rev. 0 information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. no license is granted by implication or otherwise under any patent or patent rights of analog devices. trademarks and registered trademarks are the property of their respective companies. one technology way, p.o. box 9106, norwood, ma 02062-9106, u.s.a. tel: 781/329-4700 www.analog.com fax: 781/326-8703 ?2003 analog devices, inc. all rights reserved. adr512 1.2 v precision low noise shunt voltage reference features precision 1.200 v voltage reference ultracompact 3 mm 3 mm sot-23 package no external capacitor required low output noise: 4 v p-p (0.1 hz to 10 hz) initial accuracy: 0.3% max temperature coefficient: 60 ppm/ c max operating current range: 100 a to 10 ma output impedance: 0.3 max temperature range: ?0 c to +85 c applications precision data acquisition systems battery-powered equipment: cellular phone, notebook computer, pda, and gps 3 v/5 v, 8-/12-bit data converters portable medical instruments industrial process control systems precision instruments general description designed for space critical applications, the adr512 is a low voltage (1.200 v), precision shunt-mode voltage reference in the ultracompact (3 mm 3 mm) sot-23 package. the adr512 features low temperature drift (60 ppm/ c), high accuracy ( 0.30%), and ultralow noise (4 v p-p) performance. the adr512? advanced design eliminates the need for an external capacitor, yet it is stable with any capacitive load. the minimum operating current increases from a scant 100 a to a maximum of 10 ma. this low operating current and ease of use make the adr512 ideally suited for handheld battery-powered applications. pin configuration 3-lead sot-23 1 3 2 v + v ? adr512 trim/nc a trim terminal is available on the adr512 to provide adjust- ment of the output voltage over 0.5% without affecting the temperature coefficient of the device. this feature provides users with the flexibility to trim out any system errors. v s r bias i q i l v out = 1.2v c out (optional) i l + i q v s ? v out i l + i q r bias = adr512 figure 1. typical operating circuit adr512 output initial temperature voltage accuracy coefficient model (v o ) (mv) (%) (ppm/ c) adr512art-reel7 1.200 3.5 0.3 60
rev. 0 e2e adr512especifications electrical characteristics parameter symbol conditions min typ max unit output voltage 1 v o 1.1965 1.2 1.2035 v initial accuracy v oerr e3.5 +3.5 mv v oerr% e0.3 +0.3 % temperature coefficient a grade tcv o e40 + ? = ( ? ? ) = ? + = ( = ? = ? ) ( ) + + + ( ) ? ? () = ( ) ( )( ) () ( ? ) + +
rev. 0 t ypical performance characteristicseadr512 e3e temperature ( c) v out (v) 1.204 1.203 1.202 1.201 1.200 1.199 1.198 1.197 1.196 ?15 ?40 10 35 60 85 tpc 1. typical v out vs. temperature time (100 s/div) v in = 2v/div v out = 1v/div tpc 2. turn on time time (100 s/div) v in = 2v/div v out = 1v/div tpc 3. turn on time with 1 ( ? ) = = ( ? ) = = ? = ? = ( ? )
rev. 0 e4e adr512 parameter definitions temperature coefficient this is the change of output voltage with respect to operating temperature changes, normalized by the output voltage at 25 tcv ppm c vt vt vctt o oo o ? ? ? ? ? ? = () ? () () ? () () v o ( 25 c) = v o at 25 v o (t 1 ) = v o at temperature 1 v o (t 2 ) = v o at temperature 2 thermal hysteresis thermal hysteresis is defined as the change of output voltage after the device is cycled through the temperature from +25 + + vvcv v ppm vcv vc o hys o o tc o hys ootc o __ _ _ = () ? [] = () ? () () v o ( 25 c) = v o at 25 v o_tc = v o at 25 + + + ( ) ( ) ( ) ( ) ? ? () ( ) r(vv)(ii) bias s out l q =+ () ? = ? = ( ? ) ? ()
rev. 0 adr512 e5e adjustable precision voltage source the adr512, combined with a precision low input bias op amp such as the ad8610, can be used to output a precise adjustable voltage. figure 2 illustrates the implementation of this application using the adr512. the output of the op amp, v out , is determined by the gain of the circuit, which is completely dependent on resistors r2 and r1. v r r out =+ 2 1 (4) an additional capacitor in parallel with r2 can be added to filter out high frequency noise. the value of c2 is dependent on the value of r2. v out = 1.2(1 + r2/r1) r bias r1 v cc r2 ad8610 adr512 1.2v c2 (optional) figure 2. adjustable precision voltage source output voltage trim using a mechanical or digital potentiometer, the output voltage of the adr512 can be trimmed ? r bias v cc r1 100k pot 50k adr512 v out figure 3. output voltage trim using the adr512 with precision data converters the compact adr512 package and the device?s low minimum operating current requirement make it ideal for use in battery- powered portable instruments, such as the ad7533 cmos multiplying dac, that use precision data converters. figure 4 shows the adr512 serving as an external reference to the ad7533, a cmos multiplying dac. such a dac requires a negative voltage input in order to provide a positive output range. in this application, the adr512 is supplying a e1.2 v reference to the ref input of the ad7533. msb v dd v out = 0v to 1.2v ?v dd g n lsb 1 2 3 1 1 15 09 r2 adr512 ad7533 figure 4. adr512 as a reference for a 10-bit cmos dac (ad7533) precise negative voltage reference the adr512 is suitable for use in applications where a precise negative voltage reference is desired, including the application detailed in figure 4. figure 5 shows the adr512 configured to provide a e1.2 v output. ?1.2v ? ?v dd r1 adr512 figure 5. precise e1.2 v reference configuration since the adr512 characteristics resemble those of a zener diode, the cathode shown in figure 5 will be 1.2 v higher with respect to the anode (v+ with respect to ve on the adr512 package). since the cathode of the adr512 is tied to ground, the anode must be e1.2 v. r1 in figure 5 should be chosen so that 100 r v i dd 1 = ()
rev. 0 e6e adr512 outline dimensions 3-lead small outline transistor package [sot-23] (rt-3) dimensions shown in millimeters 3.04 2.90 2.80 pin 1 1.40 1.30 1.20 2.64 2.10 1.90 bsc 1 2 3 seating plane 1.12 0.89 0.10 0.01 0.50 0.30 0.20 0.08 0.60 0.50 0.40 0.95 bsc compliant to jedec standards to-236ab
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