CIRRUS VRE202_1

VRE202
VRE202
P r o VRE202
duct Innovation From
Precision Voltage Reference
FEATURES
♦ Very High Accuracy: +2.5 V Output, ±300 µV
♦ Extremely Low Drift: 0.73 ppm/°C (25°C to
+85°C)
♦ Low Warm-up Drift: 1 ppm Typical
♦ Excellent Stability: 6 ppm/1000 Hrs. Typical
♦ Excellent Line Regulation: 6 ppm/V Typical
♦ Hermetic 20-Terminal Ceramic LCC
♦ Military Processing Option
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
VRE202 Series Precision Voltage References provide
ultrastable +2.5 V outputs with ±300 μV initial accuracy
and temperature coefficient as low as 0.73 ppm/°C over
the full military temperature range. This improvement
in accuracy is made possible by a unique, proprietary
multipoint laser compensation technique. Significant
improvements have been made in other performance
parameters as well, including initial accuracy, warmup drift, line regulation, and longterm stability, making
the VRE202 series the most accurate and stable 2.5 V
surface mount references available.
VRE202 devices are available in two operating temperature ranges, -25°C to +85°C and -55°C to +125°C,
and two electrical performance grades. All devices
are packaged in 20-terminal ceramic LCC packages
for maximum long-term stability. “M” versions are
screened for high reliability and quality.
Figure 1. BLOCK DIAGRAM
11
SELECTION GUIDE
Model
VRE202C
VRE202CA
Output (V)
Temperature
Operating Range
Volt Deviation
(MAX)
+2.5V
+2.5V
-25°C to +85°C
-25°C to +85°C
±250µV
±200µV
20-terminal Ceramic LCC
Package Style HD
VRE202DS
www.cirrus.com
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
NOV 20091
APEX − VRE202DSREVI
VRE202
Product Innovation From
1. CHARACTERISTICS AND SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
VPS =+15V, T = +25°C, RL = 10KΩ UNLESS OTHERWISE NOTED.
Grade
C
Parameter
Min
Typ
CA
Max
Min
+13.5
+22
Operating Temperature
-25
Storage Temperature
-65
Typ
Max
Units
*
*
V
+85
*
*
ºC
+150
*
*
ºC
ABSOLUTE MAXIMUM RATINGS
Power Supply
Short Circuit Protection
Continuous
*
+2.5
*
OUTPUT VOLTAGE
VRE202
V
OUTPUT VOLTAGE ERRORS
Initial Error
±350
Warmup Drift
TMIN - TMAX
±300
2
(Note1)
1
250
µV
ppm
200
µV
Long-Term Stability
6
*
ppm/1000hrs.
Noise (0.1 - 10Hz)
1.5
*
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)
VRE202 +PS
5
7
*
*
mA
VRE202 -PS
5
7
*
*
mA
NOTES:
* Same as C 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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VRE202DS
VRE202
Product Innovation From
2. TYPICAL PERFORMANCE CURVES
VOUT vs. TEMPERATURE
VOUT vs. TEMPERATURE
0.25
0.2
-0.25
-0.2
Temperature oC
VRE202CA
Temperature oC
VRE202C
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 V 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 2.5 V output. The gain is determined
by the resistor networks R3 and R4: G=1 + R4/R3. The 6.3 V 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. Then by adjusting
the slope, a very stable voltage over wide temperature ranges is produced. 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, a voltage reference is produced that also has very good long term stability.
VRE202DS
3
VRE202
Product Innovation From
4. APPLICATION INFORMATION
The proper connection of the VRE202 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 VRE202 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
PIN CONFIGURATION
-15V
3
2
NC NC NC VOUT NC
18 17 16 15 14
1
20
4
+15V
5
16
7
15
9 10
11
12 13
13 NC
NC 19
NC 20
17
6
8
Ref. Gnd.
19
18
VOUT = +2.5V
14
10KΩ
NC
1
NC
2
NC
3
12 NC
VRE202
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
information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale
supplied at the time of order acknowledgment, including those pertaining to warranty, indemnification, and limitation of liability. No responsibility is assumed by Cirrus
for the use of this information, including use of this information as the basis for manufacture or sale of any items, or for infringement of patents or other rights of third
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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.
CERTAIN APPLICATIONS USING SEMICONDUCTOR PRODUCTS MAY INVOLVE POTENTIAL RISKS OF DEATH, PERSONAL INJURY, OR SEVERE PROPERTY OR ENVIRONMENTAL DAMAGE (“CRITICAL APPLICATIONS”). CIRRUS PRODUCTS ARE NOT DESIGNED, AUTHORIZED OR WARRANTED TO BE
SUITABLE FOR USE IN PRODUCTS SURGICALLY IMPLANTED INTO THE BODY, AUTOMOTIVE SAFETY OR SECURITY DEVICES, LIFE SUPPORT PRODUCTS OR OTHER CRITICAL APPLICATIONS. INCLUSION OF CIRRUS PRODUCTS IN SUCH APPLICATIONS IS UNDERSTOOD TO BE FULLY AT THE CUSTOMER’S RISK AND CIRRUS DISCLAIMS AND MAKES NO WARRANTY, EXPRESS, STATUTORY OR IMPLIED, INCLUDING THE IMPLIED WARRANTIES OF
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Cirrus Logic, Cirrus, and the Cirrus Logic logo designs, Apex Precision Power, Apex and the Apex Precision Power logo designs are trademarks of Cirrus Logic, Inc.
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VRE202DS