LH0070

LT1031 LINER

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TECHNOLOGY Precision 10 Volt Reference FEATURES DESCRIPTION = Pin Compatible with LHOO70 and AD581* The LT1031 is a precision 10V reference with ultra low = Ultra Low Drift—5ppm/°C Max Slope drift and noise, extremely good long term stability, and = Trimmed Output Voltage almost total immunity to input voltage variations. The ™ Operates in Series or Shunt Mode reference output will both source and sink up to 10mA = Output Sinks and Sources in Series Mode and can be used as a shunt regulator (two terminal zener) = Very Low Noise < 1ppm p-p 0.1Hz to 10Hz with the same precision characteristics as the three ter- = >100dB Ripple Rejection minal connection. Special care has been taken to mini- = Minimum Input Voltage of 11V mize thermal regulation effects and temperature induced hysteresis. The T1031 reference is based on a buried zener diode structure which eliminates noise and stability problems APPLICATIONS associated with surface breakdown devices. Further, a =A to D and D to A Converters subsurface zener exhibits better temperature drift and Em = Precision Regulators time stability than even the best band-gap references. Digital Volt if . : inrtt lavgaten systems Unique circuit design makes the LT1031 the first three = Precision Scales terminal IC reference to offer ultra low drift without the = Portable Reference Standard use of high power on-chip heaters. Output voltage is pre- trimmed to 0.05% accuracy. The LT1031 can be used as a plug-in replacement for the “See LHOO70 Electrical Characteristics table and ADS81 cross reference AD581 and LH0070*, with improved electrical and ther- guide. mal performance. UU an Basic Positive and Distribution of Output Accuracy Negative Connections 0 Sec L71031 L11031 a) . se eee we o |)? ee potty | oe BCU Vy |_| Ky OUTPUT ACCURACY (%) NS LT Wye 3-65

ABSOLUTE MAXIMUM RATINGS PACKAGE/ORDER INFORMATION Output to Ground Voltage BOTTOM VIEW Trim Pin to Ground Voltage co" HOOK Output Short Circuit Duration LT1031BMH VINH=35V 0 eee eee eee 10806 LT1031CMH Operating Temperature Range H PACKAGE LT1031BCH ed ELECTRICAL CHARACTERISTICS LT1031 Vin =15V, lour=0, Ta=25°C, Mil or Comm version, unless otherwise noted 11031 " ah ee eee LT1031¢ 9.990 10.000 10.010 v LT1031D 9.980 10.000 10.020 v 7 ek: ree AT Coefficient (Note 2) LT1031B 3 5 ppm/°c LT1031¢ 6 15 ppm/2c L71031D 10 25 ppm/°c Ve Line Regulation (Note 3) 11.5V <Viy 3 14.5V 1 4 ppm/V ae 6 ppm/V 14.5V<Viy<40V 0.5 2 ppm/V 4 ppm/V AVR Load Regulation (Sourcing Current) OSloyr<10mA 12 25 ppm/mA Alo (Note 3) 40 ppm/mA Va Load Regulation (Shunt Mode) 1.7MA <|syynt << 10MA 50 100 ppm/mA Alo (Notes 3, 4) 150 ppm/mA f Series Mode Supply Current 1.2 1.7 mA a a PY 1.7 mA [output Short Oreut Curent | _tWsvwssv | =| CSCS mA |" Minimum Input Votage Wote6) | tqrstma «| «| SSCOCO v 0.1Hz =f 10kHz aVrms AVa Long Term Stability of At=1000 Hrs 15 ppm “ATime- Output Voltage | Non-Cumulative | Tempera hyseese fount | av=soro | 5 vom a 3-66 LT Wee

Vin=15V, RL=10kO, —55°C <Ta< +125°C unless otherwise noted SYMBOL CONDITIONS MIN TYP MAX UNITS Ve | OutputVotage Siamese Ct AVR Output Accuracy Ta=25°C 0, -1 +£0.03 +01 % 72 0.02 +0.05 % AVR Output Accuracy Ta= —55°C, 125°C -0, -1 +0.3 % 2 +0.2 % AVa Output Voltage Change Note 5 aT with Temperature 0 +0.2 % a +0.02 +01 % 2 +0.01 +£0.04 % AVa Line Regulation 13V <Viy $33V, Ty =25°C 2 0.006 0.03 % ing Vota Range a AVa Load Regulation OmA <igyr=5MA | 0.01 0.03 % Eq Alp la 13V Vin =30V fej ema Alo Change in Quiescent Current AVin = 20V from 13V to 33V 04 1.5 mA AVin en] apa Woe Vorage a a to | Ouipat Resistance Si SSSCS~d 02 a6 a AV7 Long Term Stability Ta= 25°C (Note 7) tine -0,-1 #0.2 %IYe 2 +£0.05 %HINt The @ denotes the specifications which apply over the full operating Note 3: Line and load regulation are measured on a pulse basis. Output temperature range. changes due to die temperature change must be taken into account Note 1: Output voltage is measured immediately after turn-on. Changes separately. Package thermal resistance is 150°C/W. due to chip warm-up are typically less than 0.005%. Note 4: Shunt mode regulation is measured with the input open. With Note 2: Temperature coefficient is measured by dividing the change in the input connected, shunt mode current can be reduced to OmA. Load output voltage over the temperature range by the change in temperature. Fegulation will remain the same Separate tests are done for hot and Cold; Tyiy to 25°C, and 25°C to Note 5: Temperature drift is guaranteed from —25°C to + 85°C on Tmax. Incremental slope is also measured at 25°C. For LT1031BMH, the LH0070 Sppm/°C drift specification is for — 25°C to 85°C. Drift over the full Note 6: See curve for guaranteed minimum Viy versus Igyr. —55°C to + 125°C range is guaranteed to 7ppm/°C. Note 7: Guaranteed by design. CE ood CROSS REFERENCE Cross Reference Guide—LT1031 to AD581 he followin it The following cross reference guide may be used to select AD581J order LT10310CH LT1031 grades which meet or exceed output voltage, AD581K order LT1031CCH temperature drift, load and line regulation, and output vege AD581L order LT1031BCH current specifications of the AD581 reference. . F ADS81S order LT1031DMH Parameters such as noise, hysteresis, and long term a sane AD581T order LT1031CMH stability will be significantly better for all LT1031 grades AD581U order LT1031BMH compared to the AD581. eo

LT1031/LHO070 ‘ nN TYPICAL PERFORMANCE CHARACTERISTICS Ripple Rejection Ripple Rejection Minimum Input Voltage 115 130 = 11.6 = ry WE LLLLELLI = I " Pea er ee A -* so oo ICT 2 ee sett Lett | eSCmiciecom) ace oo E100 5 NU VA SCE) CmeP SS eco a ‘ on eLLET TTT] | Sciam oooh Oo 5 0 15 2 2 30 35 40 10 100 tk 10k 0 2 4 6 8 10 12 14 16 18 20 INPUT VOLTAGE (V) FREQUENCY (Hz) OUTPUT CURRENT (mA) Start-Up (Series Mode) Start-Up (Shunt Mode) Output Voltage Noise Spectrum 13 " 400 TTT) "TALC Sooo ; mae Seg A ex SEE 2 LV a Se] gl Pee Ce 4 ee e.-trTrrrry i, Sot eee eT BNI LILO 5 s_] TT Ty yy 57 y'? pe s PE TH Lee ee aiiimiiiinii Serre) OL EE EE) * icici 0 2 4 6 8 10 12 14 i) 2 4 6 8 10 12 10 100 tk 10k TIME (us) TIME (us) FREQUENCY (Hz) Output Voltage Temperature Output Voltage Noise Load Regulation Drift ell = Seo" [TLL 14 PFILTER=1 POLE. 4 Fee tall AA EH Ss 2 < Z 0 wm ET TTT TT] E1000 ean ee eee eee ee a HUT Cg EET TC (CIT TT b= PCE UT TM eee ome EET TMT eee EEE ° OANDMOOTH (ish ia on sac oon s “9 3 ° TEMPERATURE °C)” os ‘UF eee 3-68 LT Wee

TYPICAL PERFORMANCE CHARACTERISTICS Input Supply Current Shunt Characteristics Shunt Mode Current Limit 14 = 25° gia oD NCO §, LTT pul tS et tet ETT sel fA |i ti tl ¢,[ pep | § i] “wit TP TT) et beeper Tt & REE i7T | | tT Ty Ty aL to | | | to " “TT PTET yy TT} wit tit tt Al | | | T 4 5 ae 0 5 0 1 20 2 WwW 35 4 oO 2 4 6 8 10 12 0 2 4 6 8 0 12 14 6 18 INPUT VOLTAGE (V) OUTPUT TO GROUND VOLTAGE (V) QUTPUT VOLTAGE (V) Load Transient Response Load Transient Response Em” Thermal Regulation Croap=0 Croan =1000pF Zo =a al itt TT tow 7] [VL TT fom | | got Hie] eT /secCeCCCUSE 2 o| We rune |_| SUPA Veron) gL T el ee co eT TT Terry g opecs 02m | TVisen iors] B | agece tl Ware) | [rome] PT att TAT TT TAT ay aA TTA a PPT TTT Visn=2-om] LTT LIT TT] ‘eer COPErrit rt 0 2 40 6 8 100 120 140 0123 401 23 4 024 6802 46 8 TIME (ms) TIME (us) TIME (us) “INDEPENDENT OF TEMPERATURE COEFFICIENT NOTE VERTICAL SCALE CHANGE NOTE VERTICAL SCALE CHANGE BETWEEN SOURCING AND SINKING BETWEEN SOURCING AND SINKING Output Noise 0.1Hz to 10Hz pera] | ~ 2 POLES AT 10Hz g itt ft Ear Tr Ue SVE E en A tii dBi na hina a{ itt [ | Tf at] et a 0 1 2 3 4 5 6 TIME (MINUTES) LY lite 3-69

LT1031/LHOO70 : pe! APPLICATIONS INFORMATION Maximum Allowable Reference Trimming Output Voltage Drift 10 eS The LT1031 output can be trimmed by driving the ground s ReSSEEEEES pin. The suggested method is shown in the accompany- 3 A ett ing figure. A 5Q resistor is inserted in series with the és ALKLLEI rm round pin and the top of the resistor is supplied current BE N {bent | trom a trim potentiometer. This technique requires fairly Se 1 Neel high trim current—up to 1.5mA from the LT1031 or 8 ASS 3.5mA from the —15V supply, but it is necessary to a maintain low drift in the reference. Ground pin current 3 SNCS Seeee changes in the LT1031 (with temperature) could be as 2 high as 4yA/°C. This, coupled with the 50 external 10 LEN TEE resistor, creates up to 2ppm/°C drift in the reference TEMPERATURE SPAN (°C) (50 x 4uA/°C = 20nV/°C'=2ppm/°C). If induced drift higher than this can be tolerated, all resistor values inthe Capacitive Loading and Transient Response trim hut can be raised proportionately 10 reduoe CUr- TH. 74931 i stable with all caactve loads, but for opt- . mum settling with load transients, output capacitance Output Voltage Trimming should be under 1000pF. The output stage of the reference is class AB with a fairly low idling current. This makes tran- L131 sient response worst-case at light load currents. Because of Yin—F IN on Your internal current drain on the output, actual worst-case oc- GND curs at ILoan=1.4mA (sinking). Significantly better load 3 transient response is obtained by moving slightly away from . 50k these points. See Load Transient Response curves for a details. In general, best transient response is obtained + ~i8v when the output is sourcing current. In critical applications, CAM BE INCREASED TO 5.8% FOR a 10,F solid tantalum capacitor with several ohms in series eae meroTe80 provides optimum ouput bypass. Effect of Reference Drift on System Accuracy Kelvin Connections A large portion of the temperature drift error budget in Although the LT1031 does not have true force/sense many systems is the system reference voltage. This capability at its outputs, significant improvements in graph indicates the maximum temperature coefficient ground loop and line loss problems can be achieved allowable if the reference is to contribute no more than © with proper hook-up. In series mode operation, the YeLSB error to the overall system performance. The ex- ground pin of the LT1031 carries only = 1mA and can ample shown is a 12-bit system designed to operate over be used as a sense line, greatly reducing ground loop a temperature range from 25°C to 65°C. Assuming the —_and loss problems on the low side of the reference. The system calibration is performed at 25°C, the temperature high side supplies load current so line resistance must span is 40°C. It can be seen from the graph that the be kept low. Twelve feet of #22 gauge hook up wire or temperature coefficient of the reference must benoworse _1 foot of 0.025 inch printed circuit trace will create 2mV than 3ppm/ °C if it is to contribute less than Y2LSBerror. loss at 10mA output current. This is equivalent to 1LSB For this reason, the LT1031 has been optimized for low in a 10V, 12-bit system. drift. Vn 3-70 Owe

Rn eee ww eee) APPLICATIONS INFORMATION The circuits below show proper hook up to minimize — movementcan create noise because of thermoelectric dif- errors due to ground loops and line losses. Losses inthe — ferences between IC package leads (especially kovar output lead can be greatly reduced by addingaPNP boost lead TO-5) and printed circuit board materials and/or transistor if load currents are SmA or higher. R2 canbe —_ sockets. Power dissipation in the reference, even though added to further reduce current in the output sense lead. —_it rarely exceeds 20mW, is enough to cause ro tem- perature gradients in the package leads. Variations in thermal resistance, caused by uneven air flow, create dif- Standard Series Mode ferential lead temperatures, thereby causing thermoelec- tric voltage noise at the output of the reference. The XY inast plotter trace shown below dramatically illustrates this ef- wweut-—tm our} KEEP THIS LINE RESISTANCE LOW fect. The first half of the plot was done with the LT1031 . shielded from ambient air with a small foam cup. The cup so was then removed for the second half of the trace. Ambi- ent in both cases was a lab environment with no exces- sive air turbulence from air conditioners, opening/ erm closing doors, etc. Removing the foam cup increases the output noise by almost an order of magnitude in the 0.01Hz to 1Hz band! The kovar leads of the TO-5 (H) Series Mode wih Bost Transistor frames used on Guile packages ae nt reat 2 input sensitive to thermally generated noise because they are 7 intrinsically matched. 2N3306 There is nothing magical about foam cups—any enclo- sure which blocks air flow from the reference will do. Smaller enclosures are better since they do not allow the Cy build-up of internally generated air movement. Naturally, Ltvost out heat generating components external to the reference oe itself should not be included inside the enclosure. T Noise Induced by Air Turbulence (TO-5 Package) GROUND "*OPTIONAL—REDUCES CURRENT IN OUTPUT SENSE LEAD 2 i | {| | tt] eco i 3 Gobenloeeh I Effects of Air Movement on Low Frequency Noise 4 |_| Nl a The LT1031 has very low noise because of the buried 3} | t| [Vy PY zener used in its design. In the 0.1Hz to 10Hz band, E r | | [ | [| peak-to-peak noise is about 0.5ppm of the DC output. To 3 achieve this low noise, however, care must be taken to it ti tt shield the reference from ambient air turbulence. Air 9 2 fe minutes) o SSS AT nee 3-71

. { APPLICATION CIRCUITS Negative Series Reference +18V Rt 4.7k LT1031 ~1v a sma 2N2905 Boosted Output Current With No Current Limit Boosted Output Current With Current Limit V+>12.8V) V+211.8V. or 2209 2N2905, 2N2905 cy ) ere ) ‘ = c) sou0 ae sou TANT TANT *GLOWS IN CURRENT LIMIT. ‘DO NOT OMIT. SS SS SSS 3-72 7 @ Ais

Handling Higher Load Currents +15V soma RI 7 3 ™ Ur1031_ OUT Vour 10V |r tq ae I a, TYPICAL LOAD © U CURRENT =30mA “SELECT R1 TO DELIVER TYPICAL LOAD CURRENT. LT1031 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, Strain Gauge Conditioner for 3502 Bridge Rt as7a 172 26mA (11031 28.5mA +15V N out 5V i 3500 STRAIN Sx 71 GAUGE BRIDGE R3 \\ ua 20k Your x100 r00pF e RS | i] 2M L J = 2a" 3570 —18V “THIS RESISTOR PROVIDES POSITIVE FEEDBACK TO BRIDGE IS ULTRA LINEAR WHEN ALL LEGS ARE THE BRIDGE TO ELIMINATE LOADING EFFECT OF ACTIVE, TWO IN COMPRESSION AND TWO IN TENSION, THE AMPLIFIER. EFFECTIVE Zy OF AMPLIFIER (OR WHEN ONE SIDE IS ACTIVE WITH ONE COMPRESSED STAGE IS 1MN. IF R2-R5 ARE CHANGED, AND ONE TENSIONED LEG. SET R6=R3. TOFFSET AND DRIFT OF LM301A ARE VIRTUALLY ELIMINATED BY DIFFERENTIAL CONNECTION OF LT1012C. SSS

Ultra Linear Platinum Temperature Sensor* Lr1031 ouT N +20V GND R2* + oe = RI 253k R10 ae 182k 1% Rit 6.65M RIS 1% 10k art i Ann = Ri2 100k 1k ° R13 +20V RS 2 7 24.3k Ra" RA 3 200k ae 5k 4.75k 1% 6= Vour=100mv/°C TT | 1% | 50°C sTs 150°C 1 4 Rst - 4008 i} 15 | @orc} Re 619k R7 L _I 1% STANDARD INDUSTRIAL 1000 PLATINUM 4-WIRE SENSOR, 392k ROSEMOUNT 78S, OR EQUIVALENT. o¢=0.00385 % TRIM R9 FOR Voyt=0 @ 0°C =15V TRIM R12 FOR Voyr=10V @ 100°C = TRIM R14 FOR Voyr=5V @ 50°C. USE TRIM SEQUENCE AS SHOWN. TRIMS ARE NON-INTERACTIVE ‘SO THAT ONLY ONE TRIM SEQUENCE IS NORMALLY REQUIRED. “FEEDBACK LINEARIZES OUTPUT TO + 0.005°C FROM —50°C TO + 150°C **WIREWOUND RESISTORS WITH LOW TC 2-Pole Low Pass Filtered Reference MYLAR LT1031 Ri R2 D4, 36k 36k nF Vain OUT GND f=10Hz 0.5yF TOTAL NOISE MYLAR s2uvrms 4Hz<f-<10kHz aN —Veer SS 3-74 LT Wee

Negative Shunt Reference Driven by Current Source Ut03t r our =10V (gaps ima) fps wae ig LI ; —11V TO —40V Precision DAC Reference with System TC Trim T1031 +150 IN “OUT NO ork ‘50k ROOM TEMP o1 ra | 10k a 10.36k 1N457. 50k % : 1% TC TRIM* aE i 1% 1457, = = [rm 8.45k *TRIMS 1mA REFERENCE CURRENT = ‘TC BY +40ppm/°C. THIS TRIM ‘SCHEME HAS VERY LITTLE EFFECT ON ROOM. TEMPERATURE CURRENT TO MINIMIZE ITERATIVE TRIMMING. SS LT WER 3-75

O a ourPut fe GE . 4 6ND ee nel PACKAGE DESCRIPTION 10-5 0,350—0.370 (8.890 —9.398) OA 0.305 -0.335 0.165—0.195 7 747=8.509) (4.191 —4.953) DIA aro) | I 0.016 -0.019 v (0.406—0.483} DIA 9.200 (6.080) TYP 0.100 (0.660 —1.143) wee 0.028-0.034 Ce, ean (711-0. "%K ° 45° 171031 85°C 150°C/W 45°C/W ETE ee 3-76 LT We