VRE310
Low Cost
Precision Reference
DESCRIPTION
FEATURES
The VRE310 is a low cost, high precision 10.0V
reference. Packaged in the industry standard 8
pin DIP, the device is ideal for upgrading systems
that use lower performance references.
The device provides ultrastable +10.000V output
with 1.000 mV (.01%) initial accuracy and a
temperature coefficient of 0.6 ppm/C. This
improvement in accuracy is made possible by a
unique, patented 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 VRE310 series the
most accurate reference available in the standard
8 pin DIP package.
For enhanced performance, the VRE310 has an
external trim option for users who want less than
0.01% initial error. For ultra low noise
applications, an external capacitor can be
attached between the noise reduction pin and the
ground pin. A reference ground pin is provided to
eliminate socket contact resistance errors.
5
6
7
8
VRE310
TOP
VIEW
1
2
3
4
N/C
+V
IN
TEMP
GND
NOISE
REDUCTION
REF. GND
V
OUT
TRIM
PIN CONFIGURATION
The VRE310 is recommended for use as a
reference for 14-, 16-, or 18-bit D/A converters
which require an external precision reference.
The device is also ideal for calibrating scale factor
on high resolution A/D converters. The VRE310
offers superior performance over monolithic
references.
10.000 V OUTPUT 1.000 mV (.01%)
TEMPERATURE DRIFT: 0.6 ppm/C
LOW NOISE: 6
V
p-p
(0.1-10Hz)
INDUSTRY STD PINOUT- 8 PIN DIP OR
SURFACE MOUNT PACKAGE
EXCELLENT LINE REGULATION: 6ppm/V Typ.
OUTPUT TRIM CAPABILITY
FIGURE 1
VRE310DS REV. D MAY 2001
SELECTION GUIDE
Model
Temp.
Range
C
Temp.
Coeff.
ppm/C
VRE310A
1.0
0.6
0C to +70C
VRE310B
1.6
1.0
0C to +70C
VRE310C
2.0
2.0
0C to +70C
VRE310J
1.0
0.6
-40C to +85C
VRE310K
1.6
1.0
-40C to +85C
VRE310L
2.0
2.0
-40C to +85C
For package option add D for DIP or S for Surface Mount
to end of model number.
Initial
Error
mV
THALER CORPORATION 2015 N. FORBES BOULEVARD TUCSON, AZ. 85745 (520) 882-4000
MODEL
A/J
B/K
C/L
PARAMETER
MIN
TYP
MAX
MIN
TYP
MAX
MIN TYP
MAX
UNITS
ABSOLUTE RATINGS
Power Supply
+13.5
+15
+22
*
*
*
*
*
*
V
Operating Temp. (
A,B,C
)
0
+70
*
*
*
*
C
Operating Temp. (
J,K,L
)
-40
+85
*
*
*
*
C
Storage Temperature
-65
+150
*
*
*
*
C
Short Circuit Protection
Continuous
*
*
OUTPUT VOLTAGE
VRE310
10.000
*
*
V
Temp. Sensor Voltage
630
*
*
mV
OUTPUT VOLTAGE ERRORS
Initial Error
1.00
1.60
2.00
mV
Warmup Drift
1
2
3
ppm
T
min
- T
max
0.6
1.0
2.0
ppm/C
Long-Term Stability
6
*
*
ppm/1000hrs
Noise (.1-10Hz)
6
*
*
Vpp
OUTPUT CURRENT
Range
10
*
*
mA
REGULATION
Line
3
10
*
*
*
*
ppm/V
Load
3
*
*
ppm/mA
OUTPUT ADJUSTMENT
Range
20
*
*
mV
POWER SUPPLY CURRENTS
VRE310 +PS
5
7
*
*
*
*
mA
VRE310
NOTES: *Same as A/J Models.
1. The temp. reference TC is 2.1mV/C
2. The specified values are without external trim.
3. The temperature coefficient is determined by the box
method using the following formula:
V
max
- V
min
T.C. =
x 10
6
V
nominal
x (T
max
-T
min
)
(1)
(5)
(2)
(3)
VRE310DS REV. D MAY 2001
Vps =+15V, T = 25C, RL = 10K
unless otherwise noted.
ELECTRICAL SPECIFICATIONS
4. The specified values are without the external
noise reduction capacitor.
5. The specified values are unloaded.
(4)
TYPICAL PERFORMANCE CURVES
Temperature
o
C
VRE310A
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE310B
V
OUT
vs. TEMPERATURE
VRE310DS REV. D MAY 2001
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE310C
Temperature
o
C
VRE310J
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE310K
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE310L
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)
THEORY OF OPERATION
The following discussion refers to the schematic in
figure 2 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 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.
DISCUSSION OF PERFORMANCE
VRE310DS REV. D MAY 2001
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
Figure 3 shows the proper connection of the VRE310
series voltage references with the optional trim resistor.
The VRE310 reference has the ground terminal brought
out on two pins (pin 4 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 4 to
the power supply ground and pin 7 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. Pay careful
attention to the circuit layout to avoid noise pickup and
voltage drops in the lines.
VRE310
FIGURE 2
EXTERNAL CONNECTIONS
FIGURE 3
8
4
6
5
+ V
OUT
2
+ V
IN
VRE310
10k
C
N
1F
OPTIONAL
NOISE REDUCTION
CAPACITOR
OPTIONAL
FINE TRIM
ADJUSTMENT
3
V
TEMP OUT
7
REF. GND
VRE310DS REV. D MAY 2001
MECHANICAL
DIM
MIN
MAX
MIN
MAX
DIM
MIN
MAX MIN
MAX
A
.115
.125
2.92
3.17 E
.397
.403
10.0
10.2
B
.018
.022
.457
.558
E1
.264
.270
6.70
6.85
B1
.046
.051
1.14 1.29
G1
.290
.310
7.36
7.87
B2
.098
.102
2.48
2.59
L
.195
.215
4.95
5.46
C
.009
.012
0.22
0.30
P
.085
.095
2.15
2.41
D .397
.403
10.0
10.2 Q
.055
.065
1.39
1.65
D 1
.372
.380
9.44
9.65
S
.045
.055
1.14
1.39
INCHES MILLIMETER
INCHES MILLIMETER
MECHANICAL
FIGURE 4
FIGURE 3
INCHES MILLIMETER
DIM
MIN
MAX
MIN
MAX
DIM
MIN
MAX
MIN
MAX
A
.115
.125
2.92
3.17
D2
.018
.023
0.46
0.58
B
.098
.102
2.48
2.59
E
.507
.513
12.8
13.0
B1
.046
.051
1.14
1.29
E1
.397
.403
10.0
10.2
C
.107
.113
2.71
2.89
E2
.264
.270
6.70
6.85
C1
.009
.012
0.22
0.30
P
.085
.095
2.15
2.41
C2
.052
.058
1.32
1.47
Q
.020
.030
.508
.762
D
.397
.403
10.0
10.2
S
.045
.055
1.14
1.39
D1
.372
.380
9.44
9.65
INCHES MILLIMETER
D2
E
E1
E2
PIN 1 IDENTIFIER
D
D1
BASE
SEATING
A
Q
B
B1
S
E1
C1
C
C2
P
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