5962-01-374-9579 [ADI]
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ADI |
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High Precision
10 V Reference
a
AD587
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Laser Trimmed to High Accuracy:
10.000 V ؎5 mV (L and U Grades)
Trimmed Temperature Coefficient:
5 ppm/؇C max, (L and U Grades)
Noise Reduction Capability
NOISE
REDUCTION
+V
IN
2
8
R
S
Low Quiescent Current: 4 mA max
Output Trim Capability
MIL-STD-883 Compliant Versions Available
A1
V
OUT
6
5
R
F
R
T
TRIM
R
I
AD587
4
GND
NOTE:
PINS 1,3, AND 7 ARE INTERNAL TEST POINTS.
NO CONNECTIONS TO THESE POINTS.
PRODUCT DESCRIPTION
PRODUCT HIGHLIGHTS
The AD587 represents a major advance in the state-of-the-art in
monolithic voltage references. Using a proprietary ion-implanted
buried Zener diode and laser wafer trimming of high stability
thin-film resistors, the AD587 provides outstanding perfor-
mance at low cost.
1. Laser trimming of both initial accuracy and temperature
coefficients results in very low errors over temperature with-
out the use of external components. The AD587L has a
maximum deviation from 10.000 V of ±8.5 mV between 0°C
and +70°C, and the AD587U guarantees ±14 mV maximum
total error between –55°C and +125°C.
The AD587 offers much higher performance than most other
10 V references. Because the AD587 uses an industry standard
pinout, many systems can be upgraded instantly with the
AD587. The buried Zener approach to reference design pro-
vides lower noise and drift than bandgap voltage references. The
AD587 offers a noise reduction pin which can be used to further
reduce the noise level generated by the buried Zener.
2. For applications requiring higher precision, an optional fine
trim connection is provided.
3. Any system using an industry standard pinout 10 volt refer-
ence can be upgraded instantly with the AD587.
4. Output noise of the AD587 is very low, typically 4 µV p-p. A
noise reduction pin is provided for additional noise filtering
using an external capacitor.
The AD587 is recommended for use as a reference for 8-, 10-,
12-, 14- or 16-bit D/A converters which require an external
precision reference. The device is also ideal for successive
approximation or integrating A/D converters with up to 14 bits
of accuracy and, in general, can offer better performance than
the standard on-chip references.
5. The AD587 is available in versions compliant with MIL-
STD-883. Refer to the Analog Devices Military Products
Databook or current AD587/883B data sheet for detailed
specifications.
The AD587J, K and L are specified for operation from 0°C to
+70°C, and the AD587S, T and U are specified for –55°C to
+125°C operation. All grades are available in 8-pin cerdip. The
J and K versions are also available in an 8-pin Small Outline IC
(SOIC) package for surface mount applications, while the J, K,
and L grades also come in an 8-pin plastic package.
REV. D
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
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
Fax: 781/326-8703
World Wide Web Site: http://www.analog.com
© Analog Devices, Inc., 2000
(TA = +25؇C, VIN = +15 V unless otherwise noted)
AD587–SPECIFICATIONS
Model
AD587J/S
Typ
AD587K/T
Typ
AD587L/U
Typ
Min
Max
Min
Max
Min
Max
Units
OUTPUT VOLTAGE
9.990
10.010
9.995
10.005
9.995
10.005
V
OUTPUT VOLTAGE DRIFT1
0°C to +70°C
–55°C to +125°C
20
20
10
10
5
5
ppm/°C
GAIN ADJUSTMENT
+3
–1
+3
–1
+3
–1
%
LINE REGULATION1
13.5 V ≤ + VIN ≤ 36 V
TMIN to TMAX
100
100
100
100
100
100
±µV/V
LOAD REGULATION1
Sourcing 0 < IOUT < 10 mA
TMIN to TMAX
±µV/mA
Sourcing –10 < IOUT < 0 mA2
TMIN to TMAX
100
4
100
4
100
4
QUIESCENT CURRENT
POWER DISSIPATION
2
2
2
mA
30
30
30
mW
OUTPUT NOISE
0.1 Hz to 10 Hz
4
4
4
µV p-p
Spectral Density, 100 Hz
100
100
100
nV/√Hz
LONG-TERM STABILITY
15
30
30
15
30
30
15
30
30
± ppm/1000 Hr.
SHORT-CIRCUIT CURRENT-TO-GROUND
SHORT-CIRCUIT CURRENT-TO-VIN
70
70
70
70
70
70
mA
mA
TEMPERATURE RANGE
Specified Performance (J, K, L)
Operating Performance (J, K, L)3
Specified Performance (S, T, U)
Operating Performance (S, T, U)3
0
–40
–55
+70
+85
+125
0
–40
–55
+70
+85
+125
0
–40
–55
+70
+85
+125
°C
–55
+125
–55
+125
–55
+125
NOTES
1Spec is guaranteed for all packages and grades. Cerdip packaged parts are 100% production test.
2Load Regulation (Sinking) specification for SOIC (R) package is ±200 µV/mA.
3The operating temperature ranged is defined as the temperatures extremes at which the device will still function. Parts may deviate from their specified performance
outside their specified temperature range.
Specifications subject to change without notice.
ORDERING GUIDE
Initial
Error
Temperature
Coefficient
Temperature
Range
Package
Options2
Model1
AD587JQ
AD587JR
AD587JN
AD587KQ
AD587KR
AD587KN
AD587LQ
AD587LN
AD587SQ
AD587TQ
AD587UQ
10 mV
10 mV
10 mV
5 mV
5 mV
5 mV
5 mV
5 mV
10 mV
10 mV
5 mV
20 ppm/°C
20 ppm/°C
20 ppm/°C
10 ppm/°C
10 ppm/°C
10 ppm/°C
5 ppm/°C
5 ppm/°C
20 ppm/°C
10 ppm/°C
5 ppm/°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
–55°C to +125°C
–55°C to +125°C
–55°C to +125°C
Q-8
SO-8
N-8
Q-8
SO-8
N-8
Q-8
N-8
Q-8
Q-8
Q-8
AD587JCHIPS 10 mV
20 ppm/°C
0°C to +70°C
NOTES
1For details on grade and package offerings screened in accordance with MIL-STD-883, refer to the
Analog Devices Military Products Databook or current AD587/883B data sheet.
2N = Plastic DIP; Q = Cerdip; SO = SOIC.
–2–
REV. D
AD587
PIN CONFIGURATION
ABSOLUTE MAXIMUM RATINGS*
VIN to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 V
Power Dissipation (+25°C) . . . . . . . . . . . . . . . . . . . . . 500 mW
Storage Temperature . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature (Soldering, 10 sec) . . . . . . . . . . . . +300°C
Package Thermal Resistance
θJC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22°C/W
θJA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110°C/W
Output Protection: Output safe for indefinite short to ground and
momentary short to VIN.
NOISE
REDUCTION
1
2
3
4
8
7
6
5
TP*
AD587
TOP VIEW
(Not to Scale)
+V
IN
TP*
V
OUT
TP*
GND
TRIM
*TP DENOTES FACTORY TEST POINT.
NO CONNECTIONS SHOULD BE MADE
TO THESE PINS.
*Stresses above those listed under Absolute Maximum Ratings may cause perma-
nent 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
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
The following specifications are tested at the die level for AD587JCHIPS. These die are probed at +25°C only.
(T = +25°C, V = +15 V unless otherwise noted)
DIE SPECIFICATIONS
A
IN
DIE LAYOUT
AD587JCHIPS
Parameter
Min Typ Max
Units
Output Voltage
Gain Adjustment
9.990
–1
10.010 V
3
%
Line Regulation
13.5 V < + VIN < 36 V
100
±µV/V
Load Regulation
Sourcing 0 < IOUT < 10 mA
Sinking –10 < IOUT < 0 mA
100
100
µV/mA
µV/mA
Quiescent Current
2
4
mA
mA
mA
Short-Circuit Current-to-Ground
Short-Circuit Currrent-to-VOUT
70
70
Die Size: 0.081 × 0.060 Inches
NOTES
1Both VOUT pads should be connected to the output.
2Sense and force grounds must be tied together.
Die Thickness: The standard thickness of Analog Devices Bipolar dice is 24 mils ± 2 mils.
Die Dimensions: The dimensions given have a tolerance of ± 2 mils.
Backing: The standard backside surface is silicon (not plated). Analog Devices does not recommend
gold-backed dice for most applications.
Edges: A diamond saw is used to separate wafers into dice thus providing perpendicular edges half-
way through the die.
In contrast to scribed dice, this technique provides a more uniform die shape and size . The perpen-
dicular edges facilitate handling (such as tweezer pick-up) while the uniform shape and size simplifies
substrate design and die attach.
Top Surface: The standard top surface of the die is covered by a layer of glassivation . All areas are
covered except bonding pads and scribe lines.
Surface Metalization: The metalization to Analog Devices bipolar dice is aluminum. Minimum
thickness is 10,000Å.
Bonding Pads: All bonding pads have a minimum size of 4 mils by 4 mils. The passivation windows
have 3.5 mils by 3.5 mils minimum.
REV. D
–3–
AD587
THEORY OF OPERATION
NOISE PERFORMANCE AND REDUCTION
The AD587 consists of a proprietary buried Zener diode refer-
ence, an amplifier to buffer the output and several high stability
thin-film resistors as shown in the block diagram in Figure 1.
This design results in a high precision monolithic 10 V output
reference with initial offset of 5 mV or less. The temperature
compensation circuitry provides the device with a temperature
coefficient of under 5 ppm/°C.
The noise generated by the AD587 is typically less than 4 µV
p-p over the 0.1 Hz to 10 Hz band. Noise in a 1 MHz band-
width is approximately 200 µV p-p. The dominant source of
this noise is the buried Zener which contributes approximately
100 nV/√Hz. In comparison, the op amp’s contribution is negli-
gible. Figure 3 shows the 0.1 Hz to 10 Hz noise of a typical
AD587. The noise measurement is made with a bandpass filter
made of a 1-pole high-pass filter with a corner frequency at
0.1 Hz and a 2-pole low-pass filter with a corner frequency at
12.6 Hz to create a filter with a 9.922 Hz bandwidth.
NOISE
+V
IN
REDUCTION
2
8
R
S
A1
V
OUT
6
5
R
F
R
T
TRIM
R
I
AD587
4
GND
NOTE:
PINS 1,3, AND 7 ARE INTERNAL TEST POINTS.
NO CONNECTIONS TO THESE POINTS.
Figure 1. AD587 Functional Block Diagram
Figure 3. 0.1 Hz to 10 Hz Noise
A capacitor can be added at the NOISE REDUCTION pin (Pin
8) to form a low-pass filter with RS to reduce the noise contribu-
tion of the Zener to the circuit.
If further noise reduction is desired, an external capacitor may
be added between the NOISE REDUCTION pin and ground as
shown in Figure 2. This capacitor, combined with the 4 kΩ RS
and the Zener resistances, form a low-pass filter on the output
of the Zener cell. A 1 µF capacitor will have a 3 dB point at
40 Hz, and it will reduce the high frequency (to 1 MHz) noise
to about 160 µV p-p. Figure 4 shows the 1 MHz noise of a typi-
cal AD587 both with and without a 1 µF capacitor.
APPLYING THE AD587
The AD587 is simple to use in virtually all precision reference
applications. When power is applied to Pin 2, and Pin 4 is
grounded, Pin 6 provides a 10 V output. No external compo-
nents are required; the degree of desired absolute accuracy is
achieved simply by selecting the required device grade. The
AD587 requires less than 4 mA quiescent current from an oper-
ating supply of +15 V.
Fine trimming may be desired to set the output level to exactly
10.000 V (calibrated to a main system reference). System cali-
bration may also require a reference voltage that is slightly differ-
ent from 10.000 V, for example, 10.24 V for binary applications.
In either case, the optional trim circuit shown in Figure 2 can
offset the output by as much as 300 mV, if desired, with mini-
mal effect on other device characteristics.
+V
IN
2
V
IN
Figure 4. Effect of 1 µF Noise Reduction Capacitor on
Broadband Noise
OPTIONAL
NOISE
REDUCTION
CAPACITOR
NOISE
REDUCTION
V
6
5
8
OUTPUT
O
AD587
TURN-ON TIME
C
N
10kΩ
TRIM
1µF
Upon application of power (cold start), the time required for the
output voltage to reach its final value within a specified error
band is defined as the turn-on settling time. Two components
normally associated with this are: the time for the active circuits
to settle, and the time for the thermal gradients on the chip to
stabilize. Figure 5 shows the turn-on characteristics of the
AD587. It shows the settling to be about 60 µs to 0.01%. Note
the absence of any thermal tails when the horizontal scale is ex-
panded to 1 ms/cm in Figure 5b.
GND
4
Figure 2. Optional Fine Trim Configuration
–4–
REV. D
AD587
DYNAMIC PERFORMANCE
Output turn-on time is modified when an external noise reduc-
tion capacitor is used. When present, this capacitor acts as an
additional load to the internal Zener diode’s current source, re-
sulting in a somewhat longer turn-on time. In the case of a 1 µF
capacitor, the initial turn-on time is approximately 400 ms to
0.01% (see Figure 5c).
The output buffer amplifier is designed to provide the AD587
with static and dynamic load regulation superior to less com-
plete references.
Many A/D and D/A converters present transient current loads
to the reference, and poor reference response can degrade the
converter’s performance.
Figure 6 displays the characteristics of the AD587 output ampli-
fier driving a 0 mA to 10 mA load.
V
OUT
7.0V
1kΩ
10V
0V
V
L
AD587
Figure 6a. Transient Load Test Circuit
Figure 6b. Large-Scale Transient Response
Figure 6c. Fine Scale Settling for Transient Load
a. Electrical Turn-On
b. Extended Time Scale
c. Turn-On with 1 µF CN
Figure 5. Turn-On Characteristics
REV. D
–5–
AD587
In some applications, a varying load may be both resistive and
capacitive in nature, or the load may be connected to the
AD587 by a long capacitive cable.
Some confusion exists in the area of defining and specifying ref-
erence voltage error over temperature. Historically, references
have been characterized using a maximum deviation per degree
Centrigrade; i.e., ppm/°C. However, because of nonlinearities in
temperature characteristics which originated in standard Zener
references (such as “S” type characteristics), most manufactur-
ers have begun to use a maximum limit error band approach to
specify devices. This technique involves the measurement of the
output at three or more different temperatures to specify an out-
put voltage error band.
Figure 7 displays the output amplifier characteristics driving a
1000 pF, 0 mA to 10 mA load.
V
OUT
C
L
7.0V
1000pF
1kΩ
Figure 9 shows the typical output voltage drift for the AD587L
and illustrates the test methodology. The box in Figure 9 is
bounded on the sides by thc operating temperature extremes,
and on the top and the bottom by the maximum and minimum
output voltages measured over the operating temperature range.
The slope of the diagonal drawn from the lower left to the upper
right corner of the box determines the performance grade of the
device.
10V
0V
V
L
AD587
Figure 7a. Capacitive Load Transient /Response Test Circuit
Figure 9. Typical AD587L Temperature Drift
Figure 7b. Output Response with Capacitive Load
Each AD587J, K, L grade unit is tested at 0°C, +25°C and
+70°C. Each AD587S, T, and U grade unit is tested at –55°C,
+25°C and +125°C. This approach ensures that the variations
of output voltage that occur as the temperature changes within
the specified range will be contained within a box whose diago-
nal has a slope equal to the maximum specified drift. The posi-
tion of the box on the vertical scale will change from device to
device as initial error and the shape of the curve vary. The maxi-
mum height of the box for the appropriate temperature range
and device grade is shown in Figure 10. Duplication of these
results requires a combination of high accuracy and stable
temperature control in a test system. Evaluation of the AD587
will produce a curve similar to that in Figure 9, but output
readings may vary depending on the test methods and equip-
ment utilized.
LOAD REGULATION
The AD587 has excellent load regulation characteristics. Figure
8 shows that varying the load several mA changes the output by
only a few µV.
Figure 8. Typical Load Regulation Characteristics
TEMPERATURE PERFORMANCE
The AD587 is designed for precision reference applications
where temperature performance is critical. Extensive tempera-
ture testing ensures that the device’s high level of performance is
maintained over the operating temperature range.
Figure 10. Maximum Output Change in mV
–6–
REV. D
AD587
The AD587 can also be used as a precision reference for mul-
tiple DACs. Figure 13 shows the AD587, the AD7628 dual
DAC and the AD712 dual op amp hooked up for single supply
operation to produce 0 V to –10 V outputs. Because both DACs
are on the same die and share a common reference and output
op amps; the DAC outputs will exhibit similar gain TCs.
NEGATIVE REFERENCE VOLTAGE FROM AN AD587
The AD587 can be used to provide a precision –10.000 V output
as shown in Figure 11. The VIN pin is tied to at least a +3.5 V
supply, the output pin is grounded, and the AD587 ground pin
is connected through a resistor, RS, to a –15 V supply. The
–10 V output is now taken from the ground pin (Pin 4) instead
of VOUT. It is essential to arrange the output load and the sup-
ply resistor RS so that the net current through the AD587 is be-
tween 2.5 mA and 10.0 mA. The temperature characteristics
and long-term stability of the device will be essentially the same as
that of a unit used in the standard +10 V output configuration.
+3.5V → +26V
2
V
IN
V
OUT
6
AD587
GND
4
← I
L
–10V
1nF
R
S
Figure 13. AD587 as a 10 V Reference for a CMOS Dual
DAC
5V
R
S
2.5mA <
–I <10mA
L
–15V
PRECISION CURRENT SOURCE
Figure 11. AD587 as a Negative 10 V Reference
The design of the AD587 allows it to be easily configured as a
current source. By choosing the control resistor RC in Figure 14,
you can vary the load current from the quiescent current (2 mA
typically) to approximately 10 mA.
USING THE AD587 WITH CONVERTERS
The AD587 is an ideal reference for a wide variety of 8-, 12-,
14- and 16-bit A/D and D/A converters. Several representative
examples follow.
+V
IN
2
10 V REFERENCE WITH MULTIPLYING CMOS D/A OR
A/D CONVERTERS
V
IN
10V
V
OUT
6
I
=
+ I
BIAS
L
The AD587 is ideal for applications with 10- and 12-bit multi-
plying CMOS D/A converters. In the standard hookup, as
shown in Figure 12, the AD587 is paired with the AD7545
12-bit multiplying DAC and the AD711 high-speed BiFET Op
Amp. The amplifier DAC configuration produces a unipolar 0 V
to –10 V output range. Bipolar output applications and other
operating details can be found on the individual product data
sheets.
R
C
R
AD587
C
500Ω
MIN
GND
4
Figure 14. Precision Current Source
Figure 12. Low Power 12-Bit CMOS DAC Application
REV. D
–7–
AD587
PRECISION HIGH CURRENT SUPPLY
capacitor is required only if the load has a significant capacitive
component. If the load is purely resistive, improved high fre-
quency supply rejection results can be obtained by removing the
capacitor.
For higher currents, the AD587 can easily be connected to a
power PNP or power Darlington PNP device. The circuit in
Figure 15 can deliver up to 4 amps to the load. The 0.1 µF
Figure 15b. Precision High-Current Voltage Source
Figure 15a. Precision High-Current Current Source
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
Small Outline (R-8) Package
Cerdip (Q-8) Package
Mini-DIP (N-8) Package
–8–
REV. D
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