CIRRUS VRE204_1

VRE204
VRE204
P r o VRE204
duct Innovation From
Precision Voltage Reference
FEATURES
♦ Very High Accuracy: +4.5 V Output, ±0.8 mV
♦ Extremely Low Drift: 0.74 ppm/°C (-55°C to
+125°C)
♦ Excellent Stability: 6 ppm/1000 Hrs. Typical
♦ Excellent Line Regulation: 6 ppm/V Typical
♦ Wide Supply Range: ±13.5 V to ±22.0 V
♦ Hermetic 20-terminal Ceramic LCC
♦ Military Processing Available
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
DESCRIPTION
VRE204 Series Precision Voltage References provide
ultrastable +4.5 V outputs with up to ±0.8 mV initial
accuracy and temperature coefficient as low as 0.74
ppm/°C over the full military temperature range.
These references are specifically designed to be used
with successive-approximation type Analog-to-Digital
Converters (ADCs). Specify an ADC with exceptional
temperature drift, which can only be as good as the
external reference used. The VRE204 combined with
the right ADC will provide the lowest drift data conversion obtainable.
The VRE204 series is available in the military operating temperature range -55°C to +125°C, and two performance grades. All devices are packaged in 20-terminal LCC ceramic packages for maximum long-term
stability. These “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 4.5 V reference. High-accuracy test and
measurement instrumentation, and transducer excitation are some other applications which can benefit
from the high accuracy of the VRE204.
Figure 1. BLOCK DIAGRAM
11
SELECTION GUIDE
Model
VRE204M
VRE204MA
VRE204DS
www.cirrus.com
Output (V)
Temperature
Operating Range
Volt Deviation (MAX)
+4.5V
+4.5V
-55°C to +125°C
-55°C to +125°C
±0.69mV
±0.60mV
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
20-terminal Ceramic LCC
Package Style HD
NOV 20091
APEX − VRE204DSREVH
VRE204
Product Innovation From
1. CHARACTERISTICS AND SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
VPS =+15V, T = +25°C, RL = 10K Ω UNLESS OTHERWISE NOTED.
Model
M
Parameter
Min
Typ
MA
Max
Min
+13.5
+22
Operating Temperature
-55
Storage Temperature
-65
Typ
Max
Units
*
*
V
+125
*
*
ºC
+150
*
*
ºC
ABSOLUTE MAXIMUM RATINGS
Power Supply
Short Circuit Protection
Continuous
*
+4.5
*
OUTPUT VOLTAGE
VRE204
V
OUTPUT VOLTAGE ERRORS
Initial Error
±890
Warmup Drift
TMIN - TMAX
±800
2
(Note1)
1
690
µV
ppm
600
µV
Long-Term Stability
6
*
ppm/1000hrs.
Noise (0.1 - 10Hz)
3
*
µVpp
OUTPUT CURRENT
Range
±10
*
mA
REGULATION
Line
6
Load
3
10
*
*
*
ppm/V
Range
10
*
mV
Temperature Coefficient
4
*
µV/ºC/mV
ppm/mA
OUTPUT ADJUSTMENT
POWER SUPPLY CURRENT (Note 2)
VRE204 +PS
5
7
*
*
mA
NOTES:
* Same as M Models.
1. Using the box method, the specified value is the maximum deviation from the output voltage at 25°C
over the specified operating temperature range.
2. The specified values are unloaded.
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VRE204DS
VRE204
Product Innovation From
2. TYPICAL PERFORMANCE GRAPHS
VOUT vs. TEMPERATURE
VOUT vs. TEMPERATURE
Temperature oC
VRE204M
Temperature oC
VRE204MA
0.69
-0.69
QUIESCENT CURRENT VS. TEMP
Temperature oC
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Output Current (mA)
PSRR VS. FREQUENCY
Frequency (Hz)
3. THEORY OF OPERATION
The following discussion refers to the block diagram in Figure 1. 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 4.5 V 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.
A nonlinear compensation network of thermistors and resistors 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, the VRE204 series 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.
VRE204DS
3
VRE204
Product Innovation From
4. APPLICATION INFORMATION
The proper connection of the VRE204 series voltage references with the optional trim resistors is shown below. 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 20 ppm. 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.
EXTERNAL CONNECTIONS
3
2
1
20
4
+15V
Ref. Gnd.
PIN CONFIGURATION
NC NC NC VOUT NC
19
18
18 17 16 15 14
5
17
NC 19
13 NC
6
16
NC 20
12 NC
7
15
8
14
9 10
11
12 13
VOUT = +4.5V
10KΩ
NC
1
NC
2
NC
3
VRE204
11 TRIM
TOP VIEW
10 GND
Δ
4
9
5
NC VIN
6
7
REF GND
8
NC NC NC
CONTACTING CIRRUS LOGIC SUPPORT
For all Apex Precision Power product questions and inquiries, call toll free 800-546-2739 in North America.
For inquiries via email, please contact [email protected]
International customers can also request support by contacting their local Cirrus Logic Sales Representative.
To find the one nearest to you, go to www.cirrus.com
IMPORTANT NOTICE
Cirrus Logic, Inc. and its subsidiaries ("Cirrus") believe that the information contained in this document is accurate and reliable. However, the information is subject
to change without notice and is provided "AS IS" without warranty of any kind (express or implied). Customers are advised to obtain the latest version of relevant
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supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus
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does not extend to other copying such as copying for general distribution, advertising or promotional purposes, or for creating any work for resale.
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VRE204DS