ETC VRE304-6CD

VRE304-6
Low Cost
Precision Reference
THALER CORPORATION • 2015 N. FORBES BOULEVARD • TUCSON, AZ. 85745 • (520) 882-4000
FEATURES
•4.096 V OUTPUT ± 0.409 mV (.01%)
PIN CONFIGURATION
•TEMPERATURE DRIFT: 0.6 ppm/°C
•LOW NOISE: 3µV p-p (0.1-10Hz)
•INDUSTRY STD PINOUT- 8 PIN DIP OR
SURFACE MOUNT PACKAGE
N/C
1
+VIN
2
TEMP
3
GND
4
VRE304-6
TOP
VIEW
8
NOISE
REDUCTION
7
REF. GND
6
VOUT
5
TRIM
•EXCELLENT LINE REGULATION: 6ppm/V Typ.
•OPERATES ON +15V SUPPLY
FIGURE 1
DESCRIPTION
The VRE304-6 is a low cost, high precision
4.096V 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 +4.096V output
with ±0.409 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 VRE304-6 series
the most accurate reference available in the
standard 8 pin DIP package.
For enhanced performance, the VRE304-6 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.
The VRE304-6 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 VRE3046 offers superior performance over monolithic
references.
SELECTION GUIDE
Model
Initial
Error
mV
Temp.
Coeff.
ppm/°C
Temp.
Range
°C
VRE304-6A
VRE304-6B
VRE304-6C
VRE304-6J
VRE304-6K
VRE304-6L
0.41
0.64
0.82
0.41
0.64
0.82
0.6
1.0
2.0
0.6
1.0
2.0
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.
VRE304-6DS REV. D JUN 1999
ELECTRICAL SPECIFICATIONS
VRE304-6
Vps =+15V, T = 25°C, RL = 10KΩ unless otherwise noted.
MODEL
A/J
PARAMETER
MIN
TYP
+13
0
-40
-65
+15
B/K
MAX
C/L
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
V
°C
°C
°C
ABSOLUTE RATINGS
Power Supply
Operating Temp. (A,B,C)
Operating Temp. (J,K,L)
Storage Temperature
Short Circuit Protection
+22
+70
+85
+150
Continuous
*
*
*
*
*
*
OUTPUT VOLTAGE
VRE304-6
(1)
Temp. Sensor Voltage
4.096
630
V
mV
OUTPUT VOLTAGE ERRORS
(2)
Initial Error
Warmup Drift
Tmin - Tmax (3)
Long-Term Stability
Noise (.1-10Hz) (4)
0.41
0.64
1
0.82
2
0.6
3
1.0
6
3
2.0
*
*
*
*
mV
ppm
ppm/ °C
ppm/1000hrs
µVpp
OUTPUT CURRENT
Range
±10
*
*
mA
REGULATION
Line
Load
6
3
10
*
*
*
*
*
*
ppm/V
ppm/mA
OUTPUT ADJUSTMENT
Range
10
POWER SUPPLY CURRENTS
*
mV
(5)
VRE304-6 +PS
NOTES:
*
5
7
*Same as A/J Models.
1. The temp. reference TC is 2.1mV/ °C
2. The specified values are without external trim.
*
*
*
*
mA
4. The specified values are without the external
noise reduction capacitor.
5. The specified values are unloaded.
3. The temperature coefficient is determined by the box
method using the following formula:
Vmax - Vmin
x 106
T.C. =
Vnominal x (Tmax-Tmin)
VRE304-6DS REV. D JUN 1999
TYPICAL PERFORMANCE CURVES
VOUT vs. TEMPERATURE
Temperature oC
VRE304-6A
VOUT vs. TEMPERATURE
Temperature oC
VRE304-6J
QUIESCENT CURRENT VS. TEMP
Temperature oC
VOUT vs. TEMPERATURE
VOUT vs. TEMPERATURE
Temperature oC
VRE304-6B
Temperature oC
VRE304-6C
VOUT vs. TEMPERATURE
Temperature oC
VRE304-6K
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
VOUT vs. TEMPERATURE
Temperature oC
VRE304-6L
PSRR VS. FREQUENCY
Frequency (Hz)
VRE304-6DS REV. D JUN 1999
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 4.096V 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.
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 VRE304-6
series voltage references with the optional trim resistor for
initial error and the optional capacitor for noise reduction.
The VRE304-6 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.
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.
VRE304-6
FIGURE 2
EXTERNAL CONNECTIONS
+ VIN
2
V TEMP OUT
3
8
OPTIONAL
NOISE REDUCTION
CAPACITOR
6
VRE304-6
CN
1µF
5
7
FIGURE 3
+ VOUT
4
10k?
OPTIONAL
FINE TRIM
ADJUSTMENT
REF. GND
VRE304-6DS REV. D JUN 1999
MECHANICAL SPECIFICATIONS
FIGURE 3
INCHES
MILLIMETER
MAX
INCHES
MILLIMETER
DIM
MIN
MAX
MIN
DIM
MIN
MAX
MIN
A
.110
.120
2.794 3.048
D1
.372
.380
9.45
MAX
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
9.65
D
D1
E2 E1
E
1
A
P
C1
B
S
B1
C
C2
VRE304-6DS REV. D JUN 1999
MECHANICAL SPECIFICATIONS
INCHES
MILLIMETER
MILLIMETER
DIM
MIN
MAX
MIN
DIM
MIN
MAX
MIN
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
S
.045
.055
1.14
1.40
9.45
MAX
INCHES
9.65
MAX
D
D1
E2 E1
E
1
P
A
C1
L
C
S
B
G
B1
VRE304-4DS REV. D JUN 1999