Datasheet AD581 Datasheet (Analog Devices)

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FUNCTIONAL BLOCK DIAGRAM
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.
a
High Precision
AD581*
FEATURES Laser Trimmed to High Accuracy:
10.000 Volts 5 mV (L and U)
Trimmed Temperature Coefficient:
5 ppm/C max, 0C to +70C (L) 10 ppm/C max, –55C to +125C (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
PRODUCT DESCRIPTION
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 co­efficient of the AD581L represent the best performance combi­nation available in a monolithic voltage reference.
The bandgap 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 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 equiva­lent 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 refer­ence. The device is also ideal for all types of A/D converters up to 14-bit accuracy, either successive approximation or integrat­ing 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.
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 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 sepa­ration 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 unregu­lated 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 un­regulated input voltage down to 13 volts. With an exter­nal resistor, the device will operate with a supply as low as 11.4 volts.
5. The AD581 is available in versions compliant with MIL­STD-883. Refer to the Analog Devices Military Prod­ucts Databook or current AD581/883B data sheet for detailed specifications.
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
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AD581–SPECIFICATIONS
Model AD581J AD581K AD581L
Min Typ Max Min Typ Max Min Typ Max Units
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, T
MIN
to T
MAX
(Temperature Coefficient) 30 15 5 ppm/°C
LINE REGULATION
15 V ≤ V
IN
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 I
OUT
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 hrs.
SHORT-CIRCUIT CURRENT 30 30 30 mA
OUTPUT CURRENT
Source @ +25°C 101010 mA
Source T
MIN
to T
MAX
555 mA
Sink T
MIN
to T
MAX
555 µA
Sink –55°C to +85°C––– mA
TEMPERATURE RANGE
Specified 0 +70 0 +70 0 +70 °C Operating –65 +150 –65 +150 –65 +150 °C
PACKAGE OPTION
2
TO-5 (H-03B) AD581JH AD581KH AD581LH
Model AD581S AD581T AD581U
Min Typ Max Min Typ Max Min Typ Max Units
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, T
MIN
to T
MAX
(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 I
OUT
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 hrs.
SHORT-CIRCUIT CURRENT 30 30 30 mA
OUTPUT CURRENT
Source @ +25°C 101010 mA
Source T
MIN
to T
MAX
555 mA
Sink T
MIN
to T
MAX
200 200 200 µA
Sink –55°C to +85°C555 mA
TEMPERATURE RANGE
Specified –55 +125 –55 +125 –55 +125 °C Operating –65 +150 –65 +150 –65 +150 °C
PACKAGE OPTION
2
TO-5 (H-03B) AD581SH AD581TH AD581UH
NOTES
1
See Figure 7.
2
H = Hermetic Metal Can.
Specifications subject to change without notice.
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.
(@ VIN = +15 V and +25ⴗC)
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AD581
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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 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 quiescent current from an operating supply range of 12 to 30 volts.
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 resistor), if needed, with minimal effect on other device characteristics.
Figure 2. Optional Fine Trim Configuration
Figure 3. 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 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 manu­facturers 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 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 guaran­tees 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,
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AD581
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Figure 7. Spectral Noise Density and Total rms Noise vs. Frequency
Figure 8. Quiescent Current vs. Temperature
PRECISION HIGH CURRENT 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 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
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 posi­tive supply or ground. The output voltage vs. output current characteristics of the device are shown in Figure 5. Source cur­rent is displayed as negative current in the figure; sink current is positive. Note that the short circuit current (i.e., zero volts out­put) is about 28 mA; when shorted to +15 volts, the sink cur­rent goes to about 20 mA.
Figure 5. AD581 Output Voltage vs. Sink and Source Current
DYNAMIC PERFORMANCE
Many low power instrument manufacturers are becoming in­creasingly concerned with the turn-on characteristics of the components being 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 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.
Figure 6. Output Settling Characteristic
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AD581
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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 capabil­ity such as operation from 12 V ±5% as shown in Figure 10. The 560 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.
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 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 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 11. A Two-Component Precision Current Limiter
NEGATIVE 10-VOLT REFERENCE
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 con­nection increases from 0.2 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 be­tween 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.
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 per­formance 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 pri­mary supply can be used, as low as 10.5 volts. This type of op­eration 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 opera­tion beyond +85°C).
Figure 12. Two Terminal Negative 10-Volt Reference
10 VOLT REFERENCE WITH MULTIPLYING CMOS D/A OR A/D CONVERTERS
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 applica­tions and other operating details can be found in the data sheets for the CMOS products.
Figure 13. Low Power 10-Bit CMOS DAC Application
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AD581
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THE PRECISION 12-BIT D/A CONVERTER REFERENCE
AD562, like most D/A converters, is designed to operate with a +10 volt reference element. In the AD562, this 10 volt 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 AD562 is primarily governed by the temperature tracking of the
19.95 k resistor and the 5k/10k span resistors; gain TC is guaranteed to 3 ppm/°C. Thus, using the AD581L (at 5 ppm/°C) as the 10 volt reference guarantees a maximum full-scale tem­perature coefficient of 8 ppm/°C over commercial range. The 10 volt reference also supplies the normal 1 mA bipolar offset cur­rent through the 9.95k bipolar offset resistor. The bipolar offset TC thus depends only on TC matching of the bipolar offset resistor to the input reference resistor and is guaranteed to 3 ppm/°C.
Figure 14. AD581 as Negative 10-Volt Reference for CMOS ADC
Figure 15. Precision 12-Bit D/A Converter
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
C418d–0–3/00 (rev. B)
PRINTED IN U.S.A.
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