Sample & Buy Product Folder Support & Community Tools & Software Technical Documents Reference Design 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-m PMOS switch using state-of-the-art 0.5-m 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-m 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 x 3.00 mm SOT-23 (5) 1.60 mm x 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 www.ti.com 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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. Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 3 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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) RJA (2) SOT-23 (DBV WSON (NGG) 5 PINS 6 PINS UNIT 163.4 54.9 C/W RJC(top) Junction-to-case (top) thermal resistance 114.4 50.8 C/W RJB Junction-to-board thermal resistance 26.8 29.2 C/W JT Junction-to-top characterization parameter 12.4 0.6 C/W JB Junction-to-board characterization parameter 26.2 29.3 C/W RJC(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" x 3" PC board with 2 oz. copper on 4 layers in still air. Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 6.5 Electrical Characteristics VIN = 5 V unless otherwise indicated under the Test Conditions column. Limits are for TJ = 25C. Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25C, and are provided for reference purposes only. PARAMETER TEST CONDITIONS VFB Feedback Voltage WSON and SOT-23 Package VFB/VIN Feedback Voltage Line Regulation VIN = 3 V to 5 V IB Feedback Input Bias Current MIN TJ = 25C -40C to 125C TYP 0.600 0.588 0.612 0.02 TJ = 25C UVLO Undervoltage Lockout 100 TJ = 25C 2.73 -40C to 125C VIN Falling 2.90 TJ = 25C -40C to 125C 2.3 0.43 LM2831-X TJ = 25C -40C to 125C 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 = 25C 130 -40C to 125C ICL Switch Current Limit VIN = 3.3 V VEN_TH Shutdown Threshold Voltage -40C to 125C Enable Threshold Voltage -40C to 125C ISW Switch Leakage IEN Enable Pin Current Sink/Source LM2831X VFB = 0.55 TJ = 25C 2.5 IQ Quiescent Current (switching) TJ = 25C 0.4 1.8 TJ = 25C 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 mA 4.3 -40C to 125C TSD V 100 -40C to 125C LM2831Z VFB = 0.55 A 1.8 -40C to 125C LM2831Y VFB = 0.55 m 195 TJ = 25C -40C to 125C MHz 3 2.25 TJ = 25C -40C to 125C 1.95 0.4 TJ = 25C -40C to 125C V V 0.55 TJ = 25C -40C to 125C LM2831-Y 1.2 TJ = 25C -40C to 125C nA 1.6 TJ = 25C -40C to 125C V V 1.85 UVLO Hysteresis UNIT %/V 0.1 -40C to 125C VIN Rising MAX 5 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 = 25C, 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. 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 (C) 20 50 80 110 125 130 TEMPERATURE (C) Figure 5. Oscillator Frequency vs Temperature - X Option 6 -10 Figure 6. Oscillator Frequency vs Temperature - Y Option Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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 = 25C, 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 (C) -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 (C) Figure 11. LM2831X IQ (Quiescent Current) Figure 12. LM2831Y IQ (Quiescent Current) Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 7 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 = 25C, 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 (C) 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 (C) 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 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 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 9 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 s. 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 165C. After thermal shutdown occurs, the output switch doesn't turn on until the junction temperature drops to approximately 150C. 10 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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. Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 11 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Cap 2x22 F, 6.3 V, X5R TDK C3216X5ROJ226M D1, Catch Diode 0.3 Vf Schottky 1.5 A, 30 VR TOSHIBA CRS08 L1 3.3 H, 2.2 A TDK VLCF5020T-3R3N2R0-1 R2 15.0 k, 1% Vishay CRCW08051502F R1 15.0 k, 1% Vishay CRCW08051502F R3 100 k, 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 x 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 + iL (4) 'i L IOUT VOUT L VIN - VOUT L DTS TS t Figure 20. Inductor Current VIN - VOUT 2DiL = L DTS (5) Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 13 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com In general, iL = 0.1 x (IOUT) 0.2 x (IOUT) (6) If iL = 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 iL, 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: ae DT L=c S e 2DiL o / VIN - VOUT o (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 F. 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: e Di2 u IRMS _ IN D eIOUT 2 (1 - D) + u 3 uu ee (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 (2fL) 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 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: ae o 1 VOUT = DIL c RESR + / 8 FSW COUT o e (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 F 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 x (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 k. When designing a unity gain converter (Vo = 0.6 V), R1 should be from 0 to 100 , and R2 should be equal or greater than 10 k. VOUT - 1 x R2 R1 = VREF (13) VREF = 0.60 V (14) Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 15 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 8.2.1.3 Application Curves See Typical Characteristics. VIN = 5 V VO = 1.8 V and 3.3 V Figure 21. vs Load - X Option VIN = 5 V VO = 1.8 V and 3.3 V Figure 22. vs Load - Y Option VIN = 5 V VO = 1.8 V and 3.3 V Figure 23. vs Load - Z Option 16 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Capacitor 2x22 F, 6.3 V, X5R TDK C3216X5ROJ226M D1, Catch Diode 0.3 Vf Schottky 1.5 A, 30 VR TOSHIBA CRS08 L1 3.3 H, 2.2 A TDK VLCF5020T- 3R3N2R0-1 R2 10.0 k, 1% Vishay CRCW08051000F R1 0 R3 100 k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 17 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Cap 2x22 F, 6.3 V, X5R TDK C3216X5ROJ226M D1, Catch Diode 0.3 Vf Schottky 1.5 A, 30 VR TOSHIBA CRS08 L1 2.7 H 2.3 A TDK VLCF5020T-2R7N2R2-1 R2 10.0 k, 1% Vishay CRCW08051002F R1 45.3 k, 1% Vishay CRCW08054532F R3 100 k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Cap 2x22 F, 6.3 V, X5R TDK C3216X5ROJ226M D1, Catch Diode 0.3 Vf Schottky 1.5 A, 30 VR TOSHIBA CRS08 L1 4.7 H 2.1 A TDK SLF7045T-4R7M2R0-PF R1 45.3 k, 1% Vishay CRCW080545K3FKEA R2 10.0 k, 1% Vishay CRCW08051002F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 19 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Cap 2x22 F, 6.3 V, X5R TDK C3216X5ROJ226M D1, Catch Diode 0.3 Vf Schottky 1.5 A, 30 VR TOSHIBA CRS08 L1 6.8 H 1.8 A TDK SLF7045T-6R8M1R7 R1 10.0 k, 1% Vishay CRCW08051002F R2 10.0 k, 1% Vishay CRCW08051002F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Cap 2x22 F, 6.3 V, X5R TDK C3216X5ROJ226M D1, Catch Diode 0.3 Vf Schottky 1.5 A, 30 VR TOSHIBA CRS08 L1 1.6 H 2.0 A TDK VLCF4018T-1R6N1R7-2 R2 10.0 k, 1% Vishay CRCW08051002F R1 45.3 k, 1% Vishay CRCW08054532F R3 100 k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 21 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Cap 2x22 F, 6.3 V, X5R TDK C3216X5ROJ226M D1, Catch Diode 0.3 Vf Schottky 1.5 A, 30 VR TOSHIBA CRS08 L1 1.6 H, 2.0 A TDK VLCF4018T- 1R6N1R7-2 R2 10.0 k, 1% Vishay CRCW08051002F R1 10.0 k, 1% Vishay CRCW08051002F R3 100 k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, C4 Output Cap 2x22 F, 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 H, 2.2 A TDK VLCF5020T-3R3N2R0-1 R2, R4, R5 10.0 k, 1% Vishay CRCW08051002F R1, R6 45.3 k, 1% Vishay CRCW08054532F R3 100 k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 23 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 F, 6.3 V, X5R TDK C3216X5ROJ226M C2, Output Cap 22 F, 6.3 V, X5R TDK C3216X5ROJ226M C1608X5R0J225M C3 - C6 2.2 F, 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 H, 800 mA CoilCraft ME3220-103 L1 3.3 H, 2.2 A TDK VLCF5020T-3R3N2R0-1 R2 45.3 k, 1% Vishay CRCW08054532F R1 10.0 k, 1% Vishay CRCW08051002F Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 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. 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 x 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 x IOUT x (1-D) (20) Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 25 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 x 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 x RDSON x 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 x IOUT x FSW x TRISE) PSWF = 1/2(VIN x IOUT x FSW x TFALL) PSW = PSWR + PSWF (24) (25) (26) Another loss is the power required for operation of the internal circuitry: PQ = IQ x 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 m PCOND 156 mW INDDCR 70 m PIND 110 mW D 0.667 PLOSS 481 mW 88% PINTERNAL 183 mW PCOND + PSW + PDIODE + PIND + PQ = PLOSS PCOND + PSWF + PSWR + PQ = PINTERNAL PINTERNAL = 183 mW 26 (28) (29) (30) Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 10.1.2 Thermal Definitions TJ Chip junction temperature TA Ambient temperature RJC Thermal resistance from chip junction to device case RJA 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 RJA. 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. RJC is the thermal impedance from all six sides of an IC package to silicon junction. RJC is the thermal impedance from top case to the silicon junction. In this data sheet we will use RJC so that it allows the user to measure top case temperature with a small thermocouple attached to the top case. RJC is approximately 30C/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 = (RJC x PLOSS) + TC (34) From the previous example: Tj = (RJC x PINTERNAL) + TC Tj = 30C/W x 0.189 W + TC (35) (36) Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 27 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com The second method can give a very accurate silicon junction temperature. The first step is to determine RJA of the application. The LM2831 has overtemperature protection circuitry. When the silicon temperature reaches 165C, the device stops switching. The protection circuitry has a hysteresis of about 15C. Once the silicon temperature has decreased to approximately 150C, the device will start to switch again. Knowing this, the RJA for any application can be characterized during the early stages of the design one may calculate the RJA 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 165C. Knowing the internal power dissipation from the above methods, the junction temperature, and the ambient temperature RJA can be determined. 165C - 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 RJA for an application using the Texas Instruments LM2831 WSON demonstration board is shown below. The four layer PCB is constructed using FR4 with 1/2 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 x 3 cm. It was placed in an oven with no forced airflow. The ambient temperature was raised to 144C, and at that temperature, the device went into thermal shutdown. From the previous example: PINTERNAL = 189 mW RqJA (38) 165C - 144C = = 111C / W 189 mW (39) If the junction temperature was to be kept below 125C, then the ambient temperature could not go above 109C Tj - (RJA x PLOSS) = TA 125C - (111C/W x 189 mW) = 104C (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 RJA for the application can be reduced. 28 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 29 LM2831 SNVS422D - AUGUST 2006 - REVISED SEPTEMBER 2015 www.ti.com 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 (R) 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 E2ETM 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 Submit Documentation Feedback Copyright (c) 2006-2015, Texas Instruments Incorporated Product Folder Links: LM2831 PACKAGE OPTION ADDENDUM www.ti.com 6-Feb-2020 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) SN Level-1-260C-UNLIM -40 to 125 SKYB LM2831XMFX/NOPB ACTIVE SOT-23 DBV 5 3000 Green (RoHS & no Sb/Br) 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) SN Level-3-260C-168 HR -40 to 125 L193B LM2831XSDX/NOPB ACTIVE WSON NGG 6 4500 Green (RoHS & no Sb/Br) SN Level-3-260C-168 HR -40 to 125 L193B LM2831YMF/NOPB ACTIVE SOT-23 DBV 5 1000 Green (RoHS & no Sb/Br) SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YMFX/NOPB ACTIVE SOT-23 DBV 5 3000 Green (RoHS & no Sb/Br) SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YSD/NOPB ACTIVE WSON NGG 6 1000 Green (RoHS & no Sb/Br) SN Level-3-260C-168 HR -40 to 125 L194B LM2831ZMF/NOPB ACTIVE SOT-23 DBV 5 1000 Green (RoHS & no Sb/Br) SN Level-1-260C-UNLIM -40 to 125 SLAB LM2831ZSD/NOPB ACTIVE WSON NGG 6 1000 Green (RoHS & no Sb/Br) 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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com (4) 6-Feb-2020 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. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 29-Sep-2019 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 29-Sep-2019 *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 210.0 185.0 35.0 LM2831XSD/NOPB WSON NGG 6 1000 210.0 185.0 35.0 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 210.0 185.0 35.0 LM2831ZMF/NOPB SOT-23 DBV 5 1000 210.0 185.0 35.0 LM2831ZSD/NOPB WSON NGG 6 1000 210.0 185.0 35.0 Pack Materials-Page 2 PACKAGE OUTLINE DBV0005A SOT-23 - 1.45 mm max height SCALE 4.000 SMALL OUTLINE TRANSISTOR C 3.0 2.6 1.75 1.45 PIN 1 INDEX AREA 1 0.1 C B A 5 2X 0.95 1.9 1.45 0.90 3.05 2.75 1.9 2 4 0.5 5X 0.3 0.2 3 (1.1) C A B 0.15 TYP 0.00 0.25 GAGE PLANE 8 TYP 0 0.22 TYP 0.08 0.6 TYP 0.3 SEATING PLANE 4214839/E 09/2019 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 0.15 mm per side. www.ti.com EXAMPLE BOARD LAYOUT DBV0005A SOT-23 - 1.45 mm max height SMALL OUTLINE TRANSISTOR PKG 5X (1.1) 1 5 5X (0.6) SYMM (1.9) 2 2X (0.95) 3 4 (R0.05) TYP (2.6) LAND PATTERN EXAMPLE EXPOSED METAL SHOWN SCALE:15X SOLDER MASK OPENING METAL SOLDER MASK OPENING METAL UNDER SOLDER MASK EXPOSED METAL EXPOSED METAL 0.07 MIN ARROUND 0.07 MAX ARROUND NON SOLDER MASK DEFINED (PREFERRED) SOLDER MASK DEFINED SOLDER MASK DETAILS 4214839/E 09/2019 NOTES: (continued) 5. Publication IPC-7351 may have alternate designs. 6. Solder mask tolerances between and around signal pads can vary based on board fabrication site. www.ti.com EXAMPLE STENCIL DESIGN DBV0005A SOT-23 - 1.45 mm max height SMALL OUTLINE TRANSISTOR PKG 5X (1.1) 1 5 5X (0.6) SYMM (1.9) 2 2X(0.95) 4 3 (R0.05) TYP (2.6) SOLDER PASTE EXAMPLE BASED ON 0.125 mm THICK STENCIL SCALE:15X 4214839/E 09/2019 NOTES: (continued) 7. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. 8. 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