TI LM2831ZMF/NOPB Lm2831 high-frequency 1.5-a load â step-down dc-dc regulator Datasheet

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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, highfrequency, PWM step-down DC-DC converter in a 5pin 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.
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
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
BODY SIZE (NOM)
WSON (6)
3.00 mm × 3.00 mm
SOT-23 (5)
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
LM2831
R3
VIN
Efficiency vs Load
FB
EN
100
GND
L1
SW
"X"
VO = 3.3V @ 1.5A
VIN = 5V
R1
90
C1
D1
R2
C3
EFFICIENCY (%)
C2
80
70
60
50
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
1
2
3
4
5
6
7
Features ..................................................................
Applications ...........................................................
Description .............................................................
Revision History.....................................................
Pin Configuration and Functions .........................
Specifications.........................................................
1
1
1
2
3
4
6.1
6.2
6.3
6.4
6.5
6.6
4
4
4
4
5
6
Absolute Maximum Ratings ......................................
ESD Ratings..............................................................
Recommended Operating Conditions.......................
Thermal Information ..................................................
Electrical Characteristics...........................................
Typical Characteristics ..............................................
Detailed Description .............................................. 9
7.1 Overview ................................................................... 9
7.2 Functional Block Diagram ......................................... 9
7.3 Feature Description................................................... 9
7.4 Device Functional Modes........................................ 11
8
Application and Implementation ........................ 12
8.1 Application Information............................................ 12
8.2 Typical Applications ............................................... 12
9 Power Supply Recommendations...................... 25
10 Layout................................................................... 25
10.1 Layout Guidelines ................................................. 25
10.2 Layout Example .................................................... 29
11 Device and Documentation Support ................. 30
11.1
11.2
11.3
11.4
11.5
11.6
Device Support......................................................
Documentation Support ........................................
Community Resources..........................................
Trademarks ...........................................................
Electrostatic Discharge Caution ............................
Glossary ................................................................
30
30
30
30
30
30
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
•
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
•
2
Page
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
GND
2
SW
3
6 EN
DAP
5 VINA
4 VIND
DBV Package
5-Pin SOT-23
Top View
EN
4
3
FB
2 GND
VIN
5
1
SW
Pin Functions
PIN
I/O
DESCRIPTION
6
I
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.
3
1
I
Feedback pin. Connect to external resistor divider to set output voltage.
GND
2
2
PWR
Signal and power ground pin. Place the bottom resistor of the feedback
network as close as possible to this pin.
SW
1
3
O
VIN
5
—
PWR
Input supply voltage
VINA
—
5
PWR
Control circuitry supply voltage. Connect VINA to VIND on PC board.
VIND
—
4
PWR
Power input supply
Die Attach
Pad
—
DAP
PWR
Connect to system ground for low thermal impedance, but it cannot be
used as a primary GND connection.
NAME
SOT-23
WSON
EN
4
FB
Output switch. Connect to the inductor and catch diode.
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6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1) (2)
MIN
MAX
UNIT
VIN
–0.5
7
V
FB Voltage
–0.5
3
V
EN Voltage
–0.5
7
V
SW Voltage
–0.5
7
V
150
°C
220
°C
150
°C
Junction Temperature
(3)
Soldering Information
Infrared or Convection Reflow (15 sec)
Storage Temperature, Tstg
(1)
(2)
(3)
–65
Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and
specifications.
Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device.
6.2 ESD Ratings
V(ESD)
(1)
Human body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1)
Electrostatic discharge
VALUE
UNIT
±2000
V
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
VIN
Junction Temperature
NOM
MAX
UNIT
3
5.5
V
–40
125
°C
6.4 Thermal Information
LM2831
THERMAL METRIC
(1)
Junction-to-ambient thermal resistance (2)
RθJA
(2)
SOT-23 (DBV
WSON (NGG)
5 PINS
6 PINS
UNIT
163.4
54.9
°C/W
RθJC(top)
Junction-to-case (top) thermal resistance
114.4
50.8
°C/W
RθJB
Junction-to-board thermal resistance
26.8
29.2
°C/W
ψJT
Junction-to-top characterization parameter
12.4
0.6
°C/W
ψJB
Junction-to-board characterization parameter
26.2
29.3
°C/W
RθJC(bot)
Junction-to-case (bottom) thermal resistance
N/A
9.2
°C/W
(1)
(2)
4
For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report, SPRA953.
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
VFB
Feedback Voltage
WSON and SOT-23
Package
ΔVFB/VIN
Feedback Voltage Line Regulation
VIN = 3 V to 5 V
IB
Feedback Input Bias Current
MIN
TJ = 25°C
–40°C to 125°C
TYP
0.600
0.588
0.612
0.02
TJ = 25°C
UVLO
Undervoltage Lockout
100
TJ = 25°C
2.73
–40°C to 125°C
VIN Falling
2.90
TJ = 25°C
–40°C to 125°C
2.3
0.43
LM2831-X
TJ = 25°C
–40°C to 125°C
FSW
Switching Frequency
LM2831-Y
LM2831-Z
LM2831-X
DMAX
Maximum Duty Cycle
LM2831-Z
DMIN
RDS(ON)
Minimum Duty Cycle
Switch On Resistance
0.7
3.75
94%
86%
96%
90%
90%
82%
LM2831-X
5%
LM2831-Y
2%
LM2831-Z
7%
WSON Package
150
SOT-23 Package
TJ = 25°C
130
–40°C to 125°C
ICL
Switch Current Limit
VIN = 3.3 V
VEN_TH
Shutdown Threshold Voltage
–40°C to 125°C
Enable Threshold Voltage
–40°C to 125°C
ISW
Switch Leakage
IEN
Enable Pin Current
Sink/Source
LM2831X VFB = 0.55
TJ = 25°C
2.5
IQ
Quiescent Current (switching)
TJ = 25°C
0.4
1.8
TJ = 25°C
nA
100
nA
3.3
5
2.8
4.5
Quiescent Current (shutdown)
All Options VEN = 0 V
Thermal Shutdown Temperature
6.5
30
nA
165
°C
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mA
4.3
–40°C to 125°C
TSD
V
100
–40°C to 125°C
LM2831Z VFB = 0.55
A
1.8
–40°C to 125°C
LM2831Y VFB = 0.55
mΩ
195
TJ = 25°C
–40°C to 125°C
MHz
3
2.25
TJ = 25°C
–40°C to 125°C
1.95
0.4
TJ = 25°C
–40°C to 125°C
V
V
0.55
TJ = 25°C
–40°C to 125°C
LM2831-Y
1.2
TJ = 25°C
–40°C to 125°C
nA
1.6
TJ = 25°C
–40°C to 125°C
V
V
1.85
UVLO Hysteresis
UNIT
%/V
0.1
–40°C to 125°C
VIN Rising
MAX
5
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SNVS422D – AUGUST 2006 – REVISED SEPTEMBER 2015
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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
OUTPUT (V)
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
Figure 1. η vs Load – X, Y, and Z Options
VO = 1.8 V (All Options)
Figure 2. Load Regulation
1.806
3.302
1.804
3.301
OUTPUT (V)
OUTPUT (V)
1.802
1.800
3.300
3.299
1.798
3.298
1.796
1.794
3.297
0.25
0
0.5
0.75
1
1.25
1.5
0
0.25
0.5
LOAD (A)
VIN = 5 V
0.75
1
1.25
1.5
LOAD (A)
VO = 1.8 V (All Options)
VIN = 5 V
Figure 3. Load Regulation
VO = 3.3 V (All Options)
Figure 4. Load Regulation
0.60
OSCILLATOR FREQUENCY (MHz)
OSCILLATOR FREQUENCY (MHz)
1.81
1.76
1.71
1.66
1.61
1.56
1.51
1.46
1.41
1.36
-45 -40
0.58
0.56
0.54
0.52
0.50
0.48
0.46
-10
20
50
80
110
125 130
-45 -40
TEMPERATURE (ºC)
20
50
80
110
125 130
TEMPERATURE (ºC)
Figure 5. Oscillator Frequency vs Temperature – X Option
6
-10
Figure 6. Oscillator Frequency vs Temperature – Y Option
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Typical Characteristics (continued)
3.45
2900
3.35
2800
3.25
2700
CURRENT LIMIT (mA)
OSCILLATOR FREQUENCY (MHz)
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.
3.15
3.05
2.95
2.85
2600
2500
2400
2300
2.75
2200
2.65
2100
-45
2.55
-45 -40
-10
20
50
80
110
125 130
-40
TEMPERATURE (ºC)
-10
20
50
80
110
125
130
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
3.5
2.55
2.5
IQ (mA)
IQ (mA)
3.4
3.3
2.45
2.4
2.35
3.2
2.3
2.25
3.1
2.2
3.0
-45
-40
-10
20
50
80
110
125
130
2.15
-45
-40
-10
20
50
80
110
125
130
TEMPERATURE (°C)
TEMPERATURE (ºC)
Figure 11. LM2831X IQ (Quiescent Current)
Figure 12. LM2831Y 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
IQ (mA)
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)
FEEBACK VOLTAGE (V)
0.610
0.605
0.600
0.595
0.590
-45
-40
-10
20
50
80
110 125 130
TEMPERATURE (ºC)
VIN = 5 V
Figure 15. VFB vs Temperature
VO = 1.2 V at 1 A
Figure 16. Gain vs Frequency
VIN = 5 V
VO = 1.2 V at 1 A
Figure 17. Phase Plot vs Frequency
8
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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
+
ENABLE and UVLO
ThermalSHDN
I SENSE
-
+
-
I LIMIT
-
1 .15 x VREF
+
OVPSHDN
Ramp Artificial
Control Logic
cv
FB
S
R
R
Q
1.6 MHz
+
I SENSE
PFET
-
+
DRIVER
Internal - Comp
SW
VREF = 0.6V
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.
VSW
D = TON/TSW
VIN
SW
Voltage
TOFF
TON
0
VD
IL
t
TSW
IPK
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.
10
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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
LM2831
R3
VIN
VIN = 5V
GND
L1
SW
VO = 1.2V @ 1.5A
R1
C1
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.
12
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Typical Applications (continued)
8.2.1.2 Detailed Design Procedure
Table 1. Bill of Materials
PART ID
PART VALUE
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831X
C1, Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Cap
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1
3.3 µH, 2.2 A
TDK
VLCF5020T-3R3N2R0-1
R2
15.0 kΩ, 1%
Vishay
CRCW08051502F
R1
15.0 kΩ, 1%
Vishay
CRCW08051502F
R3
100 kΩ, 1%
Vishay
CRCW08051003F
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):
D=
VOUT
VIN
(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:
D=
VOUT + VD
VIN + VD - VSW
(2)
VSW can be approximated by:
VSW = IOUT × RDSON
(3)
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)
'i
L
IOUT
VOUT
L
VIN - VOUT
L
DTS
TS
t
Figure 20. Inductor Current
VIN - VOUT 2DiL
=
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 DT
L=ç S
è 2DiL
ö
÷ ´ VIN - VOUT
ø
(7)
Where:
TS =
1
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
Di2 ù
IRMS _ IN D êIOUT 2 (1 - D) +
ú
3 úû
êë
(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.
14
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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
1
VOUT = DIL ç RESR +
÷
8 ´ FSW ´ COUT ø
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
- 1 x R2
R1 =
VREF
(13)
VREF = 0.60 V
(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
Figure 21. η vs Load – X Option
VIN = 5 V
VO = 1.8 V and 3.3 V
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
16
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8.2.2 LM2831X Design Example 2
FB
EN
GND
LM2831
R3
L1
VIN
VO = 0.6V @ 1.5A
SW
VIN = 5V
R1
C1
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
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831X
C1, Input Capacitor
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Capacitor
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1
3.3 µH, 2.2 A
TDK
VLCF5020T- 3R3N2R0-1
R2
10.0 kΩ, 1%
Vishay
CRCW08051000F
R1
0Ω
R3
100 kΩ, 1%
Vishay
CRCW08051003F
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8.2.3 LM2831X Design Example 3
FB
EN
LM2831
R3
GND
L1
VIN
VO = 3.3V @ 1.5A
SW
VIN = 5V
R1
C1
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
18
PART ID
PART VALUE
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831X
C1, Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Cap
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1
2.7 µH 2.3 A
TDK
VLCF5020T-2R7N2R2-1
R2
10.0 kΩ, 1%
Vishay
CRCW08051002F
R1
45.3 kΩ, 1%
Vishay
CRCW08054532F
R3
100 kΩ, 1%
Vishay
CRCW08051003F
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8.2.4 LM2831Y Design Example 4
FB
EN
LM2831
R3
GND
L1
VIN
VO = 3.3V @ 1.5A
SW
VIN = 5V
R1
C1
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
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831Y
C1, Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Cap
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1
4.7 µH 2.1 A
TDK
SLF7045T-4R7M2R0-PF
R1
45.3 kΩ, 1%
Vishay
CRCW080545K3FKEA
R2
10.0 kΩ, 1%
Vishay
CRCW08051002F
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8.2.5 LM2831Y Design Example 5
FB
EN
LM2831
R3
GND
L1
VIN
VO = 1.2V @ 1.5A
SW
VIN = 5V
R1
C1
D1
C2
R2
Figure 27. LM2831Y (550 kHz): VIN = 5 V, VOUT = 1.2 V at 1.5 A
Table 5. Bill of Materials
20
PART ID
PART VALUE
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831Y
C1, Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Cap
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1
6.8 µH 1.8 A
TDK
SLF7045T-6R8M1R7
R1
10.0 kΩ, 1%
Vishay
CRCW08051002F
R2
10.0 kΩ, 1%
Vishay
CRCW08051002F
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8.2.6 LM2831Z Design Example 6
FB
EN
LM2831
R3
GND
L1
VIN
VO = 3.3V @ 1.5A
SW
VIN = 5V
R1
C1
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
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831Z
C1, Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Cap
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1
1.6 µH 2.0 A
TDK
VLCF4018T-1R6N1R7-2
R2
10.0 kΩ, 1%
Vishay
CRCW08051002F
R1
45.3 kΩ, 1%
Vishay
CRCW08054532F
R3
100 kΩ, 1%
Vishay
CRCW08051003F
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8.2.7 LM2831Z Design Example 7
FB
EN
LM2831
R3
GND
L1
VIN
VO = 1.2V @ 1.5A
SW
VIN = 5V
R1
C1
D1
C2
R2
Figure 29. LM2831Z (3 MHz): VIN = 5 V, VO = 1.2 V at 1.5 A
Table 7. Bill of Materials
22
PART ID
PART VALUE
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831Z
C1, Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Cap
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1
1.6 µH, 2.0 A
TDK
VLCF4018T- 1R6N1R7-2
R2
10.0 kΩ, 1%
Vishay
CRCW08051002F
R1
10.0 kΩ, 1%
Vishay
CRCW08051002F
R3
100 kΩ, 1%
Vishay
CRCW08051003F
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8.2.8 LM2831X Dual Converters with Delayed Enabled Design Example 8
VIN
U1
C1
R3
VIND
VINA
L1 VO = 3.3V @ 1.5A
SW
R1
EN
LM2831
D1
R2
C2
GND
FB
U3
4
R6
3
LP3470M5X-3.08
LP3470
RESET
5
2
1
VIN
C7
U2
C3
VIND VINA
L2
SW
VO = 1.2V @ 1.5A
R4
LM2831
D2
R5
EN
C4
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
PART VALUE
MANUFACTURER
U1, U2
1.5-A Buck Regulator
TI
PART NUMBER
LM2831X
U3
Power on Reset
TI
LP3470M5X-3.08
C1, C3 Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, C4 Output Cap
2x22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C7
Trr delay capacitor
TDK
D1, D2 Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
L1, L2
3.3 µH, 2.2 A
TDK
VLCF5020T-3R3N2R0-1
R2, R4, R5
10.0 kΩ, 1%
Vishay
CRCW08051002F
R1, R6
45.3 kΩ, 1%
Vishay
CRCW08054532F
R3
100 kΩ, 1%
Vishay
CRCW08051003F
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8.2.9 LM2831X Buck Converter and Voltage Double Circuit With LDO Follower Design Example 9
VO = 5.0V @ 150mA
L2
U2
LDO
D2
U1
LM2831
VIN = 5V
VIND
SW
VINA
GND
C1
EN
C5
C4
C6
C3
L1
R1
VO = 3.3V @ 1.5A
FB
C2
D1
R2
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
24
PART ID
PART VALUE
MANUFACTURER
PART NUMBER
U1
1.5-A Buck Regulator
TI
LM2831X
U2
200-mA LDO
TI
LP2986-5.0
C1, Input Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C2, Output Cap
22 µF, 6.3 V, X5R
TDK
C3216X5ROJ226M
C1608X5R0J225M
C3 – C6
2.2 µF, 6.3 V, X5R
TDK
D1, Catch Diode
0.3 Vf Schottky 1.5 A, 30 VR
TOSHIBA
CRS08
D2
0.4 Vf Schottky 20 VR, 500 mA
ON Semi
MBR0520
L2
10 µH, 800 mA
CoilCraft
ME3220-103
L1
3.3 µH, 2.2 A
TDK
VLCF5020T-3R3N2R0-1
R2
45.3 kΩ, 1%
Vishay
CRCW08054532F
R1
10.0 kΩ, 1%
Vishay
CRCW08051002F
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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.
h=
POUT
PIN
(15)
POUT
POUT + PLOSS
(16)
Or
h=
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):
D=
VOUT + VD
VIN + VD - VSW
(17)
VSW is the voltage drop across the internal PFET when it is on, and is equal to:
VSW = IOUT × RDSON
(18)
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:
D=
VOUT + VD + VDCR
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:
PCOND = (IOUT2 x D) 1 +
'iL
1
x
3
IOUT
2
RDSON
(22)
If the inductor ripple current is fairly small, the conduction losses can be simplified to:
PCOND = IOUT2 × RDSON × D
(23)
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)
PSWF = 1/2(VIN × IOUT × FSW × TFALL)
PSW = PSWR + PSWF
(24)
(25)
(26)
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
VIN
5V
PARAMETER
VALUE
POUT
4.125 W
PDIODE
188 mW
VOUT
3.3 V
IOUT
1.25 A
VD
0.45 V
FSW
550 kHz
IQ
2.5 mA
PQ
12.5 mW
TRISE
4 nS
PSWR
7 mW
TFALL
4 nS
PSWF
7 mW
RDS(ON)
150 mΩ
PCOND
156 mW
INDDCR
70 mΩ
PIND
110 mW
D
0.667
PLOSS
481 mW
η
88%
PINTERNAL
183 mW
ΣPCOND + PSW + PDIODE + PIND + PQ = PLOSS
ΣPCOND + PSWF + PSWR + PQ = PINTERNAL
PINTERNAL = 183 mW
26
(28)
(29)
(30)
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10.1.2 Thermal Definitions
TJ
Chip junction temperature
TA
Ambient temperature
RθJC
Thermal resistance from chip junction to device case
RθJA
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:
Rq =
DT
Power
(31)
Thermal impedance from the silicon junction to the ambient air is defined as:
RqJA =
TJ - TA
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.
RθJC is the thermal impedance from all six sides of an IC package to silicon junction.
RΦJC is the thermal impedance from top case to the silicon junction.
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:
RFJC =
TJ - TC
Power
(33)
Therefore:
Tj = (RΦJC × PLOSS) + TC
(34)
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 =
PINTERNAL
(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
RqJA
(38)
165°C - 144°C
=
= 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
125°C - (111°C/W × 189 mW) = 104°C
(40)
(41)
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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10.2 Layout Example
FB
1
GND
2
6 EN
GND
PLANE
SW 3
5 VINA
4 VIND
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
Status
(1)
Package Type Package Pins Package
Drawing
Qty
Eco Plan
Lead/Ball Finish
MSL Peak Temp
(2)
(6)
(3)
Op Temp (°C)
Device Marking
(4/5)
LM2831XMF/NOPB
ACTIVE
SOT-23
DBV
5
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
SKYB
LM2831XMFX/NOPB
ACTIVE
SOT-23
DBV
5
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
SKYB
LM2831XSD
NRND
WSON
NGG
6
1000
TBD
Call TI
Call TI
-40 to 125
L193B
LM2831XSD/NOPB
ACTIVE
WSON
NGG
6
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
L193B
LM2831XSDX/NOPB
ACTIVE
WSON
NGG
6
4500
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
L193B
LM2831YMF/NOPB
ACTIVE
SOT-23
DBV
5
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
SKZB
LM2831YMFX/NOPB
ACTIVE
SOT-23
DBV
5
3000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
SKZB
LM2831YSD/NOPB
ACTIVE
WSON
NGG
6
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
L194B
LM2831ZMF/NOPB
ACTIVE
SOT-23
DBV
5
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-1-260C-UNLIM
-40 to 125
SLAB
LM2831ZSD/NOPB
ACTIVE
WSON
NGG
6
1000
Green (RoHS
& no Sb/Br)
CU SN
Level-3-260C-168 HR
-40 to 125
L195B
(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
Samples
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
LM2831XMF/NOPB
SOT-23
LM2831XMFX/NOPB
LM2831XSD
Reel
Reel
A0
Diameter Width (mm)
(mm) W1 (mm)
DBV
5
1000
178.0
SOT-23
DBV
5
3000
WSON
NGG
6
1000
LM2831XSD/NOPB
WSON
NGG
6
LM2831XSDX/NOPB
WSON
NGG
B0
(mm)
K0
(mm)
P1
(mm)
8.4
3.2
3.2
1.4
4.0
178.0
8.4
3.2
3.2
1.4
178.0
12.4
3.3
3.3
1.0
1000
178.0
12.4
3.3
3.3
6
4500
330.0
12.4
3.3
W
Pin1
(mm) Quadrant
8.0
Q3
4.0
8.0
Q3
8.0
12.0
Q1
1.0
8.0
12.0
Q1
3.3
1.0
8.0
12.0
Q1
LM2831YMF/NOPB
SOT-23
DBV
5
1000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
LM2831YMFX/NOPB
SOT-23
DBV
5
3000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
LM2831YSD/NOPB
WSON
NGG
6
1000
178.0
12.4
3.3
3.3
1.0
8.0
12.0
Q1
LM2831ZMF/NOPB
SOT-23
DBV
5
1000
178.0
8.4
3.2
3.2
1.4
4.0
8.0
Q3
LM2831ZSD/NOPB
WSON
NGG
6
1000
178.0
12.4
3.3
3.3
1.0
8.0
12.0
Q1
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
SOT-23
DBV
5
1000
210.0
185.0
35.0
LM2831XMFX/NOPB
SOT-23
DBV
5
3000
210.0
185.0
35.0
LM2831XSD
WSON
NGG
6
1000
213.0
191.0
55.0
LM2831XSD/NOPB
WSON
NGG
6
1000
213.0
191.0
55.0
LM2831XSDX/NOPB
WSON
NGG
6
4500
367.0
367.0
35.0
LM2831YMF/NOPB
SOT-23
DBV
5
1000
210.0
185.0
35.0
LM2831YMFX/NOPB
SOT-23
DBV
5
3000
210.0
185.0
35.0
LM2831YSD/NOPB
WSON
NGG
6
1000
213.0
191.0
55.0
LM2831ZMF/NOPB
SOT-23
DBV
5
1000
210.0
185.0
35.0
LM2831ZSD/NOPB
WSON
NGG
6
1000
213.0
191.0
55.0
Pack Materials-Page 2
MECHANICAL DATA
NGG0006A
SDE06A (Rev A)
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