? very high accuracy: 2.500 v output 200 v ? extremely low drift: 0.8 ppm /c 55c to +125c ? low warm - up drift: 1 ppm typ . ? excellent stability: 6 ppm /1000 hrs. typ . ? excellent line regulation: 3 ppm /v typ . ? hermetic 14 - pin ceramic dip ? military processing option vre110/111/112 precision reference supplies description applications ? precision a/d and d/a converters ? transducer excitation ? accurate comparator threshold reference ? high resolution servo systems ? digital voltmeters ? high precision test and measurement instruments features selection guide vre110 series precision voltage references provide ultrastable +2.500v (vre110), - 2.500v (vre101) and 2.500v (vre102) outputs with 200 v initial accuracy and temperature coefficient as low as 0.8 ppm/c over the full military temperature range. this improvement in accuracy is made possible by a unique, proprietary multipoint laser compensation technique developed by thaler corporation. significant improvements have been made in other performance parameters as well, including initial accuracy, warm - up drift, line regulation, and long - term stability, making the vre110 series the most accurate and stable 2.5v reference available. vre110/111/112 devices are available in two operating temperature ranges, - 25c to +85c and - 55c to +125c, and two performance type output temperature operating range max. volt deviation vre110c +2.5v - 25c to +85c 200 v vre110ca +2.5v - 25c to +85c 100 v vre110m +2.5v - 55c to +125c 400 v vre110ma +2.5v - 55c to +125c 200 v VRE111C - 2.5v - 25c to +85c 200 v VRE111Ca - 2.5v - 25c to +85c 100 v vre111m - 2.5v - 55c to +125c 400 v vre111ma - 2.5v - 55c to +125c 200 v vre112c 2.5v - 25c to +85c 200 v vre112ca 2.5v - 25c to +85c 100 v vre112m 2.5v - 55c to +125c 400 v vre112ma 2.5v - 55c to +125c 200 v grades. all devices are packaged in 14 - pin hermetic ceramic packages for maximum long - term stability. "m" versions are screened for high reliability and quality. superior stability, accuracy, and quality make these references ideal for precision applications such as a/d and d/a converters, high - accuracy test and measurement instrumentation, and transducer ex citation. vre110ds rev. d nov 2000 thaler corporation ? 2015 n. forbes boulevard ? tucson, az. 8574 5 ? (520) 882 - 4000
model c ca m ma parameters min typ max min typ max min typ max min typ max units absolute maximum ratings power supply 13.5 22 * * * * * * v operating temperature - 25 85 * * - 55 125 - 55 125 c storage temperature - 65 150 * * * * * * c short circuit protection continuous * * * output voltage vre110 +2.5 * * * v vre111 - 2.5 * * * v vre112 2.5 * * * v output voltage errors initial error 300 200 300 200 v warmup drift 2 1 2 1 ppm tmin - tmax 200 100 400 200 v long - term stability 6 * * * ppm/1000hr. noise (.1 - 10hz) 1.0 * * * vpp output current range 10 * * * ma regulation line 3 10 * * * * * * ppm/v load 3 * * * ppm/ma output adjustment range 20 * * * mv temperature coefficient 1 * * * v/c/mv power supply currents vre110 +ps 5 7 * * * * * * ma vre110/111 - ps 5 7 * * * * * * ma vre112 +ps 7 9 * * * * * * ma vre112 - ps 4 6 * * * * * * ma vre110/111/112 notes: *same as c models. 1. using the box method, the specified value is the maximum deviation from the output voltage at 25c over the specified operating temperature range. 2. the specified values are unloaded. (1) (2) vps =15v, t = 25c, rl = 10k ? unless otherwise noted. electrical specifications vre110ds rev. d nov 2000
typical performance curves vre110ds rev. d nov 2000 temperature o c vre110/111/112c v out vs. temperature v out vs. temperature v out vs. temperature temperature o c vre110/111/112ca temperature o c vre110/111/112m temperature o c vre110/111/112ma quiescent current vs. temp temperature o c junction temp. rise vs. output current output current ( ma ) psrr vs. frequency frequency (hz) vre110/111 vre112 quiescent current vs. temp temperature o c junction temp. rise vs. output current output current ( ma ) psrr vs. frequency frequency (hz) positive output negative output quiescent current vs. temp temperature o c junction temp. rise vs. output current output current ( ma ) psrr vs. frequency frequency (hz)
theory of operation the following discussion refers to the schematic below. a fet current source is used to bias a 6.3v zener diode. the zener voltage is divided by the resistor network r1 and r2. this voltage is then applied to the noninverting input of the operational amplifier which amplifies the voltage to produce a 2.500v output. the gain is determined by the resistor networks r3 and r4: g=1 + r4/r3. the 6.3v zener diode is used because it is the most stable diode over time and temperature. the current source provides a closely regulated zener current, which determines the slope of the reference's voltage vs. temperature function. by trimming the zener current, a lower drift over temperature can be achieved. but since the voltage vs. temperature function is nonlinear, this method leaves a residual error over wide temperature ranges. to remove this residual error, thaler corporation has developed a nonlinear compensation network of thermistors and resistors that is used in the vre110 series references. this proprietary network eliminates most of the nonlinearity in the voltage vs. temperature function. by then adjusting the slope, thaler corporation produces a very stable voltage over wide temperature ranges. this network is less than 2% of the overall network resistance so it has a negligible effect on long term stability. discussion of performance application information figure 1 shows the proper connection of the vre110 series voltage reference with the optional trim resistors. when trimming the vre112, the positive voltage should be trimmed first since the negative voltage tracks the positive side. pay careful attention to the circuit layout to avoid noise pickup and voltage drops in the lines. the vre110 series voltage references have the ground terminal brought out on two pins (pin 6 and pin 7) which are connected together internally. this allows the user to achieve greater accuracy when using a socket. voltage references have a voltage drop across their power supply ground pin due to quiescent current flowing through the contact resistance. if the contact resistance was constant with time and temperature, this voltage drop could be trimmed out. when the reference is plugged into a socket, this source of error can be as high as 20ppm. by connecting pin 7 to the power supply ground and pin 6 to a high impedance ground point in the measurement circuit, the error due to the contact resistance can be eliminated. if the unit is soldered into place the contact resistance is sufficiently small that it doesn't effect performance. vre110 vre112 vre110ds rev. d nov 2000
14 - pin hybrid package top view top view vre112 vre110 (vre111) gnd ref. gnd nc - ps nc nc nc fine adj. +2.5v ( - 2.5v) fine adj. +ps ( - ps) nc nc nc fine +adj. +2.5v fine +adj. +ps nc nc nc gnd ref. gnd nc - 2.5v fine - adj. fine - adj. - ps external connections figure 1 mechanical pin configuration 1. optional fine adjust for approximately 5mv. vre111 trim pot center tap connect to - 15v. vre110ds rev. d nov 2000 dim min max min max dim min max min max e .480 .500 12.1 12.7 a .120 .155 3.0 4.0 l .195 .215 4.9 5.4 q .015 .035 0.4 0.9 d .775 .805 19.7 20.4 q1 n/a .030 n/a 0.7 b .016 .020 0.4 0.5 c .009 .012 0.2 0.3 b1 .038 .042 0.9 1.0 g1 .290 .310 7.3 7.8 b2 .095 .105 2.4 2.6 s .085 .105 2.1 2.6 p .004 .006 0.10 0.15 inches millimeter inches millimeter
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