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ADR370ART-REEL7
2.048 V Tiny Package Precision Reference
REV.A
Precision Low Power 2.048 V
SOT-23 Voltage Reference*.Patent No. 5,969,657; other patents pending.
PIN CONFIGURATION
3-Lead SOT-23
Table I.ADR370 Products
FEATURES
Initial Accuracy: �4 mV Max
Initial Accuracy Error: �0.2%
Low TCVO: �50 ppm/�C Max from –40�C to +125�C,
30 ppm/�C Max from +25�C to +70�C
Load Regulation: 200 �V/mA, 100 ppm/mA
Line Regulation: 25 �V/V, 20 ppm/V
Wide Operating Range: VIN = 2.3 V to 15 V
Low Power: 72 �A Max
High Output Sink/Source Current: �5 mA Min
Wide Temperature Range: –40�C to +125�C
Tiny 3-Lead SOT-23 Package with Standard Pinout
APPLICATIONS
Battery-Powered Instrumentation
Portable Medical Instruments
Data Acquisition Systems
Industrial Process Control Systems
Automotive
GENERAL DESCRIPTIONThe ADR370 is a low cost, 3-terminal (series) band-gap voltage
reference featuring high accuracy, high stability, and low power
consumption packaged in a tiny 3-lead SOT-23 package. Precise
matching and thermal tracking of on-chip components, as well as
patented temperature drift curvature correction design techniques,
have been employed to ensure that the ADR370 provides an
accurate 2.048V output.
This micropowered, low dropout voltage device will source or
sink up to 5 mA of load current while providing a stable 2.048V
output. The compact footprint, high accuracy, and an operating
range of 2.3 V to 12 V make the ADR370 ideal for use in 3V
and 5 V systems where there may be wide variations in supply
voltage and a need to minimize power dissipation.
The ADR370 is offered in A and B grades; all devices are specified
over the extended industrial range of –40°C to +125°C.
ADR370–SPECIFICATIONS
ELECTRICAL CHARACTERISTICSOutput Voltage Temperature Drift
Line Regulation
Quiescent Current
*Guaranteed by characterization.
Specifications subject to change without notice.
(TA = TMIN to TMAX, VIN = 5 V, unless otherwise noted.)
ABSOLUTE MAXIMUM RATINGS*Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18 V
Storage Temperature Range
RT Package . . . . . . . . . . . . . . . . . . . . . . . .–65°C to +125°C
Operating Temperature Range . . . . . . . . . . .–40°C to +125°C
Lead Temperature Range
Soldering, 60 sec . . . . . . . . . . . . . . . . . . . . . . . . . . . .215°C
Infrared, 15 sec . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220°C
*Absolute maximum ratings apply at 25°C, unless otherwise noted.
CAUTIONESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000V readily
accumulate on the human body and test equipment and can discharge without detection. Although the
ADR370 features proprietary ESD protection circuitry, permanent damage may occur on devices
subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended
to avoid performance degradation or loss of functionality.
ORDERING GUIDEADR370BRT-R2
ADR370BRT-REEL7
ADR370ART-R2
ADR370–Typical Performance CharacteristicsTPC 1.Load Regulation vs. Load Current
TPC 2. Output Voltage vs. Temperature
TPC 3.Supply Current vs. Temperature
TPC 4.Line Regulation vs. Temperature
TPC 5.Voltage Noise 0.1 Hz to 10 Hz
TPC 6.Voltage Noise 10 Hz to 100 kHz
TPC 7.Turn-On Response
TPC 8. Turn-Off Response
TPC 9.Line Transient Response
TPC 10.Load Transient Response
ADR370
PARAMETER DEFINITIONS
Temperature CoefficientTemperature coefficient is the change of output voltage with
respect to operating temperature changes, normalized by the
output voltage at 25°C. This parameter is expressed in ppm/°C
and can be determined with the following equation(1)
where:
VO (25°C) = VO at 25°C.
VO (T1) = VO at Temperature 1.
VO (T2) = VO at Temperature 2.
Line RegulationLine regulation is the change in output voltage due to a specified
change in input voltage. This parameter accounts for the effects
of self-heating. Line regulation is expressed in either percent per
volt, parts-per-million per volt, or microvolts per volt change in
input voltage.
Load RegulationLoad regulation is the change in output voltage due to a specified
change in load current. This parameter accounts for the effects
of self-heating. Load regulation is expressed in either microvolts
per milliampere, parts-per-million per milliampere, or ohms of
dc output resistance.
Long Term StabilityLong term stability is the typical shift of output voltage at 25°C
on a sample of parts subjected to a test of 1,000 hours at 25°C.(2)
where:
VO (T1) = VO at 25°C at time 0.
VO (T2) = VO at 25°C after 1,000 hours operation at 25°C.
Thermal HysteresisThermal hysteresis is defined as the change of output voltage after
the device is cycled through temperature from +25°C to –40°C
to +125°C and back to +25°C. This is a typical value from a sample
of parts put through such a cycle.(3)
where:
VO (25°C) = VO at 25°C.
VO_TC = VO at 25°C after temperature cycle at +25°C to –40°C
to +125°C and back to +25°C.
THEORY OF OPERATIONThe ADR370 uses the band-gap concept to produce a stable,
low temperature coefficient voltage reference suitable for high
accuracy data acquisition components and systems. This device
makes use of underlying temperature characteristics of a silicon
transistor’s base-emitter voltage (VBE) in the forward biased
operating region. Under this condition, all such transistors have
a –2 mV/°C temperature coefficient (TC) and a VBE that, when
extrapolated to absolute zero, 0 K, (with collector current pro-
portional to absolute temperature) approximates the silicon
band-gap voltage. By summing a voltage that has an equal and
opposite temperature coefficient of 2 mV/°C with a VBE of a
forward biased transistor, an almost zero TC reference can be
developed. The simplified circuit diagram in Figure 1 shows how
a compensating voltage, V1, is achieved by driving two transistors
at different current densities and amplifying the resultant VBE
difference (∆VBE, which has a positive TC). The sum (VBG) of VBE
and V1 is then buffered and amplified to produce a stable reference
voltage of 2.048 V at the output.
Figure 1.Simplified Schematic
Applying the ADR370In order to achieve the specified performance, two external
components should be used in conjunction with the ADR370,4.7µF capacitor and a 1 µF capacitor should be applied to the
input and output, respectively. Figure 2 shows the ADR370 with
both the input and output capacitors attached.
For further transient response optimization, an additional 0.1 µF
capacitor in parallel with the 4.7 µF input capacitor can be used.
A 1 µF output capacitor will provide stable performance for all
loading conditions. The ADR370 can, however, operate under
low (–100 µA < IOUT < +100 µA) current conditions with just a
0.2µF output capacitor and a 1 µF input capacitor.
Figure 2.Typical Connection Diagram
