CIRRUS VRE302KS

VRE302
VRE302
P r o VRE302
duct Innovation From
Precision Voltage Reference
FEATURES
♦ +2.5 V Output, ± 0.40 mV (.016%)
♦ Temperature Drift: 1.0 ppm/ºC
♦ Low Noise: 1.5 μVP-P (0.1-10Hz)
♦ Industry Standard Pinout: 8-pin DIP or Surface
Mount Package
♦ Excellent Line Regulation: 6 ppm/V Typical
♦ Output Trim Capability
APPLICATIONS
The VRE302 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 VRE302 offers superior performance over monolithic references.
DESCRIPTION
The VRE302 is a low cost, high precision +2.5 V 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 +2.5 V output with
±0.40 mV (.016%) initial accuracy and a temperature
coefficient of 1.0 ppm/ºC. This improvement in accuracy is made possible by a unique, patented multipoint
laser compensation technique. 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
VRE302 series the most accurate reference available
in the standard 8-pin DIP package.
For enhanced performance, the VRE302 has an external trim option for users who want less than 0.01%
initial error. A reference ground pin is provided to eliminate socket contact resistance errors.
Figure 1. BLOCK DIAGRAM
SELECTION GUIDE
Model
VRE302CS
VRE302CD
VRE302JS
VRE302JD
VRE302KS
VRE302LS
VRE302LD
VRE302DS
Initial Error Temp. Coeff.
(mV)
(ppm/ºC)
0.60
0.60
0.40
0.40
0.50
0.60
0.60
www.cirrus.com
2.2
2.2
1.0
1.0
2.0
2.2
2.2
Temp. Range
(ºC)
Package
Options
0ºC to +70ºC
0ºC to +70ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
SMT8 (GD)
DIP8 (KD)
SMT8 (GD)
DIP8 (KD)
SMT8 (GD)
SMT8 (GD)
DIP8 (KD)
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
8-pin Surface Mount
8-pin DIP
Package Style GD
Package Style KD
DEC 20091
APEX − VRE302DSREVI
VRE302
Product Innovation From
1. CHARACTERISTICS AND SPECIFICATIONS
ELECTRICAL SPECIFICATIONS
VPS =±15V, T = +25ºC, RL = 10KΩ Unless Otherwise Noted.
Model
A/J
Parameter
Min
K
C/L
Typ
Max
Min
Typ
Max
Min
Typ
Max
Units
±15
±22
*
*
*
*
*
*
V
+70
*
*
*
*
ºC
ABSOLUTE MAXIMUM RATINGS
Power Supply
±13.5
Operating Temperature (A,B)
0
Operating Temperature (K)
-40
+85
*
*
*
*
ºC
Storage Temperature
-65
+150
*
*
*
*
ºC
Short Circuit Protection
Continuous
*
*
VRE302
+2.5
*
*
V
Temp. Sensor Voltage (Note 1)
630
*
*
mV
OUTPUT VOLTAGE
OUTPUT VOLTAGE ERRORS
Initial Error
(Note 2)
0.40
Warmup Drift
TMIN - TMAX
1
(Note3)
2
1.0
Long-Term Stability
Noise (0.1 - 10Hz)
0.50
(Note 4)
0.60
mV
2.2
ppm/ºC
3
2.0
ppm
6
*
*
ppm/1000hrs.
1.5
*
*
µVpp
OUTPUT CURRENT
Range
±10
*
mA
REGULATION
Line
6
10
*
*
*
*
ppm/V
Load
3
*
*
ppm/mA
10
*
*
mV
OUTPUT ADJUSTMENT
Range
POWER SUPPLY CURRENT (Note 5)
VRE302 +PS
NOTES:
2
5
7
*
*
*
*
mA
* Same as A Models.
1. The temp. reference TC is 2.1mV/ ºC
2. The specified values are without external trim.
3. The temperature coefficient is determined by the box method using the following formula:
VMAX – VMIN
T.C. =
x 106
VNOMINAL x (TMAX – TMIN)
4. The specified values are without the external noise reduction capacitor.
5. The specified values are unloaded.
VRE302DS
VRE302
Product Innovation From
2. TYPICAL PERFORMANCE CURVES
VOUT vs. TEMPERATURE
VOUT vs. TEMPERATURE
Temperature oC
VRE302J
Temperature oC
VRE302C
VOUT vs. TEMPERATURE
VOUT vs. TEMPERATURE
Temperature oC
VRE302K
Temperature oC
VRE302L
POSITIVE OUTPUT (TYP)
QUIESCENT CURRENT VS. TEMP JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Temperature oC
VRE302DS
Output Current (mA)
PSRR VS. FREQUENCY
Frequency
(Hz)
3
VRE302
Product Innovation From
3. THEORY OF OPERATION
The following discussion refers to the schematic 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 non-inverting 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. By adjusting the
slope, a very stable voltage is produced 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 proper connection of the VRE302 series voltage references with the optional trim resistor for initial error is
shown below. The VRE302 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 20 ppm. 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.
EXTERNAL CONNECTIONS
+ VIN
V TEMP OUT
2
OPTIONAL
NOISE REDUCTION
CAPACITOR
CN
1µF
3
8
6
VRE302
5
4
7
+ VOUT
10kΩ
OPTIONAL
FINE TRIM
ADJUSTMENT
REF. GND
PIN CONFIGURATION
4
N.C.
1
+VIN
2
TEMP
3
GND
4
VRE302
TOP
VIEW
8
NOISE
7
REF. GND
6
VOUT
5
TRIM
VRE302DS
Product Innovation From
VRE302
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
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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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VRE302DS
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