High Precision
10 V IC Reference
AD581
Rev. C
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FEATURES
Laser trimmed to high accuracy
10.000 V ±5 mV (L and U models)
Trimmed temperature coefficient
5 ppm/°C maximum, 0°C to 70°C (L model)
10 ppm/°C maximum, −55°C to +125°C (U model)
Excellent long-term stability
25 ppm/1000 hrs (noncumulative)
−10 V reference capability
Low quiescent current: 1.0 mA maximum
10 mA current output capability
3-pin TO-5 package
MIL-STD-883 compliant versions available
FUNCTIONAL BLOCK DIAGRAM
TO-5
BOTTOM VIEW
+V
S
V
OUT
GND
AD581
08014-001
Figure 1.
GENERAL DESCRIPTION
The AD581 is a 3-pin, temperature compensated, monolithic,
band gap voltage reference that provides a precise 10.00 V output
from an unregulated input level ranging from 12 V to 30 V.
Laser wafer trimming (LWT) is used to trim both the initial
error at +25°C as well as the temperature coefficient, resulting
in high precision performance previously available only in expen-
sive hybrids or oven regulated modules. The 5 mV initial error
tolerance and 5 ppm/°C guaranteed temperature coefficient of
the AD581L is available in a monolithic voltage reference.
The band gap circuit design used in the AD581 offers several
advantages over classical Zener breakdown diode techniques.
Most important, no external components are required to
achieve full accuracy and significant stability to low power
systems. In addition, total supply current to the device,
including the output buffer amplifier (which can supply up
to 10 mA) is typically 750 A. The long-term stability of the
band gap design is equivalent to selected Zener reference
diodes.
The AD581 is recommended for use as a reference for 8-, 10-
or 12-bit digital-to-analog converters (DACs) that require an
external precision reference. The device is also ideal for all types
of analog-to-digital converters (ADCs) up to 14-bit accuracy,
either successive approximation or integrating designs, and can
generally offer better performance than that provided by standard
self-contained references.
The AD581J, AD581K, and AD581L are specified for operation
from 0°C to 70°C; the AD581S, AD581T, and AD581U are
specified for the −55°C to +125°C range. All grades are
packaged in a hermetically sealed 3-pin TO-5 metal can.
PRODUCT HIGHLIGHTS
1. Laser trimming of both initial accuracy and temperature
coefficient results in very low errors over temperature
without the use of external components. The AD581L has
a maximum deviation from 10.000 V of ±7.25 mV from
0°C to 70°C, whereas the AD581U guarantees ±15 mV
maximum total error without external trims from −55°C
to +125°C.
2. Because the laser trimming is done on the wafer prior to
separation into individual chips, the AD581 is extremely
valuable to hybrid designers for its ease of use, lack of
required external trims, and inherent high performance.
3. The AD581 can also be operated in a 2-pin Zener mode to
provide a precision −10 V reference with just one external
resistor to the unregulated supply. The performance in this
mode is nearly equal to that of the standard 3-pin confi-
guration.
4. Advanced circuit design using the band gap concept allows
the AD581 to give full performance with an unregulated
input voltage down to 13 V. With an external resistor, the
device operates with a supply as low as 11.4 V.
5. The AD581 is available in versions compliant with
MILSTD-883. Refer to the military datasheet for detailed
specifications.
AD581
Rev. C | Page 2 of 12
TABLE OF CONTENTS
Features .............................................................................................. 1
Functional Block Diagram .............................................................. 1
General Description ......................................................................... 1
Product Highlights ........................................................................... 1
Revision History ............................................................................... 2
Specifications ..................................................................................... 3
Absolute Maximum Ratings ............................................................ 5
ESD Caution .................................................................................. 5
Applying the AD581 ......................................................................... 6
Voltage Variation vs. Temperature ............................................. 6
Output Current Characteristics ...................................................7
Dynamic Performance ..................................................................7
Precision High Current Supply ...................................................8
Connection for Reduced Primary Supply ..................................8
The AD581 as a Current Limiter .....................................................9
Negative 10 V Reference ...............................................................9
10 V Reference with Multiplying CMOS DACs or ADCs .......9
Precision 12-Bit DAC Reference .................................................9
Outline Dimensions ........................................................................ 11
Ordering Guide ........................................................................... 11
REVISION HISTORY
4/09—Rev. B to Rev. C
Updated Format .................................................................. Universal
Changes to Table 1 ............................................................................ 3
Changes to Figure 2 .......................................................................... 6
Changes to Figure 11 ........................................................................ 8
Changes to 10 V Reference with Multiplying CMOS DACs
or ADCs Section ............................................................................... 9
Changes to Precision 12-Bit DAC Reference Section .................. 9
Changes to Figure 13 ........................................................................ 9
Changes to Figure 15 and Figure 16 ............................................. 10
Updated Outline Dimensions ....................................................... 11
Changes to Ordering Guide .......................................................... 11
AD581
Rev. C | Page 3 of 12
SPECIFICATIONS
@ VIN = +15 V and TA = +25°C.
Specifications shown in boldface are tested on all production units at final electrical test. Results from those tests are used to calculate
outgoing quality levels. All minimum and maximum specifications are guaranteed, although only those shown in boldface are tested on
all production units.
Table 1.
Model
AD581J AD581K AD581L
Units Min Typ Max Min Typ Max Min Typ Max
OUTPUT VOLTAGE TOLERANCE
(Error from Nominal 10,000 V Output) ±30 ±10 ±5 mV
OUTPUT VOLTAGE CHANGE
Maximum Deviation from +25°C ±13.5 ±6.75 ±2.25 mV
Value, TMIN to TMAX
Temperature Coefficient 30 15 5 ppm/°C
LINE REGULATION
15 V ≤ VIN ≤ 30 V 3.0 3.0 3.0 mV
(0.002) (0.002) (0.002) %/V
13 V ≤ VIN ≤ 15 V 1.0 1.0 1.0 mV
(0.005) (0.005) (0.005) %/V
LOAD REGULATION
0 ≤ IOUT ≤ 5 mA 200 500 200 500 200 500 μV/mA
QUIESCENT CURRENT 0.75 1.0 0.75 1.0 0.75 1.0 mA
TURN-ON SETTLING TIME TO 0.1%1
200 200 200 μs
NOISE (0.1 Hz TO 10 Hz) 40 40 40 μV (p-p)
LONG-TERM STABILITY 25 25 25 ppm/1000 hr
SHORT-CIRCUIT CURRENT 30 30 30 mA
OUTPUT CURRENT
Source @ +25°C 10 10 10 mA
Source TMIN to TMAX 5 5 5 mA
Sink TMIN to TMAX 5 5 5 μA
TEMPERATURE RANGE
Specified 0 70 0 70 0 70 °C
Operating −65 +150 −65 +150 −65 +150 °C
PACKAGE OPTION2
TO-5 (H-03B) AD581JH AD581KH AD581LH
1 See Figure 7.
2 H indicates the hermetic metal can.
AD581
Rev. C | Page 4 of 12
Table 2.
Model
AD581S AD581T AD581U
Units Min Typ Max Min Typ Max Min Typ Max
OUTPUT VOLTAGE TOLERANCE
(Error from Nominal 10,000 V Output) ±30 ±10 ±5 mV
OUTPUT VOLTAGE CHANGE
Maximum Deviation from +25°C ±30 ±15 ±10 mV
Value, TMIN to TMAX
Temperature Coefficient 30 15 10 ppm/°C
LINE REGULATION
15 V ≤ VIN ≤ 30 V 3.0 3.0 3.0 mV
(0.002) (0.002) (0.002) %/V
13 V ≤ VIN ≤ 15 V 1.0 1.0 1.0 mV
(0.005) (0.005) (0.005) %/V
LOAD REGULATION
0 ≤ IOUT ≤ 5 mA 200 500 200 500 200 500 μV/mA
QUIESCENT CURRENT 0.75 1.0 0.75 1.0 0.75 1.0 mA
TURN-ON SETTLING TIME TO 0.1%1
200 200 200 μs
NOISE (0.1 Hz TO 10 Hz) 40 40 40 μV (p-p)
LONG-TERM STABILITY 25 25 25 ppm/1000 hr
SHORT-CIRCUIT CURRENT 30 30 30 mA
OUTPUT CURRENT
Source @ +25°C 10 10 10 mA
Source TMIN to TMAX 5 5 5 mA
Sink TMIN to TMAX 200 200 200 μA
Sink −55°C to +85°C 5 5 5 mA
TEMPERATURE RANGE
Specified −55 +125 −55 +125 −55 +125 °C
Operating −65 +150 −65 +150 −65 +150 °C
PACKAGE OPTION2
TO-5 (H-03B) AD581SH AD581TH AD581UH
1 See Figure 7.
2 H indicates hermetic metal can.
AD581
Rev. C | Page 5 of 12
ABSOLUTE MAXIMUM RATINGS
Table 3.
Parameter Rating
Input Voltage 40 V
Power Dissipation @ +25°C 600 mW
Operating Junction Temperature Range −55°C to +150°C
Lead Temperature (Soldering 10 sec) +300°C
Thermal Resistance
Junction-to-Ambient 150°C/W
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
AD581
Rev. C | Page 6 of 12
APPLYING THE AD581
The AD581 is easy to use in virtually all precision reference
applications. The three pins are simply: primary supply, ground,
and output, with the case grounded. No external components
are required even for high precision applications; the degree of
desired absolute accuracy is achieved simply by selecting the
required device grade. The AD581 requires less than 1 mA quies-
cent current from an operating supply range of 13 V to 30 V.
+V
S
V
OUT
GND
AD581
10V
13V T O 30
V
08014-002
Figure 2. Pin Configuration (Bottom View)
An external fine trim may be desired to set the output level to
exactly 10.000 V within less than a millivolt (calibrated to a
main system reference). System calibration may also require a
reference slightly different from 10.00 V. In either case, the
optional trim circuit shown in Figure 3 can offset the output by
up to ±30 mV (with the 22 resistor), if needed, with minimal
effect on other device characteristics.
+V
S
V
OUT
6.8kΩ
10kΩ
4.3kΩ
GND
AD581
+10V
R
+15
V
–15V
RTRIM
RANGE MAX
Δ TCR
22Ω±30mV 3.5ppm/°C
12Ω±10mV 2.0ppm/°C
3.9Ω±5mV 0.6ppm/°C
08014-003
Figure 3. Optional Fine Trim Configuration
V+
10V
V–
Q12
Q14
Q11
Q20
C52
Q6
Q16 Q13
C50
C51
Q10
R40 R41
Q7
Q8
Q15 R42
R34
R37
R35
R36R30
R31
R39
Q4Q3
Q5
Q1Q2
R32R33
0
8014-004
Figure 4. Simplified Schematic
VOLTAGE VARIATION vs. TEMPERATURE
Some confusion exists in the area of defining and specifying
reference voltage error over temperature. Historically, references
have been characterized using a maximum deviation per degree
Celsius; that is, 10 ppm/°C. However, because of nonlinearities
in temperature characteristics, which originated in standard
Zener references (such as S-type characteristics) manufacturers
opt for the maximum limit error band approach to specify devices.
This technique involves measurement of the output at three,
five, or more different temperatures to guarantee that the output
voltage falls within the given error band. The temperature charac-
teristic of the AD581 consistently follows the S-curve shown in
Figure 5. Three-point measurement of each device guarantees
the error band over the specified temperature range.
10.005
9.995
TEM P E RATURE (° C)
V
OUT
(V)
10.000
–50–55 –40 –30 –20 –10 010 20 30 40 50 60 70 80 90 100 110 120 125
08014-005
Figure 5. Typical Temperature Characteristic
AD581
Rev. C | Page 7 of 12
The error band which is guaranteed with the AD581 is the
maximum deviation from the initial value at +25°C; this error
band is of more use to a designer than one which simply guarantees
the maximum total change over the entire range (that is, in the
latter definition, all of the changes could occur in the positive
direction). Thus, with a given grade of the AD581, the designer
can easily determine the maximum total error from initial toler-
ance plus temperature variation (for example, for the AD581T, the
initial tolerance is ±10 mV, the temperature error band is ±15 mV,
thus the unit is guaranteed to be 10.000 V ±25 mV from −55°C
to +125°C).
OUTPUT CURRENT CHARACTERISTICS
The AD581 has the capability to either source or sink current
and provide good load regulation in either direction, although
it has better characteristics in the source mode (positive current
into the load). The circuit is protected for shorts to either positive
supply or ground. The output voltage vs. output current charac-
teristics of the device are shown in Figure 6. Source current
is displayed as negative current in the figure; sink current is
positive. Note that the short-circuit current (that is, 0 V output)
is about 28 mA; when shorted to +15 V, the sink current goes to
about 20 mA.
–20 –15 –10 –5 0 5 10 15 20
14
12
10
8
6
4
2
0
OUTPUT VOLTAGE (V)
OUTPUT CURRENT (mA)
SOURCE SINK
+V
S
= 15V
T
A
= 25°C
08014-006
Figure 6. Output Voltage vs. Sink and Source Current
DYNAMIC PERFORMANCE
Many low power instrument manufacturers have been in-
creasingly concerned with the turn-on characteristics of the
components used in their systems. Fast turn-on components often
enable the end user to keep power off when not needed, and yet
respond quickly when the power is turned on for operation.
Figure 7 displays the turn-on characteristic of the AD581. This
characteristic is generated from a cold start operation and repre-
sents the true turn-on waveform after an extended period with
the supplies off. The figure shows both the coarse and fine transient
characteristics of the device; the total settling time to within
±10 mV is about 180 s, and there is no long thermal tail
appearing after the point.
0 50 100 150 200 250
12
V
11V
10V
20V
10V
0V
10.03V
OUTPUT
10.02V
10.01V
10.00V
SETTLING T I ME (µs)
OUTPUTINPUT
08014-007
Figure 7. Output Settling Characteristic
1000
110 1M
FREQ UE NCY (Hz )
100 1k 10k 100k
10
100
NOI S E SPECTRAL DENSI TY (nV/ Hz)
TOTAL NOISE (µV rms) UP
TO SPECIFIED FREQUENCY
08014-008
Figure 8. Spectral Noise Density and Total rms Noise vs. Frequency
1000
500
TEM P E RATURE (° C)
SUPPLY CURRENT (µA)
–50–55 –40 –30 –20 –10 010 20 30 40 50 60 70 80 90 100 110 120 125
900
800
700
600
1.5µA/°C
08014-009
Figure 9. Quiescent Current vs. Temperature
AD581
Rev. C | Page 8 of 12
PRECISION HIGH CURRENT SUPPLY CONNECTION FOR REDUCED PRIMARY SUPPLY
The AD581 can be easily connected with power pnp or power
Darlington pnp devices to provide much greater output current
capability. The circuit shown in Figure 10 delivers a precision
10 V output with up to 4 A supplied to the load. The 0.1 F
capacitor is required only if the load has a significant capacitive
component. If the load is purely resistive, improved high frequency
supply rejection results from removing the capacitor.
Whereas line regulation is specified down to 13 V, the typical
AD581 works as specified ≤12 V. The current sink capability
allows even lower supply voltage capability such as operation
from 12 V ±5% as shown in Figure 11. The 560 resistor reduces
the current supplied by the AD581 to a manageable level at a
full 5 mA load. Note that the other band gap references, without
current sink capability, may be damaged by use in this circuit
configuration.
AD581
V
IN
≥ 15
V
470Ω
0.1µF
+V
S
V
OUT
GND
2N6040
V
OUT
10V @ 4A
0
8014-010
AD581
GND
+V
S
V
OUT
12V ±5%
10V @ 0mA T O 5mA
560Ω 5%
08014-011
Figure 11. 12 V Supply Connection
Figure 10. High Current Precision Supply
AD581
Rev. C | Page 9 of 12
THE AD581 AS A CURRENT LIMITER
The AD581 represents an alternative to current limiter diodes
that require factory selection to achieve a desired current. This
approach often results in temperature coefficients of 1%/°C.
The AD581 approach is not limited to a defined set current
limit; it can be programmed from 0.75 mA to 5 mA with the
insertion of a single external resistor. Of course, the minimum
voltage required to drive the connection is 13 V. The AD580,
which is a 2.5 V reference, can be used in this type of circuit
with compliance voltage down to 4.5 V.
+V
S
V
OUT
GND
A
D581
R
LOAD
i = R
10V
~ ___ + 0.75mA
10V =
BOTTOM VIEW OF
10V PRECISION
REFE RE NCE CIRCUIT
IN TO-5 CASE
08014-012
Figure 12. A Two-Component Precision Current Limiter
NEGATIVE 10 V REFERENCE
The AD581 can also be used in a 2-pin Zener mode to provide a
precision −10.00 V reference. As shown in Figure 13, the +VS and
VOUT pins are connected together to the high supply (in this
case, ground). The ground pin is connected through a resistor
to the negative supply. Thus, the output is taken from the
ground pin instead of VOUT. With 1 mA flowing through the
AD581 in this mode, a typical unit shows a 2 mV increase in
output level over that produced in the 3-pin mode. Note also
that the effective output impedance in this connection increases
from 0.2 typical to 2 . It is essential to arrange the output
load and the supply resistor, RS, so that the net current through
the AD581 is always between 1 mA and 5 mA. For operation to
+125°C, the net current should be between 2 mA and 5 mA. The
temperature characteristics and long-term stability of the device
are essentially the same as that of a unit used in the standard
3-pin mode.
The AD581 can also be used in a 2-pin mode to develop a
positive reference. +VS and VOUT are tied together and to the
positive supply through an appropriate supply resistor. The
performance characteristics are similar to those of the negative
2-pin connection. The only advantage of this connection over
the standard 3-pin connection is that a lower primary supply
can be used, as low as 10.5 V. This type of operation requires con-
siderable attention to load and primary supply regulation to
maintain the AD581 within its regulating range of 1 mA to 5 mA
(2 mA to 5 mA for operation beyond +85°C).
AD581
GND
+V
S
V
OUT
0.1µF
–15V
1.2kΩ 5%
V
REF
–10V
A
NALOG
GND
0
8014-013
Figure 13. 2-Pin −10 V Reference
10 V REFERENCE WITH MULTIPLYING CMOS DACs
OR ADCs
The AD581 is ideal for application with the entire AD7533
series of 10- and 12-bit multiplying CMOS DACs, especially for
low power applications. It is equally suitable for the AD7574
8-bit ADC. In the standard hook-up, as shown in Figure 15, the
+10 V reference is inverted by the amplifier/DAC configuration
to produce a 0 V to −10 V range. If an OP1177 amplifier is used,
total quiescent supply current is typically 2 mA. If a 0 V to +10 V
full-scale range is desired, the AD581 can be connected to the
CMOS DAC in its −10 V Zener mode, as shown in Figure 13
(the −10 VREF output is connected directly to the VREF IN of the
CMOS DAC). The AD581 is normally used in the −10 V mode
with the AD7574 to give a 0 V to +10 V ADC range. This is
shown in Figure 15. Bipolar output applications and other
operating details can be found in the data sheets for the CMOS
products.
AD581
+15
V
+10V
V
REF I N
BIT 1 ( M S B)
BIT 10 (L S B) GND
DIGITAL
INPUT +15V
–15V
V
OUT
0V T O –10V
R
FEEDBACK
I
OUT1
I
OUT2
15 14
3
4
5
13
16
1
2
08014-014
Figure 14. Low Power 10-Bit CMOS DAC Application
PRECISION 12-BIT DAC REFERENCE
AD565A, like most DACs, is designed to operate with a +10 V
reference element. In the AD565A, this 10 V reference voltage is
converted into a reference current of approximately 0.5 mA via
the internal 19.95 k resistor (in series with the external 100
trimmer). The gain temperature coefficient of the AD565A is
primarily governed by the temperature tracking of the 19.95 k
resistor and the 5 kΩ to10 kΩ span resistors; gain TC is guaran-
teed to 3 ppm/°C. Thus, using the AD581L (at 5 ppm/°C) as the
AD581
Rev. C | Page 10 of 12
10 V reference guarantees a maximum full-scale temperature
coefficient of 8 ppm/°C over the commercial range. The 10 V
reference also supplies the normal 1 mA bipolar offset current
through the 9.95 kΩ bipolar offset resistor. Consequently, the
bipolar offset TC depends only on TC matching of the bipolar
offset resistor to the input reference resistor and is guaranteed
to 3 ppm/°C.
118
2
3
4
5
AD7574
(TOP VI E W)
AD581
DIGITAL
SUPPLY
RETURN
GROUND
INTERTIE
ANALOG
GROUND
ANALOG
SUPPLY
RETURN
R3
1.2kΩ
5%
GND
+V
S
V
OUT
0.1µF
+5
V
–
15
V
–10V REF R1 1kΩ 10%
1
GAIN TRIM
1
R2 2kΩ
SIGNAL
INPUT
0V T O +10V
1
R1 AND R2 CAN BE OM ITTED IF GAI N TRIM
IS NOT REQUIRED.
08014-015
Figure 15. AD581 as −10 V Reference for CMOS ADC
PNP LOGIC SWITCHES AND LEVEL SHIFTERS
0.1µF
0.1µF
OP1177
OP AMP
OUTPUT
5kΩ
(8kΩ)
A
5kΩ
(8kΩ)
R4
20kΩ, 15T
R3
3.0MΩ
9.950kΩ
(15.95k)
CONTROL
AMP
CONT ROL AMP
SUMMING
JUNCTION
100Ω, 15T
R2
GAIN ADJ.
10V
V
OUT
R1
100Ω, 15T
BIPOLAR O FFS E T ADJ.
GND
19.95kΩ
0.5mA
–15V
AD565A
+15V
–15V
UNIPOLAR
OFFSE T ADJ.
A = ANALO G GROUND
24
BIT 1
(MSB)
23
BIT 2
22
BIT 3
21
BIT 4
20
BIT 5
19
BIT 6
18
BIT 7
17
BIT 8
16
BIT 9
15
BIT 10
14
BIT 11
13
2
3
11
10
9
12
8
7
BIT 12
(LSB)
216
4
5
3
A
–
15
V
+5V/+15
V
+15V
+V
S
AD581
08014-016
Figure 16. Precision 12-Bit DAC
AD581
Rev. C | Page 11 of 12
030309-A
CONT ROLL ING DI MENSIONS ARE I N INCHES; M ILL IMET E R DIMENSIONS
(I N PARENTHESES ) ARE ROUNDED-OFF INCH EQUIVALE NTS FOR
REFE RE NCE ONLY AND ARE NOT APP ROPRIATE FOR USE I N DE S IGN.
OUTLINE DIMENSIONS
0.185 (4.70)
0.165 (4.19) 0.500 (12.70)
MIN
0.019 ( 0.48)
0.016 ( 0.41)
0.030 (0.76) M A X
0.335 ( 8.51)
0.305 ( 7.75)
0.370 (9.40)
0.335 (8.51)
0.100 (2.54) T Y P
0.034 (0.86)
0.028 (0.71)
0.045 ( 1 .14)
0.029 ( 0 .74)
3
1
0.200
(5.08)
TYP
45°
2
BASE & SEATING PLANE
Figure 17. 3-Pin Metal Header Package [TO-5]
(H-03B)
Dimensions shown in inches and (millimeters)
ORDERING GUIDE
Model Temperature Range Package Description Package Option
AD581JH1
0°C to +70°C 3-Pin Metal Header Package (TO-5) H-03B
AD581KH1
0°C to +70°C 3-Pin Metal Header Package (TO-5) H-03B
AD581LH1
0°C to +70°C 3-Pin Metal Header Package (TO-5) H-03B
AD581SH1
−55°C to +125°C 3-Pin Metal Header Package (TO-5) H-03B
AD581TH1
−55°C to +125°C 3-Pin Metal Header Package (TO-5) H-03B
AD581UH1
−55°C to +125°C 3-Pin Metal Header Package (TO-5) H-03B
1 RoHS compliant model as of Date Code 0713.
AD581
Rev. C | Page 12 of 12
NOTES
©2009 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D08014-0-4/09(C)
