ltz1000/ltz1000a 1 1000afe for more information www.linear.com/ltz1000 typical application features applications description ultra precision reference the lt z 1000 and lt z 1000a are ultra-stable temperature controllable references. they are designed to provide 7 v outputs with temperature drifts of 0.05 ppm/c, about 1.2v p-p of noise and long-term stability of 2v/ khr . included on the chip is a subsurface zener reference, a heater resistor for temperature stabilization, and a tem - perature sensing transistor. external circuitry is used to set operating currents and to temperature stabilize the reference. this allows maximum flexibility and best long- term stability and noise.the lt z 1000 and lt z 1000a references can provide su - perior per formance to older devices such as the lm199, provided that the user implements the heater control and properly manages the thermal layout. to simplify thermal insulation, the lt z 1000a uses a proprietary die attach method to provide significantly higher thermal resistance than the lt z 1000. low noise reference n 1.2 v p-p noise n 2 v/khr long-term stability n very low hysteresis n 0.05 ppm/c drift n temperature stabilized n 400 c/w thermal resistance for lt z 1000a reduces insulation requirements n specified for ?55c to 125c temperature range n offered in to-99 package n voltmeters n calibrators n standard cells n scales n low noise rf oscillators long-term stability l , lt , lt c , lt m , linear technology and the linear logo are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. ? + ltz1000 output 1n4148 lt ? 1006 v in 10v 30k 3 74 6 2 0.02f 120 1000 ta01 days 0 C2 (ppm) 0 2 10 long-term stability of a typical device from time = 0 with no preconditioning or aging 1000 ta01b 30 20 downloaded from: http:///
ltz1000/ltz1000a 2 1000afe for more information www.linear.com/ltz1000 absolute maximum ratings heater to substrate ................................................... 35 v collector emitter breakdown q1 ............................... 15 v collector emitter breakdown q2 ............................... 35 v emitter base reverse bias .......................................... 2v operating temperature range ......... C55 c t a 125 c storage temperature range ............ ?65 c t a 150 c substrate forward bias ............................................ 0.1 v (note 1) electrical characteristics note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. parameter conditions min typ max units zener voltage l z = 5ma, (v z + vbe q1 ) i q1 = 100a l z = 1ma, (v z + vbe q1 ) i q1 = 100a 7.0 6.9 7.2 7.15 7.5 7.45 v v zener change with current 1ma i z < 5ma 80 240 mv zener leakage current v z = 5v 20 200 a zener noise l z = 5ma, 0.1hz < f < 10hz 1 q1 = 100a 1.2 2 v p-p heater resistance i l 100a 200 300 420 heater breakdown voltage 35 v transistor q1 breakdown i c = 10a, lvceo 15 20 v transistor q2 breakdown i c = 10a, lvceo 35 50 v q1, q2 current gain i c = 100a 80 200 450 thermal resistance lt z 1000 time = 5 minutes lt z 1000a time = 5 minutes 80 400 c/w c/w long-t erm stability t = 65c 2 v khr ( note 2) note 2: all testing is done at 25c. pulse testing is used for lt z 1000a to minimize temperature rise during testing. lt z 1000 and lt z 1000a devices are qa tested at ?55c and 125c. pin configuration bottom view h8 package to-5 metal can 1 7v q1 q2 3 5 4 8 7 6 2 t jmax = 150c, lt z 1000ch: ja = 80c/w lt z 1000ach: ja = 400c/w order information lead free finish part marking package description specified temperature range lt z 1000ach#pbf lt z 1000ach 8-lead to-5 metal can (.200 inch pcd) ?55c to 125c lt z 1000ch#pbf lt z 1000ch 8-lead to-5 metal can (.200 inch pcd) ?55c to 125c lead based finish part marking package description specified temperature range lt z 1000ach lt z 1000ach 8-lead to-5 metal can (.200 inch pcd) ?55c to 125c lt z 1000ch lt z 1000ch 8-lead to-5 metal can (.200 inch pcd) ?55c to 125c consult lt c marketing for parts specified with wider operating temperature ranges. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ this product is only offered in trays. for more information go to: http://www.linear.com/packaging/ downloaded from: http:///
ltz1000/ltz1000a 3 1000afe for more information www.linear.com/ltz1000 typical performance characteristics zener voltage vs current zener voltage noise spectrum zener noise die temperature rise vs heater power die temperature vs time die temperature rise vs time pin functions pin 1: heater positive. must have a higher positive value than pin 2 and pin 4.pin 2: heater negative. must have a higher positive value than pin 4. must have equal or lower potential than pin 1. pin 3: zener positive. must have a higher positive value than pin 4. pin 4: substrate and zener negative. must have a higher positive value than pin 7. if q1 is zenered ( about 7 v) a permanent degradation in beta will result. pin 5: temperature compensating transistor collector. pin 6: temperature sensing transistor base. if the base emitter junction is zenered ( about 7 v) the transistor will suffer permanent beta degradation.pin 7: emitter of sensing and compensating transistors . pin 8: collector of sensing transistor. zener current (ma) 0 zener voltage change (mv) 60 8070 50 30 100 90 4.0 4020 10 0 1.0 0.5 2.0 1.5 3.0 3.5 4.5 2.5 5.0 zener alone zener with kelvin sensed q1 1000 g01 frequency (hz) 0.1 200 zener voltage noise (nv /hz) 250 300 350 400 1 10 100 150 100 50 0 450 500 zener current = 0.5ma zener current = 4ma 1000 g02 time (seconds) 0 zener voltage noise (2v/d) 10 20 30 40 50 60 i z = 4ma i z = 0.5ma 1000 g03 die temperature above ambient (c) 25 heater power (w) 0.80.7 0.6 0.5 0.4 0.3 0.2 0.1 0 105 45 65 85 125 95 35 55 75 115 ltz1000 ltz1000a 1000 g04 time (seconds) die temperature rise (c) 125 25 100 7550 0.1 10 100 1000 0 1 heater power = 0.1w heater power = 0.2w heater power = 0.3w ltz1000a 1000 g05 time (seconds) die temperature rise (c) 125 25 100 7550 0.1 10 100 1000 0 1 heater power = 0.3w heater power = 0.7w ltz1000 1000 g06 heater power = 0.5w downloaded from: http:///
ltz1000/ltz1000a 4 1000afe for more information www.linear.com/ltz1000 applications information lt z 1000 and lt z 1000a are capable of providing ultimate voltage reference performance. temperature drifts of better than 0.03 ppm/c and long-term stability on the order of 1v per month can be achieved. noise of about 0.15 ppm can also be obtained. this performance is at the expense of circuit complexity, since external influences can easily cause output voltage shifts of more than 1ppm. thermocouple effects are one of the worst problems and can give apparent drifts of many ppm/c as well as cause low frequency noise. the kovar input leads of the to-5 package form thermocouples when connected to copper pc boards. these thermocouples generate outputs of 35v/c. it is mandatory to keep the zener and transistor leads at the same temperature, otherwise 1 ppm to 5 ppm shifts in the output voltage can easily be expected from these thermocouples. air currents blowing across the leads can also cause small temperature variations, especially since the package is heated. this will look like 1 ppm to 5 ppm of low frequency noise occurring over a several minute period. for best results, the device should be located in an enclosed area and well shielded from air currents. certainly, any temperature gradient externally generated, say from a power supply, should not appear across the critical circuitry. the leads to the transistor and zener should be connected to equal size pc traces to equalize the heat loss and maintain them at similar temperatures. the bottom portion of the pc board should be shielded against air currents as well. resistors, as well as having resistance temperature coef- ficients, can generate thermocouple effects. some types of resistors can generate hundreds of microvolts of thermo- couple voltage. these thermocouple effects in the resistor can also interfere with the output voltage. wire wound resistors usually have the lowest thermocouple voltage, while tin oxide type resistors have very high thermocouple voltage. film resistors, especially vishay precision film resistors, can have low thermocouple voltage. ordinary breadboarding techniques are not good enough to give stable output voltage with the lt z 1000 family devices. for breadboarding, it is suggested that a small printed circuit board be made up using the reference, the amplifier and wire wound resistors. care must be taken to ensure that heater current does not flow through the same ground lead as the negative side of the reference ( emitter of q1). current changes in the heater could add to, or subtract from, the reference voltage causing errors with temperature. single point grounding using low resistance wiring is suggested. block diagram 1 8 q2 q1 3 5 6 2 4 7 * * * *substrate devicesCdo not forward bias 1000 ta07 downloaded from: http:///
ltz1000/ltz1000a 5 1000afe for more information www.linear.com/ltz1000 typical applications negative voltage reference C + C + lt1013 1n4148 1n4148 zener C forcezener C sense zener + sense 2 1 7 7 3 3 4 1 2 0.022f 0.1f 0.1f v C 10v 4 6 6 5 400k* r1r2 r3 r4/r5 ratio 100ppm = ? r() 0.012 77 ? r = 0.01% ? v z 1ppm 0.3ppm0.2ppm 1ppm *provides temperature compensation, delete for ltz1000a both a1 and a2 contribute less than 2v of output drift over a 50c range approximate change in reference voltage for a 100ppm change in resistor values: 2n3904 1k 10k 1m 8 v + 15v gnd lt1013 8 5 r270k r51k r413k r370k r1120 1000 ta02 setting control temperature the emitter-base voltage of the control transistor sets the stabilization temperature for the lt z 1000. with the values given in the applications, temperature is normally 60 c . this provides 15 c of margin above a maximum ambient of 45 c , for example. production variations in emitter - base voltage will typically cause about 10 c variation. since the emitter-base voltage changes about 2 mv/c and is very predictable, other temperatures are easily set. because higher temperatures accelerate aging and decrease long - term stability, the lowest temperature consistent with the operating environment should be used. the lt z 1000a should be set about 10 c higher than the lt z 1000. this is because normal operating power dissipation in the lt z 1000a causes a temperature rise of about 10 c. of course both types of devices should be insulated from ambient. several minutes of warm-up is usual. for applications not requiring the extreme precision or the low noise of the lt z 1000, linear technology makes a broad line of voltage references. devices like the lt1021 can provide drifts as low as 2 ppm/c and devices such as the lm399a can provide drifts of 1 ppm/c. only applica - tions requiring the very low noise or low drift with time of the lt z 1000 should use this device. see application notes an-82 and an-86 for further information. consult the linear technology applications department for additional help. applications information downloaded from: http:///
ltz1000/ltz1000a 6 1000afe for more information www.linear.com/ltz1000 adjusting temperature coefficient in unstabilized applications typical applications C + 7 5 4 3 2 3 120 lt1006 4 6 2 1 70k 15v 1n4148 v out + 0.022f r1 200 * heater 1n4148 1 min 1 min off on * * pulse heater on and off to heat and cool the reference. adjust r1 for minimum voltage change through a temperature cycle. the C2mv/c tempco of the v be cancels the +2mv/c tempco of the zener. 1000 ta05 averaging reference voltage for lower noise and better stability improving supply rejection 1.6k v in 15v 0.01% output 1.6k 30* 30* 150 150 *r = kt q i c 1000 ta03 i c v in 15v 1.5k 150 supply rejection at v out2 = 3mv/v supply rejection at v out1 = 20mv/v v out2 v out1 50 1000 ta04 7v positive reference circuit C + C + 2n3904 1n4148 1n4148 a2 lt1013 a1 lt1013 1m 1 1 7 5 3 3 4 4 8 8 57 6 1k 2 2 0.1f 0.002f 0.1f 400k* 10k r413k r1120 r370k r270k r51k zener C sense zener + sense groundzener C force heater return (tied to ground) v + 15v *provides tc compensation, delete for ltz1000a approximate change in reference voltage for a 100ppm (0.01%) change in resistor values: r1r2 r3 r4/r5 ratio ?r() 0.012 77 ?r = 0.01% ?v z 1ppm 0.3ppm0.2ppm 1ppm both a1 and a2 contribute less than 2v of output drift over a 50c range 1000 ta06 downloaded from: http:///
ltz1000/ltz1000a 7 1000afe for more information www.linear.com/ltz1000 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 representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. revision history rev date description page number d 4/12 corrected thermal information on h8 package drawing corrected order information tableupdated block diagram to show substrate diode added 1n4148 label to diode in application circuit added ltc6655 to related parts table 22 4 5 8 e 11/15 web links added correction to block diagram, resistor added to substrate diode pin numbers corrected on negative voltage reference diagram all 45 (revision history begins at rev d) downloaded from: http:///
ltz1000/ltz1000a 8 1000afe for more information www.linear.com/ltz1000 linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 ? linear technology corporation 1987 lt 1115 rev e ? printed in usa (408) 432-1900 fax : (408) 434-0507 www.linear.com/ltz1000 related parts part number description comments lm399 7v precision shunt reference 0.2% accuracy, 0.5ppm/c drift, 20v rms noise lt1021 5v, 7v and 10v precision reference available in t0-5, C55c to 125c, series or shunt operation lt1236 5v and 10v low drift precision reference 0.05% accuracy, 5ppm/c drift, series or shunt operation lt1389 1.25v, 2.5v, 4v and 5v nanopower shunt reference 800na, 0.05% accuracy, 10ppm/c drift lt1634 1.25v and 2.5v micropower shunt reference 0.05%, 10ppm/c, 10a current ltc6655 precision low noise reference family 2ppm/c, maximum drift, 650nv p-p noise (0.1hz to 10hz) .050 (1.270) max .016 C .021** (0.406 C 0.533) .010 C .045* (0.254 C 1.143) seating plane .040 (1.016) max .165 C .185 (4.191 C 4.699) gaugeplane reference plane .500 C .750 (12.700 C 19.050) .305 C .335 (7.747 C 8.509) .335 C .370 (8.509 C 9.398) dia .200 (5.080) typ .027 C .045 (0.686 C 1.143) .028 C .034 (0.711 C 0.864) .110 C .160 (2.794 C 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 C .024 (0.406 C 0.610) * ** pin 1 h package 8-lead to-5 metal can (.200 inch pcd) (reference ltc dwg # 05-08-1320) package description please refer to http:// www .linear.com/product/ lt z 1000#packaging for the most recent package drawings. downloaded from: http:///
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