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VRE120/121/122
Precision High Temperature
Reference Supplies
THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000
FEATURES
•• WIDE OPERATING RANGE: -55°C TO +180°C
•• EXTREMELY LOW DRIFT: 1 ppm /°C -55°C to +150°C
•• LOW WARM-UP DRIFT: 1 ppm Typ.
•• EXCELLENT STABILITY: 6 ppm / 1000 Hrs. Typ.
•• EXCELLENT LINE REGULATION: 3 ppm / V Typ.
•• HERMETIC 14-PIN CERAMIC DIP
•• PIN & FUNCTION COMPATIBLE WITH
AD2700, AD2710, MAX 670/671 REFERENCES
APPLICATIONS
•• PRECISION A/D and D/A CONVERTERS
•• TRANSDUCER EXCITATION
•• ACCURATE COMPARATOR THRESHOLD
REFERENCE
•• HIGH RESOLUTION SERVO SYSTEMS
•• DIGITAL VOLTMETERS
•• HIGH PRECISION TEST and
MEASUREMENT INSTRUMENTS
•• GEOLOGICAL EQUIPMENT
DESCRIPTION
VRE120 series references are designed to operate
over an extremely wide temperature range (-55°C
to +180°C) and still provide excellent accuracy.
The VRE120 provides a +10V output, the VRE121
provides a -10V and the VRE122 provides a ±10V
output. All types are available in commercial (C
suffix) and military (M suffix) models. The "M"
models are screened for high reliability and quality.
Two accuracy grades (standard and "A") are
available for all models.
The adjacent selector guide shows the limits of the
most important parameters of the VRE120 series
voltage references. The maximum voltage
deviation increases linearly with temperature from
the 150°C specification to the 180°C specification.
For example, the A grade maximum voltage
deviation of 1mV increases to 2mV at 175°C and is
3mV at 180°C. This degree of accuracy over such
a large temperature range has been achieved
using the Thaler Corporation patented multipoint
compensation technique.
All devices are packaged in 14-pin hermetic ceramic packages for maximum long term stability. They are pin
and function compatible with other Thaler references and AD2700, AD2710 and MAX 670/671 References
Type
VRE120C +10V 1.5mV 5.0mV 1.0mV
VRE120CA +10V 1.0mV 3.0mV 0.5mV
VRE120M +10V 1.5mV 5.0mV 1.5mV
VRE120MA +10V 1.0mV 3.0mV 0.8mV
VRE121C -10V 1.5mV 5.0mV 1.0mV
VRE121CA -10V 1.0mV 3.0mV 0.5mV
VRE121M -10V 1.5mV 5.0mV 1.5mV
VRE121MA -10V 1.0mV 3.0mV 0.8mV
VRE122C ±10V 1.5mV 5.0mV 1.0mV
VRE122CA ±10V 1.0mV 3.0mV 0.5mV
VRE122M ±10V 1.5mV 5.0mV 1.5mV
VRE122MA ±10V 1.0mV 3.0mV 0.8mV
SELECTION GUIDE
Max. Volt
Output
Deviation
(-55°C
to +150°C)
Max. Volt
Deviation
(150°C
to +180°C)
Initial
Accuracy
(Max)
Superior stability, accuracy, and quality make these references ideal for precision applications such as A/D
and D/A converters, high-accuracy test and measurement instrumentation, and transducer excitation.
VRE120DS REV. C SEPT 1994
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ELECTRICAL SPECIFICATIONS
Vps =±15V, T = 25°C, RL = 10KΩ unless otherwise noted.
VRE120/121/122
MODEL C CA M MA
PARAMETERS MIN TYP MAX MIN TYP MAX MIN TYP MAX MIN TYP MAX UNITS
ABSOLUTE MAXIMUM RATINGS
Power Supply ±13.5 ±22 * * * * * * V
Operating Temperature -55 180 * * * * * * °C
Storage Temperature -65 150 * * * * * * °C
Short Circuit Protection Continuous * * *
OUTPUT VOLTAGE
VRE120 +10 * * * V
VRE121 -10 * * * V
VRE122 ±10 * * * V
OUTPUT VOLTAGE ERRORS
Initial Error 1.0 0.5 1.5 0.8 mV
Warmup Drift 2 1 2 1 ppm
-55°C to 150°C 1.5 1.0 * * mV
(1)
(3)
150°C to 180°C 5.0 3.0 * * mV
Long-Term Stability 6 * * * ppm/1000hr.
Noise (.1-10Hz) 6 * * * µVpp
OUTPUT CURRENT
Range ±10 * * * mA
REGULATION
Line 3 10 * * * * * * ppm/V
Load 3 * * * ppm/mA
OUTPUT ADJUSTMENT
Range 10 * * * mV
Temperature Coefficient 4 * * * µV/°C/mV
POWER SUPPLY CURRENTS
(2)
VRE120 +PS 5 7 * * * * * * mA
VRE121 -PS 5 7 * * * * * * mA
VRE122 +PS 7 9 * * * * * * mA
VRE122 -PS 4 6 * * * * * * mA
NOTES: *Same as C Models.
1.Using the box method, the specified value is the
maximum deviation from the output voltage at 25°C
over the specified operating temperature range.
4-57
2.The specified values are unloaded.
3. Cone widening from 150 °C value to specified value.
VRE120DS REV. C SEPT 1994
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V
vs. TEMPERATURE
OUT
TYPICAL PERFORMANCE CURVES
V
V
vs. TEMPERATURE
OUT
vs. TEMPERATURE
OUT
V
vs. TEMPERATURE
OUT
Temperature oC
VRE120/121/122C
QUIESCENT CURRENT VS. TEMP
Temperature oC
QUIESCENT CURRENT VS. TEMP
Temperature oC
VRE120/121/122CA
VRE120/121/122M
VRE120/121
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
VRE122
POSITIVE OUTPUT
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Temperature oC
Temperature oC
VRE120/121/122MA
PSRR VS. FREQUENCY
Frequency (Hz)
PSRR VS. FREQUENCY
Temperature oC
QUIESCENT CURRENT VS. TEMP
Temperature oC
Output Current (mA)
NEGATIVE OUTPUT
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
Frequency (Hz)
PSRR VS. FREQUENCY
Frequency (Hz)
VRE120DS REV. C SEPT.1994
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DISCUSSION OF PERFORMANCE
THEORY OF OPERATION
The following discussion refers to the schematic
below. In operation, approximately 6.3 volts is
applied to the noninverting input of the op amp. The
voltage is amplified by the op amp to produce a
10.000V output. The gain is determined by the
networks R1 and R2: G=1 + R2/R1. The 6.3V zener
diode is used because it is the most stable diode
over time and temperature.
The zener operating current is derived from the
regulated output voltage through R3. This feedback
arrangement provides a closely regulated zener
current. This current determines the slope of the
reference's voltage vs. temperature function. By
trimming the zener current lower drift over
temperature can be achieved. But since the voltage
vs. temperature function is nonlinear this
compensation technique is not well suited for wide
temperature ranges.
Thaler Corporation has developed a nonlinear
compensation network of thermistors and resistors
that is used in the VRE120 series voltage
references. This proprietary network eliminates
most of the nonlinearity in the voltage vs.
temperature function. By then adjusting the slope,
Thaler Corporation produces a very stable voltage
over wide temperature ranges. This network is less
than 2% of the overall network resistance so it has
a negligible effect on long term stability. By using
highly stable resistors in our network, we produce a
voltage reference that also has very good long term
stability.
APPLICATION INFORMATION
Figure 1 shows the proper connection of the
VRE120 series voltage reference with the optional
trim resistors. When trimming the VRE122, the
positive voltage should be trimmed first since the
negative voltage tracks the positive side. Pay careful
attention to the circuit layout to avoid noise pickup
and voltage drops in the lines.
When using the precision voltage references at
high temperatures it is best to keep them powered
up. If the zener diode isn't powered up at high
temperatures the junction will collect ions, and then
when power is applied, the voltage will drift until the
charge build up is depleted.
The VRE120 series voltage references have the
ground terminal brought out on two pins (pin 6 and
pin 7) which are connected together internally. This
allows the user to achieve greater accuracy when
using a socket. Voltage references have a voltage
drop across their power supply ground pin due to
quiescent current flowing through the contact
resistance. If the contact resistance was constant
with time and temperature, this voltage drop could be
trimmed out. When the reference is plugged into a
socket, this source of error can be as high as 20ppm.
By connecting pin 7 to the power supply ground and
pin 6 to a high impedance ground point in the
measurement circuit, the error due to the contact
resistance can be eliminated. If the unit is soldered
into place the contact resistance is sufficiently small
that it doesn't effect performance.
VRE120
VRE122
FIGURE 2
FIGURE 3
VRE120DS REV. C SEPT 1994
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EXTERNAL CONNECTIONS
FIGURE 1
1. Optional Fine Adjust for approximately ±10mV. VRE122 center tap connects to -PS.
2. Pin 6 is internally connected to Pin 7 and can be used as Ref. GND.
PIN CONFIGURATION
NC
NC
NC
NC
NC
REF. GND
GND
14-PIN HYBRID
PACKAGE
TOP VIEW
FINE ADJ.
+10V
FINE ADJ.
VRE120 VRE121
+PS
NC
NC
NC
REF. GND
GND
TOP VIEW
NC
NC
NC
NC
NC
MECHANICAL
INCHES MILLIMETER
DIM MIN MAX MIN MAX DIM MIN MAX MIN MAX
E .480 .500 12.1 12.7 A .120 .155 3.0 4.0
L .195 .215 4.9 5.4 Q .015 .035 0.4 0.9
D .775 .805 19.7 20.4 Q1 N/A .030 N/A 0.7
B .016 .020 0.4 0.5 C .009 .012 0.2 0.3
B1 .038 .042 0.9 1.0 G1 .290 .310 7.3 7.8
B2 .095 .105 2.4 2.6
S .085 .105 2.1 2.6
P .004 .006 0.10 0.15
FINE ADJ.
-10V
FINE ADJ.
-PS
NC
NC
NC
-ADJ.
-10V
-ADJ.
-PS
NC
REF. GND
GND
TOP VIEW
+ADJ.
+10V
+ADJ.
VRE122
INCHES MILLIMETER
+PS
NC
NC
NC
VRE120DS REV. C SEPT 1994
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