WIDE OPERATING RANGE: -55C TO +180C
EXTREMELY LOW DRIFT: 1 ppm /C -55C to +150C
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
VRE120/121/122
Precision High Temperature
Reference Supplies
DESCRIPTION
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
SELECTION GUIDE
VRE120 series references are designed to operate
over an extremely wide temperature range (-55C
to +180C) 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 150C specification to the 180C specification.
For example, the A grade maximum voltage
deviation of 1mV increases to 2mV at 175C and is
3mV at 180C. This degree of accuracy over such
a large temperature range has been achieved
using the Thaler Corporation patented multipoint
compensation technique.
Type
Output
Max. Volt
Deviation
(-55C
to +150C)
Initial
Accuracy
(Max)
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
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
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
Max. Volt
Deviation
(150C
to +180C)
FEATURES
APPLICATIONS
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
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
THALER CORPORATION 2015 N. FORBES BOULEVARD TUCSON, AZ. 85745 (520) 882-4000
4-56
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
-55C to 150C
1.5
1.0
*
*
mV
150C to 180C
5.0
3.0
*
*
mV
Long-Term Stability
6
*
*
*
ppm/1000hr.
Noise (.1-10Hz)
6
*
*
*
Vpp
OUTPUT CURRENT
Range
10
*
*
*
mA
REGULATION
Line
3
10
*
*
*
*
*
*
ppm/V
Load
3
*
*
*
ppm/mA
OUTPUT ADJUSTMENT
Range
10
*
*
*
mV
Temperature Coefficient
4
*
*
*
V/C/mV
POWER SUPPLY CURRENTS
VRE120 +PS
5
7
*
*
*
*
*
*
mA
VRE121 -PS
5
7
*
*
*
*
*
*
mA
VRE122 +PS
7
9
*
*
*
*
*
*
mA
VRE122 -PS
4
6
*
*
*
*
*
*
mA
VRE120/121/122
NOTES: *Same as C Models.
1.Using the box method, the specified value is the
maximum deviation from the output voltage at 25C
over the specified operating temperature range.
2.The specified values are unloaded.
3. Cone widening from 150 C value to specified value.
(1)
(2)
(3)
VRE120DS REV. C SEPT 1994
Vps =15V, T = 25C, RL = 10K
unless otherwise noted.
ELECTRICAL SPECIFICATIONS
4-57
TYPICAL PERFORMANCE CURVES
VRE120DS REV. C SEPT.1994
Temperature
o
C
VRE120/121/122C
V
OUT
vs. TEMPERATURE
V
OUT
vs. TEMPERATURE
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE120/121/122CA
Temperature
o
C
VRE120/121/122M
Temperature
o
C
VRE120/121/122MA
V
OUT
vs. TEMPERATURE
QUIESCENT CURRENT VS. TEMP
Temperature
o
C
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
PSRR VS. FREQUENCY
Frequency (Hz)
VRE120/121
VRE122
QUIESCENT CURRENT VS. TEMP
Temperature
o
C
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
PSRR VS. FREQUENCY
Frequency (Hz)
POSITIVE OUTPUT
NEGATIVE OUTPUT
4-58
QUIESCENT CURRENT VS. TEMP
Temperature
o
C
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
PSRR VS. FREQUENCY
Frequency (Hz)
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.
DISCUSSION OF PERFORMANCE
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
4-59
INCHES MILLIMETER
14-PIN HYBRID
PACKAGE
TOP VIEW
TOP VIEW
TOP VIEW
VRE122
VRE120
VRE121
GND
REF. GND
NC
NC
NC
NC
NC
FINE ADJ.
+10V
FINE ADJ.
+PS
NC
NC
NC
-PS
NC
NC
NC
+ADJ.
+10V
+ADJ.
+PS
NC
NC
NC
GND
REF. GND
NC
NC
NC
NC
NC
GND
REF. GND
NC
FINE ADJ.
FINE ADJ.
-10V
-10V
-ADJ.
-ADJ.
-PS
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
EXTERNAL CONNECTIONS
FIGURE 1
INCHES MILLIMETER
MECHANICAL
PIN CONFIGURATION
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.
VRE120DS REV. C SEPT 1994
4-60
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