AD581 View Datasheet(PDF) - Analog Devices
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AD581 Datasheet PDF : 12 Pages
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AD581
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.
13V TO 30V
+VS
AD581 VOUT
10V
GND
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 Ω resistor), if needed, with minimal
effect on other device characteristics.
+15V
R
22Ω
12Ω
3.9Ω
TRIM
RANGE
±30mV
±10mV
±5mV
MAX
Δ TCR
3.5ppm/°C
2.0ppm/°C
0.6ppm/°C
6.8kΩ
+VS
AD581 VOUT
GND
+10V
10kΩ
R
–15V
4.3kΩ
Figure 3. Optional Fine Trim Configuration
R40
Q10
C52
C51
Q6
R41
Q20
Q11
Q12
Q14
Q8
Q15
V+
Q7
R42
10V
R34
Q16
Q13
C50
R37
Q5
R33 R32 R35
Q3 Q4
Q2 Q1
R39
R30
R36
R31
V–
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
10.000
9.995
–55 –50 –40 –30 –20 –10 0 10 20 30 40 50 60 70 80 90 100 110 120 125
TEMPERATURE (°C)
Figure 5. Typical Temperature Characteristic
Rev. C | Page 6 of 12
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