LM2831 TI | Alldatasheet
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0.1 1 EFFICIENCY (%) LOAD (A) "X" GND FBEN VIN SW VIN = 5V C2 C3 VO = 3.3V @ 1.5A LM2831 Product Folder Sample & Buy T echnical Documents Tools & Software Support & Community Reference Design LM2831 SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015 LM2831High-Frequency1.5-ALoad— Step-DownDC-DCRegulator
1 Features 3 Description
The LM2831 regulator is a monolithic, high- 1• Space-Saving SOT-23 Package frequency, PWM step-down DC-DC converter in a 5-• Input Voltage Range of 3 V to 5.5 V pin SOT-23 and a 6-Pin WSON package. The
- Output Voltage Range of 0.6 V to 4.5 V LM2831 provides all the active functions to provide local DC-DC conversion with fast transient response• 1.5-A Output Current and accurate regulation in the smallest possible PCB• High Switching Frequencie area. With a minimum of external components, the – 1.6 MHz (LM2831X) LM2831 is easy to use. The ability to drive 1.5-A loads with an internal 130-mΩ PMOS switch using– 0.55 MHz (LM2831Y) state-of-the-art 0.5-µm BiCMOS technology results in– 3 MHz (LM2831Z) the best power density available. The world-class• 130-mΩ PMOS Switch control circuitry allows on-times as low as 30 ns, thus
- 0.6-V, 2% Internal Voltage Reference supporting exceptionally high frequency conversion over the entire 3 V to 5.5 V input operating range,• Internal Soft Start down to the minimum output voltage of 0.6 V.• Current Mode, PWM Operation Switching frequency is internally set to 550 kHz, 1.6
- Thermal Shutdown MHz, or 3 MHz, allowing the use of extremely small surface mount inductors and chip capacitors. Even• Overvoltage Protection though the operating frequency is high, efficiencies of up to 93% are easy to achieve. External shutdown is2 Applications included, featuring an ultra-low standby current of 30
- Local 5 V to Vcore Step-Down Converters nA. The LM2831 utilizes current-mode control and internal compensation to provide high-performance• Core Power in HDDs regulation over a wide range of operating conditions.• Set-Top Boxes Additional features include internal soft-start circuitry• USB Powered Devices to reduce inrush current, pulse-by-pulse current limit,
- DSL Modems thermal shutdown, and output overvoltage protection. Device Information(1) PART NUMBER PACKAGE BODY SIZE (NOM) WSON (6) 3.00 mm × 3.00 mm LM2831 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 Efficiency vs Load 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.
SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015 www.ti.com Table of Contents
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (April 2013) to Revision D Page
- Added ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Changes from Revision B (April 2013) to Revision C Page
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5 Pin Configuration and Functions
FB 3 1 I Feedback pin. Connect to external resistor divider to set output voltage. Signal and power ground pin. Place the bottom resistor of the feedbackGND 2 2 PWR network as close as possible to this pin. SW 1 3 O Output switch. Connect to the inductor and catch diode. 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 Connect to system ground for low thermal impedance, but it cannot be— DAP PWRPad used as a primary GND connection. Copyright © 2006–2015, Texas Instruments Incorporated Submit Documentation Feedback 3 Product Folder Links: LM2831
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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 Junction Temperature(3) 150 °C Soldering Information Infrared or Convection Reflow (15 sec) 220 °C Storage Temperature, Tstg –65 150 °C (1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. (2) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. (3) Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device.
6.2 ESD Ratings
V(ESD) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±2000 V (1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted) MIN NOM MAX UNIT VIN 3 5.5 V Junction Temperature –40 125 °C
6.4 Thermal Information
THERMAL METRIC(1) SOT-23 (DBV WSON (NGG) UNIT
5 PINS 6 PINS
RθJA Junction-to-ambient thermal resistance(2) 163.4 54.9 °C/W RθJC(top) Junction-to-case (top) thermal resistance(2) 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) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953. (2) Applies for packages soldered directly onto a 3”× 3”PC board with 2 oz. copper on 4 layers in still air.
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6.5 Electrical Characteristics
VIN = 5 V unless otherwise indicated under the Test Conditions column. Limits are for TJ = 25°C. Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT WSON and SOT-23 TJ = 25°C 0.600 VFB Feedback Voltage VPackage –40°C to 125°C 0.588 0.612 ΔVFB/VIN Feedback Voltage Line Regulation VIN = 3 V to 5 V 0.02 %/V IB Feedback Input Bias Current TJ = 25°C 0.1 nA –40°C to 125°C 100 VIN Rising TJ = 25°C 2.73 V –40°C to 125°C 2.90 Undervoltage Lockout UVLO VIN Falling TJ = 25°C 2.3 V –40°C to 125°C 1.85 UVLO Hysteresis 0.43 V LM2831-X TJ = 25°C 1.6 –40°C to 125°C 1.2 1.95 LM2831-Y TJ = 25°C 0.55 FSW Switching Frequency MHz –40°C to 125°C 0.4 0.7 LM2831-Z TJ = 25°C 3 –40°C to 125°C 2.25 3.75 LM2831-X TJ = 25°C 94% –40°C to 125°C 86% LM2831-Y TJ = 25°C 96% DMAX Maximum Duty Cycle –40°C to 125°C 90% LM2831-Z TJ = 25°C 90% –40°C to 125°C 82% LM2831-X 5% DMIN Minimum Duty Cycle LM2831-Y 2% LM2831-Z 7% RDS(ON) Switch On Resistance SOT-23 Package TJ = 25°C 130 mΩ –40°C to 125°C 195 ICL Switch Current Limit VIN = 3.3 V TJ = 25°C 2.5 A –40°C to 125°C 1.8 Shutdown Threshold Voltage –40°C to 125°C 0.4 VEN_TH V Enable Threshold Voltage –40°C to 125°C 1.8 ISW Switch Leakage 100 nA IEN Enable Pin Current Sink/Source 100 nA LM2831X VFB = 0.55 TJ = 25°C 3.3 –40°C to 125°C 5 LM2831Y VFB = 0.55 TJ = 25°C 2.8 Quiescent Current (switching) mA IQ –40°C to 125°C 4.5 LM2831Z VFB = 0.55 TJ = 25°C 4.3 –40°C to 125°C 6.5 Quiescent Current (shutdown) All Options VEN = 0 V 30 nA TSD Thermal Shutdown Temperature 165 °C Copyright © 2006–2015, Texas Instruments Incorporated Submit Documentation Feedback 5 Product Folder Links: LM2831
6.6 Typical Characteristics
datasheet. TJ = 25°C, unless otherwise specified. Figure 1. η vs Load – X, Y, and Z Options Figure 2. Load Regulation Figure 3. Load Regulation Figure 4. Load Regulation Figure 5. Oscillator Frequency vs Temperature – X Option Figure 6. Oscillator Frequency vs Temperature – Y Option
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datasheet. TJ = 25°C, unless otherwise specified. Figure 14. Line RegulationFigure 13. LM2831Z IQ (Quiescent Current) Figure 15. VFB vs Temperature Figure 16. Gain vs Frequency Figure 17. Phase Plot vs Frequency
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S R R Q GND FB SW VINEN DRIVER ArtificialRamp SHDNThermal SHDNOVP
1.6 MHz
15 . 1 xREFV Control Logic VREF = 0.6V LM2831 www.ti.com SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015
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
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 Copyright © 2006–2015, Texas Instruments Incorporated Submit Documentation Feedback 9 Product Folder Links: LM2831
Figure 18. Typical Waveforms
7.3.2 Soft Start
output to ramp up in a controlled fashion, which helps reduce inrush current.
7.3.3 Output Overvoltage Protection
switch is turned off, which allows the output voltage to decrease toward regulation.
7.3.4 Undervoltage Lockout
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 next switching cycle begins.
7.3.6 Thermal Shutdown
drops to approximately 150°C.
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7.4 Device Functional Modes
The LM2831 has an enable pin (EN) control Input. A logic high enables device operation. Do not float this pin or let this pin be greater than VIN + 0.3 V for the SOT package option, or VINA + 0.3 V for the WSON package option. Copyright © 2006–2015, Texas Instruments Incorporated Submit Documentation Feedback 11 Product Folder Links: LM2831
8 Application and Implementation
validate and test their design implementation to confirm system functionality.
8.1 Application Information
component selection, see Detailed Design Procedure.
8.2 Typical Applications
8.2.1 LM2831X Design Example 1
Figure 19. LM2831X (1.6 MHz): VIN = 5 V, VO = 1.2 V at 1.5 A
8.2.1.1 Design Requirements
start-up will depend on the output capacitor selection. More details are provided in Detailed Design Procedure.
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8.2.1.2 Detailed Design Procedure
Table 1. Bill of Materials
8.2.1.2.1 Inductor Selection
VD, the higher the operating efficiency of the converter. The inductor value determines the output ripple current. inductor value will decrease the output ripple current. Figure 20. Inductor Current
RMS _ IN OUTI I D(1 D)/c61 /c180 /c45 RMS _ IN OUT iI D I (1 D) 3 /c233 /c249 /c68/c45 /c43/c234 /c250 /c234 /c250 /c235 /c251 S S 1T f/c61 S IN OUT L DTL V V2 i /c230 /c246/c61 /c180 /c45 /c231 /c247 /c68/c232 /c248 LM2831 SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015 www.ti.com 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: (7) Where: (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: (9) Neglecting inductor ripple simplifies the above equation to: (10) It can be shown from the above equation that maximum RMS capacitor current occurs when D = 0.5. Always calculate the RMS at the point where the duty cycle D is closest to 0.5. The ESL of an input capacitor is usually determined by the effective cross sectional area of the current path. A large leaded capacitor will have high ESL and a 0805 ceramic chip capacitor will have very low ESL. At the operating frequencies of the LM2831, leaded capacitors may have an ESL so large that the resulting impedance (2πfL) will be higher than that required to provide stable operation. As a result, surface mount capacitors are strongly recommended. Sanyo POSCAP, Tantalum or Niobium, Panasonic SP, and multilayer ceramic capacitors (MLCC) are all good choices for both input and output capacitors and have very low ESL. For MLCCs it is recommended to use X7R or X5R type capacitors due to their tolerance and temperature characteristics. Consult capacitor manufacturer data sheets to see how rated capacitance varies over operating conditions.
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x R2R1 = VREF VOUT - 1 OUT L ESR SW OUT 1V I R 8 F C /c230 /c246/c61 /c68 /c43 /c231 /c247 /c180 /c180/c232 /c248 LM2831 www.ti.com SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015
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: (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. (13) VREF = 0.60 V (14) Copyright © 2006–2015, Texas Instruments Incorporated Submit Documentation Feedback 15 Product Folder Links: LM2831
8.2.1.3 Application Curves
See Typical Characteristics. Figure 21. η vs Load – X Option Figure 22. η vs Load – Y Option Figure 23. η vs Load – Z Option
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8.2.2 LM2831X Design Example 2
Figure 24. LM2831X (1.6 MHz): VIN = 5 V, VO = 0.6 V at 1.5 A Table 2. Bill of Materials
8.2.3 LM2831X Design Example 3
Figure 25. LM2831X (1.6 MHz): VIN = 5 V, VO = 3.3 V at 1.5 A Table 3. Bill of Materials
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8.2.4 LM2831Y Design Example 4
Figure 26. LM2831Y (550 kHz): VIN = 5 V, VOUT = 3.3 V at 1.5 A Table 4. Bill of Materials
8.2.5 LM2831Y Design Example 5
Figure 27. LM2831Y (550 kHz): VIN = 5 V, VOUT = 1.2 V at 1.5 A Table 5. Bill of Materials
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8.2.6 LM2831Z Design Example 6
Figure 28. LM2831Z (3 MHz): VIN = 5 V, VO = 3.3 V at 1.5 A Table 6. Bill of Materials
8.2.7 LM2831Z Design Example 7
Figure 29. LM2831Z (3 MHz): VIN = 5 V, VO = 1.2 V at 1.5 A Table 7. Bill of Materials
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8.2.8 LM2831X Dual Converters with Delayed Enabled Design Example 8
Table 8. Bill of Materials
8.2.9 LM2831X Buck Converter and Voltage Double Circuit With LDO Follower Design Example 9
Table 9. Bill of Materials
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D = VOUT + VD + VDCR VIN + VD + VDCR - VSW OUT D IN D SW V VD V V V /c43/c61 /c43 /c45 OUT OUT LOSS P P P/c104 /c61 /c43 OUT IN P P/c104 /c61 LM2831 www.ti.com SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015
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. (15) Or (16) 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): (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: (19) The conduction losses in the free-wheeling Schottky diode are calculated as follows: PDIODE = VD × IOUT × (1-D) (20) Copyright © 2006–2015, Texas Instruments Incorporated Submit Documentation Feedback 25 Product Folder Links: LM2831
diode that has a low forward voltage drop. is to empirically measuring the rise and fall times (10% to 90%) of the switch at the switch node. IQ is the quiescent operating current, and is typically around 2.5 mA for the 0.55-MHz frequency option. Table 10. Power Loss Tabulation
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/c45/c61 J A JA T TR Power/c113 /c45/c61 TR Power/c113 /c68/c61 LM2831 www.ti.com SNVS422D –AUGUST 2006–REVISED SEPTEMBER 2015
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: (31) Thermal impedance from the silicon junction to the ambient air is defined as: (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: (33) Therefore: Tj = (RΦJC × PLOSS) + TC (34) From the previous example: Tj = (RΦJC × PINTERNAL) + TC (35) Copyright © 2006–2015, Texas Instruments Incorporated Submit Documentation Feedback 27 Product Folder Links: LM2831
165 C 144 CR 111 C / W189 mW/c113
165 C TaR P/c113
The second method can give a very accurate silicon junction temperature.
10.1.3 WSON Package
Figure 32. Internal WSON Connection increasing the size of ground plane, and adding thermal vias, the RθJA for the application can be reduced.
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10.2 Layout Example
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.
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Product Folder Links: LM2831
www.ti.com 23-May-2025 PACKAGING INFORMATION Orderable part number Status (1) Material type (2) Package | Pins Package qty | Carrier RoHS (3) Lead finish/ Ball material (4) MSL rating/ Peak reflow (5) Op temp (°C) Part marking (6) LM2831XMF/NOPB Active Production SOT-23 (DBV) | 5 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKYB LM2831XMF/NOPB.A Active Production SOT-23 (DBV) | 5 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKYB LM2831XMFX/NOPB Active Production SOT-23 (DBV) | 5 3000 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKYB LM2831XMFX/NOPB.A Active Production SOT-23 (DBV) | 5 3000 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKYB LM2831XSD/NOPB Active Production WSON (NGG) | 6 1000 | SMALL T&R Yes SN Level-3-260C-168 HR -40 to 125 L193B LM2831XSD/NOPB.A Active Production WSON (NGG) | 6 1000 | SMALL T&R Yes SN Level-3-260C-168 HR -40 to 125 L193B LM2831XSDX/NOPB Active Production WSON (NGG) | 6 4500 | LARGE T&R Yes SN Level-3-260C-168 HR -40 to 125 L193B LM2831XSDX/NOPB.A Active Production WSON (NGG) | 6 4500 | LARGE T&R Yes SN Level-3-260C-168 HR -40 to 125 L193B LM2831YMF/NOPB Active Production SOT-23 (DBV) | 5 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YMF/NOPB.A Active Production SOT-23 (DBV) | 5 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YMFX/NOPB Active Production SOT-23 (DBV) | 5 3000 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YMFX/NOPB.A Active Production SOT-23 (DBV) | 5 3000 | LARGE T&R Yes SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YSD/NOPB Active Production WSON (NGG) | 6 1000 | SMALL T&R Yes SN Level-3-260C-168 HR -40 to 125 L194B LM2831YSD/NOPB.A Active Production WSON (NGG) | 6 1000 | SMALL T&R Yes SN Level-3-260C-168 HR -40 to 125 L194B LM2831ZMF/NOPB Active Production SOT-23 (DBV) | 5 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 SLAB LM2831ZMF/NOPB.A Active Production SOT-23 (DBV) | 5 1000 | SMALL T&R Yes SN Level-1-260C-UNLIM -40 to 125 SLAB LM2831ZSD/NOPB Active Production WSON (NGG) | 6 1000 | SMALL T&R Yes SN Level-3-260C-168 HR -40 to 125 L195B LM2831ZSD/NOPB.A Active Production WSON (NGG) | 6 1000 | SMALL T&R Yes SN Level-3-260C-168 HR -40 to 125 L195B (1) Status: For more details on status, see our product life cycle. (2) Material type: When designated, preproduction parts are prototypes/experimental devices, and are not yet approved or released for full production. Testing and final process, including without limitation quality assurance, reliability performance testing, and/or process qualification, may not yet be complete, and this item is subject to further changes or possible discontinuation. If available for ordering, purchases will be subject to an additional waiver at checkout, and are intended for early internal evaluation purposes only. These items are sold without warranties of any kind. (3) RoHS values: Yes, No, RoHS Exempt. See the TI RoHS Statement for additional information and value definition. (4) Lead finish/Ball material: Parts may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two lines if the finish value exceeds the maximum column width. Addendum-Page 1
www.ti.com 23-May-2025 (5) MSL rating/Peak reflow: The moisture sensitivity level ratings and peak solder (reflow) temperatures. In the event that a part has multiple moisture sensitivity ratings, only the lowest level per JEDEC standards is shown. Refer to the shipping label for the actual reflow temperature that will be used to mount the part to the printed circuit board. (6) Part marking: There may be an additional marking, which relates to the logo, the lot trace code information, or the environmental category of the part. Multiple part markings will be inside parentheses. Only one part marking contained in parentheses and separated by a "~" will appear on a part. If a line is indented then it is a continuation of the previous line and the two combined represent the entire part marking for that device. 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 25-Sep-2024 TAPE AND REEL INFORMATION Reel Width (W1) REEL DIMENSIONS A0B0K0WDimension designed to accommodate the component lengthDimension designed to accommodate the component thicknessOverall width of the carrier tapePitch between successive cavity centersDimension designed to accommodate the component width TAPE DIMENSIONSK0 P1B0WA0Cavity QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE Pocket QuadrantsSprocket HolesQ1Q1Q2Q2Q3Q3Q4Q4User Direction of Feed P1ReelDiameter *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Reel Diameter (mm) Reel Width W1 (mm) (mm) (mm) (mm) (mm) W (mm) Pin1 Quadrant Pack Materials-Page 1
PACKAGE MATERIALS INFORMATION www.ti.com 25-Sep-2024 TAPE AND REEL BOX DIMENSIONS Width (mm) W LH *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/NOPB WSON NGG 6 1000 208.0 191.0 35.0 LM2831XSDX/NOPB WSON NGG 6 4500 356.0 356.0 36.0 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 208.0 191.0 35.0 LM2831ZMF/NOPB SOT-23 DBV 5 1000 210.0 185.0 35.0 LM2831ZSD/NOPB WSON NGG 6 1000 208.0 191.0 35.0 Pack Materials-Page 2
www.ti.com PACKAGE OUTLINE C 0.22
0.08 TYP
0.25 3.0 2.6 2X 0.95 1.9 1.45 0.90 0.15
0.00 TYP
5X 0.5 0.3 0.6
0.3 TYP
0 TYP
1.9 (0.1) (0.15) 4X 0 -15 4X 4 -15 A 3.05 2.75 B1.75 1.45 (1.1) SOT-23 - 1.45 mm max heightDBV0005A SMALL OUTLINE TRANSISTOR 4214839/K 08/2024 NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. Refernce JEDEC MO-178. 4. Body dimensions do not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not exceed 0.25 mm per side. 5. Support pin may differ or may not be present.
0.2 C A B
0.1 C SCALE 4.000
www.ti.com EXAMPLE BOARD LAYOUT
0.07 MAX
0.07 MIN
5X (1.1) 5X (0.6) (2.6) (1.9) 2X (0.95) (R0.05) TYP 4214839/K 08/2024 SOT-23 - 1.45 mm max heightDBV0005A SMALL OUTLINE TRANSISTOR NOTES: (continued) 6. Publication IPC-7351 may have alternate designs. 7. Solder mask tolerances between and around signal pads can vary based on board fabrication site. SYMM LAND PATTERN EXAMPLE EXPOSED METAL SHOWN SCALE:15X PKG 3 4 SOLDER MASK OPENING METAL UNDER SOLDER MASK SOLDER MASK DEFINED EXPOSED METAL METALSOLDER MASK OPENING NON SOLDER MASK DEFINED (PREFERRED) SOLDER MASK DETAILS EXPOSED METAL
www.ti.com EXAMPLE STENCIL DESIGN (2.6) (1.9) 2X(0.95) 5X (1.1) 5X (0.6) (R0.05) TYP SOT-23 - 1.45 mm max heightDBV0005A SMALL OUTLINE TRANSISTOR 4214839/K 08/2024 NOTES: (continued) 8. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. 9. Board assembly site may have different recommendations for stencil design. SOLDER PASTE EXAMPLE BASED ON 0.125 mm THICK STENCIL SCALE:15X SYMM PKG 3 4
www.ti.com SDE06A (Rev A)
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