CIRRUS VRE3025JS

VRE3025
VRE3025
P r o d u c t IInnnnoovvaa t i o n FFr roomm
Precision Voltage Reference
Features
DESCRIPTION
Applications
The device provides ultrastable +2.5 V output with
±0.25 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
VRE3025 series the most accurate reference available.
The VRE3025 is a low cost, high precision +2.5 V reference that operates from +10 V. The device features
a buried zener for low noise and excellent long term
stability. Packaged in either an 8-pin DIP or SMT option, the device is ideal for high resolution data conversion systems.
♦ +2.5 V Output, ± 0.25 mV (.01%)
♦ Temperature Drift: 0.6 ppm/ºc
♦ Low Noise: 1.5 μVP-P (0.1Hz-10Hz)
♦ Low Thermal Hysteresis: 1 ppm Typical
♦ ±15 mA Output Source and Sink Current
♦ Excellent Line Regulation: 5 ppm/V Typical
♦ Optional Noise Reduction and Voltage Trim
♦ Industry Standard Pinout: 8-pin DIP or
Surface Mount Package
The VRE3025 is recommended for use as a reference for 14, 16, or 18 bit data converters which
require an external precision reference. The device is also ideal for calibrating scale factor on
high resolution data converters. The VRE3025
offers superior performance over monolithic references.
For enhanced performance, the VRE3025 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.
Figure 1. BLOCK DIAGRAM
8
2
+
6
-
R1
R4
R2
5
R3
4
Selection Guide
Model
Initial
Error
(mV)
Temp.
Coeff.
(ppm/ºC)
Temp. Range
(ºC)
Package
Options
VRE3025AS
VRE3025AD
VRE3025BS
VRE3025BD
VRE3025CS
VRE3025CD
VRE3025JS
VRE3025JD
VRE3025LS
0.250
0.250
0.375
0.375
0.500
0.500
0.250
0.250
0.500
0.6
0.6
1.0
1.0
2.0
2.0
0.6
0.6
2.0
0ºC to +70ºC
0ºC to +70ºC
0ºC to +70ºC
0ºC to +70ºC
0ºC to +70ºC
0ºC to +70ºC
-40ºC to +85ºC
-40ºC to +85ºC
-40ºC to +85ºC
SMT8 (GF)
DIP8 (KD)
SMT8 (GF)
DIP8 (KD)
SMT8 (GF)
DIP8 (KD)
SMT8 (GF)
DIP8 (KD)
SMT8 (GF)
VRE3025DS
http://www.cirrus.com
8-pin Surface Mount
Package Style GF
Copyright © Cirrus Logic, Inc. 2009
(All Rights Reserved)
8-pin DIP
Package Style KD
JUN 20091
APEX − VRE3025DSREVG
VRE3025
P r o d u c t I n n o v a t i o nF r o m
1. Characteristics and Specifications
ABSOLUTE MAXIMUM RATINGS
Power Supply............................ -0.3V to +40V
OUT, TRIM................................. -0.3V to +12V
NR............................................... -0.3V to +6V
Operating Temp. (A,B,C)............ 0ºC to +70ºC
Operating Temp. (J,L).............. -40ºC to +85ºC
Out Short Circuit to GND Duration (VIN< 12V)............ Continuous
Out Short Circuit to GND Duration (VIN< 40V)......................5 sec
Out Short Circuit to IN Duration (VIN< 12V)................ Continuous
Continuous Power Dissipation (TA = +70ºC)..................... 300mW
Storage Temperature.......................................... -65ºC to +150ºC
Lead Temperature (soldering,10 sec)............................... +250ºC
ELECTRICAL Specifications
Vps =±15V, T = +25ºC, RL = 10KΩ Unless Otherwise Noted.
Parameter
Input Voltage
Output Voltage (Note 1)
Symbol
VOUT
Trim Adjustment Range
Supply Current
Typ
Max
Units
+2.4998
+36
V
+2.500
+2.5003
VRE3025B
+2.4996
+2.500
+2.5004
VRE3025C/L
+2.4995
+2.500
+2.5005
0.3
0.6
+8
V
VRE3025B
0.5
1.0
VRE3025C/L
1.0
2.0
∆VOUT
Figure 3
±2.5
TON
To 0.01% of final value
2
µs
0.1Hz < f < 10Hz
1.5
µVp-p
10Hz < f < 1kHz
1.5
en
Temperature Hysterisis
Long Term Stability
VRE3025A/J
VRE3025A/J
TCVOUT
Output Noise Voltage
Min
VIN
Output Voltage
Temperature Coefficient
(Note 2)
Turn-On Settling Time
Conditions
Note 4
∆VOUT/t
Load Regualtion
∆VOUT/ ∆IOUT
Line Regulation
∆VOUT/ ∆VIN
mV
3.0
µVRMS
1
ppm
6
ppm/1000hrs.
3.5
4.0
Sourcing: 0mA ≤ IOUT ≤ 15mA
8
12
Sinking: -15mA ≤ IOUT ≤ 0mA
8
12
8V ≤ VIN ≤ 10V
25
35
10V ≤ VIN ≤ 18V
5
10
IIN
ppm/ºC
mA
ppm/mA
ppm/V
NOTES:
1. The specified values are without external trim.
2. The temperature coefficient is determined by the box method. See discussion on temperature performance.
3. Line and load regulation are measured with pulses and do not include voltage changes due to temperature.
4. Hysterisis over the operating temperature range.
2
VRE3025DS
VRE3025
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
1.00
0.75
0.75
0.50
0.50
0.50
0
-0.25
Low
Loer
wer Limi
Lim itt
-0.50
Up per
0.25
0
-0.25
Lo wer
-0.50
-0.75
Lim it
∆Vout (mV)
Uper
per LiLim
it
Upp
mit
0.25
Lim it
0
20
30 40 50 60
Temperature (oC)
VRE3025A
-1.00
70
0
2.0
1.5
1.5
1.0
1.0
Up per
0.5
Lim it
0
-0.5
Lo wer
-1.0
Lim it
-1.5
-2.0
-50 -25 0
25 50 75 100
Temperature (oC)
VRE3025J
3.0
30 40 50 60
Temperature (oC)
VRE3025C
70
Lo wer
Lim it
0
-0.5
-1.5
-2.0
-50 -25
25 50 75 100
0
Temperature (oC)
VRE3025L
OUTPUT IMPEDIANCE
VS. FREQUENCY
6.0
4.0
2.0
0
0
5 10 15 20 25 30 35 40
Supply Voltage (V)
-50
JUNCTION TEMP. RISE VS.
OUTPUT CURRENT
40
Junction Temperature
Rise Above Ambient (oC)
20
Output Impediance ( Ω)
Quiescent Current (mA)
4.0
30
20
c
Vc
=
10
V
10
0
Lim it
8.0
5.0
0
Up per
QUIESCENT CURRENT VS. TEMP
0
VRE3025DS
4
8
6
2
Output Current (mA)
100
Ripple Rejection (dB)
Supply Current (mA)
6.0
0
0.5
-1.0
SUPPLY CURRENT
VS. SUPPLY VOLTAGE
Lim it
VOUT vs. TEMPERATURE
2.0
∆Vout (mV)
∆Vout (mV)
VOUT vs. TEMPERATURE
Lo wer
0
-1.00
70
Lim it
-0.25
-0.50
20 30 40 50 60
Temperature (oC)
VRE3025B
Up per
0.25
-0.75
-0.75
-1.00
VOUT vs. TEMPERATURE
1.00
0.75
∆Vout (mV)
∆Vout (mV)
1.00
10
0
50
100
Temperature (oC)
Frequency (Hz)
RIPPLE REJECTION
Vs. FREQUENCY(CNR=0µF)
TURN-ON AND TURN-OFF
TRANSIENT RESPONSE
+10V
A
0V
90
80
B
70
60
10
1k
100
Frequency (Hz)
10k
A: Vin, 10V/div
B: Vout, 1V/div
1 µs/div
3
OUTPUT NOISE-VOLTAGE
DENSITY vs. FREQUENCY
40
30
20
10
10
1k
100
10k
Frequency (Hz)
CHANGE IN OUTPUT VOLTAGE
VS. OUTPUT CURRENT
400
CHANGE IN OUTPUT VOLTAGE
VS. INPUT VOLTAGE
60
300
50
200
40
Vout (ppm)
50
P r o d u c t I n n o v a t i o nF r o m
Vout (µV)
Output Noise Density (nV/√Hz)
VRE3025
100
0
-100
30
20
10
-200
0
-300
-10
-400
0 2
4
6
8 10 12 14 16
Iout(mA)
-20
0
9 10 11 12 13 14 15 16
Vin(V)
∆Vout, 0.5µV/Div
0.1Hz to 10Hz Noise
1 Sec/Div
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 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, 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 VRE3025 series voltage references with the optional trim resistor for initial error and the
optional capacitor for noise reduction is shown below.
4
VRE3025DS
VRE3025
P r o d u c t I n n o v a t i o nF r o m
EXTERNAL CONNECTIONS
+ VIN
Optional Noise
Reduction
Capacitor
2
8
6
+ VOUT
VRE3025
CN 1µF
4
5
10kΩ
Optional Fine
Trim Adjustment
PIN DESCRIPTIONS
1, 3, 7
N. C.
Internally connected. Do not use
2
VIN
Positive power supply input
4
GND
Ground
5
TRIM
External trim input. Leave open if not
used.
6
OUT
Voltage reference output
8
NR
Noise Reduction
4. BASIC CIRCUIT CONNECTION
To achieve the specified performance, pay careful attention to the layout. A low resistance star configuration will
reduce voltage errors, noise pickup, and noise coupled from the power supply. Commons should be connected to
a single point to minimize interconnect resistances.
5. TEMPERATURE PERFORMANCE
The VRE3025 is designed for applications where the initial error at room temperature and drift over temperature
are important to the user. For many instrument manufacturers, a voltage reference with a temperature coefficient
less than 1 ppm/°C makes it possible to not have to perform a system temperature calibration, a slow and costly
process.
Of the three TC specification methods (slope, butterfly, and box), the box method is used commonly used. A box
is formed by the min/max limits for the nominal output voltage over the operating temperature range. The equation
follows:
VMAX – VMIN
T.C. =
x 106
VNOMINAL x (TMAX – TMIN)
This method corresponds more accurately to the method of test and provides a closer estimate of actual error than
the other methods. The box method guarantees limits for the temperature error but does not specify the exact shape
and slope of the device under test.
A designer who needs a 14-bit accurate data acquisition system over the industrial temperature range (-40°C to
+85°C), will need a voltage reference with a temperature coefficient (TC) of 1.0 ppm/°C if the reference is allowed
to contribute an error equivalent to 1LSB. For 1/2LSB equivalent error from the reference you would need a voltage reference with a temperature coefficient of 0.5 ppm/°C. Figure 4 shows the required reference TC vs. delta T
change from 25°C for resolution ranging from 8 bits to 20 bits.
VRE3025DS
5
VRE3025
P r o d u c t I n n o v a t i o nF r o m
10000
Reference TC (ppm/ºC)
1000
100
8 BIT
10
10 BIT
12 BIT
1
14 BIT
16 BIT
0.1
18 BIT
0.01
20 BIT
1
10
100
Reference TC vs. ∆T change from 25°C for 1 LSB change
6. THERMAL HYSTERISIS
A change in output voltage as a result of a temperature change. When references experience a temperature change
and return to the initial temperature, they do not always have the same initial voltage. Thermal hysterisis is difficult to
correct and is a major error source in systems that experience temperature changes greater than 25°C. Reference
vendors are starting to include this important specification in their datasheets.
PIN CONFIGURATION
6
N/C
1
+VIN
2
N/C
3
GND
4
VRE3025
TOP
VIEW
8
NOISE
REDUCTION
7
N/C
6
VOUT
5
TRIM
VRE3025DS
P r o d u c t I n n o v a t i o nF r o m
VRE3025
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
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VRE3025DS
7