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1 lt1021 1021fc applicatio s u features typical applicatio u descriptio u precision reference typical distribution of temperature drift output drift (ppm/ c) ? units (%) 24 21 18 15 12 9 6 3 ?0 3 1021 ta01 ? 1 1 5 2 ? ? 0 4 distribution of three runs basic positive and negative connections lt1021 out in gnd lt1021 (7 and 10 only) out in gnd v out ? out v in nc r1 = v out ?(v ) i load + 1.5ma ?5v (v ) r1 1021 ta01 ultralow drift: 5ppm/ c max slope very low noise: <1ppm p-p (0.1hz to 10hz) 100% noise tested pin compatible with most bandgap reference applications, including ref 01, ref 02, lm368, mc1400 and mc1404 with greatly improved stability, noise and drift trimmed output voltage operates in series or shunt mode output sinks and sources in series mode >100db ripple rejection minimum input/output differential of 1v available in 5-lead can, n8 and s8 packages a/d and d/a converters precision regulators digital voltmeters inertial navigation systems precision scales portable reference standard the lt 1021 is a precision reference with ultralow drift and noise, extremely good long term stability and almost total immunity to input voltage variations. the reference output will both source and sink up to 10ma. three voltages are available: 5v, 7v and 10v. the 7v and 10v units can be used as shunt regulators (two-terminal zeners) with the same precision characteristics as the three- terminal connection. special care has been taken to mini- mize thermal regulation effects and temperature induced hysteresis. the lt1021 references are based on a buried zener diode structure that eliminates noise and stability problems associated with surface breakdown devices. further, a subsurface zener exhibits better temperature drift and time stability than even the best bandgap references. unique circuit design makes the lt1021 the first ic reference to offer ultralow drift without the use of high power on-chip heaters. the lt1021-7 uses no resistive divider to set output voltage, and therefore exhibits the best long term stability and temperature hysteresis. the lt1021-5 and lt1021- 10 are intended for systems requiring a precise 5v or 10v reference with an initial tolerance as low as 0.05%. , ltc and lt are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners.
2 lt1021 1021fc a u g w a w u w a r b s o lu t exi t i s input voltage .......................................................... 40v input/output voltage differential ............................ 35v output-to-ground voltage (shunt mode current limit) lt1021-5 ............................................................. 10v lt1021-7 ............................................................. 10v lt1021-10 ........................................................... 16v trim pin-to-ground voltage positive ............................................... equal to v out negative ........................................................... ?20v output short-circuit duration v in = 35v ......................................................... 10 sec v in 20v ................................................... indefinite operating temperature range commercial ............................................ 0 c to 70 c industrial ........................................... 40 c to 85 c military ............................................ 55 c to 125 c storage temperature range ................ 65 c to 150 c lead temperature (soldering, 10 sec)................ 300 c wu u package / o rder i for atio t jmax = 150 c, ja = 150 c/w, jc = 45 c/w top view nc* nc* nc* v in v out trim ** nc* gnd 8 7 6 5 3 2 1 4 h package 8-lead to-5 metal can t jmax = 130 c, ja = 130 c/w (n) t jmax = 130 c, ja = 150 c/w (s) (note 1) 1 2 3 4 8 7 6 5 top view dnc* v in dnc* gnd dnc* dnc* v 0ut trim** n8 package 8-lead pdip s8 package 8-lead plastic so *connected internally. do not connect external circuitry to these pins. **no trim pin on lt1021-7. do not connect external circuitry to pin 5 on lt1021-7 order part number *connected internally. do not connect external circuitry to these pins. **no trim pin on lt1021-7. do not connect external circuitry to pin 5 on lt1021-7 obsolete lt1021bch-5 lt1021bmh-5 lt1021cch-5 lt1021cmh-5 lt1021bmh-10 lt1021dch-5 lt1021dmh-5 lt1021bch-7 lt1021bmh-7 lt1021dch-7 lt1021dmh-7 lt1021bch-10 lt1021cmh-10 lt1021dch-10 lt1021dmh-10 lt1021bcn8-5 lt1021ccn8-5 lt1021cin8-5 lt1021dcn8-5 lt1021din8-5 lt1021bcn8-7 lt1021dcn8-7 LT1021BCN8-10 lt1021ccn8-10 lt1021cin8-10 lt1021dcn8-10 lt1021din8-10 2105 2107 2110 n8 order part number lt1021dcs8-5 lt1021dcs8-7 lt1021dcs8-10 s8 order part number s8 part marking order options tape and reel: add #tr lead free: add #pbf lead free tape and reel: add #trpbf lead free part marking: http://www.linear.com/leadfree/ consult ltc marketing for parts specified with wider operating temperature ranges.
3 lt1021 1021fc e lectr ic al c c hara terist ics lt1021-5 parameter conditions min typ max units output voltage (note 2) lt1021c-5 4.9975 5.000 5.0025 v lt1021b-5/lt1021d-5 4.9500 5.000 5.0500 v output voltage temperature coefficient (note 3) t min t j t max lt1021b-5 2 5 ppm/ c lt1021c-5/lt1021d-5 3 20 ppm/ c line regulation (note 4) 7.2v v in 10v 4 12 ppm/v 20 ppm/v 10v v in 40v 2 6 ppm/v 10 ppm/v load regulation (sourcing current) 0 i out 10ma 10 20 ppm/ma (note 4) 35 ppm/ma load regulation (sinking current) 0 i out 10ma 60 100 ppm/ma (note 4) 150 ppm/ma supply current 0.8 1.2 ma 1.5 ma output voltage noise (note 6) 0.1hz f 10hz 3.0 v p-p 10hz f 1khz 2.2 3.5 v rms long term stability of output voltage (note 7) ? t = 1000hrs noncumulative 15 ppm temperature hysteresis of output ? t = 25 c 10 ppm lt1021-7 parameter conditions min typ max units output voltage (note 2) 6.95 7.00 7.05 v output voltage temperature coefficient (note 3) t min t j t max lt1021b-7 2 5 ppm/ c lt1021d-7 3 20 ppm/ c line regulation (note 4) 8.5v v in 12v 1.0 4 ppm/v 2.0 8 ppm/v 12v v in 40v 0.5 2 ppm/v 1.0 4 ppm/v load regulation (sourcing current) 0 i out 10ma 12 25 ppm/ma (note 4) 40 ppm/ma load regulation (shunt mode) 1.2ma i shunt 10ma 50 100 ppm/ma (notes 4, 5) 150 ppm/ma supply current (series mode) 0.75 1.2 ma 1.5 ma minimum current (shunt mode) v in is open 0.7 1.0 ma 1.2 ma output voltage noise (note 6) 0.1hz f 10hz 4.0 v p-p 10hz f 1khz 2.5 4.0 v rms long term stability of output voltage (note 7) ? t = 1000hrs noncumulative 7 ppm temperature hysteresis of output ? t = 25 c 3 ppm the denotes specifications that apply over the full operating temperature range, otherwise specifications are t a = 25 c. v in = 10v, i out = 0, unless otherwise noted. the denotes specifications that apply over the full operating temperature range, otherwise specifications are t a = 25 c. v in = 12v, i out = 0, unless otherwise noted.
4 lt1021 1021fc e lectr ic al c c hara terist ics lt1021-10 parameter conditions min typ max units output voltage (note 2) lt1021c-10 9.995 10.00 10.005 v lt1021b-10/lt1021d-10 9.950 10.00 10.050 v output voltage temperature coefficient (note 3) t min t j t max lt1021b-10 2 5 ppm/ c lt1021c-10/lt1021d-10 5 20 ppm/ c line regulation (note 4) 11.5v v in 14.5v 1.0 4 ppm/v 6 ppm/v 14.5v v in 40v 0.5 2 ppm/v 4 ppm/v load regulation (sourcing current) 0 i out 10ma 12 25 ppm/ma (note 4) 40 ppm/ma load regulation (shunt mode) 1.7ma i shunt 10ma 50 100 ppm/ma (notes 4, 5) 150 ppm/ma supply current (series mode) 1.2 1.7 ma 2.0 ma minimum current (shunt mode) v in is open 1.1 1.5 ma 1.7 ma output voltage noise (note 6) 0.1hz f 10hz 6.0 v p-p 10hz f 1khz 3.5 6 v rms long term stability of output voltage (note 7) ? t = 1000hrs noncumulative 15 ppm temperature hysteresis of output ? t = 25 c 5 ppm note 1: absolute maximum ratings are those values beyond which the life of a device may be impaired. note 2: output voltage is measured immediately after turn-on. changes due to chip warm-up are typically less than 0.005%. note 3: temperature coefficient is measured by dividing the change in output voltage over the temperature range by the change in temperature. separate tests are done for hot and cold; t min to 25 c and 25 c to t max . incremental slope is also measured at 25 c. note 4: line and load regulation are measured on a pulse basis. output changes due to die temperature change must be taken into account separately. package thermal resistance is 150 c/w for to-5 (h), 130 c/w for n and 150 c/w for the so-8. note 5: shunt mode regulation is measured with the input open. with the input connected, shunt mode current can be reduced to 0ma. load regulation will remain the same. note 6: rms noise is measured with a 2-pole highpass filter at 10hz and a 2-pole lowpass filter at 1khz. the resulting output is full-wave rectified and then integrated for a fixed period, making the final reading an average as opposed to rms. correction factors are used to convert from average to rms and correct for the non-ideal bandpass of the filters. peak-to-peak noise is measured with a single highpass filter at 0.1hz and a 2-pole lowpass filter at 10hz. the unit is enclosed in a still-air environment to eliminate thermocouple effects on the leads. test time is 10 seconds. note 7: consult factory for units with long term stability data. the denotes specifications that apply over the full operating temperature range, otherwise specifications are t a = 25 c. v in = 15v, i out = 0, unless otherwise noted.
5 lt1021 1021fc cc hara terist ics uw a t y p i ca lper f o r c e start-up (series mode) ripple rejection input voltage (v) 0 85 rejection (db) 90 95 100 105 10 20 30 40 lt1021 g01 110 115 515 25 35 f = 150hz lt1021-5 lt1021-10 lt1021-7 time ( s) 3 output voltage (v) 4 6 7 8 13 10 2 6 8 lt1021 g04 5 11 12 9 04 10 12 14 lt1021-10 lt1021-5 lt1021-7 v in = 0v to 12v output voltage noise spectrum output current (ma) 0 input/output voltage (v) 1.2 1.6 16 1021 g03 0.8 0.4 0 4 8 12 20 1.0 1.4 0.6 0.2 14 2 6 10 18 t j = 125 c t j = 55 c t j = 25 c frequency (hz) 100 noise voltage (nv/ hz) 200 250 350 400 10 1k 10k lt1021 g06 0 100 300 150 50 lt1021-10 lt1021-5 lt1021-7 ripple rejection frequency (hz) 10 90 rejection (db) 110 130 120 100 80 60 100 1k 10k lt1021 g02 70 50 v in = 15v c out = 0 lt1021-5 lt1021-10 lt1021-7 start-up (shunt mode) lt1021-7, lt1021-10 time ( s) output voltage (v) 9 10 11 48 lt1021 g05 8 7 02 61012 6 5 lt1021-10 lt1021-7 in gnd out nc 1k v out 0v v out + 2v bandwidth (hz) 10 8 rms noise ( v) 12 16 14 10 6 2 100 1k 10k lt1021 g07 4 0 c out = 0 filter = 1 pole f low = 0.1hz lt1021-10 lt1021-5 lt1021-7 output voltage temperature drift lt1021-5 output voltage noise temperature ( c) ?0 4.994 4.996 output voltage (v) 5.000 5.006 0 50 75 lt1021 g08 4.998 5.004 5.002 ?5 25 100 125 load regulation lt1021-5 output current ( ma ) ?0 output change (mv) 1 3 5 4 2 0 ? ? 6 lt1021 g09 ? ? ? ? ? 4 0 4 8 ? 2 10 v in = 8v sourcing sinking minimum input/output differential lt1021-7, lt1021-10
6 lt1021 1021fc cc hara terist ics uw a t y p i ca lper f o r c e quiescent current lt1021-5 input voltage (v) 0 0 input current (ma) 0.2 0.6 0.8 1.0 35 30 1.8 lt1021 g10 0.4 5 10152025 40 1.2 1.4 1.6 t j = 55 c t j = 25 c t j = 125 c i out = 0 sink mode* current limit lt1021-5 output voltage (v) 0 0 current into output (ma) 10 30 40 50 4 8 10 18 lt1021 g11 20 26 12 14 16 60 v in = 8v *note that an input voltage is required for 5v units. thermal regulation lt1021-5 time (ms) output change (mv) 1.0 0.5 140 lt1021 g12 20 60 100 0 0 40 80 120 load regulation thermal regulation i load = 10ma v in = 25v ? power = 200mw load transient response lt1021-5, c load = 1000pf load transient response lt1021-5, c load = 0 time ( s) output change (50mv/div) 2 lt1021 g13 1 02413 3 0 4 i source = 2-10ma i source = 0.5ma i sink = 0 i sink = 0.2ma i sink = 2-10ma 50mv 50mv ? i sink = 100 a p-p ? i source = 100 a p-p i source = 0 output noise 0.1hz to 10hz lt1021-5 time ( s) output change (20mv/div) 10 lt1021 g14 5 01020515 15 0 20 i source = 2-10ma i source = 0.2ma i sink = 0 i sink = 0.2ma i sink = 2-10ma 20mv 20mv ? i sink = 100 a p-p ? i source = 100 a p-p i source = 0 time (minutes) 035 lt1021 g15 12 46 output voltage noise (5 v/div) 5 v (1ppm) filtering = 1 zero at 0.1hz 2 poles at 10hz load regulation lt1021-7, lt1021-10 output voltage temperature drift lt1021-7 temperature ( c) ?0 6.997 6.998 output voltage (v) 7.000 7.003 0 50 75 lt1021 g16 6.999 7.002 7.001 ?5 25 100 125 output current ( ma ) ?0 output change (mv) 1 3 5 4 2 0 ? ? 6 lt1021 g17 ? ? ? ? ? 4 0 4 8 ? 2 10 v in = 12v sourcing sinking quiescent current lt1021-7 input voltage (v) 0 0 input current (ma) 0.2 0.6 0.8 1.0 35 30 1.8 lt1021 g18 0.4 5 10152025 40 1.2 1.4 1.6 t j = 55 c t j = 25 c t j = 125 c i out = 0
7 lt1021 1021fc cc hara terist ics uw a t y p i ca lper f o r c e shunt characteristics lt1021-7 shunt mode current limit lt1021-7 thermal regulation lt1021-7 output to ground voltage (v) 0 0 current into output (ma) 0.2 0.6 0.8 1.0 2 4 59 1021 g19 0.4 13 6 7 8 1.2 input pin open t j = 125 c t j = 55 c t j = 25 c output voltage (v) 0 0 current into output (ma) 10 30 40 50 4 8 10 18 lt1021 g20 20 26 12 14 16 60 input pin open time (ms) output change (mv) ?.0 0.5 0 140 lt1021 g21 ?.5 20 60 100 0 40 80 120 load regulation thermal regulation* i load = 10ma *independent of temperature coefficient v in = 27v ? power = 200mw load regulation lt1021-7, lt1021-10 temperature ( c) ?0 9.994 9.996 output voltage (v) 10.000 10.006 0 50 75 lt1021 g25 9.998 10.004 10.002 ?5 25 100 125 output voltage temperature drift lt1021-10 output current ( ma ) ?0 output change (mv) 1 3 5 4 2 0 ? ? 6 1021 g26 ? ? ? ? ? 4 0 4 8 ? 2 10 v in = 12v sourcing sinking input supply current lt1021-10 input voltage (v) 0 0 input current (ma) 0.2 0.6 0.8 1.0 35 30 1.8 1021 g27 0.4 5 10152025 40 1.2 1.4 1.6 t j = 55 c t j = 25 c t j = 125 c i out = 0 load transient response lt1021-7, c load = 0 time ( s) output voltage change 2 lt1021 g22 1 02413 3 0 4 i source = 2-10ma i source = 0.5ma i sink = 0.8ma i sink = 1.2ma i sink = 1.4ma i sink = 2-10ma 5mv 50mv ? i sink = 100 a p-p ? i source = 100 a p-p i source = 0 note vertical scale change between sourcing and sinking load transient response lt1021-7, c load = 1000pf output noise 0.1hz to 10hz lt1021-7 5 s/div output voltage change 10 lt1021 g23 5 01020515 15 0 20 i source = 2-10ma i source = 0.5ma i sink = 0.6ma i sink = 0.8ma i sink = 1ma i sink = 2-10ma 5mv 20mv ? i sink = 100 a p-p ? i source = 100 a p-p i source = 0 note vertical scale change between sourcing and sinking time (minutes) 035 lt1021 g24 12 46 output voltage noise (5 v/div) 5 v (0.7ppm) filtering = 1 zero at 0.1hz 2 poles at 10hz
8 lt1021 1021fc cc hara terist ics uw a t y p i ca lper f o r c e shunt characteristics lt1021-10 shunt mode current limit lt1021-10 thermal regulation lt1021-10 output to ground voltage (v) 0 0 current into output (ma) 0.2 0.6 0.8 1.0 8 1.8 1021 g28 0.4 4 2 6 10 12 1.2 1.4 1.6 t j = 55 c t j = 25 c input pin open t j = 125 c output voltage (v) 0 0 current into output (ma) 10 30 40 50 4 8 10 18 1021 g29 20 26 12 14 16 60 input pin open time (ms) output change (mv) ?.0 0.5 0 140 1021 g30 ?.5 20 60 100 0 40 80 120 load regulation thermal regulation* i load = 10ma *independent of temperature coefficient v in = 30v ? power = 200mw load transient response lt1021-10, c load = 0 time ( s) output voltage change 2 1021 g31 1 02413 3 0 4 i source = 2-10ma i source = 0.2ma i sink = 0.6ma i sink = 0.8ma i sink = 1ma i sink = 2-10ma 10mv 50mv ? i sink = 100 a p-p ? i source = 100 a p-p i source = 0 note vertical scale change between sourcing and sinking load transient response lt1021-10, c load = 1000pf time ( s) output voltage change 2 1021 g32 1 02413 3 0 4 i source = 2-10ma i source = 0.5ma i sink = 0.8ma i sink = 1.2ma i sink = 1.4ma i sink = 2-10ma 5mv 20mv ? i sink = 100 a p-p ? i source = 100 a p-p i source = 0 note vertical scale change between sourcing and sinking output noise 0.1hz to 10hz lt1021-10 time (minutes) 035 1021 g33 12 46 output voltage noise (10 v/div) 10 v (1ppm) filtering = 1 zero at 0.1hz 2 poles at 10hz
9 lt1021 1021fc applicatio n s i n for m atio n wu u u maximum allowable reference drift trimming output voltage lt1021-10 the lt1021-10 has a trim pin for adjusting output voltage. the impedance of the trim pin is about 12k ? with a nominal open-circuit voltage of 5v. it is designed to be driven from a source impedance of 3k ? or less to mini- mize changes in the lt1021 tc with output trimming. attenuation between the trim pin and the output is 70:1. this allows 70mv trim range when the trim pin is tied to the wiper of a potentiometer connected between the output and ground. a 10k ? potentiometer is recom- mended, preferably a 20 turn cermet type with stable characteristics over time and temperature. effect of reference drift on system accuracy a large portion of the temperature drift error budget in many systems is the system reference voltage. this graph indicates the maximum temperature coefficient allowable if the reference is to contribute no more than 0.5lsb error to the overall system performance. the example shown is a 12-bit system designed to operate over a temperature range from 25 c to 65 c. assuming the system calibra- tion is performed at 25 c, the temperature span is 40 c. it can be seen from the graph that the temperature coeffi- cient of the reference must be no worse than 3ppm/ c if it is to contribute less than 0.5lsb error. for this reason, the lt1021 family has been optimized for low drift. the lt1021-10 ??version is pre-trimmed to 5mv and therefore can utilize a restricted trim range. a 75k resistor in series with a 20k ? potentiometer will give 10mv trim range. effect on the output tc will be only 1ppm/ c for the 5mv trim needed to set the ??device to 10.000v. lt1021-5 the lt1021-5 does have an output voltage trim pin, but the tc of the nominal 4v open-circuit voltage at this pin is about 1.7mv/ c. for the voltage trimming not to affect reference output tc, the external trim voltage must track the voltage on the trim pin. input impedance of the trim pin is about 100k ? and attenuation to the output is 13:1. the technique shown below is suggested for trimming the output of the lt1021-5 while maintaining minimum shift in output temperature coefficient. the r1/r2 ratio is chosen to minimize interaction of trimming and tc shifts, so the exact values shown should be used. lt1021-5 out in gnd trim r1 27k r2 50k 1n4148 v out 1021 ai02 temperature span ( c) 10 0 maximum temperature coefficient for 0.5lsb error (ppm/ c) 30 100 lt1021 ai01 1.0 10 20 100 90 80 70 60 50 40 8-bit 10-bit 12-bit 14-bit lt1021-7 the 7v version of the lt1021 has no trim pin because the internal architecture does not have a point which could be driven conveniently from the output. trimming must therefore be done externally, as is the case with ordinary reference diodes. unlike these diodes, however, the out- put of the lt1021 can be loaded with a trim potentiometer. the following trim techniques are suggested; one for voltage output and one for current output. the voltage output is trimmed for 6.95v. current output is 1ma, as shown, into a summing junction, but all resistors may be scaled for currents up to 10ma. both of these circuits use the trimmers in a true potentio- metric mode to reduce the effects of trimmer tc. the voltage output has a 200 ? impedance, so loading must be
10 lt1021 1021fc applicatio n s i n for m atio n wu u u minimized. in the current output circuit, r1 determines output current. it should have a tc commensurate with the lt1021 or track closely with the feedback resistor around the op amp. kelvin connections although the lt1021 does not have true force/sense capability at its outputs, significant improvements in ground loop and line loss problems can be achieved with proper hook-up. in series mode operation, the ground pin of the lt1021 carries only 1ma and can be used as a sense line, greatly reducing ground loop and loss problems on the low side of the reference. the high side supplies load current so line resistance must be kept low. twelve feet of #22 gauge hook-up wire or 1 foot of 0.025 inch printed circuit trace will create 2mv loss at 10ma output current. this is equivalent to 1lsb in a 10v, 12-bit system. the following circuits show proper hook-up to minimize errors due to ground loops and line losses. losses in the output lead can be greatly reduced by adding a pnp boost transistor if load currents are 5ma or higher. r2 can be added to further reduce current in the output sense lead. capacitive loading and transient response the lt1021 is stable with all capacitive loads, but for optimum settling with load transients, output capacitance should be under 1000pf. the output stage of the reference is class ab with a fairly low idling current. this makes transient response worst-case at light load currents. be- cause of internal current drain on the output, actual worst- case occurs at i load = 0 on lt1021-5, i load = 0.8ma (sinking) on lt1021-7 and i load = 1.4ma (sink- ing) on lt1021-10. significantly better load transient response is obtained by moving slightly away from these points. see load transient response curves for details. in general, best transient response is obtained when the output is sourcing current. in critical applications, a 10 f solid tantalum capacitor with several ohms in series provides optimum output bypass. standard series mode lt1021 out in gnd keep this line resistance low load + input ground return 1021 ai05 series mode with boost transistor lt1021-7 out in gnd r3 50k resistor tc determines i out tc tc (10 ?r1) tc. r2 and r3 scale with r1 for different output currents * ** r1* 7.15k 1.000ma r2** 182k 1021 ai04 + op amp lt1021-7 out in tc tracking to 50ppm/ c gnd r3 10k r1* 200 ? 1% v out 6.950v r2* 14k 1% 1021 ai03 lt1021 out gnd in load r1 220 ? 2n3906 r2* input ground return *optionalreduces current in output sense lead r2 = 2.4k (lt1021-5), 3k (lt1021-7), 5.6k (lt1021-10) 1021 ai06
11 lt1021 1021fc applicatio n s i n for m atio n wu u u effects of air movement on low frequency noise the lt1021 has very low noise because of the buried zener used in its design. in the 0.1hz to 10hz band, peak-to-peak noise is about 0.5ppm of the dc output. to achieve this low noise, however, care must be taken to shield the reference from ambient air turbulence. air movement can create noise because of thermoelectric differences between ic package leads (especially kovar lead to-5) and printed circuit board materials and/or sockets. power dissipation in the reference, even though it rarely exceeds 20mw, is enough to cause small temperature gradients in the package leads. variations in thermal resistance, caused by uneven air flow, create differential lead temperatures, thereby causing thermoelectric voltage noise at the output of the reference. the following xy plotter trace dramati- cally illustrates this effect. the first half of the plot was done with the lt1021 shielded from ambient air with a small foam cup. the cup was then removed for the second half of the trace. ambient in both cases was a lab environ- ment with no excessive air turbulence from air condition- ers, opening/closing doors, etc. removing the foam cup increases the output noise by almost an order of magni- tude in the 0.01hz to 1hz band! the kovar leads of the to-5 (h) package are the primary culprit. alloy 42 and copper lead frames used on dual-in-line packages are not nearly as sensitive to thermally generated noise because they are intrinsically matched. there is nothing magical about foam cups?ny enclo- sure which blocks air flow from the reference will do. smaller enclosures are better since they do not allow the build-up of internally generated air movement. naturally, heat generating components external to the reference itself should not be included inside the enclosure. noise induced by air turbulence (to-5 package) time (minutes) 0610 1021 ai07 24 812 output voltage noise (20 v/div) 20 v foam cup removed lt1021-7 (to-5 package) f = 0.01hz to 10hz typical applicatio n s u restricted trim range for improved resolution, 10v, ??version only lt1021c-10 out v in in 10.000v trim range 10mv gnd trim r2 50k 1021 ta11 r1 75k 1021 ta03 lt1021-10 out in gnd trim r1* 10k v out *can be raised to 20k for less critical applications v in lt1021-10 out in gnd lt1021 ta04 d1 15v r1 4.7k ?0v at 50ma r2 4.7k ?5v 15v q1 2n2905 negative series reference lt1021-10 full trim range ( 0.7%)
12 lt1021 1021fc typical applicatio n s u boosted output current with no current limit boosted output current with current limit ultraprecise current source lt1021-10 out in trim gnd 4.32k v out = 10.24v v in 5k v = ?5v* *must be well regulated dv out dv = 15mv v 1021 ta12 trimming 10v units to 10.24v cmos dac with low drift full-scale trimming** lt1021-10 trim gnd out lt1236 ta15 + 1.2k r2 40.2 ? 1% r1 4.99k 1% ref cmos dac 7520, etc i out fb 30pf lt1007c r4* 100 ? full-scale adjust r3 4.02k 1% 10v f.s. ?5v tc less than 200ppm/ c no zero adjust required with lt1007 (v 0s 60 v) * ** lt1021-7 out in 2 *low tc 3 4 7 gnd 15v 15v trim 100 ? 15v 6 6.98k* 0.1% 17.4k 1% 1021 ta07 + lt1001 i out = 1ma regulation < 1ppm/v compliance = 13v to 7v lt1021 out v + (v out + 1.8v) gnd in 1021 ta05 2n2905 10v at 100ma 2 f solid tant r1 220 ? + lt1021 out gnd in 1021 ta06 2n2905 10v at 100ma 2 f solid tant d1* led v + v out + 2.8v 8.2 ? r1 220 ? *glows in current limit, do not omit + operating 5v reference from 5v supply 2-pole lowpass filtered reference lt1021-5 out in gnd 1021 ta16 1n914 1n914 8.5v c2* 5 f c1* 5 f 5v reference 5v logic supply cmos logic gate** f in 2khz* for higher frequencies c1 and c2 may be decreased parallel gates for higher reference current loading * ** + + lt1021 out in gnd 1021 ta13 + r1 36k 1 f mylar 0.5 f mylar r2 36k lt1001 v in v in v ref ? ref f = 10hz total noise 2 v rms 1hz f 10khz
13 lt1021 1021fc typical applicatio n s u precision dac reference with system tc trim strain gauge conditioner for 350 ? bridge negative shunt reference driven by current source lt1021-10 out in gnd 1021 ta17 15v 8.87k 1% 1.24k 1% 10k 1% d1 1n457 50k tc trim* 10k 1% d2 1n457 50k 200k 1% 50k room temp trim 10.36k 1% 8.45k 1ma trims 1ma reference current tc by 40ppm/ c. this trim scheme has very little effect on room temperature current to minimize iterative trimming * dac handling higher load currents lt1021-10 out gnd in 1021 ta08 r l 30ma 15v r1* 169 ? v out 10v typical load current = 30ma select r1 to deliver typical load current. lt1021 will then source or sink as necessary to maintain proper output. do not remove load as output will be driven unregulated high. line regulation is degraded in this application * lt1021-10 out in gnd 1021 ta09 + + lm301a ? 100pf 8 1 6 6 3 2 ?v 357 ? 1/2w ?5v r5 2m r6* 2m lt1012c 2 3 r4 20k r2 20k 5v r3 2m v out 100 350 ? strain gauge bridge** 28ma 28.5ma r1 357 ? 1/2w 15v this resistor provides positive feedback to the bridge to eliminate loading effect of the amplifier. effective z in of amplifier stage is 1m ? . if r2 to r5 are changed, set r6 = r3 * bridge is ultralinear when all legs are active, two in compression and two in tension, or when one side is active with one compressed and one tensioned leg offset and drift of lm301a are virtually eliminated by differential connection of lt1012c ** ? lt1021-10 out gnd 1021 ta14 2.5ma ?0v (i load 1ma) ?1v to 40v 27 ? lm334
14 lt1021 1021fc typical applicatio n s u ultralinear platinum temperature sensor* equivale t sche atic u w lt1021-10 out in gnd 1021 ta10 + r s ? 100 ? at 0 c r4 4.75k 1% r5 200k 1% r6 619k 1% 7 4 6 2 3 lt1001 ?5v 20v r13 24.3k r12 1k r15 10k r14 5k r f ** 654k r11 6.65m 1% r10 182k 1% r2* 5k r1** 253k r3** 5k r9 100k r8 10m ?5v v out =100mv/ c ?0 c t 150 c r7 392k 1% 20v standard industrial 100 ? platinum 4-wire sensor, rosemount 78s or equivalent. = 0.00385 trim r9 for v out = 0v at 0 c trim r12 for v out = 10v at 100 c trim r14 for v out = 5v at 50 c use trim sequence as shown. trims are noninteractive so that only one trim sequence is normally required. feedback linearizes output to 0.005 c from ?0 c to 150 c wirewound resistors with low tc ? * ** d1 d2 d3 r1 r2 gnd lt1021 es q1 q2 d4 6.3v output + a1 input q3
15 lt1021 1021fc information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights. package descriptio n u n8 1002 .065 (1.651) typ .045 ?.065 (1.143 ?1.651) .130 .005 (3.302 0.127) .020 (0.508) min .018 .003 (0.457 0.076) .120 (3.048) min 12 3 4 87 6 5 .255 .015* (6.477 0.381) .400* (10.160) max .008 ?.015 (0.203 ?0.381) .300 ?.325 (7.620 ?8.255) .325 +.035 ?015 +0.889 0.381 8.255 () note: 1. dimensions are inches millimeters *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .010 inch (0.254mm) .100 (2.54) bsc .050 (1.270) max .016 ?.021** (0.406 ?0.533) .010 ?.045* (0.254 ?1.143) seating plane .040 (1.016) max .165 ?.185 (4.191 ?4.699) gauge plane reference plane .500 ?.750 (12.700 ?19.050) .305 ?.335 (7.747 ?8.509) .335 ?.370 (8.509 ?9.398) dia .200 (5.080) typ .027 ?.045 (0.686 ?1.143) .028 ?.034 (0.711 ?0.864) .110 ?.160 (2.794 ?4.064) insulating standoff 45 h8(to-5) 0.200 pcd 0204 lead diameter is uncontrolled between the reference plane and the seating plane for solder dip lead finish, lead diameter is .016 ?.024 (0.406 ?0.610) * ** pin 1 h package 8-lead to-5 metal can (.200 inch pcd) (reference ltc dwg # 05-08-1320) n8 package 8-lead pdip (narrow .300 inch) (reference ltc dwg # 05-08-1510)
16 lt1021 1021fc ? linear technology corporation 1995 lt 1005 rev c ?printed in usa package descriptio n u .016 ?.050 (0.406 ?1.270) .010 ?.020 (0.254 ?0.508) 45 0 ?8 typ .008 ?.010 (0.203 ?0.254) so8 0303 .053 ?.069 (1.346 ?1.752) .014 ?.019 (0.355 ?0.483) typ .004 ?.010 (0.101 ?0.254) .050 (1.270) bsc 1 2 3 4 .150 ?.157 (3.810 ?3.988) note 3 8 7 6 5 .189 ?.197 (4.801 ?5.004) note 3 .228 ?.244 (5.791 ?6.197) .245 min .160 .005 recommended solder pad layout .045 .005 .050 bsc .030 .005 typ inches (millimeters) note: 1. dimensions in 2. drawing not to scale 3. these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed .006" (0.15mm) related parts part number description comments lt1019 precision bandgap reference 0.05%, 5ppm/ c lt1027 precision 5v reference 0.02%, 2ppm/ c lt1236 precision reference so-8, 5v and 10v, 0.05%, 5ppm/ c ltc 1258 micropower reference 200mv dropout, msop lt1389 nanopower shunt reference 800na operating current lt1460 micropower reference sot-23, 2.5v, 5v, 10v lt1634 micropower shunt reference 0.05%, 10ppm/ c, msop linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com s8 package 8-lead plastic small outline (narrow .150 inch) (reference ltc dwg # 05-08-1610)

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