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PDF ADR540 Data sheet ( Hoja de datos )
| Número de pieza | ADR540 | |
| Descripción | High Precision Shunt Mode Voltage References | |
| Fabricantes | Analog Devices | |
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High Precision Shunt Mode
Voltage References
ADR520/ADR525/ADR530/ADR540/ADR550
FEATURES
Ultracompact SC70 and SOT-23-3 packages
Temperature coefficient: 40 ppm/°C (maximum)
2× the temperature coefficient improvement over the
LM4040
Pin compatible with the LM4040/LM4050
Initial accuracy: ±0.2%
Low output voltage noise: 14 μV p-p @ 2.5 V output
No external capacitor required
Operating current range: 50 μA to 15 mA
Industrial temperature range: −40°C to +85°C
APPLICATIONS
Portable, battery-powered equipment
Automotive
Power supplies
Data acquisition systems
Instrumentation and process control
Energy measurement
Table 1. Selection Guide
Part
ADR520A
ADR520B
ADR525A
ADR525B
ADR530A
ADR530B
ADR540A
ADR540B
ADR550A
ADR550B
Voltage (V)
2.048
2.048
2.5
2.5
3.0
3.0
4.096
4.096
5.0
5.0
Initial
Accuracy (%)
±0.4
±0.2
±0.4
±0.2
±0.4
±0.2
±0.4
±0.2
±0.4
±0.2
Temperature
Coefficient
(ppm/°C)
70
40
70
40
70
40
70
40
70
40
PIN CONFIGURATION
V+ 1
V– 2
ADR520/
ADR525/
ADR530/
3 TRIM
ADR540/
ADR550
Figure 1. 3-Lead SC70 (KS) and 3-Lead SOT-23-3 (RT)
GENERAL DESCRIPTION
Designed for space-critical applications, the ADR520/ADR525/
ADR530/ADR540/ADR550 are high precision shunt voltage
references, housed in ultrasmall SC70 and SOT-23-3 packages.
These references feature low temperature drift of 40 ppm/°C,
an initial accuracy of better than ±0.2%, and ultralow output
noise of 14 μV p-p.
Available in output voltages of 2.048 V, 2.5 V, 3.0 V, 4.096 V,
and 5.0 V, the advanced design of the ADR520/ADR525/
ADR530/ADR540/ADR550 eliminates the need for compensa-
tion by an external capacitor, yet the references are stable with
any capacitive load. The minimum operating current increases
from a mere 50 μA to a maximum of 15 mA. This low operating
current and ease of use make these references ideally suited for
handheld, battery-powered applications.
A trim terminal is available on the ADR520/ADR525/ADR530/
ADR540/ADR550 to allow adjustment of the output voltage
over a ±0.5% range, without affecting the temperature coefficient
of the device. This feature provides users with the flexibility to
trim out any system errors.
Rev. E
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 that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarksandregisteredtrademarksarethepropertyoftheirrespectiveowners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700
www.analog.com
Fax: 781.461.3113 ©2003–2008 Analog Devices, Inc. All rights reserved.
1 page  
ADR520/ADR525/ADR530/ADR540/ADR550
ADR550 ELECTRICAL CHARACTERISTICS
IIN = 50 μA to 15 mA, TA = 25°C, unless otherwise noted.
Table 6.
Parameter
Output Voltage
Grade A
Grade B
Initial Accuracy
Grade A
Grade B
Temperature Coefficient1
Grade A
Grade B
Output Voltage Change vs. IIN
Dynamic Output Impedance
Minimum Operating Current
Voltage Noise
Turn-On Settling Time
Output Voltage Hysteresis
Symbol
VOUT
VOERR
TCVO
∆VR
(∆VR/∆IR)
IIN
eN p-p
tR
∆VOUT_HYS
Conditions
±0.4%
±0.2%
−40°C < TA < +85°C
IIN = 0.1 mA to 15 mA
−40°C < TA < +85°C
IIN = 1 mA to 15 mA
−40°C < TA < +85°C
IIN = 0.1 mA to 15 mA
−40°C < TA < +85°C
0.1 Hz to 10 Hz
IIN = 1 mA
1 Guaranteed by design; not production tested.
Min
4.980
4.990
−20
−10
50
Typ
5.000
5.000
25
15
38
2
40
Max
5.020
5.010
+20
+10
70
40
1
5
2
0.2
Unit
V
V
mV
mV
ppm/°C
ppm/°C
mV
mV
mV
Ω
μA
μV p-p
μs
ppm
Rev. E | Page 5 of 16
5 Page 
ADR520/ADR525/ADR530/ADR540/ADR550
THEORY OF OPERATION
The ADR520/ADR525/ADR530/ADR540/ADR550 use the
band gap concept to produce a stable, low temperature coefficient
voltage reference suitable for high accuracy data acquisition
components and systems. The devices use the physical nature of a
silicon transistor base-emitter voltage (VBE) in the forward-biased
operating region. All such transistors have approximately a
−2 mV/°C temperature coefficient (TC), making them unsuitable
for direct use as low temperature coefficient references. Extra-
polation of the temperature characteristics of any one of these
devices to absolute zero (with the collector current proportional
to the absolute temperature), however, reveals that its VBE
approaches approximately the silicon band gap voltage. Thus,
if a voltage develops with an opposing temperature coefficient
to sum the VBE, a zero temperature coefficient reference results.
The ADR520/ADR525/ADR530/ADR540/ADR550 circuit
shown in Figure 18 provides such a compensating voltage (V1)
by driving two transistors at different current densities and
amplifying the resultant VBE difference (ΔVBE, which has a
positive temperature coefficient). The sum of VBE and V1
provides a stable voltage reference over temperature.
+ V+
VS
R
IIN
IIN + IL
VOUT
IL
ADR550
Figure 19. Shunt Reference
Given these conditions, RBIAS is determined by the supply
voltage (VS), the load and operating currents (IL and IIN) of
the ADR520/ADR525/ADR530/ADR540/ADR550, and the
output voltage (VOUT) of the ADR520/ADR525/ADR530/
ADR540/ADR550.
R BIAS
= VS −VOUT
I L + I IN
(3)
Precision Negative Voltage Reference
The ADR520/ADR525/ADR530/ADR540/ADR550 are suit-
able for applications where a precise negative voltage is desired.
Figure 20 shows the ADR525 configured to provide a negative
output.
V1
–
+
ΔVBE
+–
VBE
–
Figure 18. Circuit Schematic
V–
APPLICATIONS
The ADR520/ADR525/ADR530/ADR540/ADR550 are a
series of precision shunt voltage references. They are designed
to operate without an external capacitor between the positive
and negative terminals. If a bypass capacitor is used to filter the
supply, the references remain stable.
All shunt voltage references require an external bias resistor (RBIAS)
between the supply voltage and the reference (see Figure 19).
RBIAS sets the current that flows through the load (IL) and the
reference (IIN). Because the load and the supply voltage can vary,
RBIAS needs to be chosen based on the following considerations:
• RBIAS must be small enough to supply the minimum IIN
current to the ADR520/ADR525/ADR530/ADR540/
ADR550, even when the supply voltage is at its minimum
value and the load current is at its maximum value.
• RBIAS must be large enough so that IIN does not exceed
15 mA when the supply voltage is at its maximum value
and the load current is at its minimum value.
ADR525
–2.5V
R
VS
Figure 20. Negative Precision Reference Configuration
Output Voltage Trim
The trim terminal of the ADR520/ADR525/ADR530/ADR540/
ADR550 can be used to adjust the output voltage over a range
of ±0.5%. This allows systems designers to trim system errors
by setting the reference to a voltage other than the preset output
voltage. An external mechanical or electrical potentiometer can
be used for this adjustment. Figure 21 illustrates how the output
voltage can be trimmed using the AD5273, an Analog Devices,
Inc., 10 kΩ potentiometer.
VS
R
ADR530
R1
470kΩ
VOUT
AD5273
POTENTIOMETER
10kΩ
Figure 21. Output Voltage Trim
Rev. E | Page 11 of 16
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet ADR540.PDF ] | |
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