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REF3112, REF3120, REF3125
REF3130, REF3133, REF3140
SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
REF31xx 15ppm/°C Maximum, 100-µA, SOT-23 Series Voltage Reference
1 Features
3 Description
•
•
•
•
•
•
The REF31xx is a family of precision, low power, low
dropout, series voltage references available in the
tiny 3-pin SOT-23 package.
1
MicroSize Package: SOT23-3
Low Dropout: 5 mV
High Output Current: ±10 mA
High Accuracy: 0.2% Maximum
Low IQ: 115 µA Maximum
Excellent Specified Drift Performance:
– 15 ppm/°C (Maximum) from 0°C to +70°C
– 20 ppm/°C (Maximum) from –40°C to +125°C
The REF31xx's small size and low power
consumption (100 μA typical) make it ideal for
portable and battery-powered applications. The
REF31xx does not require a load capacitor, but is
stable with any capacitive load and can sink or
source up to 10 mA of output current.
Unloaded, the REF31xx can operate on supplies
down to 5 mV above the output voltage. All models
are specified for the wide temperature range of –40°C
to +125°C.
2 Applications
•
•
•
•
Portable, Battery-Powered Equipment
Data Acquisition Systems
Medical Equipment
Hand-Held Test Equipment
Device Information(1)
PART NUMBER
REF31xx
PACKAGE
BODY SIZE (NOM)
SOT-23 (3)
2.92 mm × 1.30 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application
Dropout Voltage vs Load Current
3.3V
REF3133
120
V+
5W
VS
ADS7822
VREF
VCC
1mF to 10mF
0.1mF
VIN
+
+In
CS
-In
DOUT
GND
Microcontroller
100
GND
Dropout Voltage (mV)
+ 1mF to
10mF
80
60
40
DCLOCK
20
0
-15
-10
-5
0
5
10
15
Load Current (mA)
1
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.
REF3112, REF3120, REF3125
REF3130, REF3133, REF3140
SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
www.ti.com
Table of Contents
1
2
3
4
5
6
7
8
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Device Comparison Table.....................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
3
4
7.1
7.2
7.3
7.4
7.5
7.6
4
4
4
4
4
6
Absolute Maximum Ratings .....................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description ............................................ 10
8.1 Overview ................................................................. 10
8.2 Functional Block Diagram ....................................... 10
8.3 Feature Description................................................. 10
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
12.2
12.3
12.4
12.5
12.6
Device Support......................................................
Related Links ........................................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
18
18
18
18
18
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 C (February 2006) to Revision D
Page
•
Added the Device Information table, the Thermal Information table, Feature Description section, Device Functional
Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device
and Documentation Support section, and Mechanical, Packaging, and Orderable Information section. .............................. 1
•
Removed the Ordering Information table .............................................................................................................................. 1
•
Moved and updated the SOT23-3 surface mount thermal resistance data from the Electrical Characteristics table to
the Thermal Information table................................................................................................................................................. 4
•
Removed the boldface type in the Electrical Characteristics table and identified when limits apply over the specified
temperature range TA = –40°C to +125°C in the test conditions column .............................................................................. 4
•
Added Figure 19 ..................................................................................................................................................................... 8
2
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SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
5 Device Comparison Table
PRODUCT
VOLTAGE (V)
REF3112
1.25
REF3120
2.048
REF3125
2.5
REF3130
3
REF3133
3.3
REF3140
4.096
6 Pin Configuration and Functions
DBZ Package
3-Pin SOT-23
Top View
IN
1
3
OUT
GND
2
Pin Functions
PIN
NO.
NAME
I/O
DESCRIPTION
1
IN
I
Input supply voltage
2
OUT
O
Reference output voltage
3
GND
—
Ground
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SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
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7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN
MAX
UNIT
7
V
135
°C
150
°C
150
°C
Supply voltage, V+ to V–
Output short circuit
Continuous
Operating temperature
–55
Junction temperature
Storage temperature, Tstg
(1)
–65
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.
7.2 ESD Ratings
VALUE
(1)
(2)
Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001
Electrostatic
discharge
V(ESD)
(1)
UNIT
±2000
Charged-device model (CDM), per JEDEC specification JESD22-C101 (2)
V
±1000
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
over operating free-air temperature range (unless otherwise noted)
VIN
Input voltage
ILOAD
Load current
TA
Operating temperature
(1)
MIN
MAX
VREF + 0.05 (1)
5.5
UNIT
V
25
mA
–40
125
°C
Minimum supply voltage for the REF3112 is 1.8 V.
7.4 Thermal Information
REF31xx
THERMAL METRIC (1)
DBZ (SOT-23)
UNIT
3 PINS
RθJA
Junction-to-ambient thermal resistance
292.9
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
124.4
°C/W
RθJB
Junction-to-board thermal resistance
89
°C/W
ψJT
Junction-to-top characterization parameter
11.4
°C/W
ψJB
Junction-to-board characterization parameter
87.6
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
—
°C/W
(1)
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
7.5 Electrical Characteristics
at TA = 25°C, ILOAD = 0 mA, and VIN = 5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
1.2475
1.25
1.2525
UNIT
REF3312 (1) — 1.25 V
VOUT
Output voltage
Initial accuracy
Output voltage noise
(1)
4
–0.2%
V
0.2%
f = 0.1 Hz to 10 Hz
17
μVPP
f = 10 Hz to 10 kHz
24
μVRMS
Minimum supply voltage for the REF3112 is 1.8 V.
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SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
Electrical Characteristics (continued)
at TA = 25°C, ILOAD = 0 mA, and VIN = 5 V (unless otherwise noted)
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
2.0439
2.048
2.0521
UNIT
REF3120 — 2.048 V
VOUT
Output voltage
Initial accuracy
–0.2%
Output voltage noise
V
0.2%
f = 0.1Hz to 10Hz
27
μVPP
f = 10Hz to 10kHz
39
μVRMS
REF3125 — 2.5 V
VOUT
Output voltage
2.495
Initial accuracy
2.5
–0.2%
Output voltage noise
2.505
V
0.2%
f = 0.1Hz to 10Hz
33
μVPP
f = 10Hz to 10kHz
48
μVRMS
REF3130 — 3 V
VOUT
Output voltage
2.994
Initial accuracy
3
–0.2%
Output voltage noise
3.006
V
0.2%
f = 0.1Hz to 10Hz
39
μVPP
f = 10Hz to 10kHz
57
μVRMS
REF3133 — 3.3 V
VOUT
Output voltage
3.2934
Initial accuracy
3.3
–0.2%
Output voltage noise
3.3066
V
0.2%
f = 0.1Hz to 10Hz
43
μVPP
f = 10Hz to 10kHz
63
μVRMS
REF3140 — 4.096 V
VOUT
Output voltage
4.0878
Initial accuracy
4.096
–0.2%
Output voltage noise
4.1042
V
0.2%
f = 0.1Hz to 10Hz
53
μVPP
f = 10Hz to 10kHz
78
μVRMS
REF31xx (REF3112, REF3120, REF3125, REF3130, REF3133, REF3140)
dVOUT/dT
5
15
TA = –40°C to +125°C .
10
20
Long-term stability
0 to 1000 hours
70
Line regulation
VREF + 0.05 (1) ≤ VIN ≤ 5.5V
20
65
Sourcing
0mA < ILOAD < 10mA, VIN = VREF + 250mV (1)
10
30
Sinking
–10mA < ILOAD < 0mA, VIN = VREF + 100mV (1)
20
50
Output voltage temperature drift (2)
dVOUT/dILOAD
Load regulation (3)
dT
Thermal
hysteresis (4)
VIN – VOUT
Dropout voltage (1)
ILOAD
Output current
ISC
TA = 0°C to 70°C.
First Cycle
TA = –40°C to +125°C.
5
Sourcing
50
Sinking
40
Turnon settling time
To 0.1% at VIN = +5V with CL = 0μF
ppm/V
µV/mA
ppm
25
–10
Short-circuit current
ppm
100
Additional Cycles
ppm/°C
50
mV
10
mA
mA
400
µs
POWER SUPPLY
VS
IQ
(2)
(3)
(4)
Voltage
ILOAD = 0, TA = –40°C to +125°C.
Quiescent current
VREF + 0.05 (1)
5.5
ILOAD = 0, TA = 25°C
100
115
ILOAD = 0, TA = –40°C to +125°C
115
135
V
µA
Box Method used to determine temperature drift.
Typical value of load regulation reflects measurements using force and sense contacts; see Load Regulation.
Thermal hysteresis is explained in more detail in Application and Implementation of this data sheet.
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7.6 Typical Characteristics
At TA = 25°C, VIN = 5-V power supply, and REF3125 is used for typical characteristic measurements, unless otherwise noted.
25
18
16
20
Percentage of Units
Percentage of Units
14
12
10
8
6
4
15
10
5
2
0
0
0
1
2
3
4
5
6
8
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
9 10 11 12 13 14 15 16
Drift (ppm/°C)
Drift (ppm/°C)
Figure 1. Temperature Drift (0°C to 70°C)
Figure 2. Temperature Drift (–40°C to +125°C)
120
0.16
0.14
100
Dropout Voltage (mV)
Output Drift (%)
0.12
0.10
0.08
0.06
0.04
0.02
0
80
60
40
20
-0.02
0
-0.04
-60
-40
-20
0
20
40
60
80
100 120 140
-15
-10
-5
0
5
10
15
Load Current (mA)
Temperature (°C)
Figure 3. Output Voltage vs Temperature
Figure 4. Dropout Voltage vs Load Current
120
100
Output Resistance (W)
Quiescent Current (mA)
100
80
60
40
10
1
0.1
20
0
0.01
-60
-40
-20
0
20
40
60
80
100
120 140
Temperature (°C)
Figure 5. Quiescent Current vs Temperature
6
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1
10
100
1k
10k
100k
1M
Frequency (Hz)
Figure 6. Output Impedance vs Frequency
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SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
Typical Characteristics (continued)
At TA = 25°C, VIN = 5-V power supply, and REF3125 is used for typical characteristic measurements, unless otherwise noted.
2.505
80
+125°C
2.504
70
2.503
60
Output (V)
Power-Supply Rejection Ratio (dB)
90
50
40
30
2.502
2.501
+25°C
2.500
20
-40°C
2.499
10
2.498
0
1
10
100
1k
10k
100k
2.0
Frequency (Hz)
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
Supply (V)
Figure 7. PSRR vs Frequency
Figure 8. Output vs Supply
2.505
5V/div
Output Voltage (V)
2.503
VIN
1V/div
+125°C
2.504
VOUT
2.502
2.501
2.500
+25°C
2.499
-40°C
2.498
2.497
-15
-10
-5
0
5
10
15
100ms/div
Load Current (mA)
Figure 10. Step Response, CL = 0, 5-V Start-Up
Figure 9. Output Voltage vs Load Current
20
0
10V/div
Drift (ppm)
-20
-40
-60
-80
-100
-120
0
400ms/div
Figure 11. 0.1-Hz to 10-Hz Noise
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100 200 300 400
500
600 700 800 900 1000
Time (Hrs)
Figure 12. REF3112 Long-Term Stability
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Typical Characteristics (continued)
500mV/div
VIN
VIN
VOUT
20mV/div
20mV/div
500mV/div
At TA = 25°C, VIN = 5-V power supply, and REF3125 is used for typical characteristic measurements, unless otherwise noted.
VOUT
20ms/div
100ms/div
Figure 14. Line Transient CL = 10 μF
Figure 13. Line Transient CL = 0 pF
ILOAD
+10mA
ILOAD
+10mA
+10mA
+10mA
-10mA
-10mA
50mV/div
200mV/div
VOUT
VOUT
40ms/div
40ms/div
Figure 15. Load Transient CL = 0 pF, ±10-mA Output Pulse
VIN
Figure 16. Load Transient CL = 1 µF, ±10-mA Output Pulse
VIN
+1mA
+1mA
-1mA
+1mA
+1mA
-1mA
20mV/div
100mV/div
VOUT
40ms/div
Figure 17. Load Transient CL = 0 pF, ±1-mA Output Pulse
8
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VOUT
40ms/div
Figure 18. Load Transient CL = 1 µF, ±1-mA Output Pulse
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SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
Typical Characteristics (continued)
300
6
250
5
200
4
150
3
100
2
50
1
0
0
10
20
30
40
50
60
Time (ms)
70
80
90
VIN (V)
IQ (µA)
At TA = 25°C, VIN = 5-V power supply, and REF3125 is used for typical characteristic measurements, unless otherwise noted.
0
100
G001
Figure 19. REF3125 Start-Up
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8 Detailed Description
8.1 Overview
The REF31xx is a family of series, CMOS, precision bandgap voltage references. The basic bandgap topology is
shown in Functional Block Diagram. Transistors Q1 and Q2 are biased such 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 temperature coefficient. The resulting output voltage is virtually independent of
temperature. The curvature of the bandgap voltage, as shown in Figure 3, is due to the slightly nonlinear
temperature coefficient of the base-emitter voltage of Q2.
8.2 Functional Block Diagram
VBANDGAP
R1
+
+
Vbe1 Vbe2
Q1 I
N Q2
8.3 Feature Description
8.3.1 Supply Voltage
The REF31xx family of references features an extremely low dropout voltage. With the exception of the
REF3112, which has a minimum supply requirement of 1.8 V, these references can be operated with a supply of
only 5 mV above the output voltage in an unloaded condition. For loaded conditions, a typical dropout voltage
versus load is shown in Typical Characteristics.
The REF31xx features a low quiescent current, which is extremely stable over changes in both temperature and
supply. The typical room temperature quiescent current is 100 μA, and the maximum quiescent current over
temperature is just 135 μA. The quiescent current typically changes less than 2 μA over the entire supply range,
as shown in Figure 20.
QUIESCENT CURRENT vs POWER SUPPLY
Quiescent Current (mA)
100.5
100.0
99.5
99.0
98.5
98.0
1.5
2.5
3.5
4.5
5.5
Power Supply (V)
Figure 20. Supply Current vs Supply Voltage
10
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SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
Feature Description (continued)
Supply voltages below the specified levels can cause the REF31xx to momentarily draw currents greater than
the typical quiescent current. This can be prevented by using a power supply with a fast rising edge and low
output impedance.
8.3.2 Thermal Hysteresis
Thermal hysteresis for the REF31xx 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. It can be expressed as:
VHYST =
abs|VPRE - VPOST|
VNOM
6
· 10 (ppm)
Where:
VHYST = Thermal hysteresis.
VPRE = Output voltage measured at 25°C pretemperature cycling.
VPOST = Output voltage measured after the device has been cycled through the specified temperature
range of –40°C to +125°C and returned to +25°C.
(1)
8.3.3 Temperature Drift
The REF31xx is designed to exhibit minimal drift error, defined as the change in output voltage over varying
temperature. The drift is calculated using the box method, which is described in Equation 2:
æ
ö
VOUTMAX - VOUTMIN
6
Drift = ç
÷ × 10 (ppm)
V
×
Temperature
Range
è OUT
ø
(2)
The REF31xx features a typical drift coefficient of 5 ppm from 0°C to 70°C, the primary temperature range for
many applications. For the industrial temperature range of –40°C to +125°C, the REF31xx family drift increases
to a typical value of 10 ppm.
8.3.4 Noise Performance
10V/div
Typical 0.1-Hz to 10-Hz voltage noise can be seen in Figure 21. The noise voltage of the REF31xx increases
with output voltage and operating temperature. Additional filtering may be used to improve output noise levels,
although take care to ensure the output impedance does not degrade the AC performance.
400ms/div
Figure 21. 0.1-Hz to 10-Hz Noise
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Feature Description (continued)
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 shown by the long-term stability curves. The typical drift value for
the REF31xx is 70 ppm from 0 to 1000 hours. This parameter is characterized by measuring 30 units at regular
intervals for a period of 1000 hours.
20
0
Drift (ppm)
-20
-40
-60
-80
-100
-120
0
100 200 300 400
500
600 700 800 900 1000
Time (Hrs)
Figure 22. REF3112 Long-Term Stability
8.3.6 Load Regulation
Load regulation is defined as the change in output voltage due to changes in load current. The load regulation of
the REF31xx is measured using force and sense contacts as pictured in Figure 23. The force and sense lines
reduce the impact of contact and trace resistance, resulting in accurate measurement of the load regulation
contributed solely by the REF31xx. For applications requiring improved load regulation, force and sense lines
must be used.
Output Pin
Contact and
Trace Resistance
+
VOUT
Sense Line
Force Line
IL
Load
Meter
Figure 23. Accurate Load Regulation of REF31xx
12
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8.4 Device Functional Modes
8.4.1 Negative Reference Voltage
For applications requiring a negative and positive reference voltage, the REF31xx and OPA703 can be used to
provide a dual-supply reference from a ±5-V supply. Figure 24 shows the REF3125 used to provide a ±2.5-V
supply reference voltage. The low drift performance of the REF31xx complement the low offset voltage and low
drift of the OPA703 to provide an accurate solution for split-supply applications.
+5V
+2.5V
REF3125
10kW
10kW
+5V
-2.5V
OPA703
-5V
Figure 24. REF3125 Combined With OPA703 to Create Positive and Negative Reference Voltages
8.4.2 Data Acquisition
Data acquisition systems often require stable voltage references to maintain accuracy. The REF31xx family
features stability and a wide range of voltages suitable for most microcontrollers and data converters. Figure 25,
Figure 26, and Figure 27 show basic data acquisition systems.
3.3V
REF3133
V+
5W
GND
+ 1mF to
10mF
VS
ADS7822
VREF
VCC
VIN
+
1mF to 10mF
0.1mF
+In
CS
-In
DOUT
GND
Microcontroller
DCLOCK
Figure 25. Basic Data Acquisition System 1
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REF3112, REF3120, REF3125
REF3130, REF3133, REF3140
SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
www.ti.com
2.5V Supply
5W
2.5V
+
VIN
VS
ADS8324
REF3112
VOUT = 1.25V
VREF
VCC
+
0.1mF
0V to 1.25V
GND
+In
CS
-In
DOUT
GND
1mF to 10mF
1mF to 10mF
Microcontroller
DCLOCK
Figure 26. Basic Data Acquisition System 2
5V
REF3140
0.1mF
1mF
VOUT = 4.096V
1kW
10W
22mF
+5V
1kW
VIN
VREF
10W
ADS8381
THS4031
6800pF
0.22mF
500W -5V
Figure 27. REF3140 Provides an Accurate Reference for Driving the ADS8381
14
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Product Folder Links: REF3112 REF3120 REF3125 REF3130 REF3133 REF3140
REF3112, REF3120, REF3125
REF3130, REF3133, REF3140
www.ti.com
SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
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. Customers should
validate and test their design implementation to confirm system functionality.
9.1 Application Information
The REF31xx does not require a load capacitor and is stable with any capacitive load. Figure 28 shows typical
connections required for operation of the REF31xx. TI recommends a supply bypass capacitor of 0.47 μF.
VIN
1
0.47mF
VOUT
REF31xx
3
2
Figure 28. Typical Connections for Operating REF31xx
9.2 Typical Application
Figure 29 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
REF3130
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
±
REF3112
SD_16
A-ADC
R5
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
Figure 29. Low-Power Reference and Bipolar Voltage Conditioning Circuit for Low-Power ADCs
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REF3112, REF3120, REF3125
REF3130, REF3133, REF3140
SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
www.ti.com
Typical Application (continued)
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 29 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
0.0006
1.00
0.0005
Error Voltage (V)
Output Voltage (V)
9.2.3 Application Curves
0.75
0.50
0.25
0.0004
0.0003
0.0002
0.0001
0.00
0.0000
±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
Figure 30. OPA317 Output Voltage vs Input Voltage
2
3
4
5
6
C002
Figure 31. OPA317 Output Voltage Error vs Input Voltage
Output Code Error (# of Codes)
2000
1500
1000
500
0
±500
±1000
±1500
±2000
±6
±5
±4
±3
±2
±1
0
1
2
3
4
5
Input Voltage (V)
6
C003
Figure 32. Output Code Error vs Input Voltage
16
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REF3112, REF3120, REF3125
REF3130, REF3133, REF3140
www.ti.com
SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
10 Power Supply Recommendations
The REF31xx family of references features an extremely low dropout voltage. With the exception of the
REF3112, which has a minimum supply requirement of 1.8 V, these references can be operated with a supply of
only 5 mV above the output voltage in an unloaded condition. For loaded conditions, a typical dropout voltage
versus load is shown in the front page plot, Dropout Voltage vs Load Current. TI recommends a supply bypass
capacitor greater than 0.47 μF.
11 Layout
11.1 Layout Guidelines
Figure 33 illustrates an example of a printed-circuit board (PCB) layout using the REF31xx. Some key
considerations are:
• Connect low-ESR, 0.1-μF ceramic bypass capacitors at VIN of the REF31xx
• 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
REF31xx
GND
Via to Ground Plane
Figure 33. Layout Example
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REF3112, REF3120, REF3125
REF3130, REF3133, REF3140
SBVS046D – DECEMBER 2003 – REVISED MARCH 2016
www.ti.com
12 Device and Documentation Support
12.1 Device Support
For device support, see the following:
MSP430 MSP 16-bit and 32-bit Microcontrollers
12.2 Related Links
The table below lists quick access links. Categories include technical documents, support and community
resources, tools and software, and quick access to sample or buy.
Table 1. Related Links
PARTS
PRODUCT FOLDER
SAMPLE & BUY
TECHNICAL
DOCUMENTS
TOOLS &
SOFTWARE
SUPPORT &
COMMUNITY
REF3112
Click here
Click here
Click here
Click here
Click here
REF3120
Click here
Click here
Click here
Click here
Click here
REF3125
Click here
Click here
Click here
Click here
Click here
REF3130
Click here
Click here
Click here
Click here
Click here
REF3133
Click here
Click here
Click here
Click here
Click here
REF3140
Click here
Click here
Click here
Click here
Click here
12.3 Community Resources
The following links connect to TI community resources. Linked contents are 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.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
12.4 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
12.5 Electrostatic Discharge Caution
These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
12.6 Glossary
SLYZ022 — 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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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)
REF3112AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31A
REF3112AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31A
REF3112AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31A
REF3112AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31A
REF3120AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31B
REF3120AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31B
REF3120AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31B
REF3125AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31C
REF3125AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31C
REF3125AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31C
REF3125AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31C
REF3130AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31E
REF3130AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31E
REF3130AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31E
REF3130AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31E
REF3133AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31F
REF3133AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31F
REF3133AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31F
REF3140AIDBZR
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31D
REF3140AIDBZRG4
ACTIVE
SOT-23
DBZ
3
3000
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31D
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)
REF3140AIDBZT
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31D
REF3140AIDBZTG4
ACTIVE
SOT-23
DBZ
3
250
RoHS & Green
NIPDAUAG
Level-1-260C-UNLIM
-40 to 125
R31D
(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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