VERY HIGH ACCURACY: 4.5000 V OUTPUT 0.4 mV
EXTREMELY LOW DRIFT: 0.6 ppm/C -55C to +125C
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
VRE204
Precision Surface Mount
Reference Supply
DESCRIPTION
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
FEATURES
SELECTION GUIDE
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.
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.
Type
Output
Temperature
Operating Range
Max. Volt
Deviation
VRE204C
+4.5V
-25C to +85C
0.4mV
VRE204CA +4.5V
-25C to +85C
0.2mV
VRE204M
+4.5V
-55C to +125C
0.6mV
VRE204MA +4.5V
-55C to +125C
0.3mV
VRE204 series devices are available in two operating temperature ranges, -25C to +85C and -55C to
+125C, 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.
VRE204DS REV. C JUNE 1995
THALER CORPORATION 2015 N. FORBES BOULEVARD TUCSON, AZ. 85745 (520) 882-4000
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
V
Warmup Drift
2
1
2
*
ppm
T
min
- T
max
400
200
600
300
V
Long-Term Stability
6
*
*
*
ppm/1000hrs
Noise (.1-10Hz)
3
*
*
*
Vpp
OUTPUT CURRENT
Range
10
*
*
*
mA
REGULATION
Line
6
10
*
*
*
*
*
*
ppm/V
Load
3
*
*
*
ppm/mA
OUTPUT ADJUSTMENT
Range
10
*
*
*
mV
Temperature Coeff.
4
*
*
*
V/C/mV
POWER SUPPLY CURRENTS
VRE204 +PS
5
7
*
*
*
*
*
*
mA
VRE204
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.
(1)
(2)
VRE204DS REV. C JUNE 1995
Vps =15V, T = 25C, RL = 10K
unless otherwise noted.
ELECTRICAL SPECIFICATIONS
TYPICAL PERFORMANCE CURVES
VRE204DS REV. C JUNE 1995
Temperature
o
C
VRE204C
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE204CA
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)
Temperature
o
C
VRE204M
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE204MA
V
OUT
vs. TEMPERATURE
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.
DISCUSSION OF PERFORMANCE
VRE204
FIGURE 1
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.
VRE204DS REV. C JUNE 1995
EXTERNAL CONNECTIONS
FIGURE 2
MECHANICAL
PIN CONFIGURATION
REF
GND
TOP VIEW
VRE204
11 12 13
9
10
18
17
16
15
14
4
5
6
7
8
1
20 19
3
2
NC
NC
NC
NC
V
IN
NC
NC
TRIM
GND
NC
NC
V
OUT
NC
NC
NC NC NC NC NC
11
12 13
9
10
18
17
16
15
14
4
5
6
7
8
1
20
19
3
2
+15V
V
OUT
= +4.5V
10k
Ref. Gnd.
VRE204DS REV. C JUNE 1995
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
DIM
INCHES
MIN
MAX
MAX
MILLIMETER
MIN
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