a
FEATURES
Laser Trimmed to High Accuracy:
10.000 Volts 5 mV (L and U)
Trimmed Temperature Coefficient:
5 ppm/ C max, 0 C to +70 C (L)
10 ppm/ C max, –55 C to +125 C (U)
Excellent Long-Term Stability:
25 ppm/1000 hrs. (Noncumulative)
Negative 10 Volt Reference Capability
Low Quiescent Current: 1.0 mA max
10 mA Current Output Capability
3-Terminal TO-5 Package
MIL-STD-883 Compliant Versions Available
High Precision
10 V IC Reference
AD581*
FUNCTIONAL BLOCK DIAGRAM
PRODUCT DESCRIPTION
PRODUCT HIGHLIGHTS
The AD581 is a three-terminal, temperature compensated,
monolithic bandgap voltage reference which provides a precise
10.00 volt output from an unregulated input level from 12 to 30
volts. Laser Wafer Trimming (LWT) is used to trim both the
initial error at +25°C as well as the temperature coefficient,
which results in high precision performance previously available
only in expensive hybrids or oven-regulated modules. The 5 mV
initial error tolerance and 5 ppm/°C guaranteed temperature co-
efficient of the AD581L represent the best performance combi-
nation available in a monolithic voltage reference.
The bandgap circuit design used in the AD581 offers several ad-
vantages over classical Zener breakdown diode techniques. Most
important, no external components are required to achieve full
accuracy and stability of significance 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
µA.
The long-term stability of the bandgap design is equiva-
lent or superior to selected Zener reference diodes.
The AD581 is recommended for use as a reference for 8-, 10- or
12-bit D/A converters which require an external precision refer-
ence. The device is also ideal for all types of A/D converters up
to 14-bit accuracy, either successive approximation or integrat-
ing designs, and in general can offer better performance than
that provided by standard self-contained references.
The AD581J, K, and L are specified for operation from 0°C to
+70°C; the AD581S, T, and U are specified for the –55°C to
+125°C range. All grades are packaged in a hermetically sealed
three-terminal TO-5 metal can.
*Covered
by Patent Nos. 3,887,863; RE 30,586.
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 volts of
±7.25
mV
from 0°C to +70°C, while the AD581U guarantees
±
15 mV maximum total error without external trims
from –55°C to +125°C.
2. Since the laser trimming is done on the wafer prior to sepa-
ration into individual chips, the AD581 will be 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 two-terminal
“Zener” mode to provide a precision negative 10 volt
reference with just one external resistor to the unregu-
lated supply. The performance in this mode is nearly equal
to that of the standard three-terminal configuration.
4. Advanced circuit design using the bandgap concept
allows the AD581 to give full performance with an un-
regulated input voltage down to 13 volts. With an exter-
nal resistor, the device will operate with a supply as low
as 11.4 volts.
5. The AD581 is available in versions compliant with MIL-
STD-883. Refer to the Analog Devices Military Prod-
ucts Databook or current AD581/883B data sheet for
detailed specifications.
REV. B
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
World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2000
AD581–SPECIFICATIONS
Model
Min
OUTPUT VOLTAGE TOLERANCE
(Error from Nominal 10,000 V Output)
OUTPUT VOLTAGE CHANGE
Maximum Deviation from +25°C
Value, T
MIN
to T
MAX
(Temperature Coefficient)
LINE REGULATION
15 V
≤
V
IN
≤
30 V
13 V
≤
V
IN
≤
15 V
LOAD REGULATION
0
≤
I
OUT
≤
5 mA
QUIESCENT CURRENT
TURN-ON SETTLING TIME TO 0.1%
NOISE (0.1 Hz to 10 Hz)
LONG-TERM STABILITY
SHORT-CIRCUIT CURRENT
OUTPUT CURRENT
Source @ +25°C
Source T
MIN
to T
MAX
Sink T
MIN
to T
MAX
Sink –55°C to +85°C
TEMPERATURE RANGE
Specified
Operating
PACKAGE OPTION
2
TO-5 (H-03B)
Model
Min
OUTPUT VOLTAGE TOLERANCE
(Error from Nominal 10,000 V Output)
OUTPUT VOLTAGE CHANGE
Maximum Deviation from +25°C
Value, T
MIN
to T
MAX
(Temperature Coefficient)
LINE REGULATION
15 V
≤
V
IN
≤
30 V
13 V
≤
V
IN
≤
15 V
LOAD REGULATION
0
≤
I
OUT
≤
5 mA
QUIESCENT CURRENT
TURN-ON SETTLING TIME TO 0.1%
NOISE (0.1 Hz to 10 Hz)
LONG-TERM STABILITY
SHORT-CIRCUIT CURRENT
OUTPUT CURRENT
Source @ +25°C
Source T
MIN
to T
MAX
Sink T
MIN
to T
MAX
Sink –55°C to +85°C
TEMPERATURE RANGE
Specified
Operating
PACKAGE OPTION
2
TO-5 (H-03B)
NOTES
1
See Figure 7.
2
H = Hermetic Metal Can.
Specifications subject to change without notice.
1
1
(@ V
IN
= +15 V and +25 C)
Max
30
13.5
30
3.0
(0.002)
1.0
(0.005)
Min
AD581K
Typ
Max
10
6.75
15
3.0
(0.002)
1.0
(0.005)
200
0.75
200
40
25
30
10
5
5
–
+70
+150
0
–65
AD581KH
Max
30
30
30
3.0
(0.002)
1.0
(0.005)
Min
AD581T
Typ
Max
10
15
15
3.0
(0.002)
1.0
(0.005)
200
0.75
200
40
25
30
10
5
200
5
+125
+150
–55
–65
AD581TH
+125
+150
10
5
200
5
–55
–65
AD581UH
+125
+150
500
1.0
200
0.75
200
40
25
30
Min
+70
+150
10
5
5
–
0
–65
AD581LH
AD581U
Typ
Max
5
10
10
3.0
(0.002)
1.0
(0.005)
500
1.0
Units
mV
mV
ppm/°C
mV
%/V
mV
%/V
µV/mA
mA
µs
µV
(p-p)
ppm/1000 hrs.
mA
mA
mA
µA
mA
°C
°C
+70
+150
500
1.0
200
0.75
200
40
25
30
5
3.0
(0.002)
1.0
(0.005)
500
1.0
Min
AD581L
Typ
Max
5
2.25
Units
mV
mV
ppm/°C
mV
%/V
mV
%/V
µV/mA
mA
µs
µV
(p-p)
ppm/1000 hrs.
mA
mA
mA
µA
mA
°C
°C
AD581J
Typ
200
0.75
200
40
25
30
10
5
5
–
0
–65
AD581JH
AD581S
Typ
500
1.0
200
0.75
200
40
25
30
10
5
200
5
–55
–65
AD581SH
500
1.0
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 min and max specifications are
guaranteed, although only those shown in
boldface
are tested on all production units.
–2–
REV. B
AD581
ABSOLUTE MAXIMUM RATINGS
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
APPLYING THE AD581
The AD581 is easy to use in virtually all precision reference
applications. The three terminals are simply primary supply,
ground, and output, with the case grounded. No external com-
ponents are required even for high precision applications; the
degree of desired absolute accuracy is achieved simply by select-
ing the required device grade. The AD581 requires less than
1 mA quiescent current from an operating supply range of
12 to 30 volts.
Figure 3. Simplified Schematic
VOLTAGE VARIATION VS. TEMPERATURE
Figure 1. AD581 Pin Configuration (Bottom View)
An external fine trim may be desired to set the output level to
exactly 10.000 volts within less than a millivolt (calibrated to a
main system reference). System calibration may also require a
reference slightly different from 10.00 volts. In either case, the
optional trim circuit shown in Figure 2 can offset the output by
up to
±
30 millivolts (with the 22
Ω
resistor), if needed, with
minimal effect on other device characteristics.
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
Centigrade; i.e., 10 ppm/°C. However, because of nonlinearities
in temperature characteristics, which originated in standard
Zener references (such as “S” type characteristics) most manu-
facturers have begun to use a maximum limit error band approach
to specify devices. This technique involves measurement of the
output at 3, 5 or more different temperatures to guarantee that
the output voltage will fall within the given error band. The
temperature characteristic of the AD581 consistently follows the
S-curve shown in Figure 4. Three-point measurement of each
device guarantees the error band over the specified temperature
range.
Figure 2. Optional Fine Trim Configuration
Figure 4. Typical Temperature Characteristic
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 guaran-
tees the maximum total change over the entire range (i.e., 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
tolerance plus temperature variation (e.g., for the AD581T,
REV. B
–3–
AD581
the initial tolerance is
±
10 mV, the temperature error band is
±
15 mV, thus the unit is guaranteed to be 10.000 volts
±
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 posi-
tive supply or ground. The output voltage vs. output current
characteristics of the device are shown in Figure 5. Source cur-
rent is displayed as negative current in the figure; sink current is
positive. Note that the short circuit current (i.e., zero volts out-
put) is about 28 mA; when shorted to +15 volts, the sink cur-
rent goes to about 20 mA.
Figure 7. Spectral Noise Density and Total rms Noise
vs. Frequency
Figure 8. Quiescent Current vs. Temperature
Figure 5. AD581 Output Voltage vs. Sink and Source Current
DYNAMIC PERFORMANCE
PRECISION HIGH CURRENT SUPPLY
Many low power instrument manufacturers are becoming in-
creasingly concerned with the turn-on characteristics of the
components being used in their systems. Fast turn-on compo-
nents 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 6 displays the turn-on characteristic of
the AD581. This characteristic is generated from cold-start
operation and represents 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 millivolt is about 180
µs,
and there is
no long thermal tail appearing after the point.
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 9 delivers a precision
10 volt output with up to 4 amperes supplied to the load. The
0.1
µF
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.
Figure 9. High Current Precision Supply
Figure 6. Output Settling Characteristic
–4–
REV. B
AD581
CONNECTION FOR REDUCED PRIMARY SUPPLY
While line regulation is specified down to 13 volts, the typical
AD581 will work as specified down to 12 volts or below. The
current sink capability allows even lower supply voltage capabil-
ity such as operation from 12 V
±
5% as shown in Figure 10.
The 560
Ω
resistor reduces the current supplied by the AD581
to a manageable level at full 5 mA load. Note that the other
bandgap references, without current sink capability, may be
damaged by use in this circuit configuration.
The AD581 can also be used in a two-terminal mode to develop
a positive reference. V
IN
and V
OUT
are tied together and to the
positive supply through an appropriate supply resistor. The per-
formance characteristics will be similar to those of the negative
two-terminal connection. The only advantage of this connection
over the standard three-terminal connection is that a lower pri-
mary supply can be used, as low as 10.5 volts. This type of op-
eration will require considerable attention to load and primary
supply regulation to be sure the AD581 always remains within
its regulating range of 1 mA to 5 mA (2 mA to 5 mA for opera-
tion beyond +85°C).
Figure 10. 12-Volt Supply Connection
THE AD581 AS A CURRENT LIMITER
The AD581 represents an alternative to current limiter diodes
which 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 cur-
rent limit; it can be programmed from 0.75 mA to 5 mA with
the insertion of a single external resistor. Of course, the mini-
mum voltage required to drive the connection is 13 volts. The
AD580, which is a 2.5 volt reference, can be used in this type of
circuit with compliance voltage down to 4.5 volts.
Figure 12. Two Terminal Negative 10-Volt Reference
10 VOLT REFERENCE WITH MULTIPLYING CMOS D/A
OR A/D CONVERTERS
Figure 11. A Two-Component Precision Current Limiter
NEGATIVE 10-VOLT REFERENCE
The AD581 is ideal for application with the entire AD7533
series of 10- and 12-bit multiplying CMOS D/A converters,
especially for low power applications. It is equally suitable for
the AD7574 8-bit A/D converter. In the standard hook-up, as
shown in Figure 14, the +10 volt reference is inverted by the
amplifier/DAC configuration to produce a 0 volt to –10 volt
range. If an AD308 amplifier is used, total quiescent supply
current will typically be 2 mA. If a 0 volt to +10 volt full-scale
range is desired, the AD581 can be connected to the CMOS
DAC in its –10 volt “Zener” mode, as shown in Figure 12 (the
–10 V
REF
output is connected directly to the V
REF IN
of the
CMOS DAC). The AD581 will normally be used in the
–10 volt mode with the AD7574 to give a 0 volt to +10 volt
ADC range. This is shown in Figure 14. Bipolar output applica-
tions and other operating details can be found in the data sheets
for the CMOS products.
The AD581 can also be used in a two-terminal “Zener” mode
to provide a precision –10.00 volt reference. As shown in Figure
12, the V
IN
and V
OUT
terminals are connected together to the
high supply (in this case, ground). The ground pin is connected
through a resistor to the negative supply. The output is now
taken from the ground pin instead of V
OUT
. With 1 mA flowing
through the AD581 in this mode, a typical unit will show a 2 mV
increase in output level over that produced in the three-terminal
mode. Note also that the effective output impedance in this con-
nection increases from 0.2
Ω
typical to 2 ohms. It is essential to
arrange the output load and the supply resistor, R
S
, 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 be-
tween 2 mA and 5 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 three-terminal mode.
Figure 13. Low Power 10-Bit CMOS DAC Application
REV. B
–5–
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