GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
R2
R1
C2 C3
VO = 3.3V @ 1.5A
LM2831
LM2831
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SNVS422C –AUGUST 2006–REVISED APRIL 2013
LM2831 High Frequency 1.5A Load - Step-Down DC-DC Regulator
Check for Samples: LM2831
1FEATURES DESCRIPTION
The LM2831 regulator is a monolithic, high frequency,
2• Space Saving SOT-23 Package PWM step-down DC/DC converter in a 5 pin SOT-23
• Input Voltage Range of 3.0V to 5.5V and a 6 Pin WSON package. It provides all the active
• Output Voltage Range of 0.6V to 4.5V functions to provide local DC/DC conversion with fast
transient response and accurate regulation in the
• 1.5A Output Current smallest possible PCB area. With a minimum of
• High Switching Frequencies external components, the LM2831 is easy to use. The
– 1.6MHz (LM2831X) ability to drive 1.5A loads with an internal 130 mΩ
PMOS switch using state-of-the-art 0.5 µm BiCMOS
– 0.55MHz (LM2831Y) technology results in the best power density
– 3.0MHz (LM2831Z) available. The world-class control circuitry allows on-
• 130mΩPMOS Switch times as low as 30ns, thus supporting exceptionally
high frequency conversion over the entire 3V to 5.5V
• 0.6V, 2% Internal Voltage Reference input operating range down to the minimum output
• Internal Soft-Start voltage of 0.6V. Switching frequency is internally set
• Current Mode, PWM Operation to 550 kHz, 1.6 MHz, or 3.0 MHz, allowing the use of
• Thermal Shutdown extremely small surface mount inductors and chip
capacitors. Even though the operating frequency is
• Over Voltage Protection high, efficiencies up to 93% are easy to achieve.
External shutdown is included, featuring an ultra-low
APPLICATIONS stand-by current of 30 nA. The LM2831 utilizes
• Local 5V to Vcore Step-Down Converters current-mode control and internal compensation to
provide high-performance regulation over a wide
• Core Power in HDDs range of operating conditions. Additional features
• Set-Top Boxes include internal soft-start circuitry to reduce inrush
• USB Powered Devices current, pulse-by-pulse current limit, thermal
shutdown, and output over-voltage protection.
• DSL Modems
Typical Application Circuit
1Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
2All trademarks are the property of their respective owners.
PRODUCTION DATA information is current as of publication date. Copyright © 2006–2013, Texas Instruments Incorporated
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
1
2
34
6
5
EN
FB
SW
DAP VINA
VIND
GND
VIN SW
2
1
3
5
4
EN FB
GND
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
Connection Diagrams
Figure 1. 6-Pin WSON Figure 2. 5-Pin SOT-23
See Package Number NGG See Package Number DBV
PIN DESCRIPTIONS (5-PIN SOT-23)
Pin Name Function
1 SW Output switch. Connect to the inductor and catch diode.
2 GND Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible
to this pin.
3 FB Feedback pin. Connect to external resistor divider to set output voltage.
4 EN Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VIN
+ 0.3V.
5 VIN Input supply voltage.
PIN DESCRIPTIONS (6-PIN WSON)
Pin Name Function
1 FB Feedback pin. Connect to external resistor divider to set output voltage.
2 GND Signal and power ground pin. Place the bottom resistor of the feedback network as close as
possible to this pin.
3 SW Output switch. Connect to the inductor and catch diode.
4 VIND Power Input supply.
5 VINA Control circuitry supply voltage. Connect VINA to VIND on PC board.
6 EN Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than
VINA + 0.3V.
DAP Die Attach Pad Connect to system ground for low thermal impedance, but it cannot be used as a primary GND
connection.
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.
Absolute Maximum Ratings(1)(2)
VIN -0.5V to 7V
FB Voltage -0.5V to 3V
EN Voltage -0.5V to 7V
SW Voltage -0.5V to 7V
ESD Susceptibility 2kV
Junction Temperature(3) 150°C
Storage Temperature −65°C to +150°C
Soldering Information Infrared or Convection Reflow (15 sec) 220°C
(1) Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Range indicates conditions for
which the device is intended to be functional, but does not ensure specific performance limits. For ensured specifications and test
conditions, see the Electrical Characteristics.
(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.
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LM2831
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SNVS422C –AUGUST 2006–REVISED APRIL 2013
Operating Ratings
VIN 3V to 5.5V
Junction Temperature −40°C to +125°C
Electrical Characteristics
VIN = 5V unless otherwise indicated under the Conditions column. Limits in standard type are for TJ= 25°C only; limits in
boldface type apply over the junction temperature (TJ) range of -40°C to +125°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.
Symbol Parameter Conditions Min Typ Max Units
VFB Feedback Voltage WSON and SOT-23 Package 0.588 0.600 0.612 V
ΔVFB/VIN Feedback Voltage Line Regulation VIN = 3V to 5V 0.02 %/V
IBFeedback Input Bias Current 0.1 100 nA
VIN Rising 2.73 2.90 V
Undervoltage Lockout
UVLO VIN Falling 1.85 2.3
UVLO Hysteresis 0.43 V
LM2831-X 1.2 1.6 1.95
FSW Switching Frequency LM2831-Y 0.4 0.55 0.7 MHz
LM2831-Z 2.25 3.0 3.75
LM2831-X 86 94
DMAX Maximum Duty Cycle LM2831-Y 90 96 %
LM2831-Z 82 90
LM2831-X 5
DMIN Minimum Duty Cycle LM2831-Y 2 %
LM2831-Z 7
WSON Package 150
RDS(ON) Switch On Resistance mΩ
SOT-23 Package 130 195
ICL Switch Current Limit VIN = 3.3V 1.8 2.5 A
Shutdown Threshold Voltage 0.4
VEN_TH V
Enable Threshold Voltage 1.8
ISW Switch Leakage 100 nA
IEN Enable Pin Current Sink/Source 100 nA
LM2831X VFB = 0.55 3.3 5mA
Quiescent Current (switching) LM2831Y VFB = 0.55 2.8 4.5
IQLM2831Z VFB = 0.55 4.3 6.5
Quiescent Current (shutdown) All Options VEN = 0V 30 nA
WSON Package 80
Junction to Ambient
θJA °C/W
0 LFPM Air Flow(1) SOT-23 Package 118
WSON Package 18
θJC Junction to Case(1) °C/W
SOT-23 Package 80
TSD Thermal Shutdown Temperature 165 °C
(1) Applies for packages soldered directly onto a 3” x 3” PC board with 2oz. copper on 4 layers in still air.
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1.796
1.797
1.798
1.799
1.800
1.801
1.802
1.803
1.804
0 0.25 0.5 0.75 1 1.25 1.5
LOAD (A)
OUTPUT (V)
1.794
1.796
1.798
1.800
1.802
1.804
1.806
0.25 0.5 0.75 1 1.25 1.5
LOAD (A)
OUTPUT (V)
0
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
Typical Performance Characteristics
All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this
datasheet. TJ= 25°C, unless otherwise specified.
ηvs Load "X" Vin = 5V, Vo = 1.8V & 3.3V ηvs Load - "Y" Vin = 5V, Vo = 3.3V & 1.8V
Figure 3. Figure 4.
ηvs Load "Z" Vin = 5V, Vo = 3.3V & 1.8V ηvs Load "X, Y and Z" Vin = 3.3V, Vo = 1.8V
Figure 5. Figure 6.
Load Regulation Vin = 3.3V, Vo = 1.8V (All Options) Load Regulation Vin = 5V, Vo = 1.8V (All Options)
Figure 7. Figure 8.
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-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (°C)
210
0
2200
2300
2400
250
0
2600
2700
2800
2900
CURRENT LIMIT (mA)
-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (ºC)
OSCILLATOR FREQUENCY (MHz)
0.46
0.48
0.50
0.52
0.54
0.56
0.58
0.60
-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (ºC)
OSCILLATOR FREQUENCY (MHz)
2.55
2.65
2.75
2.85
2.95
3.05
3.15
3.25
3.35
3.45
-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (ºC)
OSCILLATOR FREQUENCY (MHz)
1.36
1.41
1.46
1.51
1.56
1.61
1.66
1.71
1.76
1.81
LM2831
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SNVS422C –AUGUST 2006–REVISED APRIL 2013
Typical Performance Characteristics (continued)
All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this
datasheet. TJ= 25°C, unless otherwise specified.
Load Regulation Vin = 5V, Vo = 3.3V (All Options) Oscillator Frequency vs Temperature - "X"
Figure 9. Figure 10.
Oscillator Frequency vs Temperature - "Y" Oscillator Frequency vs Temperature - "Z"
Figure 11. Figure 12.
Current Limit vs Temperature Vin = 3.3V RDSON vs Temperature (WSON Package)
Figure 13. Figure 14.
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-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (ºC)
FEEBACK VOLTAGE (V)
0.590
0.595
0.600
0.605
0.610
-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (ºC)
4.0
4.1
4.2
4.3
4.4
4.5
4.6
IQ (mA)
-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (°C)
2.15
2.2
2.25
2.3
2.35
2.4
2.45
2.5
2.55
2.6
2.65
IQ (mA)
-45 -40 -10 20 50 80 110 125 130
TEMPERATURE (ºC)
3.0
3.1
3.2
3.3
3.4
3.5
3.6
IQ (mA)
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
Typical Performance Characteristics (continued)
All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this
datasheet. TJ= 25°C, unless otherwise specified.
RDSON vs Temperature (SOT-23 Package) LM2831X IQ(Quiescent Current)
Figure 15. Figure 16.
LM2831Y IQ(Quiescent Current) LM2831Z IQ(Quiescent Current)
Figure 17. Figure 18.
Line Regulation Vo = 1.8V, Io = 500mA VFB vs Temperature
Figure 19. Figure 20.
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cv
+
-
+
-
S
R
R
Q
+
-
GND
FB
SW
VIN
EN
+
-
+
-
DRIVER
Artificial
Ramp
SHDN
Thermal
SHDN
OVP
1.6 MHz
CompInternal-
SENSE
I
LIMIT
I
LDOInternal-
STARTSOFT-
PFET
SENSE
I
ENABLE and UVLO
15.1 x REF
VControl Logic
VREF = 0.6V
LM2831
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SNVS422C –AUGUST 2006–REVISED APRIL 2013
Typical Performance Characteristics (continued)
All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this
datasheet. TJ= 25°C, unless otherwise specified.
Gain vs Frequency (Vin = 5V, Vo = 1.2V @ 1A) Phase Plot vs Frequency (Vin = 5V, Vo = 1.2V @ 1A)
Figure 21. Figure 22.
Simplified Block Diagram
Figure 23.
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0
0
VIN
VD
TON
t
t
Inductor
Current
D = TON/TSW
VSW
TOFF
TSW
IL
IPK
SW
Voltage
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
APPLICATIONS INFORMATION
THEORY OF OPERATION
The LM2831 is a constant frequency PWM buck regulator IC that delivers a 1.5A load current. The regulator has
a preset switching frequency of 550kHz, 1.6MHz, or 3.0MHz. 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 it is simple to use and requires few external
components. The LM2831 uses current-mode control to regulate the output voltage. The following operating
description of the LM2831 will refer to Figure 23 and to the waveforms in Figure 24. 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.
ILis 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
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.
Figure 24. Typical Waveforms
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 0V to its nominal value of 0.6V in approximately 600 µs. This forces the regulator
output to ramp up in a controlled fashion, which helps reduce inrush current.
OUTPUT OVERVOLTAGE PROTECTION
The over-voltage 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.
UNDERVOLTAGE LOCKOUT
Under-voltage lockout (UVLO) prevents the LM2831 from operating until the input voltage exceeds 2.73V (typ).
The UVLO threshold has approximately 430 mV of hysteresis, so the part will operate until VIN drops below 2.3V
(typ). Hysteresis prevents the part from turning off during power up if VIN is non-monotonic.
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VIN - VOUT
L=2'iL
DTS
t
L
i'
OUT
I
S
T
S
DT
L
VOUT
L
- VOUT
VIN
D = VOUT + VD
VIN + VD - VSW
D =VOUT
VIN
LM2831
www.ti.com
SNVS422C –AUGUST 2006–REVISED APRIL 2013
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 2.5A (typ), and turns off the switch until the
next switching cycle begins.
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.
Design Guide
INDUCTOR SELECTION
The Duty Cycle (D) can be approximated quickly using the ratio of output voltage (VO) to input voltage (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:
(2)
VSW can be approximated by:
VSW = IOUT x RDSON (3)
The diode forward drop (VD) can range from 0.3V to 0.7V 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 (1.8A) 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)
Figure 25. Inductor Current
(5)
In general,
ΔiL= 0.1 x (IOUT)→0.2 x (IOUT) (6)
If ΔiL= 20% of 1.50A, the peak current in the inductor will be 1.8A. The minimum ensured current limit over all
operating conditions is 1.8A. One can either reduce ΔiL, or make the engineering judgment that zero margin will
be safe enough. The typical current limit is 2.5A.
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'VOUT = 'ILRESR + 8 x FSW x COUT
1
IRMS_IN = IOUT x D(1 - D)
IRMS_IN DIOUT2 (1-D) + 'i2
3
TS = 1
fS
x (VIN - VOUT)
L = 2'iL
DTS
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
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:
(7)
Where
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 1.0A
and the peak current is 1.25A, then the inductor should be specified with a saturation current limit of > 1.25A.
There is no need to specify the saturation or peak current of the inductor at the 2.5A 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 Example Circuits.
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:
(8)
Neglecting inductor ripple simplifies the above equation to:
(9)
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
datasheets to see how rated capacitance varies over operating conditions.
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:
(10)
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K = POUT
POUT + PLOSS
K =POUT
PIN
x R2
R1 = VREF
VOUT - 1
LM2831
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SNVS422C –AUGUST 2006–REVISED APRIL 2013
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.
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 x (1-D) (11)
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.
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 VOand the FB pin. A good value for R2 is 10k. When designing a unity gain converter
(Vo = 0.6V), R1 should be between 0Ωand 100Ω, and R2 should be equal or greater than 10kΩ.
(12)
VREF = 0.60V (13)
PCB LAYOUT CONSIDERATIONS
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. Please see
Application Note AN-1229 SNVA054 for further considerations and the LM2831 demo board as an example of a
four-layer layout.
Calculating Efficiency, and Junction Temperature
The complete LM2831 DC/DC converter efficiency can be calculated in the following manner.
(14)
Or
(15)
Calculations for determining the most significant power losses are shown below. Other losses totaling less than
2% are not discussed.
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PCOND= (IOUT2 x D) 1
3
1 + x'iL
IOUT
2RDSON
D = VOUT + VD + VDCR
VIN + VD + VDCR - VSW
D = VOUT + VD
VIN + VD - VSW
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
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):
(16)
VSW is the voltage drop across the internal PFET when it is on, and is equal to:
VSW = IOUT x RDSON (17)
VDis 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:
(18)
The conduction losses in the free-wheeling Schottky diode are calculated as follows:
PDIODE = VDx IOUT x (1-D) (19)
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 = IOUT2x RDCR (20)
The LM2831 conduction loss is mainly associated with the internal PFET:
(21)
If the inductor ripple current is fairly small, the conduction losses can be simplified to:
PCOND = IOUT2x RDSON x D (22)
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 x IOUT x FSW x TRISE) (23)
PSWF = 1/2(VIN x IOUT x FSW x TFALL) (24)
PSW = PSWR + PSWF (25)
Another loss is the power required for operation of the internal circuitry:
PQ= IQx VIN (26)
IQis the quiescent operating current, and is typically around 2.5mA for the 0.55MHz frequency option.
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RTJA=TJ - TA
Power
RT='T
Power
LM2831
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SNVS422C –AUGUST 2006–REVISED APRIL 2013
Typical Application power losses are:
Table 1. Power Loss Tabulation
VIN 5.0V
VOUT 3.3V POUT 4.125W
IOUT 1.25A
VD0.45V PDIODE 188mW
FSW 550kHz
IQ2.5mA PQ12.5mW
TRISE 4nS PSWR 7mW
TFALL 4nS PSWF 7mW
RDS(ON) 150mΩPCOND 156mW
INDDCR 70mΩPIND 110mW
D 0.667 PLOSS 481mW
η88% PINTERNAL 183mW
ΣPCOND + PSW + PDIODE + PIND + PQ= PLOSS (27)
ΣPCOND + PSWF + PSWR + PQ= PINTERNAL (28)
PINTERNAL = 183mW (29)
Thermal Definitions
TJChip junction temperature
TAAmbient 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:
(30)
Thermal impedance from the silicon junction to the ambient air is defined as:
(31)
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
etc), and the surrounding circuitry.
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 13
Product Folder Links: LM2831
RTJA=165oC - 144oC
189 mW = 111o C/W
RTJA=165° - Ta
PINTERNAL
R)JC=TJ - TC
Power
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
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 needs to 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:
(32)
Therefore:
Tj= (RΦJC x PLOSS) + TC(33)
From the previous example:
Tj= (RΦJC x PINTERNAL) + TC(34)
Tj= 30°C/W x 0.189W + TC(35)
The second method can give a very accurate silicon junction temperature.
The first step is to determine RθJA of the application. The LM2831 has over-temperature 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.
(36)
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 3.0cm x 3.0cm. 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 = 189mW (37)
(38)
If the junction temperature was to be kept below 125°C, then the ambient temperature could not go above 109°C
Tj- (RθJA x PLOSS) = TA(39)
125°C - (111°C/W x 189mW) = 104°C (40)
14 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM2831
1
2
4
6
5
EN
FB
SW
VINA
VIND
GND GND
PLANE
3
LM2831
www.ti.com
SNVS422C –AUGUST 2006–REVISED APRIL 2013
WSON Package
Figure 26. Internal WSON Connection
For certain high power applications, the PCB land may be modified to a "dog bone" shape (see Figure 27). By
increasing the size of ground plane, and adding thermal vias, the RθJA for the application can be reduced.
Figure 27. 6-Lead WSON PCB Dog Bone Layout
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 15
Product Folder Links: LM2831
GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
LM2831
R2
R1
C2
VO = 1.2V @ 1.5A
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
LM2831X Design Example 1
Figure 28. LM2831X (1.6MHz): Vin = 5V, Vo = 1.2V @ 1.5A
Table 2. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831X
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1 3.3µH, 2.2A TDK VLCF5020T-3R3N2R0-1
R2 15.0kΩ, 1% Vishay CRCW08051502F
R1 15.0kΩ, 1% Vishay CRCW08051502F
R3 100kΩ, 1% Vishay CRCW08051003F
16 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM2831
GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
LM2831
R2
R1
C2
VO = 0.6V @ 1.5A
LM2831
www.ti.com
SNVS422C –AUGUST 2006–REVISED APRIL 2013
LM2831X Design Example 2
Figure 29. LM2831X (1.6MHz): Vin = 5V, Vo = 0.6V @ 1.5A
Table 3. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831X
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1 3.3µH, 2.2A TDK VLCF5020T- 3R3N2R0-1
R2 10.0kΩ, 1% Vishay CRCW08051000F
R1 0Ω
R3 100kΩ, 1% Vishay CRCW08051003F
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 17
Product Folder Links: LM2831
GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
LM2831
R2
R1
C2
VO = 3.3V @ 1.5A
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
LM2831X Design Example 3
Figure 30. LM2831X (1.6MHz): Vin = 5V, Vo = 3.3V @ 1.5A
Table 4. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831X
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1 2.7µH 2.3A TDK VLCF5020T-2R7N2R2-1
R2 10.0kΩ, 1% Vishay CRCW08051002F
R1 45.3kΩ, 1% Vishay CRCW08054532F
R3 100kΩ, 1% Vishay CRCW08051003F
18 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM2831
GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
LM2831
R2
R1
C2
VO = 3.3V @ 1.5A
LM2831
www.ti.com
SNVS422C –AUGUST 2006–REVISED APRIL 2013
LM2831Y Design Example 4
Figure 31. LM2831Y (550kHz): Vin = 5V, Vout = 3.3V @ 1.5A
Table 5. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831Y
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1 4.7µH 2.1A TDK SLF7045T-4R7M2R0-PF
R1 45.3kΩ, 1% Vishay CRCW080545K3FKEA
R2 10.0kΩ, 1% Vishay CRCW08051002F
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 19
Product Folder Links: LM2831
GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
LM2831
R2
R1
C2
VO = 1.2V @ 1.5A
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
LM2831Y Design Example 5
Figure 32. LM2831Y (550kHz): Vin = 5V, Vout = 1.2V @ 1.5A
Table 6. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831Y
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1 6.8µH 1.8A TDK SLF7045T-6R8M1R7
R1 10.0kΩ, 1% Vishay CRCW08051002F
R2 10.0kΩ, 1% Vishay CRCW08051002F
20 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM2831
GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
LM2831
R2
R1
C2
VO = 3.3V @ 1.5A
LM2831
www.ti.com
SNVS422C –AUGUST 2006–REVISED APRIL 2013
LM2831Z Design Example 6
Figure 33. LM2831Z (3MHz): Vin = 5V, Vo = 3.3V @ 1.5A
Table 7. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831Z
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1 1.6µH 2.0A TDK VLCF4018T-1R6N1R7-2
R2 10.0kΩ, 1% Vishay CRCW08051002F
R1 45.3kΩ, 1% Vishay CRCW08054532F
R3 100kΩ, 1% Vishay CRCW08051003F
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 21
Product Folder Links: LM2831
GND
FB
EN
VIN SW
VIN = 5V
C1
R3
D1
L1
LM2831
R2
R1
C2
VO = 1.2V @ 1.5A
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
LM2831Z Design Example 7
Figure 34. LM2831Z (3MHz): Vin = 5V, Vo = 1.2V @ 1.5A
Table 8. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831Z
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1 1.6µH, 2.0A TDK VLCF4018T- 1R6N1R7-2
R2 10.0kΩ, 1% Vishay CRCW08051002F
R1 10.0kΩ, 1% Vishay CRCW08051002F
R3 100kΩ, 1% Vishay CRCW08051003F
22 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM2831
LP3470M5X-3.08
U2
VINAVIND
LM2831
U3
U1
LM2831
SW
D1
FB
EN
L1
GND
C1
C2
R1
R2
C3 VINAVIND SW
FB
EN
GND
D2
L2
C4
R4
R5
R6 3
1
2
VIN
RESET
4
5
LP3470
C7
VIN
VO = 3.3V @ 1.5A
VO = 1.2V @ 1.5A
R3
LM2831
www.ti.com
SNVS422C –AUGUST 2006–REVISED APRIL 2013
LM2831X Dual Converters with Delayed Enabled Design Example 8
Figure 35. LM2831X (1.6MHz): Vin = 5V, Vo = 1.2V @ 1.5A & 3.3V @1.5A
Table 9. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1, U2 1.5A Buck Regulator TI LM2831X
U3 Power on Reset TI LP3470M5X-3.08
C1, C3 Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, C4 Output Cap 2x22µF, 6.3V, X5R TDK C3216X5ROJ226M
C7 Trr delay capacitor TDK
D1, D2 Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
L1, L2 3.3µH, 2.2A TDK VLCF5020T-3R3N2R0-1
R2, R4, R5 10.0kΩ, 1% Vishay CRCW08051002F
R1, R6 45.3kΩ, 1% Vishay CRCW08054532F
R3 100kΩ, 1% Vishay CRCW08051003F
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 23
Product Folder Links: LM2831
LDO
C5
U2
D2
L2
R1
R2
EN FB
SW
VINA
VIND
GND VO = 3.3V @ 1.5A
VO = 5.0V @ 150mA
C4
C6
C2
C3
D1
L1
U1
C1
LM2831
VIN = 5V
LM2831
SNVS422C –AUGUST 2006–REVISED APRIL 2013
www.ti.com
LM2831X Buck Converter & Voltage Double Circuit with LDO Follower Design Example 9
Figure 36. LM2831X (1.6MHz): Vin = 5V, Vo = 3.3V @ 1.5A & LP2986-5.0 @ 150mA
Table 10. Bill of Materials
Part ID Part Value Manufacturer Part Number
U1 1.5A Buck Regulator TI LM2831X
U2 200mA LDO TI LP2986-5.0
C1, Input Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C2, Output Cap 22µF, 6.3V, X5R TDK C3216X5ROJ226M
C3 – C6 2.2µF, 6.3V, X5R TDK C1608X5R0J225M
D1, Catch Diode 0.3VfSchottky 1.5A, 30VRTOSHIBA CRS08
D2 0.4VfSchottky 20VR, 500mA ON Semi MBR0520
L2 10µH, 800mA CoilCraft ME3220-103
L1 3.3µH, 2.2A TDK VLCF5020T-3R3N2R0-1
R2 45.3kΩ, 1% Vishay CRCW08054532F
R1 10.0kΩ, 1% Vishay CRCW08051002F
24 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated
Product Folder Links: LM2831
LM2831
www.ti.com
SNVS422C –AUGUST 2006–REVISED APRIL 2013
REVISION HISTORY
Changes from Revision B (April 2013) to Revision C Page
• Changed layout of National Data Sheet to TI format .......................................................................................................... 24
Copyright © 2006–2013, Texas Instruments Incorporated Submit Documentation Feedback 25
Product Folder Links: LM2831
PACKAGE OPTION ADDENDUM
www.ti.com 1-Nov-2013
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead/Ball Finish
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
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
LM2831YSDX/NOPB ACTIVE WSON NGG 6 4500 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
LM2831ZMFX/NOPB ACTIVE SOT-23 DBV 5 3000 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
LM2831ZSDX/NOPB ACTIVE WSON NGG 6 4500 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.
PACKAGE OPTION ADDENDUM
www.ti.com 1-Nov-2013
Addendum-Page 2
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)
(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.
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
LM2831XMF/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM2831XMFX/NOPB SOT-23 DBV 5 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3
LM2831XSD WSON NGG 6 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1
LM2831XSD/NOPB WSON NGG 6 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1
LM2831XSDX/NOPB WSON NGG 6 4500 330.0 12.4 3.3 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
LM2831YSDX/NOPB WSON NGG 6 4500 330.0 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
LM2831ZMFX/NOPB SOT-23 DBV 5 3000 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
LM2831ZSDX/NOPB WSON NGG 6 4500 330.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1
PACKAGE MATERIALS INFORMATION
www.ti.com 23-Oct-2013
Pack Materials-Page 1
*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
LM2831YSDX/NOPB WSON NGG 6 4500 367.0 367.0 35.0
LM2831ZMF/NOPB SOT-23 DBV 5 1000 210.0 185.0 35.0
LM2831ZMFX/NOPB SOT-23 DBV 5 3000 210.0 185.0 35.0
LM2831ZSD/NOPB WSON NGG 6 1000 213.0 191.0 55.0
LM2831ZSDX/NOPB WSON NGG 6 4500 367.0 367.0 35.0
PACKAGE MATERIALS INFORMATION
www.ti.com 23-Oct-2013
Pack Materials-Page 2
MECHANICAL DATA
NGG0006A
www.ti.com
SDE06A (Rev A)
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