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ADR395 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer ADR395
Beschreibung Precision Low Drift 2.048 V/2.5 V/4.096 V/ 5.0 V SOT-23 Reference with Shutdown
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 17 Seiten
ADR395 Datasheet, Funktion
a Precision Low Drift 2.048 V/2.5 V/4.096 V/
5.0 V SOT-23 Reference with Shutdown
ADR390/ADR391/ADR392/ADR395
FEATURES
Initial Accuracy: ؎6 mV Max
Low TCVO: 25 ppm/؇C Max
Load Regulation: 60 ppm/mA
Line Regulation: 25 ppm/V
Low Supply Headroom: 0.3 V
Wide Operating Range: (VOUT + 0.3 V) to 15 V
Low Power: 120 A Max
Shutdown to Less Than 3 A Max
Output Current: 5 mA
Wide Temperature Range:
–40؇C to +85؇C for ADR390, ADR391
–40؇C to +125؇C for ADR392, ADR395
Tiny 5-Lead SOT-23 Package
APPLICATIONS
Battery-Powered Instrumentation
Portable Medical Instruments
Data Acquisition Systems
Industrial Process Control Systems
Fault Protection Critical Systems
Automotive
PIN CONFIGURATION
5-Lead SOT-23
(RT Suffix)
SHDN
VIN
VOUT (SENSE)
1 ADR390/ 5
ADR391/
2 ADR392/
ADR395
3 (Not to Scale) 4
GND
VOUT (FORCE)
Part Number
ADR390
ADR391
ADR392
ADR395
Table I. ADR39x Products
Nominal Output Voltage (V)
2.048
2.500
4.096
5.000
GENERAL DESCRIPTION
The ADR390, ADR391, ADR392, and ADR395 are precision
2.048 V, 2.5 V, 4.096 V, and 5 V band gap voltage references
featuring high accuracy and stability and low power consump-
tion in a tiny footprint. Patented temperature drift curvature
correction techniques minimize nonlinearity of the voltage change
with temperature. The wide operating range and low power
consumption with additional shutdown capability make them
ideal for battery-powered applications. The VOUT Sense Pin
enables greater accuracy by supporting full Kelvin operation in
PCBs employing thin or long traces.
The ADR390, ADR391, ADR392, and ADR395 are micropower,
low dropout voltage (LDV) devices that provide a stable output
voltage from supplies as low as 300 mV above the output voltage.
ADR390 and ADR391 are specified over the industrial range
(–40C to +85C), while ADR392 and ADR395 are specified
over the extended industrial range (–40C to +125C). Each is
available in the tiny 5-lead SOT-23 package.
The combination of VOUT sense and shutdown functions also
enables a number of unique applications combining precision
reference/regulation with fault decision and overcurrent protec-
tion. Details are provided in the Applications section.
REV. C
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. 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
www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 2002






ADR395 Datasheet, Funktion
ADR390/ADR391/ADR392/ADR395–Typical Performance Characteristics
2.054
2.052
2.050
2.048
2.046
2.044
SAMPLE 1
SAMPLE 2
SAMPLE 3
5.006
5.004
SAMPLE 3
5.002
SAMPLE 2
5.000
4.998
SAMPLE 1
4.996
2.042
؊40
؊15 10
35
TEMPERATURE – ؇C
60
85
TPC 1. ADR390 Output Voltage vs. Temperature
4.994
–40
–5 30 65 100
TEMPERATURE – ؇C
125
TPC 4. ADR395 Output Voltage vs. Temperature
2.506
2.504
2.502
2.500
SAMPLE 1
SAMPLE 2
2.498
2.496
SAMPLE 3
2.494
؊40
؊15 10
35
TEMPERATURE – ؇C
60
85
TPC 2. ADR391 Output Voltage vs. Temperature
140
120
+85؇C
100
+25؇C
؊40؇C
80
60
40
2.5
5.0 7.5 10.0 12.5
INPUT VOLTAGE – V
15.0
TPC 5. ADR390 Supply Current vs. Input Voltage
4.100
4.098
SAMPLE 3
4.096
4.094
SAMPLE 1
4.092
SAMPLE 2
4.090
4.088
–40
0 40 80
TEMPERATURE – ؇C
125
TPC 3. ADR392 Output Voltage vs. Temperature
140
120
+85؇C
100
+25؇C
؊40؇C
80
60
40
2.5
5.0 7.5 10.0 12.5
INPUT VOLTAGE – V
15.0
TPC 6. ADR391 Supply Current vs. Input Voltage
–6– REV. C

6 Page









ADR395 pdf, datenblatt
ADR390/ADR391/ADR392/ADR395
100
90
80
70
60
CL = 0F
50
40
30
20 CL = 0.1F
CL = 1F
10
0
10 100 1k 10k 100k 1M
FREQUENCY – Hz
TPC 37. Output Impedance vs. Frequency
THEORY OF OPERATION
Band gap references are the high performance solution for low
supply voltage and low power voltage reference applications, and
the ADR390/ADR391/ADR392/ADR395 is no exception. The
uniqueness of this product lies in its architecture. By observing
Figure 2, the ideal zero TC band gap voltage is referenced to the
output, not to ground. Therefore, if noise exists on the ground
line, it will be greatly attenuated on VOUT. The band gap cell
consists of the pnp pair Q51 and Q52, running at unequal cur-
rent densities. The difference in VBE results in a voltage with a
positive
TC,
which
is
amplified
by
the
ratio
of
2×
R58
. This
R54
PTAT voltage, combined with VBEs of Q51 and Q52, produces
the stable band gap voltage.
Reduction in the band gap curvature is performed by the ratio of
the resistors R44 and R59, one of which is linearly temperature
dependent. Precision laser trimming and other patented circuit
techniques are used to further enhance the drift performance.
VIN
Q1
R59 R44
VOUT (FORCE)
VOUT (SENSE)
R58
R49
R54
SHDN
R53
Q51
Q52
R48
R60 R61
GND
Figure 2. Simplified Schematic
Device Power Dissipation Considerations
The ADR390/ADR391/ADR392/ADR395 is capable of deliver-
ing load currents to 5 mA with an input voltage that ranges from
2.8 V (ADR391 only) to 15 V. When this device is used in applica-
tions with large input voltages, care should be taken to avoid
exceeding the specified maximum power dissipation or junction
temperature that could result in premature device failure. The
following formula should be used to calculate a device’s maxi-
mum junction temperature or dissipation:
PD
=
TJ TA
θ JA
In this equation, TJ and TA are, respectively, the junction and
ambient temperatures, PD is the device power dissipation, and
JA is the device package thermal resistance.
Shutdown Mode Operation
The ADR390/ADR391/ADR392/ADR395 includes a shutdown
feature that is TTL/CMOS level compatible. A logic LOW or a
zero volt condition on the SHDN Pin is required to turn the device
off. During shutdown, the output of the reference becomes a
high impedance state where its potential would then be deter-
mined by external circuitry. If the shutdown feature is not used,
the SHDN Pin should be connected to VIN (Pin 2).
APPLICATIONS
BASIC VOLTAGE REFERENCE CONNECTION
The circuit in Figure 3 illustrates the basic configuration for the
ADR39x family. Decoupling capacitors are not required for circuit
stability. The ADR39x family is capable of driving capacitive
loads from 0 µF to 10 µF. However, a 0.1 µF ceramic output
capacitor is recommended to absorb and deliver the charge as is
required by a dynamic load.
SHUTDOWN
INPUT
*
CB 0.1F
SHDN
GND
ADR39x
VIN
VOUT(S) VOUT(F)
* NOT REQUIRED
OUTPUT
*
CB 0.1F
Figure 3. Basic Configuration for the ADR39x Family
Stacking Reference ICs for Arbitrary Outputs
Some applications may require two reference voltage sources,
which are a combined sum of standard outputs. Figure 4
circuit shows how this “stacked output” reference can be
implemented:
–12–
REV. C

12 Page





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