VRE105/107
Precision
Reference Supplies
THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000
FEATURES
•
VERY HIGH ACCURACY: 5.000 V ±0.4 mV
•
EXTREMELY LOW DRIFT: 0.6 ppm/°C -55°C to +125°C
•
EXCELLENT STABILITY: 6 ppm/1000 Hrs. Typ.
•
EXCELLENT LINE REGULATION: 6 ppm/V Typ.
•
WIDE SUPPLY RANGE: ±13.5 V to ±22.0 V
•
HERMETIC 14-PIN CERAMIC DIP
•
MILITARY PROCESSING OPTION
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
DESCRIPTION
VRE105 Series Precision Voltage References
provide ultrastable +5.000 V (VRE105) and
±5.000 V (VRE107) outputs with ±0.4 mV initial
accuracy and temperature coefficient as low as
0.6 ppm/°C over the full military temperature
range. This impovement in accuracy is made
possible by a unique, proprietary multipoint laser
compensation technique developed by Thaler
Corporation. Significant improvements have been
made in other performance parameters as well,
including initial accuracy, warm-up drift, line
regulation, and long-term stability, making the
VRE105 series the most accurate and stable 5V
references available.
SELECTION GUIDE
Type
VRE105C
VRE105CA
VRE105M
VRE105MA
VRE107C
VRE107CA
VRE107M
VRE107MA
Output
+5V
+5V
+5V
+5V
±5V
±5V
±5V
±5V
Temperature
Max. Volt
Operating Range Deviation
-25°C to +85°C
0.4mV
-25°C to +85°C
0.2mV
-55°C to +125°C
0.6mV
-55°C to +125°C
0.3mV
-25°C to +85°C
-25°C to +85°C
-55°C to +125°C
-55°C to +125°C
0.4mV
0.2mV
0.6mV
0.3mV
VRE105 series devices are available in two operating temperature ranges, -25°C to +85°C and -55°C to
+125°C, and two performance grades. All devices are packaged in 14-pin hermetic ceramic packages for
maximum long-term stablity. "M" versions are screened for high reliability and quality.
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 tranducer excitation.
VRE105DS REV. C SEPT 1994
4-32
DISCUSSION OF PERFORMANCE
THEORY OF OPERATION
The following discussion refers to the schematic
below. A FET current source is used to bias a 6.3V
zener diode. The zener voltage is divided by the
resistor network R1 and R2. This voltage is then
applied to the noninverting input of the operational
amplifier which amplifies the voltage to produce a
5.000V output. The gain is determined by the
resistor networks R3 and R4: G=1 + R4/R3. The
6.3V zener diode is used because it is the most
stable diode over time and temperature.
The current source provides a closely regulated
zener current, which determines the slope of the
reference's voltage vs. temperature function. By
trimming the zener current, a lower drift over
temperature can be achieved. But since the voltage
vs. temperature function is nonlinear, this method
leaves a residual error over wide temperature
ranges.
To remove this residual error, Thaler Corporation
has developed a nonlinear compensation network of
thermistors and resistors that is used in the VRE105
series 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.
APPLICATION INFORMATION
Figure 1 shows the proper connection of the
VRE105 series voltage reference with the optional
trim resistors. When trimming the VRE107, 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.
The VRE105 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.
VRE105
VRE107
VRE105DS REV. C SEPT 1994
4-35
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