v outmax = maximum output voltage swing of the application r l = load resistance in v+ figure 43. guard ring example for unity gain amplifier high impedance input + - t jmax t max ja xpd maxtotal () + = (eq. 1) pd max 2*v s i smax v s ( - v outmax ) v outmax r l ---------------------------- + = (eq. 2) isl28168, isl28268
14 fn6378.3 june 30, 2008 isl28168, isl28268 sot-23 package family e1 n a d e 4 3 2 1 e1 0.15 d c 2x 0.20 c 2x e b 0.20 m d c a-b b nx 6 2 3 5 seating plane 0.10 c nx 1 3 c d 0.15 a-b c 2x a2 a1 h c (l1) l 0.25 0 +3 -0 gauge plane a mdp0038 sot-23 package family symbol millimeters tolerance sot23-5 sot23-6 a 1.45 1.45 max a1 0.10 0.10 0.05 a2 1.14 1.14 0.15 b 0.40 0.40 0.05 c 0.14 0.14 0.06 d 2.90 2.90 basic e 2.80 2.80 basic e1 1.60 1.60 basic e 0.95 0.95 basic e1 1.90 1.90 basic l 0.45 0.45 0.10 l1 0.60 0.60 reference n 5 6 reference rev. f 2/07 notes: 1. plastic or metal protrusions of 0.25mm maximum per side are not included. 2. plastic interlead protrusions of 0.25mm maximum per side are not included. 3. this dimension is measured at datum plane ?h?. 4. dimensioning and tolerancing per asme y14.5m-1994. 5. index area - pin #1 i.d. will be located within the indicated zone (sot23-6 only). 6. sot23-5 version has no center lead (shown as a dashed line).
15 fn6378.3 june 30, 2008 isl28168, isl28268 small outline package family (so) gauge plane a2 a1 l l1 detail x 4 4 seating plane e h b c 0.010 b m ca 0.004 c 0.010 b m ca b d (n/2) 1 e1 e n n (n/2)+1 a pin #1 i.d. mark h x 45 a see detail ?x? c 0.010 mdp0027 small outline package family (so) symbol inches tolerance notes so-8 so-14 so16 (0.150?) so16 (0.300?) (sol-16) so20 (sol-20) so24 (sol-24) so28 (sol-28) a 0.068 0.068 0.068 0.104 0.104 0.104 0.104 max - a1 0.006 0.006 0.006 0.007 0.007 0.007 0.007 0.003 - a2 0.057 0.057 0.057 0.092 0.092 0.092 0.092 0.002 - b 0.017 0.017 0.017 0.017 0.017 0.017 0.017 0.003 - c 0.009 0.009 0.009 0.011 0.011 0.011 0.011 0.001 - d 0.193 0.341 0.390 0.406 0.504 0.606 0.704 0.004 1, 3 e 0.236 0.236 0.236 0.406 0.406 0.406 0.406 0.008 - e1 0.154 0.154 0.154 0.295 0.295 0.295 0.295 0.004 2, 3 e 0.050 0.050 0.050 0.050 0.050 0.050 0.050 basic - l 0.025 0.025 0.025 0.030 0.030 0.030 0.030 0.009 - l1 0.041 0.041 0.041 0.056 0.056 0.056 0.056 basic - h 0.013 0.013 0.013 0.020 0.020 0.020 0.020 reference - n 8 14 16 16 20 24 28 reference - rev. m 2/07 notes: 1. plastic or metal protrusions of 0.006? maximum per side are not included. 2. plastic interlead protrusions of 0.010? maximum per side are not included. 3. dimensions ?d? and ?e1? are measured at datum plane ?h?. 4. dimensioning and tolerancing per asme y14.5m - 1994
16 all intersil u.s. products are manufactured, asse mbled and tested utilizing iso9000 quality systems. intersil corporation?s quality certifications ca n be viewed at www.intersil.com/design/quality intersil products are sold by description only. intersil corpor ation reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnishe d by intersil is believed to be accurate and reliable. however, no responsibility is assumed by intersil or its subsidiaries for its use; nor for any infringements of paten ts or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of intersil or its subsidiari es. for information regarding intersil corporation and its products, see www.intersil.com fn6378.3 june 30, 2008 isl28168, isl28268 mini so package family (msop) 1 (n/2) (n/2)+1 n plane seating n leads 0.10 c pin #1 i.d. e1 e b detail x 3 3 gauge plane see detail "x" c a 0.25 a2 a1 l 0.25 c a b d a m b e c 0.08 c a b m h l1 mdp0043 mini so package family symbol millimeters tolerance notes msop8 msop10 a1.101.10 max. - a1 0.10 0.10 0.05 - a2 0.86 0.86 0.09 - b 0.33 0.23 +0.07/-0.08 - c0.180.18 0.05 - d 3.00 3.00 0.10 1, 3 e4.904.90 0.15 - e1 3.00 3.00 0.10 2, 3 e0.650.50 basic - l0.550.55 0.15 - l1 0.95 0.95 basic - n 8 10 reference - rev. d 2/07 notes: 1. plastic or metal protrusions of 0.15mm maximum per side are not included. 2. plastic interlead protrusions of 0.25mm maximum per side are not included. 3. dimensions ?d? and ?e1? are measured at datum plane ?h?. 4. dimensioning and tolerancing per asme y14.5m-1994.

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