REF3425, REF3430, REF3433, REF3440, REF3450
SBAS804F – SEPTEMBER 2017 – REVISED JUNE 2021
REF34xx Low-Drift, Low-Power, Small-Footprint Series Voltage Reference
1 Features
3 Description
•
•
•
•
•
•
The REF34xx device is a low temperature drift
(6 ppm/°C), low-power, high-precision CMOS voltage
reference, featuring ±0.05% initial accuracy, low
operating current with power consumption less than
95 μA. This device also offers very low output noise of
3.8 μVp-p /V, which enables its ability to maintain high
signal integrity with high-resolution data converters in
noise critical systems. With a small SOT-23 package,
REF34xx offers enhanced specifications and pin-topin replacement for MAX607x, ADR34xx and LT1790
(REF34xxT, no EN pin). The REF34xx family is
compatible to most of the ADC and DAC such as
ADS1287, DAC8802 and ADS1112.
Initial accuracy: ±0.05% (maximum)
Temperature coefficient : 6 ppm/°C (maximum)
Operating temperature range: −40°C to +125°C
Output current: ±10 mA
Low quiescent current: 95 μA (maximum)
Ultra-low zero load dropout voltage: 100 mV
(maximum)
Wide input voltage: 12 V
Output 1/f noise (0.1 Hz to 10 Hz): 3.8 µVp-p/V
Excellent long-term stability 25 ppm/1000 hrs
Multiple small footprint 6 pin SOT-23 package
pinouts: REF34xx and REF34xxT
2 Applications
•
•
•
•
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Stability and system reliability are further improved
by the low output-voltage hysteresis of the device
and low long-term output voltage drift. Furthermore,
the small size and low operating current of the
devices (95 μA) benefit portable and battery-powered
applications.
Data acquisition systems
Analog I/O modules
Field transmitters
Lab & field instrumentation
Servo drive control modules
DC power supply, AC source, electronic load
Voltage Reference Recommendation for Data
Converters
VOLTAGE REFERENCE
Device Information
ADC
DAC RESOLUTION
RESOLUTION
(1)
(1)
TL431LI, TLV431
10-b
8-b
LM4040, LM4050, REF30
12-b
10-b
REF31, REF33, REF4132
14-b to 16-b
12-b
REF34, REF50
16-b to 18-b
14-b to 16-b
REF70
18-b+
16-b+
(1)
REF34xx is specified for the wide temperature range
of −40°C to +125°C.
(1)
PART NAME
PACKAGE (1)
BODY SIZE (NOM)
REF34xx
REF34xxT
SOT-23 (6)
2.90 mm × 1.60 mm
For all available packages, see the orderable addendum at
the end of the data sheet
For specific ADC/DAC recommendations, see SNAA320
10
Input Signal
0.4
10
+
25°C
125°C
-40°C
0.36
124
0.32
ADS1287
1 nF
REF
VIN
CIN
1µF
REF34xx
COUT
10 µF
Dropout Voltage (V)
•
•
•
•
0.28
0.24
0.2
0.16
0.12
0.08
Copyright © 2017, Texas Instruments Incorporated
Simplified Schematic
0.04
0
0
5
Load Current (mA)
10
Dropout vs. Current Load Over Temperature
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.
REF3425, REF3430, REF3433, REF3440, REF3450
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SBAS804F – SEPTEMBER 2017 – REVISED JUNE 2021
Table of Contents
1 Features............................................................................1
2 Applications..................................................................... 1
3 Description.......................................................................1
4 Revision History.............................................................. 2
5 Device Comparison Table...............................................4
6 Pin Configuration and Functions...................................5
7 Specifications.................................................................. 6
7.1 Absolute Maximum Ratings ....................................... 6
7.2 ESD Ratings .............................................................. 6
7.3 Recommended Operating Conditions ........................6
7.4 Thermal Information ...................................................6
7.5 Electrical Characteristics ............................................7
7.6 Typical Characteristics................................................ 9
8 Parameter Measurement Information.......................... 13
8.1 Solder Heat Shift.......................................................13
8.2 Long-Term Stability................................................... 14
8.3 Thermal Hysteresis................................................... 14
8.4 Power Dissipation..................................................... 15
8.5 Noise Performance................................................... 16
9 Detailed Description......................................................17
9.1 Overview................................................................... 17
9.2 Functional Block Diagram......................................... 17
9.3 Feature Description...................................................17
9.4 Device Functional Modes..........................................18
10 Application and Implementation................................ 19
10.1 Application Information........................................... 19
10.2 Typical Application: Basic Voltage Reference
Connection.................................................................. 19
11 Power Supply Recommendations..............................22
12 Layout...........................................................................22
12.1 Layout Guidelines................................................... 22
12.2 Layout Example...................................................... 22
13 Device and Documentation Support..........................23
13.1 Documentation Support.......................................... 23
13.2 Receiving Notification of Documentation Updates..23
13.3 Support Resources................................................. 23
13.4 Trademarks............................................................. 23
13.5 Electrostatic Discharge Caution..............................23
13.6 Glossary..................................................................23
14 Mechanical, Packaging, and Orderable
Information.................................................................... 23
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision E (April 2021) to Revision F (June 2021)
Page
• Added low dropout line item to Features section................................................................................................1
• Consolidated part numbers in Device Information table..................................................................................... 1
• Changed Thermal Information parameters to correctly reflect DBV package.................................................... 6
• Added second cycle thermal hysteresis plot.....................................................................................................14
• Linked product numbers in table to datasheets................................................................................................ 19
Changes from Revision D (February 2021) to Revision E (April 2021)
Page
• Removed the "Product Preview" note for the REF34xxT package options........................................................ 4
Changes from Revision C (January 2021) to Revision D (February 2021)
Page
• Updated description and figures......................................................................................................................... 1
• Changed ENABLE TO EN.................................................................................................................................. 1
• Updated values.................................................................................................................................................13
Changes from Revision B (March 2018) to Revision C (February 2021)
Page
• Added "Device Information" to include REF34xxT............................................................................................. 1
• Added hyperlinks to "Applications"..................................................................................................................... 1
• Changed "VREF" to "VOUT" throughout document............................................................................................... 1
• Updated the numbering format for tables, figures, and cross-references throughout the document..................1
• Added REF34xxT to "Device Comparison Table"...............................................................................................4
• Added REF34xxT to "Pin Configuration and Functions".....................................................................................5
• Fixed pinout numbering...................................................................................................................................... 5
2
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•
•
•
SBAS804F – SEPTEMBER 2017 – REVISED JUNE 2021
Added Configuration Information to "Electrical Characteristics”......................................................................... 6
Changed ABS MAX IN MIN to "-0.3V"................................................................................................................6
Added REF34xxT to "Layout Guidelines" and "Layout Example".....................................................................22
Changes from Revision A (December 2017) to Revision B (March 2018)
Page
• Added 2 new GPNS: REF3440 and REF3450 .................................................................................................. 1
• Changed "Excellent Long-Term Stability 30 ppm/1000 hrs" to "Excellent Long-Term Stability 25 ppm/1000
hrs" in Section 1 .................................................................................................................................................1
• Changed "...typical drift value for the REF34xx is 30 ppm from 0 to 1000 hours" to "...typical drift value for the
REF34xx is 25 ppm from 0 to 1000 hours" and changed Figure 8-3 in Section 8.2 ........................................ 14
• Changed "(as shown in Figure 26)" to " as shown in Figure 9-1 in last paragraph of Section 10.2.2.2 ...........20
Changes from Revision * (September 2017) to Revision A (December 2017)
Page
• Added production release of 2 new output voltage option devices, REF3430 and REF3433............................ 1
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5 Device Comparison Table
PRODUCT
4
VOUT
REF3425
REF3425T
REF3430
REF3430T
3V
REF3433
REF3433T
3.3 V
REF3440
REF3440T
4.096 V
REF3450
REF3450T
5V
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2.5 V
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SBAS804F – SEPTEMBER 2017 – REVISED JUNE 2021
6 Pin Configuration and Functions
GND_F
1
6
OUT_F
GND_S
2
5
OUT_S
EN
3
4
IN
Not to scale
Figure 6-1. REF34xx
DBV Package
6-Pin SOT-23
Top View
NC
1
6
VOUT
GND
2
5
NC
NC
3
4
IN
Not to scale
Figure 6-2. REF34xxT
DBV Package
6-Pin SOT-23
Top View
Table 6-1. Pin Functions
PIN
NAME
REF34xx
(DBV)
GND_F
1
GND_S
2
GND
EN
3
IN
4
OUT_S
5
OUT_F
6
VOUT
NC
REF34xxT
(DBV)
TYPE
DESCRIPTION
Ground
Ground force connection.
Ground
Ground sense connection.
2
Ground
Device ground.
4
Power
Input
Enable connection. Enables or disables the device.
Input supply voltage connection.
Input
Reference voltage output sense connection.
Output
Reference voltage output force connection.
6
Output
Reference voltage output connection.
1,3,5
-
Not connected. Pin can be left floating or connected to voltage within device
operating range.
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7 Specifications
7.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)
MIN
MAX
UNIT
IN
–0.3
13
V
EN
–0.3
IN + 0.3
V
Output voltage
VOUT
–0.3
5.5
V
Output short circuit current
ISC
20
mA
Operating temperature range
TA
–55
150
°C
Storage temperature range
Tstg
–65
170
°C
Input voltage
(1)
Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may
degrade device reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond
those specified is not implied. These are stress ratings only and functional operation of the device at these or any other conditions
beyond those specified in the Electrical Characteristics Table is not implied.
7.2 ESD Ratings
VALUE
V(ESD)
(1)
(2)
Electrostatic discharge
Human-body model (HBM), per ANSI/ESDA/
JEDEC JS-001(1)
±2500
Charged-device model (CDM), per JEDEC
specification JESD22-C101(2)
±1500
UNIT
V
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)
MIN
NOM
VOUT +
VDO (1)
MAX
IN
Input Voltage
EN
Enable Voltage
0
IN
V
IL
Output Current
–10
10
mA
TA
Operating Temperature
–40
125
°C
(1)
12
UNIT
25
V
VDO = Dropout voltage
7.4 Thermal Information
REF34T
THERMAL METRIC(1)
6
REF34
DBV
DBV
6 PINS
6 PINS
UNIT
RθJA
Junction-to-ambient thermal resistance
122.6
122.6
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
80.2
80.2
°C/W
RθJB
Junction-to-board thermal resistance
42
42
°C/W
ΨJT
Junction-to-top characterization parameter
23.2
23.2
°C/W
ΨJB
Junction-to-board characterization parameter
41.9
41.9
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
N/A
°C/W
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SBAS804F – SEPTEMBER 2017 – REVISED JUNE 2021
7.5 Electrical Characteristics
At VIN = VOUT + VDO, COUT = 10 µF, CIN = 0.1 µF, IL = 0 mA, minimum and maximum specifications at TA = –40℃ to 125℃;
Typical specifications at TA = 25℃ unless otherwise noted
PARAMETER
TEST CONDITION
MIN
TYP
MAX
UNIT
0.05
%
ACCURACY AND DRIFT
Output voltage accuracy TA = 25℃
Output voltage
temperature coefficient
(1)
–0.05
–40°C ≤ TA ≤ 125°C
2.5
6
ppm/°C
2
15
ppm/V
Sourcing
20
30
Sinking, REF3425
40
70
Sinking, REF3430
43
75
Sinking, REF3433
48
84
Sinking, REF3440
60
98
Sinking, REF3450
70
140
18
22
LINE & LOAD REGULATION
ΔVO/ΔVIN
VIN = VOUT + VDO (2) to 12 V
Line Regulation
IL = 0 mA to 10mA, VIN
= VOUT+ VDO (3)
ΔVO/ΔIL
ISC
Load Regulation
IL = 0 mA to –10mA,
VIN = VOUT+ VDO, TA =
25°C (3)
Short circuit current
VOUT = 0 V at TA = 25°C
ppm/mA
mA
NOISE
enp-p
Low frequency noise (4)
en
Integrated wide band
noise
en
Output voltage noise
density
0.1Hz ≤ f ≤ 10Hz
5
0.1Hz ≤ f ≤ 10Hz (REF3440 and REF3450)
3.8
10Hz ≤ f ≤ 10kHz
24
f = 1kHz
µVp-p/V
µVrms
0.25
f = 1kHz (REF3440 and REF3450)
ppm/√Hz
0.2
LONG TERM STABILITY AND HYSTERESIS
Long-term stability (5)
Output voltage thermal
hysteresis (6)
DBV Package
DBV Package
0 to 1000h at 35°C
25
1000h to 2000h at 35°C
10
25°C, –40°C,125°C,
25°C Cycle 1
30
25°C, –40°C,125°C,
25°C Cycle 2
10
ppm
ppm
TURN-ON TIME
tON
Turn-on time
0.1% of output voltage settling, CL = 10 µF
2.5
ms
CAPACITIVE LOAD
CL
Stable output capacitor
range
–40°C ≤ TA ≤ 125°C
0.1
10
µF
OUTPUT VOLTAGE
VOUT
Output voltage
REF3425, REF3425T
2.5
REF3430, REF3430T
3.0
REF3433, REF3433T
3.3
REF3440, REF3440T
4.096
REF3450, REF3450T
5.0
V
POWER SUPPLY
VIN
Input voltage
IL
Output current capacity VIN = VOUT + VDO to 12 V
IQ
Quiescent current
VOUT +
VDO
12
V
–10
10
mA
Active mode
72
95
Shutdown mode
2.5
3
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7.5 Electrical Characteristics (continued)
At VIN = VOUT + VDO, COUT = 10 µF, CIN = 0.1 µF, IL = 0 mA, minimum and maximum specifications at TA = –40℃ to 125℃;
Typical specifications at TA = 25℃ unless otherwise noted
PARAMETER
VEN
ENABLE pin voltage
VDO
Dropout voltage
IEN
ENABLE pin leakage
current
(1)
(2)
(3)
(4)
(5)
(6)
8
TEST CONDITION
Voltage reference in active mode (EN = 1)
MIN
TYP
MAX
1.6
Voltage reference in shutdown mode (EN = 0)
0.5
IL = 0 mA
50
IL = 10 mA
100
500
VEN = VIN = 12V
1
2
UNIT
V
mV
µA
Temperature drift is specified according to the box method. See Low Temperature Drift section for more details.
VDO for line regulation test is 50 mV.
VDO for load regulation test is 500 mV.
The peak-to-peak noise measurement is explained in more detail in section Noise Performance.
Long-term stability measurement procedure is explained in more detail in section Long–Term Stability.
Thermal hysteresis measurement procedure is explained in more detail in section Thermal Hysteresis.
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7.6 Typical Characteristics
at TA = 25°C, VIN = VEN = 12 V, IL = 0 mA, CL = 10 µF, CIN = 0.1 µF (unless otherwise noted)
74
Population (%)
Quiescent Current (µA)
73
12V
72
71
5V
70
3.3V
69
3V
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3.25
3.50
3.75
4.00
4.25
4.50
4.75
5.00
68
-40
-15
10
D001
35
60
Temperature (°C)
85
110 125
D003
Drift (ppm/°C)
(-40°C to 125°C)
Figure 7-2. VIN vs IQ over Temperature
0.02
75
0.015
74.5
0.01
74
Quiescent Current (µA)
Output Voltage Accuracy (%)
Figure 7-1. Temperature Drift
0.005
0
-0.005
-0.01
-0.015
-0.02
-50
73.5
73
72.5
72
71.5
-25
0
25
50
Temperature (°C)
75
100
71
-50
125
Figure 7-3. Output Voltage Accuracy vs Temperature
0
25
50
Temperature (°C)
75
100
125
D004
Figure 7-4. Quiescent Current vs Temperature
0.24
-20
CL = 1uF
CL = 10uF
0.23
0.22
-40
Line Regulation (ppm/V)
Power Supply Rejection Ratio (dB)
-25
D002
-60
-80
-100
0.21
0.2
0.19
0.18
0.17
0.16
0.15
0.14
-120
10
100
1k
Frequency (Hz)
10k
100k
D005
Figure 7-5. Power-Supply Rejection Ratio vs Frequency
0.13
-40
-20
0
20
40
60
80
Temperature (°C)
100
120
140
D019
Figure 7-6. Line Regulation
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7.6 Typical Characteristics (continued)
8.7
55
8.4
52.5
Load Regulation Sinking (ppm/mA)
Load Regulation Sourcing (ppm/mA)
at TA = 25°C, VIN = VEN = 12 V, IL = 0 mA, CL = 10 µF, CIN = 0.1 µF (unless otherwise noted)
8.1
7.8
7.5
7.2
6.9
6.6
6.3
6
5.7
-40
-20
0
20
40
60
80
Temperature (°C)
100
120
140
50
47.5
45
42.5
40
37.5
35
32.5
30
-40
-20
0
20
D020
40
60
80
Temperature (°C)
100
120
140
D021
Figure 7-8. Load Regulation Sinking
Figure 7-7. Load Regulation Sourcing
ILOAD
+1mA
+1mA
-1mA
1mA/div
4mV/div
VOUT
250µs/div
(CL = 1µF, IOUT = 1mA)
Figure 7-9. Noise Performance 10 Hz to 10 kHz
D010
Figure 7-10. Load Transient
ILOAD
ILOAD
+1mA
+10mA
+1mA
+10mA
10mA/div
-10mA
-1mA
1mA/div
4mV/div
VOUT
100mV/div
250µs/div
(CL = 10µF, IOUT = 1mA)
Figure 7-11. Load Transient
10
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VOUT
250µs/div
(CL = 1µF, IOUT = 10mA)
D010
D010
Figure 7-12. Load Transient
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7.6 Typical Characteristics (continued)
at TA = 25°C, VIN = VEN = 12 V, IL = 0 mA, CL = 10 µF, CIN = 0.1 µF (unless otherwise noted)
ILOAD
-10mA
+10mA
10mA/div
VIN
4V/div
+10mA
20mV/div
VOUT
15mV/div
250µs/div
(CL = 10µF, IOUT = 10mA)
VOUT
250µs/div
D010
(CL = 1µF)
Figure 7-13. Load Transient
D011
Figure 7-14. Line Transient
Quiescent Current Off (µA)
2.6
VIN
4V/div
VOUT
5mV/div
2.5
2.4
2.3
2.2
2.1
2
-40
250µs/div
(CL = 10µF)
D011
25%
25%
20%
20%
Thermal Hysteresis - Cycle 1 (ppm)
D016
Figure 7-17. Thermal Hysteresis Distribution (Cycle 1)
110 125
D013
Thermal Hysteresis - Cycle 2 (ppm)
40
30
20
10
0
-10
80
60
0
40
0
20
5%
0
5%
-20
85
10%
-20
10%
-40
35
60
Temperature (°C)
15%
-30
15%
-40
Population (%)
30%
-60
10
Figure 7-16. Quiescent Current Shutdown Mode
30%
-80
Population (%)
Figure 7-15. Line Transient
-15
D016
Figure 7-18. Thermal Hysteresis Distribution (Cycle 2)
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7.6 Typical Characteristics (continued)
at TA = 25°C, VIN = VEN = 12 V, IL = 0 mA, CL = 10 µF, CIN = 0.1 µF (unless otherwise noted)
50%
40%
Population (%)
En
30%
1V/div
20%
VOUT
0.02
0.01
0
-0.01
0
-0.02
10%
0.5ms/div
D017
D018
Solder Heat Shift (%)
Refer to Section 8.1 for more information
Figure 7-19. Solder Heat Shift Distribution
Figure 7-20. Turnon Time (Enable)
10
2µV/div
Output Voltage Stability (ppm)
5
0
-5
-10
-15
-20
-25
-30
-35
-40
Time 1s/div
0
D08_
Figure 7-21. 0.1-Hz to 10-Hz Noise (VOUT)
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100
200
300
400
500 600
Hours
700
800
900 1000
D022
Figure 7-22. Long Term Stability - 1000 hours (VOUT)
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SBAS804F – SEPTEMBER 2017 – REVISED JUNE 2021
8 Parameter Measurement Information
8.1 Solder Heat Shift
The materials used in the manufacture of the REF34xx have differing coefficients of thermal expansion, resulting
in stress on the device die when the part is heated. Mechanical and thermal stress on the device die can cause
the output voltages to shift, degrading the initial accuracy specifications of the product. Reflow soldering is a
common cause of this error.
In order to illustrate this effect, a total of 32 devices were soldered on 2 printed circuit boards [16 devices on
each printed circuit board (PCB)] using lead-free solder paste and the paste manufacturer suggested reflow
profile. The reflow profile is as shown in Figure 8-1. The printed circuit board is comprised of FR4 material. The
board thickness is 1.65 mm and the area is 114 mm × 152 mm.
300
Temperature (ƒC)
250
200
150
100
50
0
0
50
100
150
200
250
300
Time (seconds)
350
400
C01
Figure 8-1. Reflow Profile
The reference output voltage is measured before and after the reflow process; the typical shift is displayed in
Figure 8-2. Although all tested units exhibit very low shifts (< 0.01%), higher shifts are also possible depending
on the size, thickness, and material of the printed circuit board. An important note is that the histograms display
the typical shift for exposure to a single reflow profile. Exposure to multiple reflows, as is common on PCBs
with surface-mount components on both sides, causes additional shifts in the output bias voltage. If the PCB is
exposed to multiple reflows, the device must be soldered in the last pass to minimize its exposure to thermal
stress.
50%
Population (%)
40%
30%
20%
0.02
0.01
0
-0.01
0
-0.02
10%
D017
Solder Heat Shift (%)
Figure 8-2. Solder Heat Shift Distribution, VOUT (%)
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8.2 Long-Term Stability
One of the key parameters of the REF34xx references is long-term stability. Typical characteristic expressed
as: curves shows the typical drift value for the REF34xx is 25 ppm from 0 to 1000 hours. This parameter is
characterized by measuring 32 units at regular intervals for a period of 1000 hours. It is important to understand
that long-term stability is not ensured by design and that the output from the device may shift beyond the typical
25 ppm specification at any time. For systems that require highly stable output voltages over long periods of
time, the designer should consider burning in the devices prior to use to minimize the amount of output drift
exhibited by the reference over time.
10
Output Voltage Stability (ppm)
5
0
-5
-10
-15
-20
-25
-30
-35
-40
0
100
200
300
400
500 600
Hours
700
800
900 1000
D022
Figure 8-3. Long Term Stability - 1000 hours (VOUT)
8.3 Thermal Hysteresis
Thermal hysteresis is measured with the REF34xx soldered to a PCB, similar to a real-world application.
Thermal hysteresis for the device 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. The PCB was baked at
150°C for 30 minutes before thermal hysteresis was measured. Hysteresis can be expressed by Equation 1:
VHYST
§ | VPRE VPOST | ·
6
¨
¸ u 10 ppm
V
NOM
©
¹
(1)
where
•
•
•
•
VHYST = thermal hysteresis (in units of ppm)
VNOM = the specified output voltage
VPRE = output voltage measured at 25°C pre-temperature cycling
VPOST = output voltage measured after the device has cycled from 25°C through the specified temperature
range of –40°C to +125°C and returns to 25°C.
Typical thermal hysteresis distribution is as shown in Figure 8-4 and Figure 8-5.
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30%
Population (%)
25%
20%
15%
10%
80
60
40
20
0
-20
-40
-60
0
-80
5%
D016
Thermal Hysteresis - Cycle 1 (ppm)
Figure 8-4. Thermal Hysteresis Distribution Cycle 1 (VOUT)
30%
Population (%)
25%
20%
15%
10%
Thermal Hysteresis - Cycle 2 (ppm)
40
30
20
10
0
-10
-20
-30
0
-40
5%
D016
Figure 8-5. Thermal Hysteresis Distribution Cycle 2 (VOUT)
8.4 Power Dissipation
The REF34xx voltage references are capable of source and sink up to 10 mA of load current across the rated
input voltage range. However, when used in applications subject to high ambient temperatures, the input voltage
and load current must be carefully monitored to ensure that the device does not exceeded its maximum power
dissipation rating. The maximum power dissipation of the device can be calculated with Equation 2:
TJ
TA
PD u RTJA
(2)
where
•
•
•
•
PD is the device power dissipation
TJ is the device junction temperature
TA is the ambient temperature
RθJA is the package (junction-to-air) thermal resistance
Because of this relationship, acceptable load current in high temperature conditions may be less than the
maximum current-sourcing capability of the device. In no case should the device be operated outside of its
maximum power rating because doing so can result in premature failure or permanent damage to the device.
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8.5 Noise Performance
2µV/div
Typical 0.1-Hz to 10-Hz voltage noise can be seen in Figure 8-6 . Device noise increases with output voltage
and operating temperature. Additional filtering can be used to improve output noise levels, although care must
be taken to ensure the output impedance does not degrade ac performance. Peak-to-peak noise measurement
setup is shown in Figure 8-6.
Time 1s/div
D08_
Figure 8-6. 0.1-Hz to 10-Hz Noise (VOUT)
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9 Detailed Description
9.1 Overview
The REF34xx is family of low-noise, precision bandgap voltage references that are specifically designed for
excellent initial voltage accuracy and drift. The Section 9.2 is a simplified block diagram of the REF34xx showing
basic band-gap topology.
9.2 Functional Block Diagram
GNDF
Enable
Blocks
GNDS
Digital
EN
Inrush
Current
Limit
Vdd
OUTF
OUTS
Bandgap
core
Buffer
IN
9.3 Feature Description
9.3.1 Supply Voltage
The REF34xx family of references features an extremely low dropout voltage. For loaded conditions, a typical
dropout voltage versus load is shown on the front page. The REF34xx features a low quiescent current that
is extremely stable over changes in both temperature and supply. The typical room temperature quiescent
current is 72 μA, and the maximum quiescent current over temperature is just 95 μA. Supply voltages below the
specified levels can cause the REF34xx 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.
9.3.2 Low Temperature Drift
The REF34xx is designed for minimal drift error, which is defined as the change in output voltage over
temperature. The drift is calculated using the box method, as described by Equation 3. For this equation, VREF is
VOUT which is the output voltage seen at the junction of OUT_F and OUT_S.
Drift
§
·
VREF(MAX) VREF(MIN)
¨
¸ u 106
¨ VREF(25qC) u Temperature Range ¸
©
¹
(3)
9.3.3 Load Current
The REF34xx family is specified to deliver a current load of ±10 mA per output. The device temperature
increases according to Equation 4:
TJ
TA
PD u RTJA
(4)
where
•
•
•
•
TJ = junction temperature (°C),
TA = ambient temperature (°C),
PD = power dissipated (W), and
RθJA = junction-to-ambient thermal resistance (°C/W)
The REF34xx maximum junction temperature must not exceed the absolute maximum rating of 150°C.
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9.4 Device Functional Modes
9.4.1 EN Pin
When the EN pin of the REF34xx is pulled high, the device is in active mode. The device must be in active mode
for normal operation. The REF34xx can be placed in a low-power mode by pulling the enable pin, EN, low. When
in shutdown mode, the output of the device becomes high impedance and the quiescent current of the device
reduces to 2 µA in shutdown mode. The EN pin must not be pulled higher than VIN supply voltage. See the
Section 7.5 for logic high and logic low voltage levels.
9.4.2 Negative Reference Voltage
For applications requiring a negative and positive reference voltage, the REF34xx and OPA735 can be used
to provide a dual-supply reference from a 5-V supply. Figure 9-1 shows the REF34xx used to provide a 2.5-V
supply reference voltage. The low drift performance of the REF34xx complements the low offset voltage and
zero drift of the OPA735 to provide an accurate solution for split-supply applications. Take care to match the
temperature coefficients of R1 and R2.
+5 V
3
4
5
REF3425
2
1
6
+2.5 V
R1
10 kΩ R2
10 kΩ
+5 V
OPA735
-2.5 V
-5 V
Copyright © 2017, Texas Instruments Incorporated
Figure 9-1. REF34xx and OPA735 Create Positive and Negative Reference Voltages
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10 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.
10.1 Application Information
As this device has many applications and setups, there are many situations that this datasheet can not
characterize in detail. Basic applications includes positive/negative voltage reference and data acquisition
systems. The table below shows the typical application of REF34xx and its companion ADC/DAC.
Table 10-1. Typical Applications and Companion ADC/DAC
Applications
ADC/DAC
PLC - DCS
DAC8881, ADS8332, ADS8568, ADS8317,
ADS8588S, ADS1287
Display Test Equipment
ADS8332
Video Surveillance - Thermal Cameras
ADS7279
Medical Blood Glucose Meter
ADS1112
10.2 Typical Application: Basic Voltage Reference Connection
The circuit shown in Figure 10-1 shows the basic configuration for the REF34xx references. Connect bypass
capacitors according to the guidelines in Section 10.2.2.1.
10
10
-
Input Signal
+
124
ADS1287
1 nF
REF
VIN
CIN
1µF
REF34xx
COUT
10 µF
Copyright © 2017, Texas Instruments Incorporated
Figure 10-1. Basic Reference Connection
10.2.1 Design Requirements
A detailed design procedure is described based on a design example. For this design example, use the
parameters listed in Table 10-2 as the input parameters.
Table 10-2. Design Example Parameters
DESIGN PARAMETER
Input voltage VIN
Output voltage VOUT
VALUE
5V
2.5 V
REF34xx input capacitor
1 µF
REF34xx output capacitor
10 µF
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10.2.2 Detailed Design Procedure
10.2.2.1 Input and Output Capacitors
A 1-μF to 10-μF electrolytic or ceramic capacitor can be connected to the input to improve transient response in
applications where the supply voltage may fluctuate. Connect an additional 0.1-μF ceramic capacitor in parallel
to reduce high frequency supply noise.
A ceramic capacitor of at least a 0.1 μF must be connected to the output to improve stability and help filter out
high frequency noise. An additional 1-μF to 10-μF electrolytic or ceramic capacitor can be added in parallel to
improve transient performance in response to sudden changes in load current; however, keep in mind that doing
so increases the turnon time of the device.
Best performance and stability is attained with low-ESR, low-inductance ceramic chip-type output capacitors
(X5R, X7R, or similar). If using an electrolytic capacitor on the output, place a 0.1-μF ceramic capacitor in
parallel to reduce overall ESR on the output.
10.2.2.2 4-Wire Kelvin Connections
Current flowing through a PCB trace produces an IR voltage drop, and with longer traces, this drop can reach
several millivolts or more, introducing a considerable error into the output voltage of the reference. A 1-inch long,
5-millimeter wide trace of 1-ounce copper has a resistance of approximately 100 mΩ at room temperature; at a
load current of 10 mA, this can introduce a full millivolt of error. In an ideal board layout, the reference must be
mounted as close as possible to the load to minimize the length of the output traces, and, therefore, the error
introduced by voltage drop. However, in applications where this is not possible or convenient, force and sense
connections (sometimes referred to as Kelvin sensing connections) are provided as a means of minimizing the
IR drop and improving accuracy.
Kelvin connections work by providing a set of high impedance voltage-sensing lines to the output and ground
nodes. Because very little current flows through these connections, the IR drop across their traces is negligible,
and the output and ground voltage information can be obtain with minimum IR drop error.
It is always advantageous to use Kelvin connections whenever possible. However, in applications where the IR
drop is negligible or an extra set of traces cannot be routed to the load, the force and sense pins for both VOUT
and GND can simply be tied together, and the device can be used in the same fashion as a normal 3-terminal
reference (as shown in Figure 9-1).
10.2.2.3 VIN Slew Rate Considerations
In applications with slow-rising input voltage signals, the reference exhibits overshoot or other transient
anomalies that appear on the output. These phenomena also appear during shutdown as the internal circuitry
loses power.
To avoid such conditions, ensure that the input voltage wave-form has both a rising and falling slew rate close to
6 V/ms.
10.2.2.4 Shutdown/Enable Feature
The REF34xx references can be switched to a low power shut-down mode when a voltage of 0.5 V or lower is
input to the EN pin. Likewise, the reference becomes operational for EN voltages of 1.6 V or higher. During
shutdown, the supply current drops to less than 2 μA, useful in applications that are sensitive to power
consumption.
If using the shutdown feature, ensure that the EN pin voltage does not fall between 0.5 V and 1.6 V because
this causes a large increase in the supply current of the device and may keep the reference from starting up
correctly. If not using the shutdown feature, however, the EN pin can simply be tied to the IN pin, and the
reference remains operational continuously.
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10.2.3 Application Curves
2.6
75
Quiescent Current Off (µA)
Quiescent Current (µA)
74.5
74
73.5
73
72.5
72
2.4
2.3
2.2
2.1
71.5
71
-50
2.5
-25
0
25
50
Temperature (°C)
75
100
125
D004
Figure 10-2. Quiescent Current vs Temperature
2
-40
-15
10
35
60
Temperature (°C)
85
110 125
D013
Figure 10-3. Quiescent Current Shutdown Mode
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11 Power Supply Recommendations
The REF34xx 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. TI recommends a supply bypass capacitor ranging
between 0.1 µF to 10 µF.
12 Layout
12.1 Layout Guidelines
Figure 12-1 illustrates an example of a PCB layout for a data acquisition system using the REF34xx. Some key
considerations are:
• Connect low-ESR, 0.1-μF ceramic bypass capacitors at IN, OUT_F, VOUT of the REF34xx and REF34xxT.
• Decouple other active devices in the system per the device specifications.
• Using a solid ground plane helps 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.
• 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.
12.2 Layout Example
C
GND_F 1
6 OUT_F
GND_S 2
EN
REF34XX
3
5 OUT_S
IN
4
Figure 12-1. REF34xx Layout Example
C
NC
1
GND
2
NC
3
REF34XXT
6
VOUT
5
NC
4
IN
C
Figure 12-2. REF34xxT Layout Example
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13 Device and Documentation Support
13.1 Documentation Support
13.1.1 Related Documentation
For related documentation see the following:
•
•
INA21x Voltage Output, Low- or High-Side Measurement, Bidirectional, Zero-Drift Series, Current-Shunt
Monitors
Low-Drift Bidirectional Single-Supply Low-Side Current Sensing Reference Design
13.2 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.
13.3 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.
13.4 Trademarks
TI E2E™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
13.5 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.
13.6 Glossary
TI Glossary
This glossary lists and explains terms, acronyms, and definitions.
14 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.
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PACKAGE OPTION ADDENDUM
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24-Feb-2022
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)
REF3425IDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAU
Level-2-250C-1 YEAR
-40 to 125
19ED
REF3425TIDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
2EVC
REF3430IDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
1H6D
REF3430TIDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
2EUC
REF3433IDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
1H5D
REF3433TIDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
2ETC
REF3440IDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
1MJD
REF3440TIDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
2ESC
REF3450IDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAU
Level-2-260C-1 YEAR
-40 to 125
1MKD
REF3450TIDBVR
ACTIVE
SOT-23
DBV
6
3000
RoHS & Green
NIPDAUAG
Level-2-260C-1 YEAR
-40 to 125
2ERC
(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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