REF3425, REF3430, REF3433, REF3440, REF3450
ZHCSGP2E – SEPTEMBER 2017 – REVISED APRIL 2021
REF34xx 低温漂、低功耗、小型串联电压基准
1 特性
3 说明
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REF34xx 器件是低温漂
(6ppm/°C)、低功耗、高精度 CMOS 电压基准，具有
±0.05% 初始精度、低运行电流以及小于 95μA 的功
耗。该器件还提供 3.8μVp-p/V 的超低输出噪声，这使
得它在用于噪声关键型系统中的高分辨率数据转换器时
能 够 保 持 较 高 的 信 号 完 整 性 。 REF34xx 采 用 小 型
SOT-23 封装，具有更高的规格参数并且能够以引脚对
引脚方式替代 MAX607x 和 ADR34xx。REF34xx 系列
与 大 多 数 ADC 和 DAC 兼 容 ， 如 ADS1287 、
ADUCM360、ADS1112。
初始精度：±0.05%（最大值）
温度系数：6ppm/°C（最大值）
工作温度范围：−40°C 至 +125°C
输出电流：±10mA
低静态电流：95μA（最大值）
宽输入电压：12V
输出 1/f 噪声（0.1Hz 至 10Hz）：3.8µVPP/V
出色的长期稳定性（25ppm/1000 小时）
多个小型 6SOT-23 封装引脚排列：REF34xx 和
REF34xxT
2 应用
数据采集系统
模拟 I/O 模块
现场发送器
实验室和现场仪表
电池测试设备
直流电源、交流电源、电子负载
数字万用表
REF34xx 具有 −40°C 至 +125°C 的较宽额定温度范
围。
器件信息(1)
器件名称
封装
封装尺寸（标称值）
REF3425
REF3430
SOT-23 (6)
REF3433
2.90mm × 1.60mm
REF3440
REF3450
(1)
10
Input Signal
+
如需了解所有可用封装，请参阅数据表末尾的可订购产品附录
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)
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该器件的低输出电压迟滞和低长期输出电压漂移可进一
步提高稳定性和系统可靠性。此外，器件的小尺寸和低
运行电流 (95μA) 特性使其非常适合便携式和电池供电
应用。
0.28
0.24
0.2
0.16
0.12
0.08
Copyright © 2017, Texas Instruments Incorporated
简化版原理图
0.04
0
0
5
Load Current (mA)
10
不同温度条件下压降与电流负载间的关系
本文档旨在为方便起见，提供有关 TI 产品中文版本的信息，以确认产品的概要。有关适用的官方英文版本的最新信息，请访问
www.ti.com，其内容始终优先。TI 不保证翻译的准确性和有效性。在实际设计之前，请务必参考最新版本的英文版本。
English Data Sheet: SBAS804
REF3425, REF3430, REF3433, REF3440, REF3450
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ZHCSGP2E – SEPTEMBER 2017 – REVISED APRIL 2021
Table of Contents
1 特性................................................................................... 1
2 应用................................................................................... 1
3 说明................................................................................... 1
4 Revision History.............................................................. 2
5 Device Comparison Table...............................................4
6 Pin Configuration and Functions...................................4
7 Specifications.................................................................. 5
7.1 Absolute Maximum Ratings ....................................... 5
7.2 ESD Ratings .............................................................. 5
7.3 Recommended Operating Conditions ........................5
7.4 Thermal Information ...................................................5
7.5 Electrical Characteristics ............................................6
7.6 Typical Characteristics................................................ 8
8 Parameter Measurement Information.......................... 12
8.1 Solder Heat Shift.......................................................12
8.2 Long-Term Stability................................................... 13
8.3 Thermal Hysteresis................................................... 13
8.4 Power Dissipation..................................................... 14
8.5 Noise Performance................................................... 15
9 Detailed Description......................................................16
9.1 Overview................................................................... 16
9.2 Functional Block Diagram......................................... 16
9.3 Feature Description...................................................16
9.4 Device Functional Modes..........................................17
10 Application and Implementation................................ 18
10.1 Application Information........................................... 18
10.2 Typical Application: Basic Voltage Reference
Connection.................................................................. 18
11 Power Supply Recommendations..............................20
12 Layout...........................................................................21
12.1 Layout Guidelines................................................... 21
12.2 Layout Example...................................................... 21
13 Device and Documentation Support..........................22
13.1 Documentation Support.......................................... 22
13.2 接收文档更新通知................................................... 22
13.3 支持资源..................................................................22
13.4 Trademarks............................................................. 22
13.5 静电放电警告.......................................................... 22
13.6 术语表..................................................................... 22
14 Mechanical, Packaging, and Orderable
Information.................................................................... 22
4 Revision History
注：以前版本的页码可能与当前版本的页码不同
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
• 更新了说明和图...................................................................................................................................................1
• 将 ENABLE 更改为 EN....................................................................................................................................... 1
• Updated values.................................................................................................................................................12
Changes from Revision B (March 2018) to Revision C (February 2021)
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•
•
•
•
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•
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•
Page
添加了“器件信息”以添加 REF34xxT...............................................................................................................1
添加了指向“应用”的超链接............................................................................................................................. 1
通篇将“VREF”更改为“VOUT”........................................................................................................................ 1
更新了整个文档中的表格、图和交叉参考的编号格式......................................................................................... 1
Added REF34xxT to "Device Comparison Table"...............................................................................................4
Added REF34xxT to "Pin Configuration and Functions".....................................................................................4
Fixed pinout mumbering..................................................................................................................................... 4
Added Configuration Information to "Electrical Characteristics”.......................................................................5
Changed ABS MAX IN MIN to "-0.3V"................................................................................................................5
Added REF34xxT to "Layout Guidelines" and "Layout Example".....................................................................21
Changes from Revision A (December 2017) to Revision B (March 2018)
Page
• 添加了 2 个新 GPN：REF3440 和 REF3450..................................................................................................... 1
2
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• 在节 1 中将“出色的长期稳定性（30ppm/1000 小时）”更改为“出色的长期稳定性（25ppm/1000 小时）”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 图 8-3 in 节 8.2 ....................................................... 13
• Changed "(as shown in Figure 26)" to " as shown in 图 9-1 in last paragraph of 节 10.2.2.2 ..........................19
Changes from Revision * (September 2017) to Revision A (December 2017)
Page
• 添加了 2 款全新输出电压选项器件 REF3430 和 REF3433 的产品发布............................................................. 1
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5 Device Comparison Table
PRODUCT
VOUT
REF3425
REF3425T
2.5 V
REF3430
REF3430T
3V
REF3433
REF3433T
3.3 V
REF3440
REF3440T
4.096 V
REF3450
REF3450T
5V
6 Pin Configuration and Functions
GND_F
1
6
OUT_F
GND_S
2
5
OUT_S
EN
3
4
IN
Not to scale
图 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
图 6-2. REF34xxT , DBV Package, 6-Pin SOT-23, Top View
表 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
4
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
-
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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)
Input voltage
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
(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)
REF34
DBV
DBV
6 PINS
6 PINS
UNIT
RθJA
Junction-to-ambient thermal resistance
185
185
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
156
156
°C/W
RθJB
Junction-to-board thermal resistance
29.6
29.6
°C/W
ΨJT
Junction-to-top characterization parameter
33.8
33.8
°C/W
ΨJB
Junction-to-board characterization parameter
29.1
29.1
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
N/A
°C/W
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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
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
–40°C ≤ TA ≤ 125°C
LINE & LOAD REGULATION
VIN = VOUT + VDO (2) to 12 V
ΔVO/ΔVIN 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
5
0.1Hz ≤ f ≤ 10Hz
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
VOUT +
VDO
12
V
–10
10
mA
OUTPUT VOLTAGE
POWER SUPPLY
6
VIN
Input voltage
IL
Output current capacity VIN = VOUT + VDO to 12 V
IQ
Quiescent current
VEN
ENABLE pin voltage
Active mode
72
95
Shutdown mode
2.5
3
Voltage reference in active mode (EN = 1)
1.6
Voltage reference in shutdown mode (EN = 0)
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0.5
µA
V
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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
TEST CONDITION
VDO
Dropout voltage
IEN
ENABLE pin leakage
current
(1)
(2)
(3)
(4)
(5)
(6)
MIN
IL = 0 mA
TYP
MAX
50
100
IL = 10 mA
VEN = VIN = 12V
500
1
2
UNIT
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
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
3V
-15
10
D001
Drift (ppm/°C)
(-40°C to 125°C)
35
60
Temperature (°C)
85
110 125
D003
图 7-2. VIN vs IQ over Temperature
75
0.015
74.5
0.01
74
Quiescent Current (µA)
Output Voltage Accuracy (%)
图 7-1. Temperature Drift
0.02
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
图 7-3. Output Voltage Accuracy vs Temperature
25
50
Temperature (°C)
75
100
125
D004
0.24
CL = 1uF
CL = 10uF
0.23
0.22
-40
Line Regulation (ppm/V)
Power Supply Rejection Ratio (dB)
0
图 7-4. Quiescent Current vs Temperature
-20
-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
图 7-5. Power-Supply Rejection Ratio vs Frequency
8
-25
D002
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D005
0.13
-40
-20
0
20
40
60
80
Temperature (°C)
100
120
140
D019
图 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)
120
140
D021
图 7-8. Load Regulation Sinking
图 7-7. Load Regulation Sourcing
800
ILOAD
720
+1mA
+1mA
640
Noise (nV/vHz)
100
560
-1mA
480
1mA/div
400
4mV/div
320
VOUT
240
160
80
0
10
100
1k
Frequency(Hz)
10k
250µs/div
(CL = 1µF, IOUT = 1mA)
100k
D009
D010
图 7-10. Load Transient
图 7-9. Noise Performance 10 Hz to 10 kHz
ILOAD
ILOAD
+1mA
+10mA
+1mA
+10mA
10mA/div
-10mA
-1mA
1mA/div
4mV/div
VOUT
100mV/div
250µs/div
(CL = 10µF, IOUT = 1mA)
图 7-11. Load Transient
VOUT
250µs/div
(CL = 1µF, IOUT = 10mA)
D010
D010
图 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
VOUT
15mV/div
250µs/div
(CL = 10µF, IOUT = 10mA)
250µs/div
D010
(CL = 1µF)
图 7-13. Load Transient
D011
图 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%
图 7-17. Thermal Hysteresis Distribution (Cycle 1)
D016
110 125
D013
Thermal Hysteresis - Cycle 2 (ppm)
40
30
20
10
0
-10
80
60
0
40
0
20
0
-20
5%
-40
5%
-60
85
10%
-20
10%
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35
60
Temperature (°C)
15%
-30
15%
-40
Population (%)
30%
Thermal Hysteresis - Cycle 1 (ppm)
10
10
图 7-16. Quiescent Current Shutdown Mode
30%
-80
Population (%)
图 7-15. Line Transient
-15
D016
图 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%
Population (%)
40%
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 (%)
图 7-20. Turnon Time (Enable)
Refer to 节 8.1 for more information
图 7-19. Solder Heat Shift Distribution
10
2µV/div
Output Voltage Stability (ppm)
5
0
-5
-10
-15
-20
-25
-30
-35
-40
Time 1s/div
0
D08_
图 7-21. 0.1-Hz to 10-Hz Noise (VOUT)
100
200
300
400
500 600
Hours
700
800
900 1000
D022
图 7-22. Long Term Stability - 1000 hours (VOUT)
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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 图 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
图 8-1. Reflow Profile
The reference output voltage is measured before and after the reflow process; the typical shift is displayed in 图
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 (%)
图 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
图 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 方程式 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 图 8-4.
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30%
Population (%)
25%
20%
15%
10%
Thermal Hysteresis - Cycle 1 (ppm)
80
60
40
20
0
-20
-40
-60
0
-80
5%
D016
图 8-4. Thermal Hysteresis Distribution (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 方程式 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 图 8-5 . 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 图 8-5.
Time 1s/div
D08_
图 8-5. 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 节 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 方程式 3. For this equation, VREF is
VOUT which is the output voltage seen at the junction of OUT_F and OUT_S.
VREF(MAX) VREF(MIN)
·
§
6
Drift = ¨
¸ u 10
V
Temperature
Range
u
© REF
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 方程式 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 节
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. 图 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
图 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.
表 10-1. Typical Applications and Companion ADC/DAC
Applications
ADC/DAC
PLC - DCS
DAC8881, ADS8332, ADS8568, ADS8317,
ADS8588S, ADS1287
Display Test Equipment
ADS8332
Field Transmitters - Pressure
ADUCM360
Video Surveillance - Thermal Cameras
ADS7279
Medical Blood Glucose Meter
ADS1112
10.2 Typical Application: Basic Voltage Reference Connection
The circuit shown in 图 10-1 shows the basic configuration for the REF34xx references. Connect bypass
capacitors according to the guidelines in 节 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
图 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 表 10-2 as the input parameters.
表 10-2. Design Example Parameters
DESIGN PARAMETER
Input voltage VIN
18
VALUE
5V
Output voltage VOUT
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 图 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
图 10-2. Quiescent Current vs Temperature
D004
2
-40
-15
10
35
60
Temperature (°C)
85
110 125
D013
图 10-3. Quiescent Current Shutdown Mode
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.
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12 Layout
12.1 Layout Guidelines
图 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
图 12-1. REF34xx Layout Example
C
NC
1
GND
2
NC
3
REF34XXT
6
VOUT
5
NC
4
IN
C
图 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 接收文档更新通知
要接收文档更新通知，请导航至 ti.com 上的器件产品文件夹。点击订阅更新 进行注册，即可每周接收产品信息更
改摘要。有关更改的详细信息，请查看任何已修订文档中包含的修订历史记录。
13.3 支持资源
TI E2E™ 支持论坛是工程师的重要参考资料，可直接从专家获得快速、经过验证的解答和设计帮助。搜索现有解
答或提出自己的问题可获得所需的快速设计帮助。
链接的内容由各个贡献者“按原样”提供。这些内容并不构成 TI 技术规范，并且不一定反映 TI 的观点；请参阅
TI 的《使用条款》。
13.4 Trademarks
TI E2E™ is a trademark of Texas Instruments.
所有商标均为其各自所有者的财产。
13.5 静电放电警告
静电放电 (ESD) 会损坏这个集成电路。德州仪器 (TI) 建议通过适当的预防措施处理所有集成电路。如果不遵守正确的处理
和安装程序，可能会损坏集成电路。
ESD 的损坏小至导致微小的性能降级，大至整个器件故障。精密的集成电路可能更容易受到损坏，这是因为非常细微的参
数更改都可能会导致器件与其发布的规格不相符。
13.6 术语表
TI 术语表
本术语表列出并解释了术语、首字母缩略词和定义。
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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7-Oct-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)
PREF3450TQDBVR
ACTIVE
SOT-23
DBV
6
3000
TBD
Call TI
Call TI
-40 to 125
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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