REF10 precision voltage reference features l +10.00v output l high accuracy: 0.005v untrimmed l very-low drift: 1ppm/ c max l excellent stability: 10ppm/1000hrs typ l low noise: 6 m vp-p typ, 0.1hz to 10hz l wide supply range: up to 35v description the REF10 is a precision voltage reference which provides a +10.00v output. the drift is laser-trimmed to 1ppm/ c max (km grade) over the full specifica- tion range. this is in contrast to some references which guarantee drift over a limited portion of their specification temperature range. the REF10 achieves its precision without a heater. this results in low quiescent current, fast warm-up, excellent stability, and low noise. the output can be adjusted with minimal effect on drift or stability. single supply operation over 13.5v to 35v supply range and excellent overall specifica- tions make the REF10 an ideal choice for the most demanding applications such as precision system stan- dard, d/a and a/d references, transducer excitation, etc. applications l precision calibrated voltage standard l transducer excitation l d/a and a/d converter reference l precision current reference l accurate comparator threshold reference l digital voltmeters l test equipment r 2
7k w r 4
156k w r 3
2k w r 1
12k w d21 2 6 +v cc v out 5 3 v trim v z 4 common 70
60
50
40
30
20
10
0
?0
?0
?0
?0
?0
?0
?0
0 time (hours) voltage change (ppm) time stability 1k 2k 3k international airport industrial park ? mailing address: po box 11400 ? tucson, az 85734 ? street address: 6730 s. tucson blvd. ? tucson, az 85706 tel: (520) 746-1111 ? twx: 910-952-1111 ? cable: bbrcorp ? telex: 066-6491 ? fax: (520) 889-1510 ? immediate product info: (800) 548-6132 ? 1984 burr-brown corporation pds-528b printed in u.s.a october, 1993
REF10 2 output voltage initial t a = +25 c 9.995 10.000 10.005 v trim range (1) C0.100 +0.250 v vs temperature (2) : km 0 c to +70 c 1 ppm/ c jm 0 c to +70 c 3 ppm/ c sm C55 c to +125 c 3 ppm/ c rm C55 c to +125 c 6 ppm/ c vs supply (line regulation) v cc = 13.5 to 35v 0.001 0.002 %/v vs output current (load regulation) i l = 0 to 10ma 0.001 0.002 %/ma vs time (3) t a = +25 c10 50 ppm/1000hr noise 0.1hz to 10hz 6 25 m vp-p output current source or sink 10 ma input voltage range 13.5 35 v quiescent current i out = 0 4.5 6 ma warm-up time to 0.1% 10 m s temperature range specification: jm, km 0 +70 c rm, sm C55 +125 c operating: jm, km C25 +85 c rm, sm C55 +125 c storage C65 +125 c notes: (1) trimming the offset voltage will affect the drift slightly. see installation and operating instructions for details. (2) the box method is used to specify output voltage drift vs temperature. see the discussion of performance section. (3) sample tested with power applied continuously. specifications electrical t a = +25 c, and 15vdc power supply, unless otherwise noted. REF10jm, km, rm, sm parameter conditions min typ max units ordering information temperature max drift model package range (ppm/ c) REF10jm metal to-99 0 c to +70 c3 REF10km metal to-99 0 c to +70 c1 REF10rm metal to-99 C55 c to +125 c6 REF10sm metal to-99 C55 c to +125 c3 input voltage ........................................................................................ 40v power dissipation at +25 c ............................................................ 200mv operating temperature j, k .................................................................................. C25 c to +85 c r, s ............................................................................... C55 c to +125 c storage temperature range .......................................... C65 c to +125 c lead temperature (soldering, 10s) ................................................ +300 c short-circuit protection at +25 c to common or +15vdc ........................................................ continuous absolute maximum ratings package information package drawing model package number (1) REF10jm 8-pin metal to-99 001 REF10km 8-pin metal to-99 001 REF10rm 8-pin metal to-99 001 REF10sm 8-pin metal to-99 001 note: (1) for detailed drawing and dimension table, please see end of data sheet, or appendix d of burr-brown ic data book. pin configuration top view note: (1) pin 3 is an unbuffered 6.3v output. any load will affect the output voltage and drift. a load of 1 m a on pin 3 will typically change the output voltage by 50 m v and the drift by 0.1ppm/ c. the information provided herein is believed to be reliable; however, burr-brown assumes no responsibility for inaccuracies or omissions. burr-brown assumes no responsibility for the use of this information, and all use of such information shall be entirely at the users own risk. prices and specifications are subject to change without notice. no patent rights or licenses to any of the circuits described herein are implied or granted to any third party. burr-brown does not authorize or warrant any burr-brown product for use in life support devices and/or systems. 8
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2
7
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5
3
4
v out
v z (1)
tab
common
trim
nc
+v cc
nc = no internal connection.
nc
nc
REF10 3 power turn-on response
20
15
10
5
0
?
?0
?5
power turn-on
error from final value (mv)
?0
typical performance curves t a = +25 c, and 15vdc power supply, unless otherwise noted. 400
200
0
?00
?00 t a =
+25? 5 01520 10 time (?) output voltage
cahnge (?) response to thermal shock t a = +70? device immersed in +70?
fluorinert bath 100
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30 100 0 10k 100k 1k frequency (hz) power supply rejection (db) power supply rejection vs frequency 5
4
3
2
1 ?5 temperature (?) quiescent current (ma) quiescent current vs temperature ?0 ?5 0 25 50 75 100 125 10k
1k
100
10
1 10k r s ( w ) output voltage adjustment (mv) output voltage adjustment vs r s 100k 1m 10m 100m see optional output
voltage fine adjust,
figure 4. voltage increase voltage decrease 100
80
60
40
20
0 2 068 4 output current (ma) junction temperature rise
above ambient (?) junction temperature rise
vs output current 10 max temp rise for
+85? ambient max temp rise for
+125? ambient v cc = 35v v cc = 25v v cc = 20v v cc = 15v v cc = 30v
REF10 4 typical performance curves (cont) noise test circuit t a = +25 c, and 15vdc power supply, unless otherwise noted. + opa27 dut 100? 15.8k w 20 w 2k w 8k w 2? oscilloscope gain = 100v/v
f 3db = 0.1hz and 10hz typical REF10 noise noise voltage ( m v) (referred to input) 0 C2 C4 C6 2 4 6 low frequency noise (see noise test circuit) typical bandgap reference noise noise voltage ( m v) (referred to input) 0 C2 C4 C6 2 4 6 low frequency noise (see noise test circuit) typical heated zener noise noise voltage ( m v) (referred to input) 0 C2 C4 C6 2 4 6 low frequency noise (see noise test circuit)
REF10 5 theory of operation the following discussion refers to the diagram on the first page. in operation, approximately 6.3v is applied to the noninverting input of op amp a 1 by zener diode d z1 . this voltage is amplified by a 1 to produce the 10.00v output. the gain is determined by r 1 and r 2 : g = (r 1 + r 2 )/r 1 . r 1 and r 2 are actively laser-trimmed to produce an exact 10.00v output. the zener operating current is derived from the regulated output voltage through r 3 . this feedback arrangement provides closely regulated zener current. r 3 is actively laser-trimmed to set the zener current to a level which results in low drift at the output of a 1 . r 4 allows user- trimming of the output voltage by providing for a small external adjustment of amplifier gain. since the tcr of r 4 closely matches the tcr of the gain setting resistors, the voltage trim has minimal effect on the drift of the reference. discussion of performance the REF10 is designed for applications requiring a precision voltage reference where both the initial value at room temperature and the drift over temperature are of importance to the user. two basic methods of specifying voltage refer- ence drift versus temperature are in common usage in the industrythe butterfly method and the box method. the REF10 is specified with the more commonly used box method. the box is formed by the high and low specifica- tion temperatures and a diagonal, the slope of which is equal to the maximum specified drift. for the REF10, each j and k unit is tested at temperatures of 0 c, +25 c, +50 c, and +70 c. each r and s unit is tested at C55 c, C25 c, 0 c, +25 c, +50 c, +75 c, +100 c and +125 c. the minimum and maximum test voltages must meet this condition: this assures the user that the variations of output voltage that occur as the temperature changes within the specifica- tion range, t low to t high , will be contained within a box whose diagonal has a slope equal to the maximum specified drift. since the shape of the actual drift curve is not known, the vertical position of the box is not exactly known either. it is, however, bounded by v upper bound and v lower bound (see figure 1). figure 1 uses the REF10km as an example. it has a drift specification of 1ppm/ c maximum and a specification temperature range of 0 c to +70 c. the box height (v 1 to v 2 ) is 700 m v, and upper bound and lower bound voltages are a maximum of 700 m v away from the voltage at +25 c. figure 1. REF10km output voltage drift. installation and operating instructions basic circuit connection figure 2 shows the proper connection of the REF10. to achieve the specified performance, pay careful attention to layout. a low resistance star configuration will reduce volt- age errors, noise pickup, and noise coupled from the power supply. commons should be connected as indicated being sure to minimize interconnection resistances. REF10
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4
1?
tantalum
+
r l1
r l2
r l3
(2)
(2)
(1)
(1)
v cc
figure 2. REF10 installation. notes: (1) lead resistances here of up to a few w have negligible effect on performance. (2) a resistance of 0.1 w in series with these leads will cause a 1mv error when the load current is at its maximum of 10ma. this results in a 0.01% error of 10v. optional output voltage adjustment optional output voltage adjustment circuits are shown in figures 3 and 4. trimming the output voltage will change the voltage drift by approximately 0.01ppm/ c per mv of trimmed voltage. in the circuit in figure 3, any mismatch in tcr between the two sections of the potentiometer will also v upper bound +10.0007 v 1 v nominal
+10.0000 v 2 +9.9993 025 70 output voltage (v) temperature (?) 700?
worst-case
d v out
for REF10km
v upper bound (t high ) typical drift diagonal
1ppm/? for REF10km (t low ) v out max v out min () /10v t high t low ? ? x 10 6 drift specification
REF10 6 affect drift, but the effect of the d tcr is reduced by a factor of 40 by the internal resistor divider. a high quality poten- tiometer with good mechanical stability, such as a cermet, should be used. the circuit in figure 3 has a range of approximately +250mv to C100mv. the circuit in figure 4 has less range but provides higher resolution. the mismatch in tcr between r s and the internal resistors can introduce some slight drift. this effect is minimized if r s is kept significantly larger than the 156k w internal resistor. a tcr of 100ppm/ c is normally sufficient. figure 3. REF10 optional output voltage adjust. figure 4. REF10 optional output voltage fine adjust. application information high accuracy, extremely-low drift, and small size make the REF10 ideal for demanding instrumentation and system voltage reference applications. since no heater is required, low power supply current designs are readily achievable. also the REF10 has lower output noise and much faster warm-up times than heated references, permitting high pre- cision without extra power or additional supplies. it should be considered that operating any integrated circuit at an elevated temperature will reduce its mttf. a variety of application circuits are shown in figures 5 through 11. v out
REF10
+v cc
v trim
minimum range (+2.5%, ?.0%) and minimal degradation of drift.
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6
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20k w
output
voltage
adjust
+10v
1?
tantalum
+
REF10
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4
r
1k w
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2
+v cc
f co = = 1.6hz
1
2 p rc
opa27
c
100?
v out = +10v
figure 5. precision reference with filtering. figure 6. 10v reference. REF10
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4
+10v out
?0v out
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1
6
5
3
ina105
+15v
6
figure 7. positive precision current source. v out REF10 v trim higher resolution, reduced range. 2 6 5 4 20k w
output
voltage
adjust +10v r s (1) 1?
tantalum + +v cc see information in
typical performance
curves the tcr of r s can
affect v out drift if r s
is made small. note: (1) r s typically 4m w. REF10 2 4 opa111 r i out 6 2 +v cc i out = , r 3 1k w 10v
r
REF10 7 figure 8. stacked references. notes: (1) REF10s can be stacked to obtain voltages in multiples of 10v. (2) the supply voltage should be between 10n +5 and 10n +25 where n is the number of REF10s. (3) output current of each REF10 must not exceed its rated output current of 10ma. this includes the current delivered to the lower REF10. figure 9. 5v reference. figure 10. +5v and +10v reference. REF10
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6
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5
6
3
1
+10v
+5
ina105
e o = e 1 /2, ?.01%
+v cc
REF10
2
6
4
+v cc = 24v
820 w
d v
600 w
600 w
600 w
600 w
+10v
figure 11. +10v reference with output current boost using a resistor to drive a 600 w bridge. at 10v, the 600 w bridge requires 16.7ma. an 820 w resistor connected directly from the bridge to the positive supply provides the bulk of the bridge current. the REF10 need only supply an error current to keep the bridge at 10v. since the REF10 can sink or source up to 10ma, the circuit shown can tolerate supply variations of up to 24v, 8v, or bridge resistance drift from 400 w to 1400 w . REF10 2 4 6 +5v out ?v out 3 1 6 5 2 ina105 REF10 2 6 +30v REF10 2 6 35v to 55v 4 +20v +10v 4 REF10 2 6 4
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