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VRE204
Precision Surface Mount
Reference Supply
THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000
FEATURES
•• VERY HIGH ACCURACY: 4.5000 V OUTPUT ±0.4 mV
•• EXTREMELY LOW DRIFT: 0.6 ppm/°C -55°C to +125°C
•• EXCELLENT STABILITY: 6ppm/1000 Hrs. Typ.
•• EXCELLENT LINE REGULATION: 6 ppm/V Typ.
•• WIDE SUPPLY RANGE: +13.5 V to +22.0 V
•• HERMETIC 20 TERMINAL CERAMIC LCC
•• MILITARY PROCESSING AVAILABLE
DESCRIPTION
VRE204 Series Precision Voltage References
provide ultrastable +4.500 V outputs with up to
±0.4 mV initial accuracy and temperature
coefficient as low as 0.6 ppm/°C over the full
military temperature range.
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
SELECTION GUIDE
These references are specifically designed to be
used with the Crystal Semiconductor line of
successive-approximation type Analog-to-Digital
Converters (ADCs). This line of ADCs sets new
standards for temperature drift, which can only be
as good as the external reference used. The
Thaler VRE204 combined with a Crystal ADC will
provide the lowest drift data conversion
obtainable.
VRE204 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 20 terminal LCC ceramic packages
for maximum long-term stability. "M" versions are screened for high reliability and quality.
Superior stability, accuracy, and quality make the VRE204 ideal for all precision applications which may
require a 4.5V reference. High-accuracy test and measurement instrumentation, and transducer
excitation are some other applications which can benefit from the high accuracy of the VRE204.
Type
VRE204C +4.5V -25°C to +85°C 0.4mV
VRE204CA +4.5V -25°C to +85°C 0.2mV
VRE204M +4.5V -55°C to +125°C 0.6mV
VRE204MA +4.5V -55°C to +125°C 0.3mV
Output
Temperature
Operating Range
VRE204DS REV. C JUNE 1995
Max. Volt
Deviation
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ELECTRICAL SPECIFICATIONS
Vps =±15V, T = 25°C, RL = 10KΩ unless otherwise noted.
VRE204
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 -25 85 * * -55 125 -55 125 °C
Storage Temperature -65 150 * * * * * * °C
Short Circuit Protection Continuous * * *
OUTPUT VOLTAGE
VRE204 +4.5 * * * V
OUTPUT VOLTAGE ERRORS
Initial Error 800 400 800 400 µV
Warmup Drift 2 1 2 * ppm
T
- T
min
max
(1)
400 200 600 300 µV
Long-Term Stability 6 * * * ppm/1000hrs
Noise (.1-10Hz) 3 * * * µVpp
OUTPUT CURRENT
Range ±10 * * * mA
REGULATION
Line 6 10 * * * * * * ppm/V
Load 3 * * * ppm/mA
OUTPUT ADJUSTMENT
Range 10 * * * mV
Temperature Coeff. 4 * * * µV/°C/mV
POWER SUPPLY CURRENTS
(2)
VRE204 +PS 5 7 * * * * * * 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.
2.The specified values are unloaded.
VRE204DS REV. C JUNE 1995
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TYPICAL PERFORMANCE CURVES
V
vs. TEMPERATURE
OUT
V
OUT
vs. TEMPERATURE
Temperature oC
VRE204C
V
vs. TEMPERATURE
OUT
Temperature oC
VRE204M
Temperature oC
VRE204CA
V
vs. TEMPERATURE
OUT
Temperature oC
VRE204MA
QUIESCENT CURRENT VS. TEMP
Temperature oC
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
PSRR VS. FREQUENCY
Frequency (Hz)
VRE204DS REV. C JUNE 1995
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DISCUSSION OF PERFORMANCE
THEORY OF OPERATION
The following discussion refers to the schematic
below. A FET current source is used to bias a 6.3
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
4.5000V output. The gain is determined by the
resistor networks R3 and R4: G=1 + R4/R3. The 6.3
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
references’ 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
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 VRE 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 2 shows the proper connection of the
VRE204 series voltage references with the optional
trim resistors. Pay careful attention to the circuit
layout to avoid noise pickup and voltage drops in the
lines.
The VRE204 series voltage references have the
ground terminal brought out on two pins (pin 9 and
pin 10) 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 10 to the power supply ground and
pin 9 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 does not effect performance.
VRE204
FIGURE 1
VRE204DS REV. C JUNE 1995
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FIGURE 2
EXTERNAL CONNECTIONS
1
2
20
19
18
17
16
15
14
139
11 12
10
↓
+15V
3
4
5
6
7
8
Ref. Gnd.
10kΩ
PIN CONFIGURATION
NC NC NC NC NC
1 20 19
TOP VIEW
VRE204
11 12 13
NC NCTRIMGND
18
17
16
15
14
NC
V
NC
NC
NC
3 2
4
5
IN
6
7
8
9 10
REF
GND
NC
NC
NC
V
NC
OUT
V
OUT
= +4.5V
MECHANICAL
DIM
A 0.090 0.110 2.29 2.79
B 0.022 0.028 0.56 0.71
D 0.342 0.358 8.68 9.09
D1 0.048 0.052 1.22 1.32
E 0.342 0.358 8.68 9.09
E1 0.045 0.055 1.114 1.40
j 0.010 REF .254 REF
h 0.040 REF 1.02 REF
L 0.045 0.055 1.14 1.40
MIN
INCHES
MAX
MILLIMETER
MIN
VRE204DS REV. C JUNE 1995
MAX
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