CIRRUS VRE306A

VRE306
VRE306
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Precision Voltage Reference
Features
♦ +6 V Output, ± 0.6 mV (.01%)
♦ Temperature Drift: 0.6 ppm/ºC
♦ Low Noise: 4 μVP-P (0.1-10Hz)
♦ Industry Standard Pinout: 8-pin Surface Mount
Package
♦ Excellent Line Regulation: 6 ppm/V Typical
♦ Output Trim Capability
Applications
The VRE306 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 VRE306 offers superior performance over monolithic references.
DESCRIPTION
The VRE306 is a low cost, high precision +6 V reference. Available in an industry standard 8-pin surface
mount package, the device is ideal for upgrading systems that use lower performance references.
The device provides ultrastable +6 V output with ±0.6
mV (.01%) initial accuracy and a temperature coefficient of 0.6 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 VRE306
series the most accurate reference available in a standard 8-pin SMT package.
For enhanced performance, the VRE306 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.
Figure 1. BLOCK DIAGRAM
Selection Guide
Model
VRE306A
VRE306C
Initial Error Temp. Coeff.
(mV)
(ppm/ºC)
±0.6
±1.2
0.6
2.0
Temp. Range
(ºC)
0ºC to +70ºC
0ºC to +70ºC
8-pin Surface Mount
Package Style GD
VRE306DS
http://www.cirrus.com
Copyright
© Cirrus
Logic, Inc. 2009
(All Rights Reserved)
MAR 2009
APEX − VRE306DSREVC
VRE306
P r o d u c t I n n o v a t i o nF r o m
1. Characteristics and Specifications
ELECTRICAL Specifications
Vps =±15V, T = +25ºC, RL = 10KΩ Unless Otherwise Noted.
Model
VRE306A
Parameter
VRE306C
Min
Typ
Max
Min
Typ
Max
Units
±14
±15
±16
*
*
*
V
+70
*
*
ºC
+150
*
*
ºC
ABSOLUTE MAXIMUM RATINGS
Power Supply
Operating Temperature (A,C)
0
Storage Temperature
-65
Short Circuit Protection
Continuous
*
VRE306
+6.0
*
V
Temp. Sensor Voltage (Note 1)
630
*
mV
OUTPUT VOLTAGE
OUTPUT VOLTAGE ERRORS
Initial Error
(Note 2)
±0.6
Warmup Drift
±1.2
1
TMIN - TMAX
3
(Note3)
Noise (0.1 - 10Hz)
ppm
0.6
Long-Term Stability
(Note 4)
mV
2.0
ppm/ºC
6
*
ppm/1000hrs.
4
*
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)
VRE306 +PS
5
7
*
*
mA
NOTES:
* Same as A Models.
1. The temp. reference TC is 2.1 mV/ 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.
VRE306DS
VRE306
P r o d u c t I n n o v a t i o nF r o m
2. TYPICAL PERFORMANCE CURVES
VOUT vs. TEMPERATURE
VOUT vs. TEMPERATURE
Temperature oC
VRE306A
QUIESCENT CURRENT VS. TEMP
Temperature oC
VRE306C
JUNCTION TEMP. RISE VS. OUTPUT CURRENT
Temperature oC
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 6.0V 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.
VRE306DS
VRE306
P r o d u c t I n n o v a t i o nF r o m
The proper connection of the VRE306 series voltage references with the optional trim resistor for initial error and
the optional capacitor for noise reduction is shown below. The VRE306 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.
PIN CONFIGURATION
EXTERNAL CONNECTIONS
+ VIN
V TEMP OUT
2
OPTIONAL
NOISE REDUCTION
CAPACITOR
CN
1µF
1
+VIN
2
TEMP
3
GND
4
3
8
+ VOUT
6
VRE306
10kW
5
7
N/C
VRE306
TOP
VIEW
8
NOISE
REDUCTION
7
REF. GND
6
VOUT
5
TRIM
OPTIONAL
FINE TRIM
ADJUSTMENT
4
REF. GND
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
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VRE306DS