LM2831_15 [TI]
LM2831 High-Frequency 1.5-A Load â Step-Down DC-DC Regulator;
| 型号： | LM2831_15 |
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TEXAS INSTRUMENTS |
| 描述： | LM2831 High-Frequency 1.5-A Load â Step-Down DC-DC Regulator |
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| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
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LM2831
SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015
LM2831 High-Frequency 1.5-A Load — Step-Down DC-DC Regulator
1 Features
3 Description
The LM2831 regulator is
a
monolithic, high-
1
•
Space-Saving SOT-23 Package
Input Voltage Range of 3 V to 5.5 V
Output Voltage Range of 0.6 V to 4.5 V
1.5-A Output Current
frequency, PWM step-down DC-DC converter in a 5-
pin SOT-23 and a 6-Pin WSON package. The
LM2831 provides all the active functions to provide
local DC-DC conversion with fast transient response
and accurate regulation in the smallest possible PCB
area. With a minimum of external components, the
LM2831 is easy to use. The ability to drive 1.5-A
loads with an internal 130-mΩ PMOS switch using
state-of-the-art 0.5-µm BiCMOS technology results in
the best power density available. The world-class
control circuitry allows on-times as low as 30 ns, thus
supporting exceptionally high frequency conversion
over the entire 3 V to 5.5 V input operating range,
down to the minimum output voltage of 0.6 V.
Switching frequency is internally set to 550 kHz, 1.6
MHz, or 3 MHz, allowing the use of extremely small
surface mount inductors and chip capacitors. Even
though the operating frequency is high, efficiencies of
up to 93% are easy to achieve. External shutdown is
included, featuring an ultra-low standby current of 30
nA. The LM2831 utilizes current-mode control and
internal compensation to provide high-performance
regulation over a wide range of operating conditions.
Additional features include internal soft-start circuitry
to reduce inrush current, pulse-by-pulse current limit,
thermal shutdown, and output overvoltage protection.
•
•
•
•
High Switching Frequencie
–
–
–
1.6 MHz (LM2831X)
0.55 MHz (LM2831Y)
3 MHz (LM2831Z)
•
•
•
•
•
•
130-mΩ PMOS Switch
0.6-V, 2% Internal Voltage Reference
Internal Soft Start
Current Mode, PWM Operation
Thermal Shutdown
Overvoltage Protection
2 Applications
•
•
•
•
•
Local 5 V to Vcore Step-Down Converters
Core Power in HDDs
Set-Top Boxes
USB Powered Devices
DSL Modems
Device Information(1)
PART NUMBER
LM2831
PACKAGE
WSON (6)
SOT-23 (5)
BODY SIZE (NOM)
3.00 mm × 3.00 mm
1.60 mm × 2.90 mm
(1) For all available packages, see the orderable addendum at
the end of the data sheet.
Typical Application Circuit
Efficiency vs Load
FB
EN
100
GND
SW
LM2831
R3
C1
L1
"X"
V
O
= 3.3V @ 1.5A
V
IN
V
= 5V
IN
R1
R2
90
80
70
60
50
D1
C2
C3
0.1
1
LOAD (A)
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.
LM2831
SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015
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Table of Contents
7.4 Device Functional Modes........................................ 11
Application and Implementation ........................ 12
8.1 Application Information............................................ 12
8.2 Typical Applications ............................................... 12
Power Supply Recommendations...................... 25
1
2
3
4
5
6
Features.................................................................. 1
Applications ........................................................... 1
Description ............................................................. 1
Revision History..................................................... 2
Pin Configuration and Functions......................... 3
Specifications......................................................... 4
6.1 Absolute Maximum Ratings ...................................... 4
6.2 ESD Ratings.............................................................. 4
6.3 Recommended Operating Conditions....................... 4
6.4 Thermal Information.................................................. 4
6.5 Electrical Characteristics........................................... 5
6.6 Typical Characteristics.............................................. 6
Detailed Description .............................................. 9
7.1 Overview ................................................................... 9
7.2 Functional Block Diagram ......................................... 9
7.3 Feature Description................................................... 9
8
9
10 Layout................................................................... 25
10.1 Layout Guidelines ................................................. 25
10.2 Layout Example .................................................... 29
11 Device and Documentation Support ................. 30
11.1 Device Support...................................................... 30
11.2 Documentation Support ........................................ 30
11.3 Community Resources.......................................... 30
11.4 Trademarks........................................................... 30
11.5 Electrostatic Discharge Caution............................ 30
11.6 Glossary................................................................ 30
7
12 Mechanical, Packaging, and Orderable
Information ........................................................... 30
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision C (April 2013) to Revision D
Page
•
Added ESD Ratings 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
Changes from Revision B (April 2013) to Revision C
Page
•
Changed layout of National Data Sheet to TI format ........................................................................................................... 24
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5 Pin Configuration and Functions
NGG Package
6-Pins WSON
Top View
FB
1
2
6
5
4
EN
GND
DAP
VINA
VIND
SW
3
DBV Package
5-Pin SOT-23
Top View
FB
3
2
EN
4
5
GND
SW
1
VIN
Pin Functions
PIN
SOT-23
I/O
DESCRIPTION
NAME
EN
WSON
Enable control input. Logic high enables operation. Do not allow this pin to
float or be greater than VIN + 0.3 V, or VINA + 0.3 V for WSON.
4
3
2
6
1
2
I
I
FB
Feedback pin. Connect to external resistor divider to set output voltage.
Signal and power ground pin. Place the bottom resistor of the feedback
network as close as possible to this pin.
GND
PWR
SW
1
5
3
—
5
O
Output switch. Connect to the inductor and catch diode.
Input supply voltage
VIN
PWR
PWR
PWR
VINA
VIND
—
—
Control circuitry supply voltage. Connect VINA to VIND on PC board.
Power input supply
4
Die Attach
Pad
Connect to system ground for low thermal impedance, but it cannot be
used as a primary GND connection.
—
DAP
PWR
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted)(1)(2)
MIN
–0.5
–0.5
–0.5
–0.5
MAX
7
UNIT
V
VIN
FB Voltage
3
V
EN Voltage
SW Voltage
Junction Temperature(3)
7
V
7
V
150
220
150
°C
°C
°C
Soldering Information
Infrared or Convection Reflow (15 sec)
Storage Temperature, Tstg
–65
(1) 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.
(2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
(3) Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device.
6.2 ESD Ratings
VALUE
UNIT
V(ESD)
Electrostatic discharge
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)
±2000
V
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN
3
NOM
MAX
5.5
UNIT
V
VIN
Junction Temperature
–40
125
°C
6.4 Thermal Information
LM2831
THERMAL METRIC(1)
SOT-23 (DBV
5 PINS
163.4
114.4
26.8
WSON (NGG)
UNIT
6 PINS
54.9
50.8
29.2
0.6
RθJA
Junction-to-ambient thermal resistance(2)
Junction-to-case (top) thermal resistance(2)
Junction-to-board thermal resistance
°C/W
°C/W
°C/W
°C/W
°C/W
°C/W
RθJC(top)
RθJB
ψJT
Junction-to-top characterization parameter
Junction-to-board characterization parameter
Junction-to-case (bottom) thermal resistance
12.4
ψJB
26.2
29.3
9.2
RθJC(bot)
N/A
(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
(2) Applies for packages soldered directly onto a 3” × 3” PC board with 2 oz. copper on 4 layers in still air.
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6.5 Electrical Characteristics
VIN = 5 V unless otherwise indicated under the Test Conditions column. Limits are for TJ = 25°C. Minimum and Maximum
limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at
TJ = 25°C, and are provided for reference purposes only.
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNIT
WSON and SOT-23
Package
TJ = 25°C
0.600
VFB
Feedback Voltage
V
–40°C to 125°C
0.588
0.612
ΔVFB/VIN
Feedback Voltage Line Regulation
Feedback Input Bias Current
VIN = 3 V to 5 V
0.02
0.1
%/V
nA
IB
TJ = 25°C
–40°C to 125°C
TJ = 25°C
100
VIN Rising
VIN Falling
2.73
2.3
V
–40°C to 125°C
TJ = 25°C
2.90
Undervoltage Lockout
UVLO Hysteresis
UVLO
V
V
–40°C to 125°C
1.85
0.43
1.6
LM2831-X
LM2831-Y
LM2831-Z
LM2831-X
LM2831-Y
LM2831-Z
TJ = 25°C
–40°C to 125°C
TJ = 25°C
1.2
0.4
1.95
0.7
0.55
3
FSW
Switching Frequency
MHz
–40°C to 125°C
TJ = 25°C
–40°C to 125°C
TJ = 25°C
2.25
86%
90%
82%
3.75
94%
96%
90%
–40°C to 125°C
TJ = 25°C
DMAX
Maximum Duty Cycle
Minimum Duty Cycle
–40°C to 125°C
TJ = 25°C
–40°C to 125°C
LM2831-X
5%
2%
7%
150
130
DMIN
LM2831-Y
LM2831-Z
WSON Package
SOT-23 Package
RDS(ON)
Switch On Resistance
Switch Current Limit
TJ = 25°C
mΩ
–40°C to 125°C
TJ = 25°C
195
0.4
ICL
VIN = 3.3 V
2.5
A
V
–40°C to 125°C
–40°C to 125°C
–40°C to 125°C
1.8
1.8
Shutdown Threshold Voltage
Enable Threshold Voltage
Switch Leakage
VEN_TH
ISW
IEN
100
100
3.3
nA
nA
Enable Pin Current
Sink/Source
LM2831X VFB = 0.55
TJ = 25°C
–40°C to 125°C
TJ = 25°C
5
4.5
6.5
LM2831Y VFB = 0.55
LM2831Z VFB = 0.55
All Options VEN = 0 V
2.8
4.3
Quiescent Current (switching)
mA
IQ
–40°C to 125°C
TJ = 25°C
–40°C to 125°C
Quiescent Current (shutdown)
Thermal Shutdown Temperature
30
nA
°C
TSD
165
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6.6 Typical Characteristics
All curves taken at VIN = 5 V with configuration in typical application circuit shown in Application Information section of this
datasheet. TJ = 25°C, unless otherwise specified.
1.804
1.803
1.802
1.801
1.800
1.799
1.798
1.797
1.796
0
0.25
0.5
0.75
1
1.25
1.5
LOAD (A)
VIN = 3.3
VO = 1.8 V
VIN = 3.3 V
VO = 1.8 V (All Options)
Figure 1. η vs Load – X, Y, and Z Options
Figure 2. Load Regulation
1.806
3.302
3.301
3.300
3.299
3.298
3.297
1.804
1.802
1.800
1.798
1.796
1.794
0
0.25
0.5
0.75
1
1.25
1.5
0
0.25
0.5
0.75
1
1.25
1.5
LOAD (A)
LOAD (A)
VIN = 5 V
VO = 1.8 V (All Options)
VIN = 5 V
VO = 3.3 V (All Options)
Figure 3. Load Regulation
Figure 4. Load Regulation
0.60
1.81
0.58
0.56
0.54
1.76
1.71
1.66
1.61
1.56
0.52
0.50
0.48
0.46
1.51
1.46
1.41
1.36
-45 -40
-10
20
50
80 110 125 130
-45 -40
-10
20
50
80 110 125 130
TEMPERATURE (ºC)
TEMPERATURE (ºC)
Figure 5. Oscillator Frequency vs Temperature – X Option
Figure 6. Oscillator Frequency vs Temperature – Y Option
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Typical Characteristics (continued)
All curves taken at VIN = 5 V with configuration in typical application circuit shown in Application Information section of this
datasheet. TJ = 25°C, unless otherwise specified.
2900
2800
2700
2600
2500
2400
2300
2200
2100
3.45
3.35
3.25
3.15
3.05
2.95
2.85
2.75
2.65
2.55
-45 -40 -10 20
50
80 110 125 130
-45 -40 -10 20 50
80 110 125 130
TEMPERATURE (ºC)
TEMPERATURE (°C)
VIN = 3.3 V
Figure 7. Oscillator Frequency vs Temperature – Z Option
Figure 8. Current Limit vs Temperature
Figure 9. RDSON vs Temperature (WSON Package)
Figure 10. RDSON vs Temperature (SOT-23 Package)
3.6
2.65
2.6
2.55
2.5
3.5
3.4
3.3
3.2
2.45
2.4
2.35
2.3
2.25
2.2
3.1
3.0
2.15
-45 -40 -10 20
50
80 110 125 130
-45 -40 -10 20
50
80 110 125 130
TEMPERATURE (°C)
TEMPERATURE (ºC)
Figure 12. LM2831Y IQ (Quiescent Current)
Figure 11. LM2831X IQ (Quiescent Current)
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Typical Characteristics (continued)
All curves taken at VIN = 5 V with configuration in typical application circuit shown in Application Information section of this
datasheet. TJ = 25°C, unless otherwise specified.
4.6
4.5
4.4
4.3
4.2
4.1
4.0
-45 -40 -10 20
50
80 110 125 130
TEMPERATURE (ºC)
VO = 1.8 V
IO = 500 mA
Figure 14. Line Regulation
Figure 13. LM2831Z IQ (Quiescent Current)
0.610
0.605
0.600
0.595
0.590
-45 -40 -10 20
50
80 110 125 130
TEMPERATURE (ºC)
VIN = 5 V
VO = 1.2 V at 1 A
Figure 15. VFB vs Temperature
Figure 16. Gain vs Frequency
VIN = 5 V
VO = 1.2 V at 1 A
Figure 17. Phase Plot vs Frequency
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7 Detailed Description
7.1 Overview
The LM2831 device is a constant-frequency PWM buck regulator IC that delivers a 1.5-A load current. The
regulator has a preset switching frequency of 550 kHz, 1.6 MHz, or 3 MHz. This high-frequency allows the
LM2831 to operate with small surface mount capacitors and inductors, resulting in a DC-DC converter that
requires a minimum amount of board space. The LM2831 is internally compensated, so the device is simple to
use and requires few external components.
7.2 Functional Block Diagram
EN
VIN
+
-
I
SENSE
Thermal
ENABLE and UVLO
SHDN
I
LIMIT
OVP
SHDN
-
+
1.15x V
REF
RampArtificial
Control Logic
S
R
R
Q
I
SENSE
+
1.6 MHz
+
+
-
-
PFET
FB
+
DRIVER
Internal -Comp
SW
V
= 0.6V
REF
SOFT-START
Internal - LDO
GND
7.3 Feature Description
7.3.1 Theory of Operation
The LM2831 uses current-mode control to regulate the output voltage. The following operating description of the
LM2831 will refer to Functional Block Diagram and to the waveforms in Figure 18. The LM2831 supplies a
regulated output voltage by switching the internal PMOS control switch at constant-frequency and variable duty
cycle. A switching cycle begins at the falling edge of the reset pulse generated by the internal oscillator. When
this pulse goes low, the output control logic turns on the internal PMOS control switch. During this on-time, the
SW pin voltage (VSW) swings up to approximately VIN, and the inductor current (IL) increases with a linear slope.
IL is measured by the current sense amplifier, which generates an output proportional to the switch current. The
sense signal is summed with the regulator’s corrective ramp and compared to the error amplifier’s output, which
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Feature Description (continued)
is proportional to the difference between the feedback voltage and VREF. When the PWM comparator output goes
high, the output switch turns off until the next switching cycle begins. During the switch off-time, inductor current
discharges through the Schottky catch diode, which forces the SW pin to swing below ground by the forward
voltage (VD) of the Schottky catch diode. The regulator loop adjusts the duty cycle (D) to maintain a constant
output voltage.
V
SW
D = T /T
ON SW
V
IN
SW
Voltage
T
T
OFF
ON
0
t
V
D
T
SW
I
L
I
PK
Inductor
Current
0
t
Figure 18. Typical Waveforms
7.3.2 Soft Start
This function forces VOUT to increase at a controlled rate during start up. During soft start, the error amplifier’s
reference voltage ramps from 0 V to its nominal value of 0.6 V in approximately 600 µs. This forces the regulator
output to ramp up in a controlled fashion, which helps reduce inrush current.
7.3.3 Output Overvoltage Protection
The overvoltage comparator compares the FB pin voltage to a voltage that is 15% higher than the internal
reference VREF. Once the FB pin voltage goes 15% above the internal reference, the internal PMOS control
switch is turned off, which allows the output voltage to decrease toward regulation.
7.3.4 Undervoltage Lockout
Undervoltage lockout (UVLO) prevents the LM2831 from operating until the input voltage exceeds 2.73 V
(typical). The UVLO threshold has approximately 430 mV of hysteresis, so the part will operate until VIN drops
below 2.3 V (typical). Hysteresis prevents the part from turning off during power up if VIN is non-monotonic.
7.3.5 Current Limit
The LM2831 uses cycle-by-cycle current limiting to protect the output switch. During each switching cycle, a
current limit comparator detects if the output switch current exceeds 2.5 A (typical), and turns off the switch until
the next switching cycle begins.
7.3.6 Thermal Shutdown
Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature
exceeds 165°C. After thermal shutdown occurs, the output switch doesn’t turn on until the junction temperature
drops to approximately 150°C.
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7.4 Device Functional Modes
The LM2831 has an enable pin (EN) control Input. A logic high enables device operation. Do not float this pin or
let this pin be greater than VIN + 0.3 V for the SOT package option, or VINA + 0.3 V for the WSON package
option.
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8 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.
8.1 Application Information
The LM2831 device will operate with input voltage range from 3 V to 5.5 V and provide a regulated output
voltage. This device is optimized for high-efficiency operation with minimum number of external components. For
component selection, see Detailed Design Procedure.
8.2 Typical Applications
8.2.1 LM2831X Design Example 1
FB
EN
GND
SW
LM2831
R3
C1
L1
VO = 1.2V @ 1.5A
R1
VIN
VIN = 5V
D1
C2
R2
Figure 19. LM2831X (1.6 MHz): VIN = 5 V, VO = 1.2 V at 1.5 A
8.2.1.1 Design Requirements
The device must be able to operate at any voltage within the recommended operating range. Load current must
be defined to properly size the inductor, input, and output capacitors. Inductor should be able to handle full
expected load current as well as the peak current generated during load transients and start up. Inrush current at
start-up will depend on the output capacitor selection. More details are provided in Detailed Design Procedure.
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Typical Applications (continued)
8.2.1.2 Detailed Design Procedure
Table 1. Bill of Materials
PART ID
PART VALUE
1.5-A Buck Regulator
MANUFACTURER
PART NUMBER
LM2831X
U1
TI
TDK
C1, Input Cap
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
3.3 µH, 2.2 A
C3216X5ROJ226M
C3216X5ROJ226M
CRS08
C2, Output Cap
TDK
D1, Catch Diode
TOSHIBA
TDK
L1
R2
R1
R3
VLCF5020T-3R3N2R0-1
CRCW08051502F
CRCW08051502F
CRCW08051003F
15.0 kΩ, 1%
Vishay
Vishay
Vishay
15.0 kΩ, 1%
100 kΩ, 1%
8.2.1.2.1 Inductor Selection
The duty cycle (D) can be approximated quickly using the ratio of output voltage (VO) to input voltage (VIN):
VOUT
D =
V
IN
(1)
The catch diode (D1) forward voltage drop and the voltage drop across the internal PMOS must be included to
calculate a more accurate duty cycle. Calculate D by using the following formula:
VOUT + VD
D =
V + VD - VSW
IN
(2)
(3)
VSW can be approximated by:
VSW = IOUT × RDSON
The diode forward drop (VD) can range from 0.3 V to 0.7 V depending on the quality of the diode. The lower the
VD, the higher the operating efficiency of the converter. The inductor value determines the output ripple current.
Lower inductor values decrease the size of the inductor, but increase the output ripple current. An increase in the
inductor value will decrease the output ripple current.
One must ensure that the minimum current limit (1.8 A) is not exceeded, so the peak current in the inductor must
be calculated. The peak current (ILPK) in the inductor is calculated by:
ILPK = IOUT + ΔiL
(4)
Di
L
I
OUT
V
OUT
V
- V
IN
OUT
L
L
t
DT
T
S
S
Figure 20. Inductor Current
V - VOUT 2DiL
=
IN
L
DTS
(5)
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In general,
ΔiL = 0.1 × (IOUT) → 0.2 × (IOUT
)
(6)
If ΔiL = 20% of 1.50 A, the peak current in the inductor will be 1.8 A. The minimum ensured current limit over all
operating conditions is 1.8 A. One can either reduce ΔiL, or make the engineering judgment that zero margin will
be safe enough. The typical current limit is 2.5 A.
The LM2831 operates at frequencies allowing the use of ceramic output capacitors without compromising
transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing output ripple.
See the Output Capacitor section for more details on calculating output voltage ripple. Now that the ripple current
is determined, the inductance is calculated by:
æ
ç
è
ö
÷
ø
DTS
L =
´ V - V
IN OUT
2DiL
(7)
Where:
1
TS =
fS
(8)
When selecting an inductor, make sure that it is capable of supporting the peak output current without saturating.
Inductor saturation will result in a sudden reduction in inductance and prevent the regulator from operating
correctly. Because of the speed of the internal current limit, the peak current of the inductor need only be
specified for the required maximum output current. For example, if the designed maximum output current is 1 A
and the peak current is 1.25 A, then the inductor should be specified with a saturation current limit of > 1.25 A.
There is no need to specify the saturation or peak current of the inductor at the 2.5-A typical switch current limit.
The difference in inductor size is a factor of 5. Because of the operating frequency of the LM2831, ferrite based
inductors are preferred to minimize core losses. This presents little restriction since the variety of ferrite-based
inductors is huge. Lastly, inductors with lower series resistance (RDCR) will provide better operating efficiency. For
recommended inductors, see LM2831X Design Example 2 through LM2831X Buck Converter and Voltage
Double Circuit With LDO Follower Design Example 9.
8.2.1.2.2 Input Capacitor
An input capacitor is necessary to ensure that VIN does not drop excessively during switching transients. The
primary specifications of the input capacitor are capacitance, voltage, RMS current rating, and ESL (Equivalent
Series Inductance). The recommended input capacitance is 22 µF. The input voltage rating is specifically stated
by the capacitor manufacturer. Make sure to check any recommended deratings and also verify if there is any
significant change in capacitance at the operating input voltage and the operating temperature. The input
capacitor maximum RMS input current rating (IRMS-IN) must be greater than:
é
2 ù
ú
Di
2
IRMS _IN D I
ê OUT
(1-D) +
3
ê
ë
ú
û
(9)
Neglecting inductor ripple simplifies the above equation to:
IRMS _IN = IOUT ´ D(1-D)
(10)
It can be shown from the above equation that maximum RMS capacitor current occurs when D = 0.5. Always
calculate the RMS at the point where the duty cycle D is closest to 0.5. The ESL of an input capacitor is usually
determined by the effective cross sectional area of the current path. A large leaded capacitor will have high ESL
and a 0805 ceramic chip capacitor will have very low ESL. At the operating frequencies of the LM2831, leaded
capacitors may have an ESL so large that the resulting impedance (2πfL) will be higher than that required to
provide stable operation. As a result, surface mount capacitors are strongly recommended.
Sanyo POSCAP, Tantalum or Niobium, Panasonic SP, and multilayer ceramic capacitors (MLCC) are all good
choices for both input and output capacitors and have very low ESL. For MLCCs it is recommended to use X7R
or X5R type capacitors due to their tolerance and temperature characteristics. Consult capacitor manufacturer
data sheets to see how rated capacitance varies over operating conditions.
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8.2.1.2.3 Output Capacitor
The output capacitor is selected based upon the desired output ripple and transient response. The initial current
of a load transient is provided mainly by the output capacitor. The output ripple of the converter is:
æ
ö
÷
ø
1
VOUT = DI R
+
L ç
ESR
8´FSW ´COUT
è
(11)
When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the
output ripple will be approximately sinusoidal and 90° phase shifted from the switching action. Given the
availability and quality of MLCCs and the expected output voltage of designs using the LM2831, there is really no
need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to bypass
high frequency noise. A certain amount of switching edge noise will couple through parasitic capacitances in the
inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not. Since the output
capacitor is one of the two external components that control the stability of the regulator control loop, most
applications will require a minimum of 22 µF of output capacitance. Capacitance often, but not always, can be
increased significantly with little detriment to the regulator stability. Like the input capacitor, recommended
multilayer ceramic capacitors are X7R or X5R types.
8.2.1.2.4 Catch Diode
The catch diode (D1) conducts during the switch off-time. A Schottky diode is recommended for its fast switching
times and low forward voltage drop. The catch diode should be chosen so that its current rating is greater than:
ID1 = IOUT × (1-D)
(12)
The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin.
To improve efficiency, choose a Schottky diode with a low forward voltage drop.
8.2.1.2.5 Output Voltage
The output voltage is set using the following equation where R2 is connected between the FB pin and GND, and
R1 is connected between VO and the FB pin. A good value for R2 is 10 kΩ. When designing a unity gain
converter (Vo = 0.6 V), R1 should be from 0 Ω to 100 Ω, and R2 should be equal or greater than 10 kΩ.
VOUT
x R2
- 1
R1 =
VREF
VREF = 0.60 V
(13)
(14)
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8.2.1.3 Application Curves
See Typical Characteristics.
VIN = 5 V
VO = 1.8 V and 3.3 V
VIN = 5 V
VO = 1.8 V and 3.3 V
Figure 21. η vs Load – X Option
Figure 22. η vs Load – Y Option
VIN = 5 V
VO = 1.8 V and 3.3 V
Figure 23. η vs Load – Z Option
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8.2.2 LM2831X Design Example 2
FB
EN
GND
SW
LM2831
R3
C1
L1
V
O
= 0.6V @ 1.5A
R1
V
IN
V
IN
= 5V
D1
C2
R2
Figure 24. LM2831X (1.6 MHz): VIN = 5 V, VO = 0.6 V at 1.5 A
Table 2. Bill of Materials
PART ID
PART VALUE
1.5-A Buck Regulator
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
3.3 µH, 2.2 A
MANUFACTURER
PART NUMBER
LM2831X
U1
TI
TDK
C1, Input Capacitor
C3216X5ROJ226M
C3216X5ROJ226M
CRS08
C2, Output Capacitor
TDK
D1, Catch Diode
TOSHIBA
TDK
L1
R2
R1
R3
VLCF5020T- 3R3N2R0-1
CRCW08051000F
10.0 kΩ, 1%
Vishay
0 Ω
100 kΩ, 1%
Vishay
CRCW08051003F
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8.2.3 LM2831X Design Example 3
FB
EN
GND
SW
LM2831
R3
C1
L1
V
= 3.3V @ 1.5A
R1
O
V
IN
V
= 5V
IN
D1
C2
R2
Figure 25. LM2831X (1.6 MHz): VIN = 5 V, VO = 3.3 V at 1.5 A
Table 3. Bill of Materials
PART ID
PART VALUE
1.5-A Buck Regulator
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
2.7 µH 2.3 A
MANUFACTURER
PART NUMBER
LM2831X
U1
TI
TDK
C1, Input Cap
C3216X5ROJ226M
C3216X5ROJ226M
CRS08
C2, Output Cap
TDK
D1, Catch Diode
TOSHIBA
TDK
L1
R2
R1
R3
VLCF5020T-2R7N2R2-1
CRCW08051002F
CRCW08054532F
CRCW08051003F
10.0 kΩ, 1%
Vishay
Vishay
Vishay
45.3 kΩ, 1%
100 kΩ, 1%
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8.2.4 LM2831Y Design Example 4
FB
EN
GND
SW
LM2831
R3
C1
L1
V
= 3.3V @ 1.5A
R1
O
V
IN
V
= 5V
IN
D1
C2
R2
Figure 26. LM2831Y (550 kHz): VIN = 5 V, VOUT = 3.3 V at 1.5 A
Table 4. Bill of Materials
PART ID
PART VALUE
1.5-A Buck Regulator
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
4.7 µH 2.1 A
MANUFACTURER
PART NUMBER
LM2831Y
U1
C1, Input Cap
C2, Output Cap
D1, Catch Diode
L1
TI
TDK
C3216X5ROJ226M
C3216X5ROJ226M
CRS08
TDK
TOSHIBA
TDK
SLF7045T-4R7M2R0-PF
CRCW080545K3FKEA
CRCW08051002F
R1
45.3 kΩ, 1%
Vishay
Vishay
R2
10.0 kΩ, 1%
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8.2.5 LM2831Y Design Example 5
FB
EN
GND
SW
LM2831
R3
C1
L1
VO = 1.2V @ 1.5A
VIN
VIN = 5V
R1
R2
D1
C2
Figure 27. LM2831Y (550 kHz): VIN = 5 V, VOUT = 1.2 V at 1.5 A
Table 5. Bill of Materials
PART ID
U1
PART VALUE
1.5-A Buck Regulator
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
6.8 µH 1.8 A
MANUFACTURER
PART NUMBER
LM2831Y
TI
TDK
C1, Input Cap
C3216X5ROJ226M
C3216X5ROJ226M
CRS08
C2, Output Cap
TDK
D1, Catch Diode
TOSHIBA
TDK
L1
R1
R2
SLF7045T-6R8M1R7
CRCW08051002F
CRCW08051002F
10.0 kΩ, 1%
Vishay
Vishay
10.0 kΩ, 1%
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8.2.6 LM2831Z Design Example 6
FB
EN
GND
SW
LM2831
R3
C1
L1
V
= 3.3V @ 1.5A
R1
O
V
IN
V
= 5V
IN
D1
C2
R2
Figure 28. LM2831Z (3 MHz): VIN = 5 V, VO = 3.3 V at 1.5 A
Table 6. Bill of Materials
PART ID
PART VALUE
1.5-A Buck Regulator
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
1.6 µH 2.0 A
MANUFACTURER
PART NUMBER
LM2831Z
U1
TI
TDK
C1, Input Cap
C3216X5ROJ226M
C3216X5ROJ226M
CRS08
C2, Output Cap
TDK
D1, Catch Diode
TOSHIBA
TDK
L1
R2
R1
R3
VLCF4018T-1R6N1R7-2
CRCW08051002F
CRCW08054532F
CRCW08051003F
10.0 kΩ, 1%
Vishay
Vishay
Vishay
45.3 kΩ, 1%
100 kΩ, 1%
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8.2.7 LM2831Z Design Example 7
FB
EN
GND
SW
LM2831
R3
C1
L1
VO = 1.2V @ 1.5A
VIN
VIN = 5V
R1
R2
D1
C2
Figure 29. LM2831Z (3 MHz): VIN = 5 V, VO = 1.2 V at 1.5 A
Table 7. Bill of Materials
PART ID
U1
PART VALUE
1.5-A Buck Regulator
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
1.6 µH, 2.0 A
MANUFACTURER
PART NUMBER
LM2831Z
TI
TDK
C1, Input Cap
C3216X5ROJ226M
C3216X5ROJ226M
CRS08
C2, Output Cap
TDK
D1, Catch Diode
TOSHIBA
TDK
L1
R2
R1
R3
VLCF4018T- 1R6N1R7-2
CRCW08051002F
CRCW08051002F
CRCW08051003F
10.0 kΩ, 1%
Vishay
Vishay
Vishay
10.0 kΩ, 1%
100 kΩ, 1%
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8.2.8 LM2831X Dual Converters with Delayed Enabled Design Example 8
V
IN
U1
VIND VINA
C1
R3
L1
V
= 3.3V @ 1.5A
R1
O
SW
EN
D1
C2
R2
LM2831
GND
FB
U3
4
3
2
R6
LP3470M5X-3.08
LP3470
RESET
5
1
V
IN
C7
U2
VIND VINA
C3
L2
V
= 1.2V @ 1.5A
R4
O
SW
LM2831
D2
C4
R5
EN
GND
FB
Figure 30. LM2831X (1.6 MHz): VIN = 5 V, VO = 1.2 V at 1.5 A and 3.3 V at1.5 A
Table 8. Bill of Materials
PART ID
U1, U2
PART VALUE
1.5-A Buck Regulator
Power on Reset
22 µF, 6.3 V, X5R
2x22 µF, 6.3 V, X5R
Trr delay capacitor
0.3 Vf Schottky 1.5 A, 30 VR
3.3 µH, 2.2 A
MANUFACTURER
PART NUMBER
LM2831X
TI
TI
U3
LP3470M5X-3.08
C3216X5ROJ226M
C3216X5ROJ226M
C1, C3 Input Cap
C2, C4 Output Cap
C7
TDK
TDK
TDK
D1, D2 Catch Diode
L1, L2
TOSHIBA
TDK
CRS08
VLCF5020T-3R3N2R0-1
CRCW08051002F
CRCW08054532F
CRCW08051003F
R2, R4, R5
R1, R6
10.0 kΩ, 1%
Vishay
Vishay
Vishay
45.3 kΩ, 1%
R3
100 kΩ, 1%
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8.2.9 LM2831X Buck Converter and Voltage Double Circuit With LDO Follower Design Example 9
V
O
= 5.0V @ 150mA
L2
U2
LDO
D2
C5
C4
C6
U1
C3
L1
LM2831
VIND
VINA
EN
SW
GND
FB
V
= 5V
IN
R1
R2
C1
V
= 3.3V @ 1.5A
O
C2
D1
Figure 31. LM2831X (1.6 MHz): VIN = 5 V, VO = 3.3 V at 1.5 A and LP2986-5.0 at 150 mA
Table 9. Bill of Materials
PART ID
PART VALUE
1.5-A Buck Regulator
200-mA LDO
MANUFACTURER
TI
PART NUMBER
LM2831X
U1
U2
TI
LP2986-5.0
C1, Input Cap
22 µF, 6.3 V, X5R
22 µF, 6.3 V, X5R
2.2 µF, 6.3 V, X5R
0.3 Vf Schottky 1.5 A, 30 VR
0.4 Vf Schottky 20 VR, 500 mA
10 µH, 800 mA
TDK
C3216X5ROJ226M
C3216X5ROJ226M
C1608X5R0J225M
CRS08
C2, Output Cap
TDK
C3 – C6
TDK
D1, Catch Diode
TOSHIBA
ON Semi
CoilCraft
TDK
D2
L2
L1
R2
R1
MBR0520
ME3220-103
3.3 µH, 2.2 A
VLCF5020T-3R3N2R0-1
CRCW08054532F
CRCW08051002F
45.3 kΩ, 1%
Vishay
Vishay
10.0 kΩ, 1%
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9 Power Supply Recommendations
The LM2831 device is designed to operate from various DC power supplies. The impedance of the input supply
rail should be low enough that the input current transient does not cause a drop below the UVLO level. If the
input supply is connected by using long wires, additional bulk capacitance may be required in addition to normal
input capacitor.
10 Layout
10.1 Layout Guidelines
When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The
most important consideration is the close coupling of the GND connections of the input capacitor and the catch
diode D1. These ground ends should be close to one another and be connected to the GND plane with at least
two through-holes. Place these components as close to the IC as possible. Next in importance is the location of
the GND connection of the output capacitor, which should be near the GND connections of CIN and D1. There
should be a continuous ground plane on the bottom layer of a two-layer board except under the switching node
island. The FB pin is a high impedance node and care should be taken to make the FB trace short to avoid noise
pickup and inaccurate regulation. The feedback resistors should be placed as close as possible to the IC, with
the GND of R1 placed as close as possible to the GND of the IC. The VOUT trace to R2 should be routed away
from the inductor and any other traces that are switching. High AC currents flow through the VIN, SW and VOUT
traces, so they should be as short and wide as possible. However, making the traces wide increases radiated
noise, so the designer must make this trade-off. Radiated noise can be decreased by choosing a shielded
inductor. The remaining components should also be placed as close as possible to the IC. See Application Note
AN-1229 SNVA054 for further considerations and the LM2831 demo board as an example of a 4-layer layout.
10.1.1 Calculating Efficiency and Junction Temperature
The complete LM2831 DC-DC converter efficiency can be calculated in the following manner.
POUT
h =
P
IN
(15)
(16)
Or
POUT
POUT + P
h =
LOSS
Calculations for determining the most significant power losses are shown below. Other losses totaling less than
2% are not discussed.
Power loss (PLOSS) is the sum of two basic types of losses in the converter: switching and conduction.
Conduction losses usually dominate at higher output loads, whereas switching losses remain relatively fixed and
dominate at lower output loads. The first step in determining the losses is to calculate the duty cycle (D):
VOUT + VD
D =
V + VD - VSW
IN
(17)
(18)
VSW is the voltage drop across the internal PFET when it is on, and is equal to:
VSW = IOUT × RDSON
VD is the forward voltage drop across the Schottky catch diode. It can be obtained from the diode manufactures
Electrical Characteristics section. If the voltage drop across the inductor (VDCR) is accounted for, the equation
becomes:
VOUT + VD + VDCR
D =
VIN + VD + VDCR - VSW
(19)
The conduction losses in the free-wheeling Schottky diode are calculated as follows:
PDIODE = VD × IOUT × (1-D)
(20)
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Layout Guidelines (continued)
Often this is the single most significant power loss in the circuit. Care should be taken to choose a Schottky
diode that has a low forward voltage drop.
Another significant external power loss is the conduction loss in the output inductor. The equation can be
simplified to:
PIND = IOUT2 × RDCR
(21)
The LM2831 conduction loss is mainly associated with the internal PFET:
2
DiL
IOUT
1
3
PCOND = (IOUT2 x D)
x
RDSON
1 +
(22)
(23)
If the inductor ripple current is fairly small, the conduction losses can be simplified to:
PCOND = IOUT2 × RDSON × D
Switching losses are also associated with the internal PFET. They occur during the switch on and off transition
periods, where voltages and currents overlap resulting in power loss. The simplest means to determine this loss
is to empirically measuring the rise and fall times (10% to 90%) of the switch at the switch node.
Switching power loss is calculated as follows:
PSWR = 1/2(VIN × IOUT × FSW × TRISE
)
(24)
(25)
(26)
PSWF = 1/2(VIN × IOUT × FSW × TFALL
PSW = PSWR + PSWF
)
Another loss is the power required for operation of the internal circuitry:
PQ = IQ × VIN
(27)
IQ is the quiescent operating current, and is typically around 2.5 mA for the 0.55-MHz frequency option.
Typical application power losses are:
Table 10. Power Loss Tabulation
PARAMETER
VALUE
5 V
PARAMETER
VALUE
4.125 W
188 mW
VIN
VOUT
IOUT
VD
3.3 V
POUT
1.25 A
0.45 V
550 kHz
2.5 mA
4 nS
PDIODE
FSW
IQ
PQ
PSWR
12.5 mW
7 mW
TRISE
TFALL
RDS(ON)
INDDCR
D
4 nS
PSWF
7 mW
150 mΩ
70 mΩ
0.667
88%
PCOND
PIND
PLOSS
PINTERNAL
156 mW
110 mW
481 mW
183 mW
η
ΣPCOND + PSW + PDIODE + PIND + PQ = PLOSS
ΣPCOND + PSWF + PSWR + PQ = PINTERNAL
PINTERNAL = 183 mW
(28)
(29)
(30)
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10.1.2 Thermal Definitions
TJ
Chip junction temperature
TA
Ambient temperature
RθJC
RθJA
Thermal resistance from chip junction to device case
Thermal resistance from chip junction to ambient air
Heat in the LM2831 due to internal power dissipation is removed through conduction and/or convection.
Conduction Heat transfer occurs through cross sectional areas of material. Depending on the material, the
transfer of heat can be considered to have poor to good thermal conductivity properties (insulator
vs. conductor).
Heat Transfer goes as:
Silicon → package → lead frame → PCB
Convection: Heat transfer is by means of airflow. This could be from a fan or natural convection. Natural
convection occurs when air currents rise from the hot device to cooler air.
Thermal impedance is defined as:
DT
Rq =
Power
(31)
Thermal impedance from the silicon junction to the ambient air is defined as:
TJ - TA
RqJA
=
Power
(32)
The PCB size, weight of copper used to route traces and ground plane, and number of layers within the PCB can
greatly effect RθJA. The type and number of thermal vias can also make a large difference in the thermal
impedance. Thermal vias are necessary in most applications. They conduct heat from the surface of the PCB to
the ground plane. Four to six thermal vias should be placed under the exposed pad to the ground plane if the
WSON package is used.
Thermal impedance also depends on the thermal properties of the application operating conditions (Vin, Vo, Io,
and so forth), and the surrounding circuitry.
10.1.2.1 Silicon Junction Temperature Determination Method 1
To accurately measure the silicon temperature for a given application, two methods can be used. The first
method requires the user to know the thermal impedance of the silicon junction to top case temperature.
Some clarification must be made before we go any further.
R
θJC is the thermal impedance from all six sides of an IC package to silicon junction.
ΦJC is the thermal impedance from top case to the silicon junction.
R
In this data sheet we will use RΦJC so that it allows the user to measure top case temperature with a small
thermocouple attached to the top case.
RΦJC is approximately 30°C/Watt for the 6-pin WSON package with the exposed pad. Knowing the internal
dissipation from the efficiency calculation given previously, and the case temperature, which can be empirically
measured on the bench we have:
TJ - TC
RFJC
=
Power
(33)
(34)
Therefore:
Tj = (RΦJC × PLOSS) + TC
From the previous example:
Tj = (RΦJC × PINTERNAL) + TC
Tj = 30°C/W × 0.189 W + TC
(35)
(36)
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The second method can give a very accurate silicon junction temperature.
The first step is to determine RθJA of the application. The LM2831 has overtemperature protection circuitry. When
the silicon temperature reaches 165°C, the device stops switching. The protection circuitry has a hysteresis of
about 15°C. Once the silicon temperature has decreased to approximately 150°C, the device will start to switch
again. Knowing this, the RθJA for any application can be characterized during the early stages of the design one
may calculate the RθJA by placing the PCB circuit into a thermal chamber. Raise the ambient temperature in the
given working application until the circuit enters thermal shutdown. If the SW-pin is monitored, it will be obvious
when the internal PFET stops switching, indicating a junction temperature of 165°C. Knowing the internal power
dissipation from the above methods, the junction temperature, and the ambient temperature RθJA can be
determined.
165°C - Ta
RqJA
=
P
INTERNAL
(37)
Once this is determined, the maximum ambient temperature allowed for a desired junction temperature can be
found.
An example of calculating RθJA for an application using the Texas Instruments LM2831 WSON demonstration
board is shown below.
The four layer PCB is constructed using FR4 with ½ oz copper traces. The copper ground plane is on the bottom
layer. The ground plane is accessed by two vias. The board measures 3 cm × 3 cm. It was placed in an oven
with no forced airflow. The ambient temperature was raised to 144°C, and at that temperature, the device went
into thermal shutdown.
From the previous example:
PINTERNAL = 189 mW
(38)
165°C -144°C
RqJA
=
= 111°C / W
189 mW
(39)
If the junction temperature was to be kept below 125°C, then the ambient temperature could not go above 109°C
Tj - (RθJA × PLOSS) = TA
(40)
(41)
125°C - (111°C/W × 189 mW) = 104°C
10.1.3 WSON Package
Die Attach
Material
Mold Compound
Gold Wire
Die
Cu
Exposed
Contact
Exposed Die
Attach Pad
Figure 32. Internal WSON Connection
For certain high power applications, the PCB land may be modified to a "dog bone" shape (see Figure 33). By
increasing the size of ground plane, and adding thermal vias, the RθJA for the application can be reduced.
28
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SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015
10.2 Layout Example
FB
1
2
6
EN
GND
5 VINA
4 VIND
SW
3
Figure 33. 6-Lead WSON PCB Dog Bone Layout
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11 Device and Documentation Support
11.1 Device Support
11.1.1 Third-Party Products Disclaimer
TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT
CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES
OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER
ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE.
11.2 Documentation Support
11.2.1 Related Documentation
For related documentation, see the following:
AN-1229 SIMPLE SWITCHER ® PCB Layout Guidelines, SNVA054
11.3 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.
11.4 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.5 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.
11.6 Glossary
SLYZ022 — TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
12 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.
30
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PACKAGE OPTION ADDENDUM
www.ti.com
8-Oct-2015
PACKAGING INFORMATION
Orderable Device
LM2831XMF/NOPB
LM2831XMFX/NOPB
Status Package Type Package Pins Package
Eco Plan
Lead/Ball Finish
MSL Peak Temp
Op Temp (°C)
-40 to 125
Device Marking
Samples
Drawing
Qty
(1)
(2)
(6)
(3)
(4/5)
ACTIVE
SOT-23
SOT-23
DBV
5
5
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
SKYB
SKYB
ACTIVE
DBV
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
LM2831XSD
NRND
WSON
WSON
NGG
NGG
6
6
1000
1000
TBD
Call TI
CU SN
Call TI
-40 to 125
-40 to 125
L193B
L193B
LM2831XSD/NOPB
ACTIVE
Green (RoHS
& no Sb/Br)
Level-3-260C-168 HR
LM2831XSDX/NOPB
LM2831YMF/NOPB
LM2831YMFX/NOPB
LM2831YSD/NOPB
LM2831ZMF/NOPB
LM2831ZSD/NOPB
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
ACTIVE
WSON
SOT-23
SOT-23
WSON
SOT-23
WSON
NGG
DBV
DBV
NGG
DBV
NGG
6
5
5
6
5
6
4500
1000
3000
1000
1000
1000
Green (RoHS
& no Sb/Br)
CU SN
CU SN
CU SN
CU SN
CU SN
CU SN
Level-3-260C-168 HR
Level-1-260C-UNLIM
Level-1-260C-UNLIM
Level-3-260C-168 HR
Level-1-260C-UNLIM
Level-3-260C-168 HR
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
-40 to 125
L193B
SKZB
SKZB
L194B
SLAB
L195B
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
Green (RoHS
& no Sb/Br)
(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) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability
information and additional product content details.
TBD: The Pb-Free/Green conversion plan has not been defined.
Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that
lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between
the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above.
Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight
in homogeneous material)
Addendum-Page 1
PACKAGE OPTION ADDENDUM
www.ti.com
8-Oct-2015
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
(6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish
value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
Addendum-Page 2
PACKAGE MATERIALS INFORMATION
www.ti.com
2-Sep-2015
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device
Package Package Pins
Type Drawing
SPQ
Reel
Reel
A0
B0
K0
P1
W
Pin1
Diameter Width (mm) (mm) (mm) (mm) (mm) Quadrant
(mm) W1 (mm)
LM2831XMF/NOPB
LM2831XMFX/NOPB
LM2831XSD
SOT-23
SOT-23
WSON
WSON
WSON
SOT-23
SOT-23
WSON
SOT-23
WSON
DBV
DBV
NGG
NGG
NGG
DBV
DBV
NGG
DBV
NGG
5
5
6
6
6
5
5
6
5
6
1000
3000
1000
1000
4500
1000
3000
1000
1000
1000
178.0
178.0
178.0
178.0
330.0
178.0
178.0
178.0
178.0
178.0
8.4
8.4
3.2
3.2
3.3
3.3
3.3
3.2
3.2
3.3
3.2
3.3
3.2
3.2
3.3
3.3
3.3
3.2
3.2
3.3
3.2
3.3
1.4
1.4
1.0
1.0
1.0
1.4
1.4
1.0
1.4
1.0
4.0
4.0
8.0
8.0
8.0
4.0
4.0
8.0
4.0
8.0
8.0
8.0
Q3
Q3
Q1
Q1
Q1
Q3
Q3
Q1
Q3
Q1
12.4
12.4
12.4
8.4
12.0
12.0
12.0
8.0
LM2831XSD/NOPB
LM2831XSDX/NOPB
LM2831YMF/NOPB
LM2831YMFX/NOPB
LM2831YSD/NOPB
LM2831ZMF/NOPB
LM2831ZSD/NOPB
8.4
8.0
12.4
8.4
12.0
8.0
12.4
12.0
Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION
www.ti.com
2-Sep-2015
*All dimensions are nominal
Device
Package Type Package Drawing Pins
SPQ
Length (mm) Width (mm) Height (mm)
LM2831XMF/NOPB
LM2831XMFX/NOPB
LM2831XSD
SOT-23
SOT-23
WSON
WSON
WSON
SOT-23
SOT-23
WSON
SOT-23
WSON
DBV
DBV
NGG
NGG
NGG
DBV
DBV
NGG
DBV
NGG
5
5
6
6
6
5
5
6
5
6
1000
3000
1000
1000
4500
1000
3000
1000
1000
1000
210.0
210.0
213.0
213.0
367.0
210.0
210.0
213.0
210.0
213.0
185.0
185.0
191.0
191.0
367.0
185.0
185.0
191.0
185.0
191.0
35.0
35.0
55.0
55.0
35.0
35.0
35.0
55.0
35.0
55.0
LM2831XSD/NOPB
LM2831XSDX/NOPB
LM2831YMF/NOPB
LM2831YMFX/NOPB
LM2831YSD/NOPB
LM2831ZMF/NOPB
LM2831ZSD/NOPB
Pack Materials-Page 2
MECHANICAL DATA
NGG0006A
SDE06A (Rev A)
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相关型号：
LM2832XSDX/NOPB
IC 3.25 A SWITCHING REGULATOR, 1950 kHz SWITCHING FREQ-MAX, DSO6, LLP-6, Switching Regulator or Controller
NSC
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