VRE402
Precision
Dual Reference
THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000
FEATURES
PIN CONFIGURATION
• ±2.500 V OUTPUT ± 0.250 mV (.01%)
• TEMPERATURE DRIFT: 0.6 ppm/°C
• LOW NOISE: 1.5
µ
V
pp
(0.1-10Hz)
• TRACKING ERROR: 0.2 mV max.
• EXCELLENT LINE REGULATION: 6ppm/V Typ.
• SURFACE MOUNT AND DIP PACKAGES
N/C
1
2
3
4
5
6
7
14
13
N/C
+V
OUT
N/C
+V
IN
N/C
N/C
N/C
-
V
OUT
N/C
VRE402
TOP
VIEW
12
11
10
9
8
-
V
IN
N/C
REF. GND
GND
FIGURE 1
DESCRIPTION
The VRE402 is a low cost, high precision, ±2.5V
reference. Packaged in 14 pin DIP or SMT
packages, the device is ideal for new designs that
need a high performance reference.
The device provides ultrastable ±2.500V output
with ±0.250 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.
Another key feature of this reference is the 0.3 mV
maximum tracking error between the positive and
negative output voltages over the operating
temperature range. This is extremely important in
high performance systems for reducing overall
system errors.
For designs which use the DIP package in a
socket, there is a reference ground pin to
eliminate reference ground errors.
The VRE402 is recommended for use as a
reference for high precision A/D and D/A
converters which require an external precision
reference. The device is ideal for calibrating
scale factor on high resolution A/D converters.
The VRE402 offers superior performance over
monolithic references.
SELECTION GUIDE
Initial
Error
mV
0.25
0.40
0.50
0.25
0.40
0.50
Model
VRE402A
VRE402B
VRE402C
VRE402J
VRE402K
VRE402L
Temp.
Coeff.
ppm/
°C
0.6
1.0
2.0
0.6
1.0
2.0
Temp.
Range
°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
For package option add D for DIP or S for Surface
Mount to end of model number.
VRE402DS REV. A MAY 1996
ELECTRICAL SPECIFICATIONS
Vps =
±
15V, T = 25°C, RL = 10K
Ω
unless otherwise noted.
VRE402
B/K
MAX
MIN
TYP
MAX
MIN
MODEL
PARAMETER
ABSOLUTE RATINGS
MIN
A/J
TYP
C/L
TYP
MAX
UNITS
Power Supply
±13.5
±15
±22
Operating Temp. (
A,B,C
)
0
+70
Operating Temp. (
J,K,L
)
-40
+85
Storage Temperature
-65
+150
Short Circuit Protection
Continuous
OUTPUT VOLTAGE
VRE402
OUTPUT VOLTAGE ERRORS
Initial Error
(1)
Warmup Drift
T
min
- T
max
(2)
(3)
Tracking Error
Long-Term Stability
Noise (.1-10Hz)
OUTPUT CURRENT
Range
REGULATION
Line
Load
POWER SUPPLY CURRENTS
+PS
-PS
(4)
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
V
°C
°C
°C
*
*
±2.5
*
*
V
0.25
1
0.6
0.2
6
1.5
*
*
2
0.40
3
1.0
0.3
*
*
0.50
2.0
0.4
mV
ppm
ppm/
°C
mV
ppm/1000hrs
µVpp
±10
*
*
mA
3
3
10
*
*
*
*
*
*
ppm/V
ppm/mA
7
4
9
6
*
*
*
*
*
*
*
*
mA
mA
NOTES:
*Same as A/J Models.
4. The specified values are unloaded.
1. The specified values are without external trim.
2. The temperature coefficient (tc) is determined by the
box method using the following formula:
V
max
- V
min
tc =
V
nominal
x (T
max
-T
min
)
3. The tracking error is the deviation between the
positive and negative output over the operating temp.
range.
x 10
6
VRE402DS REV. A MAY 1996
TYPICAL PERFORMANCE CURVES
V
OUT
vs. TEMPERATURE
V
OUT
vs. TEMPERATURE
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE402A
Temperature
o
C
VRE402B
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE402C
V
OUT
vs. TEMPERATURE
V
OUT
vs. TEMPERATURE
Temperature
o
C
VRE402J
Temperature
o
C
VRE402K
POSITIVE OUTPUT (TYP)
Temperature
o
C
VRE402L
QUIESCENT CURRENT VS. TEMP
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
PSRR VS. FREQUENCY
Temperature
o
C
Output Current (mA)
NEGATIVE OUTPUT (TYP)
Frequency (Hz)
QUIESCENT CURRENT VS. TEMP
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
PSRR VS. FREQUENCY
Temperature
o
C
Output Current (mA)
Frequency (Hz)
VRE402DS REV. A MAY 1996
DISCUSSION OF PERFORMANCE
THEORY OF OPERATION
The following discussion refers to the schematic in
figure 2 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
2.500V 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
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 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.
The VRE402 reference has it’s ground brought out
on two pins (pin 6 and 7) which are connected
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 does not effect
performance.
VRE402
FIGURE 2
VRE402DS REV. A MAY 1996
MECHANICAL
FIGURE 3
INCHES
DIM
A
B
B1
C
C1
C2
D
D1
MIN
.114
.098
.047
.103
.009
.054
.690
.666
MAX
.136
.103
.056
.118
.020
.062
.715
.680
MILLIMETER
MIN
2.90
2.48
1.19
2.62
0.22
1.37
17.5
16.9
MAX
3.45
2.62
1.42
3.00
0.51
1.57
18.1
17.2
DIM
E
E1
E2
P
Q
S
INCHES
MIN
.495
.390
.265
.090
.024
.040
MAX
.526
.415
.270
.110
.035
.060
MILLIMETER
MIN
12.5
9.91
6.73
2.29
0.61
1.02
MAX
13.3
10.5
6.86
2.79
.890
1.52
FIGURE 4
INCHES
DIM
A
B
B1
B2
C
D
D1
MIN
.114
.018
.047
.097
.009
.690
.666
MAX
.136
.027
.056
.103
.020
.715
.680
MILLIMETER
MIN
2.90
.460
1.19
2.46
0.22
17.5
16.9
MAX
3.45
.690
1.42
2.62
0.51
18.1
17.2
DIM
E
E1
E2
G1
L
P
Q
S
INCHES
MIN
.410
.390
.265
.285
.195
.090
.050
.040
MAX
.435
.415
.270
.315
.225
.110
.070
.060
MILLIMETER
MIN
10.4
9.91
6.73
7.24
4.95
2.29
1.27
1.02
MAX
11.0
10.5
6.86
8.00
5.72
2.79
1.79
1.52
VRE402DS REV. A MAY 1996
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