analog devices fax-on-demand hotline - page 2 -.. analog l.iiii devices i true 16-bit track-and-hold amplifier ad386 features companion to true 16-bit aid converters 16-bit linear (-40c to +85c) 14-bit linear (-55c to + 125ci fast acquisition time: 3.6 p.s to 0.00076% low droop rate: 20 p.v/ms differential amplifier for ground sense low aperture jitter: 40 ps appuca tlons medical and analytical instrumentation signal processing multichannel data acquisition systems automatic test equipment guidance and control sonar product description the ad386 is a high accuracy, adjustment free track-and- hold amplifier designed for high resolution data acquisition applications. the fast acquisition time (3.6 i-i-s to 75 j.i. v) and low aperture jitter (40 ps) make it ideal for u'se with fast nd converters. the ad386 is complete with an internal hold capacitor, and it incorporates a compensation network which minimizes the track-w-hold charge offset and dielectric absorption. the ad386 also includes an internal differential amplifier for very high accuracy applications. rev. a i"formation fumished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use; nor for any infringements of patents 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 analog devices. ad386 functional block diagram 5k 5k 5. ..15 v. tih typical applications for the ad386 include sampled data sys- tem, peak hold function, strobe measurement system and simul- taneous sampling converter systems. when used with autozero and autocalibration techniques, this tih combined with a high linearity nd wiu offer true 16-bit performance (0.00076% linearity) over the industrial temperature range, and 14-bit per- formance (0.003% linearity) over the military temperature range. one technology way; p. o. bok 9106; norwood. ma 02062.9106 u.s.a. tel: 617/329-4700 twx: 710/394-6577 telek:924491 cables: analog norwoodmass obsolete
analog devices fax-on-demand hotline - page 3 ad386 - specifications (@ +25"c unless otherwise noted. vs = :t:15 v :t: 10%) -2- rev. a AD386BD ad386td model conditions mid typ max mid typ max units differential amplifier input characteristics input range :tlo :tl0 v conunon-mode range :tl0 :tl0 v input resistance' signal 5 5 k!l ground sense io 10 ko offset1 0.6 2.0 0.6 2.0 mv offset drift tmin to t""", 10 30 10 30 ij. vi"c cmrr vcm = :tl0 80 9q 80 9q db psrr3 76 85 76 85 db - transfer characteristics gain -1 -1 vn gain error 0.02 0.02 % gain error drift tmin to tmax 1 5 1 5 ppm/"c gain linearity 0.0002 0.00076 0.0002 0.00076 % gain linearity drift tmin to tma. 0.01 0.05 0.01 0.05 ppm/"c noise (enbw = 1.8 mhz) 32 45 32 45 ij.v nns dynamic characteristics small signal bandwidth 6 6 mhz slew rate 65 65 v/v-s settling time' , 10 v step to 1/2 lsb16 2.0 3.0 jj.s 10 v step to 1/2 lsb14 0.8 1.5 0.8 1.5 ij.s 20 v step to 1/2 lsb16 2.0 3.0 ij.s 20 v step (0 1/2 lsb16 tmin to tm.. 2.0 3.0 ij.s 20 v step to 1/2 lsb14 0.8 1.5 0.8 1.5 ij.s 20 v step to 1i2 lsb14 tmin to tm.. 0.8 1.5 0.8 1.5 ij.s output voltage rload>3.5 kil, tmin to tmax :tlo :tl0 v current short circuit 15 15 ida power supply rated performance :t 15 :t 15 v operating range :t5 :t18 :t5 :t 18 v quiescent current 4.2 5.0 4.2 5.0 ma track-and-hold input characteristics input range :t1o :t1o v input resistance' 5 5 kn offsetl 0.6 2.0 0.6 2.0 mv offset drift tmin to tm.. 10 30 10 30 fj.vrc transfer characteristics gain -i -1 v/v gain error 0.02 0.02 % gain error drift tm,;ntotm.. 1 5 1 5 ppm/"c gain linearity 0.0002 0.00076 0.0002 0.00016 % gain linearity drift t min to t m.. 0.01 0.05 0.01 0.05 ppmjc psrr3 76 85 76 85 db dynamic characteristics small signal bandwidth 2 2 mhz slew rate 15 15 v/jj.s track-to-hold switching pedestal + offset 0.5 1.5 0.5 1.5 mv pedestal + offset tmintotmax 5.0 7.5 mv pedestal linearity tmin to tmax 0 . 0004 0.00076 o. 0004 0.003 % aperture delay 12 12 rls aperture jitter 40 40 ps transient settling4 to 1/2 lsb16 tmin to tm.. 600 800 os to 1/2 lsb14 t.un to t""", 400 500 400 500 ns obsolete
analog devices fax-on-demand hotline - page ad386 notes itypical resistance tolerance is :t25%. 'after 5 minute warmup at + 25"<:. 'test conditions: +vs = +15 v, -vs = -16 v to -14 v and +vs = +14 v [0 +16 v, -vs = -15 v. 'r..oad = 5 k!1, cloat) = jo pf, settling measured to 1/2 lsb at output. 'measured at i khz. 'dielectric absorption represents the magnitude of long-term settling artifacts for hold times up to 80 j..ls as a fraction of the difference in voltages between two successive held samples. 'specifications also apply for 10 v step. specifications subject to change without notice. specifications in bold are 100% production tested. rev. a -3- AD386BD ad386td model conditions min typ max min typ max units hold mode droop rate 20 100 20 100 mv/s droop rate tma. 0.2 1.0 3.6 18 vis feedthrough5 -99 -94 -99 -94 db noise (enbw = 1.7 mhz) 32 50 32 50 il v rids psrr) 60 6t' 60 66 db dielectric absorpion6 7 10 7 10 ppm hold-to-track dynamics acquisition time' 10 v step to 1/2 lsb16 3.6 4.1 fls 10 v step to 1/2 lsbi4 3.1 3.6 3.1 3.6 fj-s 20 v step to 1/2 lsb16 3.6 4.1 j..ls 20 v step to 1/2 lsb16 t",, tot""", 4.0 4.5 fj-s 20 v step to 1/2 lsb14 3.1 3.6 3.1 3.6 fls 20 v step to 1/2 lsbi4 t mi to t max 3.5 4.0 4.0 4.5 j..ls digital inputs vm t",, to tm.. 3.5 3.5 v vii. tmin to tmax 0.9 0.9 v 1m tmin to tmax -10 +10 -10 +10 ",a i[l t mi to t ma. -10 +10 -10 +10 f.la output voltage rr.oad>3.5 k!1, t mi to tm.. :::10 :::10 v current short circuit 15 15 ,ma power supply rated performance ::: 15 :t 15 v operating range :::8 :t 18 =8 :t18 v quiescent cun:ent positive supply 8.0 12.0 8.0 12.0 ma negaive supply -6.0 -sa -6.0 -5.4 ma system gain linearity t",;n to tma. 0.0003 0.0012 0.0003 0.0012 % acquisition time" 7 20 v step to 1/2 lsb16 4.1 5.1 j.ls 20 v step to 1/2 lsb16 tmintotmax 4.5 sa j.ls 20 v step to 1/2 lsbi4 3.2 3.9 3.2 3.9 j..ls 20 v step to 1/2 lsb14 t mid to t max 3.6 4.3 4.1 4.8 !-ls power dissipaion 312 435 312 435 row temperature range operating -40 +85 -55 -h25 c storage -60 +150 -60 +150 c obsolete
absolute maximum ratings1 supply voltage :h8v internal power dissipation. . . . . . . . . . . . . . . . . . .800 mw inputvoltage2 :!:18v tlhlnputvoltage o.5v,+ 16v output short circuit duration. . . . . . . . . . . . . . . .indefmite storage temperature range. . . . . . . . . . . .-65c to + 150"c operating temperature range ad386b 40cto+85c ad386t 55cto+125c lead temperature range (soldering 60 sec) .. . . . . . . + 300c notes 'stresses above those listed under "absolute maximum ratings" may cause permanent damage to the device. this is a stress rating only, and functional operation of the device at these or any other conditions above those indi- cated in the operational section of this specification is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. 'for supply vohages less than :!: 18 v, the absolute maximum input voltage is equal to the supply voltage. analog devices fax-on-demand hotline ad386 - page 5 nc= no connect %15 vb - diff ami' only ",'5 v. - sha only ad386 pin configuration sha out i 4 +15 v. gnd ordering guide *dh-24b = ceramic dip. typical periormance characteristics 100 10 ... ." '80 g .., 11/ 70 ... '" 880 :ie z iso .., 40 30 100 1k 101< frequency - hz 1004c -86 100 !i!-u , z ~ u lio ~ ~ ~ -92 -m 1m -50 -25 0 +25 +so +75 +100 +125 temperature --c ...90 ... , 280 s z 2 70 ~ ;;: "'&0 .. t ~so 140 30 100 figure 1. differential amplifier common figure 2. differential amplifier common mode rejection vs. frequency mode rejection vs. temperature (100 hz) 1k 10k frequency - hz figure 3. differential amplifier power supply rejection v5. frequency -4- 1001. 1m rev. a max linearity temperature package model error range option. AD386BD 0.00076% fsr -40"c to +85c dh-24b ad386td 0.003% fsr -55c to + 125c dh-24b ad386td/883b 0.003% fsr -55c to + 125c dh-24b i'. \ 1\ i ! ; i "" v v "" ........... ./" ! i r-, " '\ ;/,sflr ; i \.. , " " i -p5rr '-v v. = ""s.y ,\, 1 v p"i' sine wave input i' +25-c r\. obsolete
analog devices fax-on-demand hotline - page 6 ad386 4.0 3.$ ~ , 3.0 ~ ;; 2.5 ~ i 2.0 ;: .., z 1.5 e .. 1.0 0.5 0 0 $ 10 s1'p size - ii p1> 15 figure 4. differential amplifier settling time vs. step size 100 90 !ij , 80 ~ ~ 70 oj '" i80 ~ 1550 ~ 40 30 100 1k 10k frequency - h. look figure 7. t/h power supply rejection v5. frequency, hold mode 100 90 .. " , ~bo i3 ... oj 70 '" x goo :e x i; l:jiio ... 411 100 1k 'ok look frequency - hz figure 10. feedthrough vs. frequency rev. a 4.0 3.$ ;. 3.0 , 5: ~ 2.$ g '" :!i 2.0 1= " z @ 15 '" .. 1.0 20 0.$ -50 0 +25 +50 +75 +100 ~125 temperature -'c -25 100 90 .. " j :it 80 ~ ... ;;j 70 it: > ~ ~ 60 .. ffi ~50 iz 40 30 100 ik 1ok frequency-h. 100k 1m figure 5. differential amplifier settling figure 6. t/h power supply rejection v5. time v5. temperature frequency, track mode 5.0 4.5 2- .:. 4.0 ~ .. ;: 3.$ 0 l- i 30 ;: z ~2.5 .. 5 g 2.0 .. 1.5 1m 1.0 1.0 15 $ 10 step size - ii pop figure 8. tih acquisition time v5. step size 10 . ;;; i , ~ ... 0 0 it: 00.1 0.01 1m 0 +25 +50 +75 temperature - 'c +100 +125 -50 -25 figure 1,. droop rate vs. temperature -5- ---- 20 5.0 ii. = :t15 ii loll step 4.5 ';. , '" 4.0 5 '::! ;; 3.5 l- i ;: 30 z 0 ~ 25 :> 0 ;t 2.0 1.5 -50 -25 0 ~2s ~5o ~75 temperature --- 'c ~1oo ~125 figure 9. t/h acquisition time v5. temperature 4 ~ 2 , ~ l- v> ... ~ 0 ~ i- ... '" it 0 -2 -4 -so -25 0 +25 +so +75 +100 ~125 temperature - 'c figure 12. (pedesta/+offset) vs. temperature 11,- :>1511 i +n-c i " bit , , 14 bit i ! i +psrr i-- -. t-... ...... -psrr ., ii. = :15 v \ 1 v pop sine wave input +j"ci iii i i i ii " ....... - --- ! i ! i i ii. = ,,'$ ii , 20 ii step i ! ' i 16 bit ' - ..1-- i 14 bit r-r-. '" "\ r--.. '-;psrr i" '" -1 i -psjlr r\ i\.. ,/ +r\ i i '\ ii. = ""5 ii 1 ii p,p sine wave inpul +25'c '\. ii. - ",,511 20lls1'p ----- .--- " bit 14 bit / i / / ./ i obsolete
)1 ii ii ii ii i i i i ~h:= i~ i hold i --! aperture delay i ' u droop + dielectric transient i absorption i i amplitude --i '-- hold mode settling time d ~ i : - feedthrough i i -,- - - - - -j - - -,- i ; i i acquisition time --1 to specified accuracy analog input -fs track command +fs analog output . i-- s~t~~i~:e accuracy ~ figure 13. t/h characteristic features terminology aperture delay: the time required by the internal switch(es) to disconnect the hold capacitor from the input, which produces an effective delay in the sample timing. aperture jitter: the uncertainty in aperture delay caused by internal noise and the variation of switching thresholds with sig- nallevel. the error caused by aperture jitter depends on the rate of change of the input and as such determines the maxi- mum input frequency which can be sampled without error. pedestal: a step change in the output voltage which occurs when switching from track mode to hold mode. hold mode settling time: the time required for the pedestal to reach its final value to within a specified fraction of full scale. droop: the change in the held output voltage resulting from leakage currents. feedthrough: the fraction of input signal variation which appears at the output in hold mode as a result of capacitive coupling. dielectric absorption: the tendency of charges within a capacitor to redistribute themselves over time, resulting in "creep" in the voltage of an open circuit capacitor after a large rapid change. acquisition time: the time required after entering track mode for the voltage on the hold capacitor to settle to within a specified fraction of full scale. this is usually specified for a full-scale step change in output voltage. settling time: the time required in track mode for the output to reach its final value within a specified fraction of full scale fol- lowing a step change in the input voltage. nonlinearity: the degree to which a plot of output versus input deviates from the straight line defined by the end points. it is usually specified as a percentage of full scale. theory of operation the architecture of the ad386 differs from that usually encoun- tered in inverting track-and-hold (tih) circuits. the hold capacitor in a conventional tih (figure 14) is always connected from the amplifier's output to its inverting inpui. in track mode switch a is open and switch b is dosed. since the summing junction is a virtual ground, the voltage across the capacitor fol- lows the input. the switches change state in hold mode which disconnects the capacitor from the input and holds the output voltage constant. the clamping action of switch a reduces the variations across switch b, improving feed through performance. r v'n vout r a t/h figure 14. conventional inverting integrator t/h this circuit forces several tradeoffs. the hold capacitor's charg- ing current is limited by the input resistor. either the resistor or the capacitor, or both, must be made small to obtain fast acqui~ sition times. a small resistor creates greater demands on the cir- cuit which drives the tih, while a small capacitor leads to increased pedestal and droop. in addition, the parallel combina- tion of the feedback resistor and the hold capacitor acts as a low pass filter and constrains both bandwidth and acquisition time. -6- rev. a analog devices fax-on-demand hotline - page 7 ad386 +fs obsolete
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