VRE3050
Low Cost
Precision Reference
DESCRIPTION
FEATURES
The VRE3050 is a low cost, high precision 5.0V
reference that operates from +10V. The device
features a buried zener for low noise and excellent
long term stability. Packaged in an 8 pin DIP and
SMT, the device is ideal for high resolution data
conversion systems.
The device provides ultrastable +5.000V output
with ±0.5000 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 VRE3050 series
the most accurate reference available.
For enhanced performance, the VRE3050 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.
5
6
7
8
VRE3050
TOP
VIEW
1
2
3
4
N/C
+VIN
N/C
GND
NOISE
REDUCTION
VOUT
TRIM
PIN CONFIGURATION
The VRE3050 is recommended for use as a
reference for 14, 16, or 18 bit data converters
which require an external precision reference.
The device is also ideal for calibrating scale factor
on high resolution data converters. The VRE3050
offers superior performance over monolithic
references.
•5.000 V Output ± 0.500 mV (.01%)
•Temperature Drift: 0.6 ppm/°C
•Low Noise: 3µV p-p(0.1Hz-10Hz)
•Low Thermal Hysterisis: 1 ppm Typ.
•±15mA Output Source and Sink Current
•Excellent Line Regulation: 5 ppm/V Typ.
•Optional Noise Reduction and Voltage Trim
•Industry Standard Pinout FIGURE 1
VRE3050DS REV. D JULY 2000
SELECTION GUIDE
Model Temp.
Range °C
Temp.
Coeff.
ppm/°C
VRE3050A 0.5 0.6 0°C to +70°C
VRE3050B 0.8 1.0 0°C to +70°C
VRE3050C 1.0 2.0 0°C to +70°C
VRE3050J 0.5 0.6 -40°C to +85°C
VRE3050K 0.8 1.0 -40°C to +85°C
VRE3050L 1.0 2.0 -40°C to +85°C
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
N/C
ppm/
1khrs
6∆VOUT/t
Long Term Stability
µVp-p3.00.1Hz<f<10Hz
en
Output Noise Voltage
µs2 To 0.01% of final valueTon
Turn-On Settling Time
mV±5Figure 3∆VOUT
Trim Adjustment Range
1.0 2.0VRE3050C/K
0.5 1.0VRE3050B/K
4.9990 5.0000 5.0010VRE3050C/L
4.9992 5.0000 5.0008VRE3050B/K V
4.9995 5.0000 5.0005VRE3050A/J
VOUT
Output Voltage
(Note 1)
5 1010V ≤VIN ≤18V ppm/V
25 358V ≤VIN ≤10V
∆VOUT/
∆VIN
Line Regulation
(Note 3)
ppm/
mA
8 12
8 12
Sourcing:
0mA ≤IOUT ≤15mA
Sinking:
-15mA ≤IOUT ≤0mA
∆VOUT/
∆IOUT
Load Regulation
(Note 3)
mA3.5 4.0IIN
Supply Current
µVRMS
2.5 5.010Hz<f<1kHz
ppm1Note 4Temperature Hysterisis
ppm/°C
0.3 0.6VRE3050A/J
TCVOUT
Output Voltage
Temperature Coefficient
(Note 2)
V8 36VIN
UNITSMIN TYP MAXSYMBOL CONDITIONS
Input Voltage
PARAMETER
ELECTRICAL SPECIFICATIONS
Vps =+10V, T = 25°C, Iout=0mA unless otherwise noted.
Notes:
1) The specified values are without external trim.
2) The temperature coefficient is determined by the
box method. See discussion on temperature
performance.
3) Line and load regulation are measured with pulses and
do not include voltage changes due to temperature.
4) Hysterisis over the operating temperature range.
VRE3050DS REV. D JULY 2000
ABSOLUTE MAXIMUM RATINGS
Power Supply ………………………-0.3V to +40V Out Short Circuit to GND Duration (VIN< 12V)…...Continuous
OUT, TRIM …………………………-0.3V to +12V Out Short Circuit to GND Duration (VIN< 40V)…….……5 sec
NR……………………………………-0.3V to +6V Out Short Circuit to IN Duration (VIN< 12V)………Continuous
Operating Temp. (A,B,C)……………0°C to 70°C Continuous Power Dissipation (TA= +70°C)………...300mW
Operating Temp. (J,K,L)……………-40°C to 85°C Storage Temperature……………………..……-65°C to 150°C
Lead Temperature (soldering,10 sec)…………………..250°C
TYPICAL PERFORMANCE CURVES
Temperature (oC)
VRE3050A
VOUT vs. TEMPERATURE
VRE3050DS REV. D JULY 2000
SUPPLY CURRENT
VS. SUPPLY VOLTAGE QUIESCENT CURRENT VS. TEMP
Temperature (oC)
OUTPUT IMPEDIANCE
VS. FREQUENCY
Temperature (oC)
VRE3050B
VOUT vs. TEMPERATUREVOUT vs. TEMPERATURE
Temperature (oC)
VRE3050C
Temperature (oC)
VRE3050J
VOUT vs. TEMPERATURE
Temperature (oC)
VRE3050K
VOUT vs. TEMPERATURE
Temperature (oC)
VRE3050L
VOUT vs. TEMPERATURE
Supply Voltage (V)
Supply Current (mA)
Frequency (Hz)
∆Vout (mV)
∆Vout (mV)
∆Vout (mV)
∆Vout (mV)
∆Vout (mV)
∆Vout (mV)
Quiescent Current (mA)
Output Impediance ( Ω)
0
50
-50
100
6.0
4.0
2.0
0
8.0
15
25
5
35
5.0
4.0
3.0
0
6.0
10
20
30
40
0
-50
-25
0
25
50
75
100
2.0
1.5
1.0
0.5
0
-1.0
-0.5
-1.5
-2.0
Lower Limit
Upper Limit
-50
-25
0
25
50
75
100
2.0
1.5
1.0
0.5
0
-1.0
-0.5
-1.5
-2.0
Lower Limit
Upper Limit
0
20
30
40
50
60
70
1.00
0.75
0.50
0.25
0
-0.50
-0.25
-0.75
-1.00
Lower Limit
Upper Limit
0
20
30
40
50
60
70
1.00
0.75
0.50
0.25
0
-0.50
-0.25
-0.75
-1.00
Lower Limit
Upper Limit
Lower Limit
Upper Limit
-0.75
0
20
30
40
50
60
70
1.00
0.75
0.50
0.25
0
-0.50
-0.25
-1.00
Lower Limit
Upper Limit
-50
-25
0
25
50
75
100
2.0
1.5
1.0
0.5
0
-1.0
-0.5
-1.5
-2.0
Lower Limit
Upper Limit
TYPICAL PERFORMANCE CURVES
RIPPLE REJECTION
Vs. FREQUENCY(CNR=0µF)
OUTPUT NOISE-VOLTAGE
DENSITY vs. FREQUENCY
VRE3050DS REV. D JULY 2000
TURN-ON AND TURN-OFF
TRANSIENT RESPONSE
JUNCTION TEMP. RISE VS.
OUTPUT CURRENT
Output Current (mA)
CHANGE IN OUTPUT VOLTAGE
VS. INPUT VOLTAGE
CHANGE IN OUTPUT VOLTAGE
VS. OUTPUT CURRENT
Vin(V)
Vout (ppm)
Iout(mA)
Vout (µV)
Frequency (Hz)
Frequency (Hz)
0
4
2
8
6
10
30
20
10
0
40
Vcc = 1
0
V
12
13
9
15
20
0
-20
14
16
11
10
0
-10
10
30
40
50
60
Ripple Rejection (dB)
Junction Temperature
Rise Above Ambient (oC)
Output Noise Density (nV/√Hz)
8
10
2
14
0
-200
-400
12
16
6
4
0
-300
-100
100
200
300
400
1 µs/div
B
A
0V
+10V
A: Vin, 10V/div
B: Vout, 1V/div
1k
10k
90
80
70
60
100
100
10
1k
10k
80
60
40
20
100
100
10
0.1Hz to 10Hz Noise
∆Vout, 1µV/Div
1 Sec/Div
VRE3050DS REV. D JULY 2000
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 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 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. Figure 3 shows the proper connection of the
VRE3050 series voltage references with the optional trim
resistor for initial error and the optional capacitor for noise
reduction.
BASIC CIRCUIT CONNECTION
Figure 3 shows the proper connection of the VRE3050
voltage reference with the optional trim resistor for initial
error and the optional capacitor for noise reduction.
To achieve the specified performance, pay careful
attention to the layout. A low resistance star configuration
will reduce voltage errors, noise pickup, and noise
coupled from the power supply. Commons should be
connected to a single point to minimize interconnect
resistances.
Figure 3 External Connections
86
5
+VOUT
2
+ VIN
4
VRE3050
10kΩ
CN 1µF
Optional Noise
Reduction
Capacitor Optional Fine
Trim Adjustment
6
Figure 2 Functional Block Diagram
8
5
2
4
R1
R2
R3
R4
+
-
Noise ReductionNR8
Voltage reference outputOUT6
External trim input. Leave open if
not used.
TRIM5
GroundGND4
Positive power supply input
Internally connected. Do not use
Vin
N.C.
2
1,3,7
PIN DESCRIPTION
VRE3050DS REV. D JULY 2000
TEMPERATURE PERFORMANCE
The VRE3050 is designed for applications where the
initial error at room temperature and drift over
temperature are important to the user. For many
instrument manufacturers, a voltage reference with a
temperature coefficient less than 1ppm/°Cmakes it
possible to not perform a system temperature calibration,
a slow and costly process.
Of the three TC specification methods (slope, butterfly,
and box), the box method is most commonly used. A box
is formed by the min/max limits for the nominal output
voltage over the operating temperature range. The
equation follows:
This method corresponds more accurately to the
method of test and provides a closer estimate of actual
error than the other methods. The box method
guarantees limits for the temperature error but does not
specify the exact shape and slope of the device under
test.
A designer who needs a 14-bit accurate data
acquisition system over the industrial temperature range
(-40°C to +85°C), will need a voltage reference with a
temperature coefficient (TC) of 1.0ppm/°C if the reference
is allowed to contribute an error equivalent to 1LSB. For
1/2LSB equivalent error from the reference you would
need a voltage reference with a temperature coefficient of
0.5ppm/°C. Figure 4 shows the required reference TC vs.
delta T change from 25°C for resolution ranging from 8
bits to 20 bits.
THERMAL HYSTERISIS
A change in output voltage as a result of a temperature
change. When references experience a temperature
change and return to the initial temperature, they do not
always have the same initial voltage. Thermal hysterisis
is difficult to correct and is a major error source in
systems that experience temperature changes greater
than 25°C. Reference vendors are starting to include this
important specification in their datasheets.
( )
6
minmaxnominal
minmax 10.. •
−•−
=TTVVV
CT
0.01
0.1
1
10
100
1000
10000
1 10 100
20 BIT
18 BIT
16 BIT
14 BIT
12 BIT
10 BIT
8 BIT
ReferenceTC
(ppm/°C)
Reference TC vs. ∆T change from 25°C for 1 LSB change
VRE3050DS REV. D JULY 2000
MECHANICAL SPECIFICATIONS
INCHES MILLIMETER
DIM MIN MAX MIN MAX DIM MIN MAX MIN MAX
A.110 .120 2.794 3.048 D1 .372 .380 9.45 9.65
B.095 .105 2.413 2.667 E.425 .435 10.80 11.05
B1 .021 .027 0.533 0.686 E1 .397 .403 10.08 10.24
C.055 .065 1.397 1.651 E2 .264 .270 6.71 6.86
C1 .012 .020 0.305 0.508 P.085 .095 2.16 2.41
C2 .020 .040 0.508 1.016 S.045 .055 1.14 1.40
D.395 .405 10.03 10.29
INCHES MILLIMETER
D1
D
1
E2 E1 E
A
B
B1
S
P
C1
CC2
VRE3050DS REV. D JULY 2000
MECHANICAL SPECIFICATIONSMECHANICAL SPECIFICATIONS
D1
D
1
E2 E1 E
B
B1
S
P
C1
C
G
INCHES MILLIMETER
DIM MIN MAX MIN MAX DIM MIN MAX MIN MAX
A.170 .180 4.318 4.572 E.425 .435 10.80 11.05
B.095 .105 2.413 2.667 E1 .397 .403 10.08 10.24
B1 .016 .020 0.406 0.508 E2 .264 .270 6.71 6.86
C.008 .011 0.203 0.279 G.290 .310 7.36 7.87
C1 .055 .065 1.397 1.651 L.175 .225 4.46 5.72
D.395 .405 10.03 10.29 P.085 .095 2.16 2.41
D1 .372 .380 9.45 9.65 S.045 .055 1.14 1.40
INCHES MILLIMETER
A
L
