lt1027 1 sn1027 1027fcs precision 5v reference analog inputs v in v out v trim gnd 10k 22 m f 8v to 40v lt1027 to m c ch0ch1 ch2 ch3 ch4 ch5 ch6 ch7 v cc ref + ref com agnd v dgnd ltc1290 1027 ta01 s clk a clk d out d in cs + 2.2 m f + temperature ( c) ?0 output voltage (v) 5.002 5.004 5.006 25 75 1027 ta02 5.000 4.998 ?5 0 50 100 4.996 4.994 output voltage , ltc and lt are registered trademarks of linear technology corporation. supplying v ref and v cc to the ltc 1290 12-bit adc very low drift: 2ppm/ c max tc pin compatible with lt1021-5, ref-02,(pdip package) output sources 15ma, sinks 10ma excellent transient response suitable fora-to-d reference inputs noise reduction pin excellent long term stability less than 1ppm p-p noise (0.1hz to 10hz) the lt 1027 is a precision reference with extra-low drift, superior accuracy, excellent line and load regulation andlow output impedance at high frequency. this device is intended for use in 12- to 16-bit a-to-d and d-to-a systems where demanding accuracy requirements must be met without the use of power hungry, heated substrate references. the fast settling output recovers quickly from load transients such as those presented by a-to-d converter reference inputs. the lt1027 brings together both outstanding accuracy and temperature coefficient specifications. the lt1027 reference is based on ltc? proprietary advanced subsurface zener bipolar process which eliminates noise and stability problems associated with surface breakdown devices. a-to-d and d-to-a converters digital voltmeters reference standard precision current source features descriptio u applicatio s u typical applicatio u downloaded from: http:///
lt1027 2 sn1027 1027fcs symbol parameter conditions min typ max units v out output voltage (note 2) lt1027a 4.9990 5.000 5.0010 v lt1027b, c, d 4.9975 5.000 5.0025 lt1027e 4.9950 5.000 5.0050 tcv out output voltage temperature coefficient lt1027a, b 1 2 ppm/ c (note 3) lt1027c 23 lt1027d 25 lt1027e 3 7.5 supply voltage (v in ) ............................................... 40v input-output voltage differential ............................ 35v output to ground voltage ......................................... 7v v trim to ground voltage positive ................................................................ 5v negative .......................................................... 0.3v output short-circuit duration v in > 20v ........................................................ 10 sec v in 20v ................................................... indefinite operating temperature range lt1027c ................................................ 0 c to 70 c lt1027m (obsolete) ............... ?5 c to 125 c storage temperature range all devices ....................................... 65 c to 150 c lead temperature (soldering, 10 sec)................. 300 c a u g w a w u w a r b s o lu t ex i t i s wu u package / o rder i for atio top view nc* nc* nc* v in v out v trim nr gnd 8 7 6 5 3 2 1 4 h package 8-lead to-5 metal can t jmax = 150 c, q ja = 150 c/w, q jc = 45 c/w order part number order part number order part number t jmax = 100 c, q ja = 130 c/w t jmax = 100 c, q ja = 180 c/w 12 3 4 87 6 5 top view v in nc*nc* nc* nr gnd v trim v out s8 package 8-lead plastic so 12 3 4 5 6 7 8 top view nc* nc* nc* v in v out v trim nr gnd n8 package 8-lead pdip lt1027ach-5lt1027bch-5 lt1027cch-5 lt1027dch-5 lt1027ech-5 lt1027bcn8-5lt1027ccn8-5 lt1027dcn8-5 lt1027ecn8-5 lt1027ccs8-5 lt1027dcs8-5 lt1027ecs8-5 1027c5 1027d5 1027e5 s8 part marking *connected internally. do not connect external circuitry to these pins. consult ltc marketing for parts specified with wider operating temperature ranges. e lectr ic al c c hara terist ics the denotes specifications which apply over the full operating temperature range otherwise specifications are at t a = 25 c. v in = 10v, i load = 0, unless otherwise specified. (note 1) obsolete package consider the n8 or s8 packages for alternate source downloaded from: http:///
lt1027 3 sn1027 1027fcs symbol parameter conditions min typ max units line regulation (note 4) 8v v in 10v 6 12 ppm/v 25 ppm/v 10v v in 40v 3 6 ppm/v 8 ppm/v load regulation (notes 4, 6) sourcing current 8 3 6 ppm/ma 0 i out 15ma 10 8 ppm/ma sinking current 30 120 ppm/ma 0 3 i out 3 10ma supply current 2.2 3.1 ma 3.5 ma v trim adjust range 30 50 mv e n output noise (note 5) 0.1hz f 10hz 3 m v p-p 10hz f 1khz 2.0 6.0 m v rms temperature hysteresis h package; d t = 25 c 10 ppm long term stability h package 20 ppm/month note 5: rms noise is measured with an 8-pole bandpass filter with a center frequency of 30hz and a q of 1.5. the filter output is then rectifiedand integrated for a fixed time period, resulting in an average, as opposed to rms voltage. a correction factor is used to convert average to rms. this value is then used to obtain rms noise voltage in the 10hz to 1000hz frequency band. this test also screens for low frequency "popcorn" noise within the bandwidth of the filter. consult factory for 100% 0.1hz to 10hz noise testing. note 6: devices typically exhibit a slight negative dc output impedance of 0.015 w . this compensates for pc trace resistance, improving regulation at the load. note 1: absolute maximum ratings are those values beyond which the life of the part 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 determined by the "box" method in which the maximum d v out over the temperature range is divided by d t. note 4: line and load regulation measurements are done on a pulse basis. output voltage changes due to die temperature change must be taken intoaccount separately. package thermal resistance is 150 c/w for to-5 (h), 130 c/w for pdip (n8), and 180 c/w for plastic so (so-8). ripple rejection cc hara terist ics uw a t y p i ca lper f o r c e frequency (hz) 10 90 rejection (db) 100 110 120 100 100 1k 10k 1027 g01 8070 60 50 v in = 10v frequency (hz) 0.01 output impedance ( w ) 0.1 1 10 100 10 10k 100k 1m 1027 g02 100 1k d i = 3ma ac i source = 5ma output impedance vs frequency output voltage temperature ( c) ?0 output voltage (v) 5.002 5.004 5.006 25 75 1027 g03 5.000 4.998 ?5 0 50 100 4.996 4.994 e lectr ic al c c hara terist ics the denotes specifications which apply over the full operating temperature range otherwise specifications are at t a = 25 c. v in = 10v, i load = 0, unless otherwise specified. downloaded from: http:///
lt1027 4 sn1027 1027fcs cc hara terist ics uw a t y p i ca lper f o r c e v out 1v/div start-up and turn-off 10v v in r l = 1k, c l = 4.7 m f quiescent current 10v v in start-up and turn-off (no load) 1 m s/div v out 1v/div 1027 g04 500 m s/div 1027 g05 input voltage (v) 0 supply current (ma) 1.5 2.0 2.5 15 25 40 1027 g06 1.0 0.5 0 510 20 30 35 ?0 change in output voltage ( m v) 0 400 800 8 1027 g07 400 800 ?600 26 4 ?200 ? ? ? 2 0 10 12 14 16 i out (ma) sink source load regulation output settling time (sourcing) v out 400 m v/div ac coupled line regulation frequency (hz) 10 80 100 120 140 160 100 1k 10k 1027 g09 60 4020 0 180 200 c nr = 1 m f c nr = 0 output noise density (nv/ hz) output noise voltage density input voltage (v) 8 change in output voltage ( m v) 300 400 500 20 28 40 1027 g08 200 0 100 12 16 24 32 36 ?00 ?00?00 400 500 1 0ma load step 2 m s/div 1027 g10 0.1hz to 10hz output noisefiltering = 1 zero at 0.1hz 2 poles at 10hz 1sec/div 5 m v/div 1027 g12 output settling time (sinking) ?0ma load step 2 m s/div v out 400 m v/div ac coupled 1027 g11 downloaded from: http:///
lt1027 5 sn1027 1027fcs u s a o pp l ic at i wu u i for atio to approximately 1.2 m v rms in a 10hz to 1khz bandwidth. transient response is not affected by this capacitor. start-up settling time will increase to several milliseconds due to the 7k w impedance looking into the nr pin. the capacitor must be a low leakage type. electrolytics are not suitable for this application. just 100na leakage current will result in a 150ppm error in output voltage. this pin is the most sensitive pin on the device. for maximum protec- tion a guard ring is recommended. the ring should be driven from a resistive divider from v out set to 4.4v (the open-circuit voltage on the nr pin).transient response the lt1027 has been optimized for transient response. settling time is under 2 m s when an ac-coupled 10ma load transient is applied to the output. the lt1027 achievesfast settling by using a class b npn/pnp output stage. when sinking current, the device may oscillate with ca- pacitive loads greater than 100pf. the lt1027 is stable with all capacitive loads when at no dc load or when sourcing current, although for best settling time either no output bypass capactor or a 4.7 m f tantalum unit is recom- mended. an 0.1 m f ceramic output capacitor will maximize output ringing and is not recommended. kelvin connectionsalthough the lt1027 does not have true force-sense capability, proper hook-up can improve line loss and ground loop problems significantly. since the ground pin of the lt1027 carries only 2ma, it can be used as a low- side sense line, greatly reducing ground loop problems on the low side of the reference. the v out pin should be close to the load or connected via a heavy trace as the resistanceof this trace directly affects load regulation. it is important to remember that a 1.22mv drop due to trace resistance is equivalent to a 1lsb error in a 5v fs , 12-bit system. the circuits in figures 2 and 3 illustrate proper hook-up tominimize errors due to ground loops and line losses. losses in the output lead can be further reduced by adding a pnp boost transistor if load current is 5ma or higher. r2 can be added to further reduce current in the output sense load. effect of reference drift on system accuracya large portion of the temperature drift error budget in many systems is the system reference voltage. figure 1 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 lt1027 has been optimized for low drift. figure 1. maximum allowable reference drift trimming output voltagethe lt1027 has an adjustment pin for trimming output voltage. the impedance of the v adj pin is about 20k w with an open-circuit voltage of 2.5v. a 30mv guaranteed trim range is achievable by tying the v adj pin to the wiper of a 10k potentiometer connecting between the output andground. trimming output voltage does not affect the tc of the device. noise reduction the positive input of the internal scaling amplifier is brought out as the noise reduction (nr) pin. connecting a 1 m f mylar capacitor between this pin and ground will reduce the wideband noise of the lt1027 from 2.0 m v rms temperature span ( c) 10 0 maximum temperature coefficient for 0.5lsb error (ppm/ c) 30 100 1027 ai01 1.0 10 20 100 90 80 70 60 50 40 8-bit 10-bit 12-bit 14-bit downloaded from: http:///
lt1027 6 sn1027 1027fcs u s a o pp l ic at i wu u i for atio in out gnd + ground return keep this line resistance low 1027 f02 input lt1027 load figure 2. standard hook-up in out gnd lt1027 ground return input r191 w r2*2.4k load 1027 f03 *optional reduces current in output sense lead 4.7 m f + 2n4403 figure 3. driving higher load currents lt1027 v in 7 1 f 1 f 0.01 f v out 16 13 12 11 17 14 ltc1043 8 1027 ta04 v in out gnd + lt1097 lt1027 v in 1027 ta03 in out v trim gnd 5k 5k* 10.00voutput 5k* * 0.1% metal film 10v reference 10v reference operating 5v reference from 5v supply c25 f* ? 8.5v 5vreference 1n914 lt1027 c1 5 f* 1n914 5vlogic supply cmos logic gate** *for higher frequencies c1 and c2 may be decreased**parallel gates for higher reference current loading f in 3 2khz* in out gnd 1027 ta05 + + typical applicatio n s u downloaded from: http:///
lt1027 7 sn1027 1027fcs 0.050 (1.270) max 0.016 ?0.021** (0.406 ?0.533) 0.010 ?0.045* (0.254 ?1.143) seating plane 0.040 (1.016) max 0.165 ?0.185 (4.191 ?4.699) gaugeplane referenceplane 0.500 ?0.750 (12.700 ?19.050) 0.305 ?0.335 (7.747 ?8.509) 0.335 ?0.370 (8.509 ?9.398) dia 0.230 (5.842) typ 0.027 ?0.045 (0.686 ?1.143) 0.028 ?0.034 (0.711 ?0.864) 0.110 ?0.160 (2.794 ?4.064) insulating standoff 45 typ h8 (to-5) 0.230 pcd 1197 lead diameter is uncontrolled between the reference plane and 0.045" below the reference plane for solder dip lead finish, lead diameter is 0.016 ?0.024 (0.406 ?0.610) * ** pin 1 package descriptio u h package 8-lead to-5 metal can (.230 inch pcd) (reference ltc dwg # 05-08-1321) obsolete package sche t equivale atic uw output current limit andbias circuits not shown nr gnd v out v adj 1027 es v in 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. downloaded from: http:///
lt1027 8 sn1027 1027fcs package descriptio u ? linear technology corporation 1992 lt/cpi 1101 1.5k rev c ? printed in usa part number description comments lt1019 precision series bandgap reference, 0.05%, 5ppm/ c drift 2.5v, 4.5v, 5v, 10v outputs; industrial, military grades available lt1021 precision buried zener diode reference, 5v, 7v, 10v outputs; 8-pin pdip, so, to-5 packages; 0.5%, 5ppm/ c drift military grades available lt1236 precision series reference, 0.05%, 5ppm/ c drift 5v, 10v outputs; 8-pin pdip, so packages; industrial grade available lt1460 micropower precision series bandgap reference, 2.5v, 5v, 10v outputs; 8-pin pdip, so, msop; 0.075%, 10ppm/ c drift to-92 and sot-23 packages lt1461 low dropout 3ppm/ c drift, 0.04% series reference 2.5v, so-8 package lt1798 low dropout, micropower reference 2.5v, 3v, 4.096v, 5v, adjustable in so-8 related parts 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) 0.016 ?0.050 (0.406 ?1.270) 0.010 ?0.020 (0.254 ?0.508) 45 0 ?8 typ 0.008 ?0.010 (0.203 ?0.254) so8 1298 0.053 ?0.069 (1.346 ?1.752) 0.014 ?0.019 (0.355 ?0.483) typ 0.004 ?0.010 (0.101 ?0.254) 0.050 (1.270) bsc 1 2 3 4 0.150 ?0.157** (3.810 ?3.988) 8 7 6 5 0.189 ?0.197* (4.801 ?5.004) 0.228 ?0.244 (5.791 ?6.197) dimension does not include mold flash. mold flash shall not exceed 0.006" (0.152mm) per side dimension does not include interlead flash. interlead flash shall not exceed 0.010" (0.254mm) per side * ** n8 package 8-lead pdip (narrow .300 inch) (reference ltc dwg # 05-08-1510) n8 1098 0.009 ?0.015 (0.229 ?0.381) 0.300 ?0.325 (7.620 ?8.255) 0.325 +0.035 0.015 +0.889 0.381 8.255 () 0.100 (2.54) bsc 0.065 (1.651) typ 0.045 ?0.065 (1.143 ?1.651) 0.130 0.005 (3.302 0.127) 0.020 (0.508) min 0.018 0.003 (0.457 0.076) 0.125 (3.175) min 12 3 4 87 6 5 0.255 0.015* (6.477 0.381) 0.400* (10.160) max *these dimensions do not include mold flash or protrusions. mold flash or protrusions shall not exceed 0.010 inch (0.254mm) downloaded from: http:///
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