REF3012, REF3020, REF3025, REF3030, REF3033, REF3040
SBVS032I – MARCH 2002 – REVISED JULY 2022
REF30xx 50-ppm/°C Max, 50-μA, CMOS Voltage Reference in SOT-23-3
1 Features
3 Description
•
•
•
•
•
•
The REF30xx is a precision, low-power, low-dropout
voltage, reference family available in a tiny 3-pin
SOT-23 package. The REF30xx offers excellent
temperature drift and initial accuracy while operating
at a quiescent current of 42 µA (typical).
microSize Package: SOT-23-3
Low Dropout: 1 mV
High Output Current: 25 mA
High Accuracy: 0.2%
Low IQ: 42 µA (Typical)
Excellent Specified Drift Performance:
– 50 ppm/°C (Maximum) From 0°C to 70°C
– 75 ppm/°C (Maximum) From –40°C to +125°C
2 Applications
Temperature and Pressure Transmitters
Portable, Battery-Powered Equipment
Data Acquisition Systems
Medical Equipment
Handheld Test Equipment
The REF30xx operates with supplies within 1 mV of
output voltage under zero-load conditions. Engineers
can use the low dropout, small size, and low power
consumption of the REF30xx in portable and batterypowered applications.
Device Information
PART NUMBER
REF30xx
PACKAGE
BODY SIZE (NOM)
SOT-23 (3)
2.92 mm × 1.30 mm
350
3.3 V
REF3033
V+
+ 1 μF to
10 μF
VREF
0.1 μF
VIN
VCC
ADS7822
+In
–In
GND
CS
VS
+
300
GND
5Ω
1 μF to 10 μF
Microcontroller
DOUT
DCLOCK
Dropout Voltage (mV)
•
•
•
•
•
The low power consumption and the relatively high
precision make the REF30xx very attractive for looppowered industrial applications such as pressure and
temperature transmitter applications. The REF30xx
is easy to use in intrinsically safe and explosionproof applications because it does not require a load
capacitor to be stable. The REF30xx is specified over
the extended industrial temperature range of –40°C to
+125°C.
250
200
150
100
50
Copyright © 2016, Texas Instruments Incorporated
Typical Application
0
0
5
10
15
20
25
30
Load Current (mA)
Dropout Voltage vs Load Current
An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
REF3012, REF3020, REF3025, REF3030, REF3033, REF3040
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SBVS032I – MARCH 2002 – REVISED JULY 2022
Table of Contents
1 Features............................................................................1
2 Applications..................................................................... 1
3 Description.......................................................................1
4 Revision History.............................................................. 2
5 Device Comparison Table...............................................3
6 Pin Configuration and Functions...................................3
7 Specifications.................................................................. 4
7.1 Absolute Maximum Ratings........................................ 4
7.2 ESD Ratings............................................................... 4
7.3 Recommended Operating Conditions.........................4
7.4 Thermal Information....................................................4
7.5 Electrical Characteristics.............................................5
7.6 Typical Characteristics................................................ 7
8 Detailed Description...................................................... 11
8.1 Overview................................................................... 11
8.2 Functional Block Diagram......................................... 11
8.3 Feature Description...................................................11
8.4 Device Functional Modes..........................................13
9 Application and Implementation.................................. 15
9.1 Application Information............................................. 15
9.2 Typical Application.................................................... 15
10 Power Supply Recommendations..............................17
11 Layout........................................................................... 17
11.1 Layout Guidelines................................................... 17
11.2 Layout Example...................................................... 17
12 Device and Documentation Support..........................18
12.1 Documentation Support.......................................... 18
12.2 Related Links.......................................................... 18
12.3 Receiving Notification of Documentation Updates..18
12.4 Support Resources................................................. 18
12.5 Trademarks............................................................. 18
12.6 Electrostatic Discharge Caution..............................18
12.7 Glossary..................................................................18
13 Mechanical, Packaging, and Orderable
Information.................................................................... 18
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision H (February 2018) to Revision I (July 2022)
Page
• Updated the numbering format for tables, figures, and cross-references throughout the document..................1
Changes from Revision G (November 2015) to Revision H (February 2018)
Page
• Changed section header From: REF33xx (REF3312, REF3318, REF3320, REF3325, REF3330, REF3333)
To: REF30xx (REF3012, REF3020, REF3025, REF3030, REF30333, REF3040) in the Section 7.5 ...............5
• Added turnon settling time TYP value of 120 µs (deleted by mistake in the previous revision) ........................ 5
• Added NOTE to the Section 9 section ............................................................................................................. 15
Changes from Revision F (August 2008) to Revision G (November 2015)
Page
• Added Device Information, ESD Ratings, Recommended Operating Conditions, and Thermal Information
tables.................................................................................................................................................................. 1
• Added Detailed Description, Applications and Implementation, Power-Supply Recommendations, Layout,
Device and Documentation Support, and Mechanical, Packaging, and Orderable Information sections...........1
• Changed text in Description section .................................................................................................................. 1
• Deleted thermal resistance parameter in Electrical Characteristics; see new Thermal Information table.......... 5
• Moved temperature parameters from Electrical Characteristics to Recommended Operating Conditions.........5
2
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5 Device Comparison Table
PART NUMBER
VOLTAGE (V)
REF3012
1.25
REF3020
2.048
REF3025
2.5
REF3030
3.0
REF3033
3.3
REF3040
4.096
6 Pin Configuration and Functions
IN
1
3
OUT
GND
2
Not to scale
Figure 6-1. DBZ Package 3-Pin SOT-23 Top View
Table 6-1. Pin Functions
PIN
NO.
1
NAME
I/O
IN
Input
2
OUT
Output
3
GND
—
DESCRIPTION
Input supply voltage
Reference output voltage
Ground
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SBVS032I – MARCH 2002 – REVISED JULY 2022
7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)
MIN
Supply voltage, V+ to V–
Output short-circuit
current(2)
–40
Junction temperature
Storage temperature, Tstg
(2)
UNIT
7.0
V
Continuous
Operating temperature
(1)
MAX
–65
125
°C
150
°C
150
°C
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress
ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under
Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device
reliability.
Short circuit to ground.
7.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/JEDEC
JS-001(1)
UNIT
±4000
Charged-device model (CDM), per JEDEC specification JESD22-C101(2)
V
±1500
JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
7.3 Recommended Operating Conditions
at TA = 25°C, VIN = 5 V, and ILOAD = 0 mA (unless otherwise noted)
MIN
VIN
Input voltage
ILOAD
Load current
TA
Operating temperature
(1)
NOM
MAX
UNIT
VREF + 0.05(1)
5.5
V
25
mA
–40
125
°C
For IL > 0, see Section 7.6. Minimum supply voltage for REF3012 is 1.8 V .
7.4 Thermal Information
REF30xx
THERMAL METRIC(1)
DBZ (SOT-23)
UNIT
3 PINS
RθJA
Junction-to-ambient thermal resistance
297.3
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
128.5
°C/W
RθJB
Junction-to-board thermal resistance
91.7
°C/W
ψJT
Junction-to-top characterization parameter
12.8
°C/W
ψJB
Junction-to-board characterization parameter
90.3
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
°C/W
(1)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
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7.5 Electrical Characteristics
at TA = 25°C, VIN = 5 V, and ILOAD = 0 mA (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
1.2475
1.25
1.2525
UNIT
REF3012 (1.25 V)(1)
VOUT
Output voltage
Initial accuracy
V
0.2%
Output voltage noise
Line regulation
f = 0.1 Hz to 10 Hz
14
μVPP
f = 10 Hz to 10 kHz
42
µVrms
1.8 V ≤ VIN ≤ 5.5 V
60
190
2.048
2.052
µV/V
REF3020 (2.048 V)
VOUT
Output voltage
2.044
Initial accuracy
V
0.2%
Output voltage noise
Line regulation
f = 0.1 Hz to 10 Hz
23
μVPP
f = 10 Hz to 10 kHz
65
µVrms
VREF + 50 mV ≤ VIN ≤ 5.5 V
110
290
2.50
2.505
µV/V
REF3025 (2.5 V)
VOUT
Output voltage
2.495
Initial accuracy
V
0.2%
Output voltage noise
Line regulation
f = 0.1 Hz to 10 Hz
28
μVPP
f = 10 Hz to 10 kHz
80
µVrms
VREF + 50 mV ≤ VIN ≤ 5.5 V
120
325
3.0
3.006
µV/V
REF3030 (3.0 V)
VOUT
Output voltage
2.994
Initial accuracy
V
0.2%
Output voltage noise
Line regulation
f = 0.1 Hz to 10 Hz
33
μVPP
f = 10 Hz to 10 kHz
94
µVrms
VREF + 50 mV ≤ VIN ≤ 5.5 V
120
375
3.30
3.306
µV/V
REF3033 (3.3 V)
VOUT
Output voltage
3.294
Initial accuracy
V
0.2%
Output voltage noise
Line regulation
f = 0.1 Hz to 10 Hz
36
μVPP
f = 10 Hz to 10 kHz
105
µVrms
VREF + 50 mV ≤ VIN ≤ 5.5 V
130
400
4.096
4.104
µV/V
REF3040 (4.096 V)
VOUT
Output voltage
4.088
Initial accuracy
V
0.2%
Output voltage noise
Line regulation
Copyright © 2022 Texas Instruments Incorporated
f = 0.1 Hz to 10 Hz
45
μVPP
f = 10 Hz to 10 kHz
128
µVrms
VREF + 50 mV ≤ VIN ≤ 5.5 V
160
410
µV/V
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7.5 Electrical Characteristics (continued)
at TA = 25°C, VIN = 5 V, and ILOAD = 0 mA (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
0°C ≤ TA ≤ 70°C
20
50
–30°C ≤ TA ≤ +85°C
28
60
–40°C ≤ TA ≤ +85°C
30
65
–40°C ≤ TA ≤ +125°C
35
75
0000h to 1000h
24
1000h to 2000h
15
UNIT
REF30xx (REF3012, REF3020, REF3025, REF3030, REF30333, REF3040)
dVOUT/dT
Output voltage temperature drift(2)
Long-term stability
0 mA < ILOAD < 25 mA, VIN = VREF +
500 mV(1)
ΔVO(ΔIL)
Load regulation(3)
dT
Thermal hysteresis(4)
VIN – VOUT
Dropout voltage
ISC
Short-circuit current
Turnon settling time
To 0.1% with CL = 1 μF
ppm/°C
ppm
3
100
µV/mA
25
100
ppm
1
50
mV
45
mA
120
µs
POWER SUPPLY
IQ
(1)
(2)
(3)
(4)
6
42
Quiescent current
–40°C ≤ TA ≤ +125°C
50
59
μA
The minimum supply voltage for the REF3012 is 1.8 V.
Box method used to determine over temperature drift.
Typical value of load regulation reflects measurements using a force and sense contacts; see Section 8.3.6 section.
Thermal hysteresis procedure explained in more detail in Section 8.3.2 section.
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7.6 Typical Characteristics
50
100
45
90
40
80
35
70
Number of Units
Number of Units
at TA = 25°C, VIN = 5 V, and REF3025 used for typical characteristics (unless otherwise noted)
30
25
20
15
60
50
40
30
10
20
5
10
0
0
5
10 15 20 25 30 35 40 45 50 55 60 65
5
10 15 20 25 30 35 40 45 50 55 60 65
Drift (ppm/°C)
Drift (ppm/°C)
0°C to 70°C
–40°C to +125°C
Figure 7-1. Temperature Drift
Figure 7-2. Temperature Drift
35
Maximum Load Current (mA)
2.502
Output Voltage (V)
2.500
2.498
2.496
2.494
2.492
30
25
20
15
10
5
2.490
-40
0
-20
20
40
60
80
100
120
140
-40
-20
0
40
60
80
100
120
140
Figure 7-4. Maximum Load Current vs Temperature
Figure 7-3. Output Voltage vs Temperature
6
60
5
50
4
40
IQ (μA)
Load Regulation (μV/mA)
20
Temperature (°C)
Temperature (°C)
3
30
2
20
1
10
0
0
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
Figure 7-5. Load Regulation vs Temperature
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140
-40
-20
0
20
40
60
80
100
120
140
Temperature (°C)
Figure 7-6. Quiescent Current vs Temperature
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7.6 Typical Characteristics (continued)
at TA = 25°C, VIN = 5 V, and REF3025 used for typical characteristics (unless otherwise noted)
100
150
Output Impedance (dB)
Line Regulation (μV/V)
200
100
50
0
10
1
0.1
0.01
-50
-40
0
-20
20
40
60
80
100
120
1
140
10
100
10k
100k
Figure 7-8. Output Impedance vs Frequency
Figure 7-7. Line Regulation vs Temperature
2.500010
80
2.500000
70
2.499990
Output Voltage (V)
90
60
PSRR (dB)
1k
Frequency (Hz)
Temperature (°C)
50
40
30
2.499980
2.499970
2.499960
2.499950
2.499940
20
2.499930
10
2.499920
0
1
10
100
1k
10k
2.5
100k
3
3.5
4
4.5
5
5.5
6
Supply (V)
Frequency (Hz)
No Load
Figure 7-9. Power-Supply Rejection Ratio vs Frequency
2.500200
2.500010
2.500100
2.500000
2.500000
2.499990
Output Voltage (V)
Output Voltage (V)
Figure 7-10. Output Voltage vs Supply Voltage
2.499900
2.499800
2.499700
2.499600
2.499500
2.499980
2.499970
2.499960
2.499950
2.499940
2.499400
2.499930
2.499300
2.5
3
3.5
4
4.5
5
5.5
Supply (V)
ILOAD = 25 mA
6
0
5
10
15
20
25
30
Load Current (mA)
Figure 7-12. Output Voltage vs Load Current
Figure 7-11. Output Voltage vs Supply Voltage
8
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7.6 Typical Characteristics (continued)
3 V/div
VIN
5 V/div
VIN
1 V/div
VOUT
1 V/div
at TA = 25°C, VIN = 5 V, and REF3025 used for typical characteristics (unless otherwise noted)
VOUT
40 ms/div
10 ms/div
CL = 0, 3-V startup
CL = 0, 5-V startup
Figure 7-14. Step Response
IL = 1 mA
VIN
IL = 0 mA
20 mV/div
50 mV/div
500 mV/div
Figure 7-13. Step Response
VOUT
VOUT
10 ms/div
10 ms/div
Figure 7-15. Line Transient Response
CL = 0
Figure 7-16. 0-mA to 1-mA Load Transient
IL = 5 mA
IL = 6 mA
20 mV/div
20 mV/div
IL = 0 mA
VOUT
10 ms/div
CL = 0
Figure 7-17. 0-mA to 5-mA Load Transient
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IL = 0 mA
VOUT
40 ms/div
CL = 1 μF
Figure 7-18. 1-mA to 6-mA Load Transient
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7.6 Typical Characteristics (continued)
at TA = 25°C, VIN = 5 V, and REF3025 used for typical characteristics (unless otherwise noted)
IL = 25 mA
10 mV/div
20 mV/div
IL = 1 mA
VOUT
1.0 s/div
100 ms/div
Figure 7-20. 0.1-Hz to 10-Hz Noise
CL = 1 μF
Figure 7-19. 1-mA to 25-mA Load Transient
80
Absolute Output Voltage Drift (ppm)
Absolute Output Voltage Drift (ppm)
80
70
60
50
40
30
20
10
70
60
50
40
30
20
10
0
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000
0
0
100
200
300
400
500
600
700
800
900 1000
Time (hours)
Time (hours)
Figure 7-21. Long-Term Stability: 0 to 1000 Hours
Figure 7-22. Long-Term Stability: 1000 to 2000 Hours
Absolute Output Voltage Drift (ppm)
80
70
60
50
40
30
20
10
0
0
200
400
600
800 1000 1200 1400 1600 1800 2000
Time (hours)
Figure 7-23. Long-Term Stability: 0 to 2000 Hours
10
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8 Detailed Description
8.1 Overview
The REF30xx is a series, CMOS, precision bandgap voltage reference. Its basic topology is shown in the
Section 8.2 section. Transistors Q1 and Q2 are biased so that the current density of Q1 is greater than that of
Q2. The difference of the two base-emitter voltages, Vbe1 – Vbe2, has a positive temperature coefficient and
is forced across resistor R1. This voltage is gained up and added to the base-emitter voltage of Q2, which
has a negative coefficient. The resulting output voltage is virtually independent of temperature. The curvature
of the bandgap voltage, as shown in Figure 7-3, is due to the slightly nonlinear temperature coefficient of the
base-emitter voltage of Q2.
8.2 Functional Block Diagram
+
+
Vbe1 Vbe2
Q1
R1
Q2
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8.3 Feature Description
8.3.1 Supply Voltage
The REF30xx family of references features an extremely low dropout voltage. With the exception of the
REF3012, which has a minimum supply requirement of 1.8 V, the REF30xx can be operated with a supply
of only 1 mV above the output voltage in an unloaded condition. For loaded conditions, a typical dropout voltage
versus load is shown on the front page.
The REF30xx features a low quiescent current that is extremely stable over changes in both temperature and
supply. The typical room temperature quiescent current is 42 μA, and the maximum quiescent current over
temperature is just 59 μA. Additionally, the quiescent current typically changes less than 2.5 μA over the entire
supply range, as shown in Figure 8-1.
Supply voltages below the specified levels can cause the REF30xx to momentarily draw currents greater than
the typical quiescent current. Use a power supply with a fast rising edge and low output impedance to easily
prevent this issue.
42.5
IQ (μA)
42.0
41.5
41.0
40.5
40.0
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
VIN (V)
Figure 8-1. Supply Current vs Supply Voltage
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8.3.2 Thermal Hysteresis
Thermal hysteresis for the REF30xx is defined as the change in output voltage after operating the device at
25°C, cycling the device through the specified temperature range, and returning to 25°C, and can be expressed
as shown in Equation 1:
æ abs VPRE - VPOST
VHYST = ç
ç
VNOM
è
ö
6
÷÷ • 10 (ppm)
ø
(1)
where
•
•
•
VHYST = Calculated hysteresis
VPRE = Output voltage measured at 25°C pretemperature cycling
VPOST = Output voltage measured when device has been operated at 25°C, cycled through specified range of
–40°C to +125°C, and returned to operation at 25°C.
8.3.3 Temperature Drift
The REF30xx exhibits minimal drift error, defined as the change in output voltage over varying temperature.
Using the box method of drift measurement, the REF30xx features a typical drift coefficient of 20 ppm from 0°C
to 70°C, the primary temperature range of use for many applications. For industrial temperature ranges of –40°C
to +125°C, the REF30xx family drift increases to a typical value of 50 ppm.
8.3.4 Noise Performance
The REF30xx generates noise less than 50 μVPP between frequencies of 0.1 Hz to 10 Hz, and can be seen
in Figure 7-20 The noise voltage of the REF30xx increases with output voltage and operating temperature.
Additional filtering may be used to improve output noise levels; however, ensure the output impedance does not
degrade AC performance.
8.3.5 Long-Term Stability
Long-term stability refers to the change of the output voltage of a reference over a period of months or years.
This effect lessens as time progresses as is apparent by the long-term stability curves. The typical drift value for
the REF30xx is 24 ppm from 0 hours to 1000 hours, and 15 ppm from 1000 hours to 2000 hours. This parameter
is characterized by measuring 30 units at regular intervals for a period of 2000 hours.
8.3.6 Load Regulation
Load regulation is defined as the change in output voltage as a result of changes in load current. Load regulation
for the REF30xx is measured using force and sense contacts as shown in Figure 8-2. The force and sense lines
tied to the contact area of the output pin reduce the impact of contact and trace resistance, resulting in accurate
measurement of the load regulation contributed solely by the REF30xx. For applications requiring improved load
regulation, use force and sense lines.
Output Pin
Contact and
Trace Resistance
+
VOUT
IL
Sense Line
Force Line
Load
Meter
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Figure 8-2. Accurate Load Regulation of REF30xx
12
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SBVS032I – MARCH 2002 – REVISED JULY 2022
8.4 Device Functional Modes
8.4.1 Negative Reference Voltage
For applications requiring a negative and positive reference voltage, the OPA703 and REF30xx can be used
to provide a dual-supply reference from a ±5-V supply. Figure 8-3 shows the REF3025 used to provide a
±2.5-V supply reference voltage. The low offset voltage and low drift of the OPA703 complement the low drift
performance of the REF30xx to provide an accurate solution for split-supply applications.
+5V
+2.5 V
REF3025
10 kW
10 kW
+5 V
OPA703
-2.5 V
-5 V
Copyright © 2016, Texas Instruments Incorporated
Figure 8-3. REF3025 Combined With OPA703 to Create Positive and Negative Reference Voltages.
Copyright © 2022 Texas Instruments Incorporated
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13
REF3012, REF3020, REF3025, REF3030, REF3033, REF3040
www.ti.com
SBVS032I – MARCH 2002 – REVISED JULY 2022
8.4.2 Data Acquisition
Often data acquisition systems require stable voltage references to maintain necessary accuracy. The REF30xx
family features stability and a wide range of voltages suitable for most microcontrollers and data converters.
Figure 8-4 and Figure 8-5 show two basic data acquisition systems.
3.3 V
REF3033
V+
GND
5Ω
+ 1 μF to
10 μF
VREF
0.1 μF
VIN
VCC
ADS7822
+In
CS
–In
DOUT
GND
VS
+
1 μF to 10 μF
Microcontroller
DCLOCK
Copyright © 2016, Texas Instruments Incorporated
Figure 8-4. Basic Data Acquisition System 1
2.5-V Supply
5Ω
2.5 V
+
VIN
REF3012
VOUT
1.25 V
VREF
VS
VCC
+
0.1 μF
ADS8324
1 μF to 10 μF
1 μF to 10 μF
GND
0 V to 1.25 V
+In
CS
–In
DOUT
GND
Microcontroller
DCLOCK
Copyright © 2016, Texas Instruments Incorporated
Figure 8-5. Basic Data Acquisition System 2
14
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Product Folder Links: REF3012 REF3020 REF3025 REF3030 REF3033 REF3040
REF3012, REF3020, REF3025, REF3030, REF3033, REF3040
www.ti.com
SBVS032I – MARCH 2002 – REVISED JULY 2022
9 Application and Implementation
Note
Information in the following applications sections is not part of the TI component specification,
and TI does not warrant its accuracy or completeness. TI’s customers are responsible for
determining suitability of components for their purposes, as well as validating and testing their design
implementation to confirm system functionality.
9.1 Application Information
For normal operation, the REF30xx does not require a capacitor on the output. If a capacitive load is connected,
take special care when using low equivalent series resistance (ESR) capacitors and high capacitance. This
precaution is especially true for low-output voltage devices; therefore, for the REF3012 use a low-ESR
capacitance of 10 μF or less. Figure 9-1 shows the typical connections required for operation of the REF30xx. A
supply bypass capacitor of 0.47 μF is always recommended.
VIN
1
0.47 mF
VOUT
REF30xx
3
2
Copyright © 2016, Texas Instruments Incorporated
Figure 9-1. Typical Connections for Operating REF30xx
9.2 Typical Application
Figure 9-2 shows a low-power reference and conditioning circuit. This circuit attenuates and level-shifts a bipolar
input voltage within the proper input range of a single-supply low power 16-Bit ΔΣ ADC, such as the one inside
the MSP430 or other similar single-supply ADCs. Precision reference circuits are used to level-shift the input
signal, provide the ADC reference voltage and to create a well-regulated supply voltage for the low-power analog
circuitry. A low-power, zero-drift, op-amp circuit is used to attenuate and level-shift the input signal.
3.3 V
REF3030
IN
3.0 V
OUT
1.25 V
R2
20 k
R3
100 k
20 k
3.0 V
MSP430F2013
Launchpad
3.3 V
VOUT
+
VIN
±5 V
J1.2/A1+
OPA317
+
±
IN+
J1.3/A1±
R4
±
R5
REF3012
SD_16
A-ADC
10 k
100 k
3.0 V
IN±
VREF
+
R1
1.25 V
J1.5/VREF
IN OUT
R6
47 k
R7
47 k
0.625 V
C2
47 µF
Copyright © 2016, Texas Instruments Incorporated
Figure 9-2. Low-Power Reference and Bipolar Voltage Conditioning Circuit for Low-Power ADCs
Copyright © 2022 Texas Instruments Incorporated
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15
REF3012, REF3020, REF3025, REF3030, REF3033, REF3040
www.ti.com
SBVS032I – MARCH 2002 – REVISED JULY 2022
9.2.1 Design Requirements
•
•
•
•
Supply Voltage: 3.3 V
Maximum Input Voltage: ±6 V
Specified Input Voltage: ±5 V
ADC Reference Voltage: 1.25 V
The goal for this design is to accurately condition a ±5-V bipolar input voltage into a voltage suitable for
conversion by a low-voltage ADC with a 1.25-V reference voltage, VREF, and an input voltage range of VREF / 2.
The circuit should function with reduced performance over a wider input range of at least ±6 V to allow for easier
protection of overvoltage conditions.
9.2.2 Detailed Design Procedure
Figure 9-2 depicts a simplified schematic for this design showing the MSP430 ADC inputs and full input
conditioning circuitry. The ADC is configured for a bipolar measurement where final conversion result is the
differential voltage between the voltage at the positive and negative ADC inputs. The bipolar, GND-referenced
input signal must be level-shifted and attenuated by the op amp so that the output is biased to VREF / 2 and has
a differential voltage that is within the ±VREF / 2 input range of the ADC.
1.25
-0.0001
1
-0.00015
Error Voltage (V)
Output Voltage (V)
9.2.3 Application Curves
0.75
0.5
-0.0002
-0.00025
-0.0003
0.25
-0.00035
0
±6
±5
±4
±3
±2
±1
0
1
2
3
4
5
Input Voltage (V)
±6
6
±5
±4
±3
±2
±1
0
1
Input Voltage (V)
C001
2
3
4
5
6
C00
Figure 9-4. OPA317 Output Voltage Error vs Input
Voltage
Figure 9-3. OPA317 Output Voltage vs Input
Voltage
Output Code Error (# of codes)
150
100
50
0
±50
±100
±150
±200
±6
±5
±4
±3
±2
±1
0
1
Input Voltage (V)
2
3
4
5
6
C003
Figure 9-5. Output Code Error vs Input Voltage
16
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REF3012, REF3020, REF3025, REF3030, REF3033, REF3040
www.ti.com
SBVS032I – MARCH 2002 – REVISED JULY 2022
10 Power Supply Recommendations
The REF30xx family of references feature an extremely low-dropout voltage. These references can be operated
with a supply of only 50 mV above the output voltage. For loaded reference conditions, a typical dropout voltage
versus load is shown in the front page plot, Figure 3-1. Use a supply bypass capacitor greater than 0.47 µF.
11 Layout
11.1 Layout Guidelines
Figure 11-1 illustrates an example of a printed-circuit board (PCB) layout using the REF30xx. Some key
considerations are:
• Connect low-ESR, 0.1-μF ceramic bypass capacitors at VIN of the REF30xx
• Decouple other active devices in the system per the device specifications
• Use a solid ground plane to help distribute heat and reduces electromagnetic interference (EMI) noise pickup
• Place the external components as close to the device as possible. This configuration prevents parasitic errors
(such as the Seebeck effect) from occurring
• Minimize trace length between the reference and bias connections to the INA and ADC to reduce noise
pickup
• Do not run sensitive analog traces in parallel with digital traces. Avoid crossing digital and analog traces if
possible, and only make perpendicular crossings when absolutely necessary
11.2 Layout Example
To ADC
To Input Power Supply
IN
OUT
C
C
REF30xx
GND
Via to Ground Plane
Figure 11-1. Layout Example
Copyright © 2022 Texas Instruments Incorporated
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17
REF3012, REF3020, REF3025, REF3030, REF3033, REF3040
www.ti.com
SBVS032I – MARCH 2002 – REVISED JULY 2022
12 Device and Documentation Support
12.1 Documentation Support
12.1.1 Related Documentation
CMOS, Rail-to-Rail, I/O Operational Amplifiers (SBOS180)
REF29xx 100 ppm/°C, 50 μA in 3-Pin SOT-23 CMOS Voltage Reference (SBVS033)
12.2 Related Links
Table 12-1 lists quick access links. Categories include technical documents, support and community resources,
tools and software, and quick access to sample or buy.
Table 12-1. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
REF3012
Click here
Click here
Click here
Click here
Click here
REF3020
Click here
Click here
Click here
Click here
Click here
REF3025
Click here
Click here
Click here
Click here
Click here
REF3030
Click here
Click here
Click here
Click here
Click here
REF3033
Click here
Click here
Click here
Click here
Click here
REF3040
Click here
Click here
Click here
Click here
Click here
12.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. Click on
Subscribe to updates to register and receive a weekly digest of any product information that has changed. For
change details, review the revision history included in any revised document.
12.4 Support Resources
TI E2E™ support forums are an engineer's go-to source for fast, verified answers and design help — straight
from the experts. Search existing answers or ask your own question to get the quick design help you need.
Linked content is provided "AS IS" by the respective contributors. They do not constitute TI specifications and do
not necessarily reflect TI's views; see TI's Terms of Use.
12.5 Trademarks
TI E2E™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
12.6 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled
with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may
be more susceptible to damage because very small parametric changes could cause the device not to meet its published
specifications.
12.7 Glossary
TI Glossary
This glossary lists and explains terms, acronyms, and definitions.
13 Mechanical, Packaging, and Orderable Information
The following pages include mechanical packaging and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
18
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Copyright © 2022 Texas Instruments Incorporated
Product Folder Links: REF3012 REF3020 REF3025 REF3030 REF3033 REF3040
PACKAGE OPTION ADDENDUM
www.ti.com
13-Aug-2021
PACKAGING INFORMATION
Orderable Device
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
REF3012AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30A
REF3012AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30A
REF3012AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30A
REF3012AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30A
REF3020AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30B
REF3020AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30B
REF3020AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30B
REF3020AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30B
REF3025AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30C
REF3025AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30C
REF3025AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30C
REF3025AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30C
REF3030AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30F
REF3030AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30F
REF3030AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30F
REF3030AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30F
REF3033AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30D
REF3033AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30D
REF3033AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30D
REF3033AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30D
Addendum-Page 1
Samples
PACKAGE OPTION ADDENDUM
www.ti.com
Orderable Device
13-Aug-2021
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
(2)
Lead finish/
Ball material
MSL Peak Temp
Op Temp (°C)
Device Marking
(3)
(4/5)
(6)
REF3040AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30E
REF3040AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30E
REF3040AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R30E
(1)
The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2)
RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of
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