LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 LM2831 High Frequency 1.5A Load - Step-Down DC-DC Regulator Check for Samples: LM2831 FEATURES DESCRIPTION * * * * * The LM2831 regulator is a monolithic, high frequency, PWM step-down DC/DC converter in a 5 pin SOT-23 and a 6 Pin WSON package. It 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 1.5A 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 ontimes as low as 30ns, thus supporting exceptionally high frequency conversion over the entire 3V to 5.5V input operating range down to the minimum output voltage of 0.6V. Switching frequency is internally set to 550 kHz, 1.6 MHz, or 3.0 MHz, allowing the use of extremely small surface mount inductors and chip capacitors. Even though the operating frequency is high, efficiencies up to 93% are easy to achieve. External shutdown is included, featuring an ultra-low stand-by 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 over-voltage protection. 1 2 * * * * * * Space Saving SOT-23 Package Input Voltage Range of 3.0V to 5.5V Output Voltage Range of 0.6V to 4.5V 1.5A Output Current High Switching Frequencies - 1.6MHz (LM2831X) - 0.55MHz (LM2831Y) - 3.0MHz (LM2831Z) 130m PMOS Switch 0.6V, 2% Internal Voltage Reference Internal Soft-Start Current Mode, PWM Operation Thermal Shutdown Over Voltage Protection APPLICATIONS * * * * * Local 5V to Vcore Step-Down Converters Core Power in HDDs Set-Top Boxes USB Powered Devices DSL Modems Typical Application Circuit FB EN LM2831 R3 VIN GND L1 SW VO = 3.3V @ 1.5A VIN = 5V R1 C1 D1 C2 C3 R2 1 2 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. All trademarks are the property of their respective owners. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 2006-2013, Texas Instruments Incorporated LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com Connection Diagrams FB 1 GND 2 SW 3 EN 6 EN DAP 4 3 FB 2 GND 5 VINA 4 VIND VIN Figure 1. 6-Pin WSON See Package Number NGG 5 1 SW Figure 2. 5-Pin SOT-23 See Package Number DBV PIN DESCRIPTIONS (5-PIN SOT-23) Pin Name 1 SW 2 GND Function Output switch. Connect to the inductor and catch diode. Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin. 3 FB Feedback pin. Connect to external resistor divider to set output voltage. 4 EN Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VIN + 0.3V. 5 VIN Input supply voltage. PIN DESCRIPTIONS (6-PIN WSON) Pin Name 1 FB 2 GND Function Feedback pin. Connect to external resistor divider to set output voltage. Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin. 3 SW 4 VIND Output switch. Connect to the inductor and catch diode. Power Input supply. 5 VINA Control circuitry supply voltage. Connect VINA to VIND on PC board. 6 EN DAP Die Attach Pad Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VINA + 0.3V. Connect to system ground for low thermal impedance, but it cannot be used as a primary GND connection. These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. Absolute Maximum Ratings (1) (2) VIN -0.5V to 7V FB Voltage -0.5V to 3V EN Voltage -0.5V to 7V SW Voltage -0.5V to 7V ESD Susceptibility 2kV Junction Temperature (3) 150C -65C to +150C Storage Temperature Soldering Information (1) (2) (3) 2 Infrared or Convection Reflow (15 sec) 220C Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Range indicates conditions for which the device is intended to be functional, but does not ensure specific performance limits. For ensured specifications and test conditions, see the Electrical Characteristics. 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. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 Operating Ratings VIN 3V to 5.5V -40C to +125C Junction Temperature Electrical Characteristics VIN = 5V unless otherwise indicated under the Conditions column. Limits in standard type are for TJ = 25C only; limits in boldface type apply over the junction temperature (TJ) range of -40C to +125C. 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. Symbol VFB VFB/VIN IB UVLO Conditions Min Typ Max Feedback Voltage Parameter WSON and SOT-23 Package 0.588 0.600 0.612 Feedback Voltage Line Regulation VIN = 3V to 5V 0.02 0.1 100 nA VIN Rising 2.73 2.90 V Feedback Input Bias Current Undervoltage Lockout FSW DMAX DMIN RDS(ON) ICL VEN_TH Maximum Duty Cycle Minimum Duty Cycle Switch On Resistance Switch Current Limit 1.85 2.3 LM2831-X 1.2 1.6 LM2831-Y 0.4 0.55 0.7 LM2831-Z 2.25 3.0 3.75 LM2831-X 86 94 LM2831-Y 90 96 LM2831-Z 82 90 0.43 LM2831-X 5 LM2831-Y 2 LM2831-Z 7 WSON Package 150 SOT-23 Package 130 VIN = 3.3V 1.8 Switch Leakage Enable Pin Current MHz % % 195 m A 0.4 Enable Threshold Voltage IEN V 1.95 2.5 Shutdown Threshold Voltage ISW 1.8 V 100 nA Sink/Source 100 nA LM2831X VFB = 0.55 3.3 5 LM2831Y VFB = 0.55 2.8 4.5 LM2831Z VFB = 0.55 4.3 6.5 Quiescent Current (shutdown) All Options VEN = 0V 30 JA Junction to Ambient 0 LFPM Air Flow (1) WSON Package 80 SOT-23 Package 118 JC Junction to Case (1) WSON Package 18 SOT-23 Package 80 TSD Thermal Shutdown Temperature IQ (1) Switching Frequency V %/V VIN Falling UVLO Hysteresis Units Quiescent Current (switching) 165 mA nA C/W C/W C Applies for packages soldered directly onto a 3" x 3" PC board with 2oz. copper on 4 layers in still air. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 3 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this datasheet. TJ = 25C, unless otherwise specified. vs Load "X" Vin = 5V, Vo = 1.8V & 3.3V vs Load - "Y" Vin = 5V, Vo = 3.3V & 1.8V Figure 3. Figure 4. vs Load "Z" Vin = 5V, Vo = 3.3V & 1.8V vs Load "X, Y and Z" Vin = 3.3V, Vo = 1.8V Figure 5. Figure 6. Load Regulation Vin = 3.3V, Vo = 1.8V (All Options) Load Regulation Vin = 5V, Vo = 1.8V (All Options) 1.806 1.804 1.803 1.804 OUTPUT (V) OUTPUT (V) 1.802 1.801 1.800 1.799 1.802 1.800 1.798 1.798 1.796 1.797 1.794 1.796 0 0.25 0.5 0.75 1 1.25 1.5 Figure 7. 4 0 0.25 0.5 0.75 1 1.25 1.5 LOAD (A) LOAD (A) Figure 8. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 Typical Performance Characteristics (continued) All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this datasheet. TJ = 25C, unless otherwise specified. Load Regulation Vin = 5V, Vo = 3.3V (All Options) Oscillator Frequency vs Temperature - "X" 3.302 OSCILLATOR FREQUENCY (MHz) 1.81 OUTPUT (V) 3.301 3.300 3.299 3.298 3.297 0 0.25 0.5 0.75 1 1.25 1.76 1.71 1.66 1.61 1.56 1.51 1.46 1.41 1.36 -45 -40 1.5 LOAD (A) 20 50 80 110 125 130 TEMPERATURE (C) Figure 9. Figure 10. Oscillator Frequency vs Temperature - "Y" Oscillator Frequency vs Temperature - "Z" 3.45 OSCILLATOR FREQUENCY (MHz) 0.60 OSCILLATOR FREQUENCY (MHz) -10 0.58 0.56 0.54 0.52 0.50 0.48 0.46 -45 -40 -10 20 50 80 110 125 130 3.35 3.25 3.15 3.05 2.95 2.85 2.75 2.65 2.55 -45 -40 -10 20 50 80 110 125 130 TEMPERATURE (C) TEMPERATURE (C) Figure 11. Figure 12. Current Limit vs Temperature Vin = 3.3V RDSON vs Temperature (WSON Package) 2900 CURRENT LIMIT (mA) 2800 2700 2600 250 0 2400 2300 2200 210 0 -45 -40 -10 20 50 80 110 125 130 TEMPERATURE (C) Figure 13. Figure 14. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 5 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this datasheet. TJ = 25C, unless otherwise specified. RDSON vs Temperature (SOT-23 Package) LM2831X IQ (Quiescent Current) 3.6 3.5 IQ (mA) 3.4 3.3 3.2 3.1 3.0 -45 -40 -10 20 50 80 110 125 130 TEMPERATURE (C) Figure 15. Figure 16. LM2831Y IQ (Quiescent Current) LM2831Z IQ (Quiescent Current) 2.65 4.6 2.6 4.5 2.55 4.4 IQ (mA) IQ (mA) 2.5 2.45 2.4 2.35 4.3 4.2 2.3 2.25 4.1 2.2 2.15 -45 -40 -10 20 50 80 4.0 -45 110 125 130 TEMPERATURE (C) -40 -10 20 50 80 110 125 130 TEMPERATURE (C) Figure 17. Figure 18. Line Regulation Vo = 1.8V, Io = 500mA VFB vs Temperature FEEBACK VOLTAGE (V) 0.610 0.605 0.600 0.595 0.590 -45 -40 -10 20 50 80 110 125 130 TEMPERATURE (C) Figure 19. 6 Figure 20. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 Typical Performance Characteristics (continued) All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this datasheet. TJ = 25C, unless otherwise specified. Gain vs Frequency (Vin = 5V, Vo = 1.2V @ 1A) Phase Plot vs Frequency (Vin = 5V, Vo = 1.2V @ 1A) Figure 21. Figure 22. Simplified Block Diagram 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 Figure 23. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 7 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com APPLICATIONS INFORMATION THEORY OF OPERATION The LM2831 is a constant frequency PWM buck regulator IC that delivers a 1.5A load current. The regulator has a preset switching frequency of 550kHz, 1.6MHz, or 3.0MHz. This high frequency allows the LM2831 to operate with small surface mount capacitors and inductors, resulting in a DC/DC converter that requires a minimum amount of board space. The LM2831 is internally compensated, so it is simple to use and requires few external components. The LM2831 uses current-mode control to regulate the output voltage. The following operating description of the LM2831 will refer to Figure 23 and to the waveforms in Figure 24. The LM2831 supplies a regulated output voltage by switching the internal PMOS control switch at constant frequency and variable duty cycle. A switching cycle begins at the falling edge of the reset pulse generated by the internal oscillator. When this pulse goes low, the output control logic turns on the internal PMOS control switch. During this on-time, the SW pin voltage (VSW) swings up to approximately VIN, and the inductor current (IL) increases with a linear slope. 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 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 t TSW IL IPK Inductor Current t 0 Figure 24. Typical Waveforms SOFT-START This function forces VOUT to increase at a controlled rate during start up. During soft-start, the error amplifier's reference voltage ramps from 0V to its nominal value of 0.6V in approximately 600 s. This forces the regulator output to ramp up in a controlled fashion, which helps reduce inrush current. OUTPUT OVERVOLTAGE PROTECTION The over-voltage comparator compares the FB pin voltage to a voltage that is 15% higher than the internal reference VREF. Once the FB pin voltage goes 15% above the internal reference, the internal PMOS control switch is turned off, which allows the output voltage to decrease toward regulation. UNDERVOLTAGE LOCKOUT Under-voltage lockout (UVLO) prevents the LM2831 from operating until the input voltage exceeds 2.73V (typ). The UVLO threshold has approximately 430 mV of hysteresis, so the part will operate until VIN drops below 2.3V (typ). Hysteresis prevents the part from turning off during power up if VIN is non-monotonic. 8 Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 CURRENT LIMIT The LM2831 uses cycle-by-cycle current limiting to protect the output switch. During each switching cycle, a current limit comparator detects if the output switch current exceeds 2.5A (typ), and turns off the switch until the next switching cycle begins. THERMAL SHUTDOWN Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature exceeds 165C. After thermal shutdown occurs, the output switch doesn't turn on until the junction temperature drops to approximately 150C. Design Guide 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: VOUT + VD D= VIN + VD - VSW (2) VSW can be approximated by: VSW = IOUT x RDSON (3) The diode forward drop (VD) can range from 0.3V to 0.7V depending on the quality of the diode. The lower the VD, the higher the operating efficiency of the converter. The inductor value determines the output ripple current. Lower inductor values decrease the size of the inductor, but increase the output ripple current. An increase in the inductor value will decrease the output ripple current. One must ensure that the minimum current limit (1.8A) is not exceeded, so the peak current in the inductor must be calculated. The peak current (ILPK) in the inductor is calculated by: ILPK = IOUT + iL (4) 'i L I OUT VIN - VOUT VOUT L L DTS TS t Figure 25. Inductor Current VIN - VOUT L = 2'iL DTS (5) In general, iL = 0.1 x (IOUT) 0.2 x (IOUT) (6) If iL = 20% of 1.50A, the peak current in the inductor will be 1.8A. The minimum ensured current limit over all operating conditions is 1.8A. One can either reduce iL, or make the engineering judgment that zero margin will be safe enough. The typical current limit is 2.5A. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 9 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com The LM2831 operates at frequencies allowing the use of ceramic output capacitors without compromising transient response. Ceramic capacitors allow higher inductor ripple without significantly increasing output ripple. See the OUTPUT CAPACITOR section for more details on calculating output voltage ripple. Now that the ripple current is determined, the inductance is calculated by: DTS x (VIN - VOUT) L= 2'iL (7) Where TS = 1 fS When selecting an inductor, make sure that it is capable of supporting the peak output current without saturating. Inductor saturation will result in a sudden reduction in inductance and prevent the regulator from operating correctly. Because of the speed of the internal current limit, the peak current of the inductor need only be specified for the required maximum output current. For example, if the designed maximum output current is 1.0A and the peak current is 1.25A, then the inductor should be specified with a saturation current limit of > 1.25A. There is no need to specify the saturation or peak current of the inductor at the 2.5A typical switch current limit. The difference in inductor size is a factor of 5. Because of the operating frequency of the LM2831, ferrite based inductors are preferred to minimize core losses. This presents little restriction since the variety of ferrite-based inductors is huge. Lastly, inductors with lower series resistance (RDCR) will provide better operating efficiency. For recommended inductors see Example Circuits. INPUT CAPACITOR An input capacitor is necessary to ensure that VIN does not drop excessively during switching transients. The primary specifications of the input capacitor are capacitance, voltage, RMS current rating, and ESL (Equivalent Series Inductance). The recommended input capacitance is 22 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: IRMS_IN D IOUT2 (1-D) + 'i2 3 (8) Neglecting inductor ripple simplifies the above equation to: IRMS_IN = IOUT x D(1 - D) (9) It can be shown from the above equation that maximum RMS capacitor current occurs when D = 0.5. Always calculate the RMS at the point where the duty cycle D is closest to 0.5. The ESL of an input capacitor is usually determined by the effective cross sectional area of the current path. A large leaded capacitor will have high ESL and a 0805 ceramic chip capacitor will have very low ESL. At the operating frequencies of the LM2831, leaded capacitors may have an ESL so large that the resulting impedance (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 datasheets to see how rated capacitance varies over operating conditions. OUTPUT CAPACITOR The output capacitor is selected based upon the desired output ripple and transient response. The initial current of a load transient is provided mainly by the output capacitor. The output ripple of the converter is: 1 'VOUT = 'IL RESR + 8 x FSW x COUT (10) 10 Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 When using MLCCs, the ESR is typically so low that the capacitive ripple may dominate. When this occurs, the output ripple will be approximately sinusoidal and 90 phase shifted from the switching action. Given the availability and quality of MLCCs and the expected output voltage of designs using the LM2831, there is really no need to review any other capacitor technologies. Another benefit of ceramic capacitors is their ability to bypass high frequency noise. A certain amount of switching edge noise will couple through parasitic capacitances in the inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not. Since the output capacitor is one of the two external components that control the stability of the regulator control loop, most applications will require a minimum of 22 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. CATCH DIODE The catch diode (D1) conducts during the switch off-time. A Schottky diode is recommended for its fast switching times and low forward voltage drop. The catch diode should be chosen so that its current rating is greater than: ID1 = IOUT x (1-D) (11) The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin. To improve efficiency, choose a Schottky diode with a low forward voltage drop. OUTPUT VOLTAGE The output voltage is set using the following equation where R2 is connected between the FB pin and GND, and R1 is connected between VO and the FB pin. A good value for R2 is 10k. When designing a unity gain converter (Vo = 0.6V), R1 should be between 0 and 100, and R2 should be equal or greater than 10k. VOUT - 1 x R2 R1 = VREF (12) VREF = 0.60V (13) PCB LAYOUT CONSIDERATIONS When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The most important consideration is the close coupling of the GND connections of the input capacitor and the catch diode D1. These ground ends should be close to one another and be connected to the GND plane with at least two through-holes. Place these components as close to the IC as possible. Next in importance is the location of the GND connection of the output capacitor, which should be near the GND connections of CIN and D1. There should be a continuous ground plane on the bottom layer of a two-layer board except under the switching node island. The FB pin is a high impedance node and care should be taken to make the FB trace short to avoid noise pickup and inaccurate regulation. The feedback resistors should be placed as close as possible to the IC, with the GND of R1 placed as close as possible to the GND of the IC. The VOUT trace to R2 should be routed away from the inductor and any other traces that are switching. High AC currents flow through the VIN, SW and VOUT traces, so they should be as short and wide as possible. However, making the traces wide increases radiated noise, so the designer must make this trade-off. Radiated noise can be decreased by choosing a shielded inductor. The remaining components should also be placed as close as possible to the IC. Please see Application Note AN-1229 SNVA054 for further considerations and the LM2831 demo board as an example of a four-layer layout. Calculating Efficiency, and Junction Temperature The complete LM2831 DC/DC converter efficiency can be calculated in the following manner. K= POUT PIN (14) Or K= POUT POUT + PLOSS (15) Calculations for determining the most significant power losses are shown below. Other losses totaling less than 2% are not discussed. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 11 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com Power loss (PLOSS) is the sum of two basic types of losses in the converter: switching and conduction. Conduction losses usually dominate at higher output loads, whereas switching losses remain relatively fixed and dominate at lower output loads. The first step in determining the losses is to calculate the duty cycle (D): D= VOUT + VD VIN + VD - VSW (16) VSW is the voltage drop across the internal PFET when it is on, and is equal to: VSW = IOUT x RDSON (17) 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 (18) The conduction losses in the free-wheeling Schottky diode are calculated as follows: PDIODE = VD x IOUT x (1-D) (19) Often this is the single most significant power loss in the circuit. Care should be taken to choose a Schottky diode that has a low forward voltage drop. Another significant external power loss is the conduction loss in the output inductor. The equation can be simplified to: PIND = IOUT2 x RDCR (20) The LM2831 conduction loss is mainly associated with the internal PFET: PCOND = (IOUT2 x D) 1 + 'iL 1 x 3 IOUT 2 RDSON (21) If the inductor ripple current is fairly small, the conduction losses can be simplified to: PCOND = IOUT2 x RDSON x D (22) Switching losses are also associated with the internal PFET. They occur during the switch on and off transition periods, where voltages and currents overlap resulting in power loss. The simplest means to determine this loss is to empirically measuring the rise and fall times (10% to 90%) of the switch at the switch node. Switching Power Loss is calculated as follows: PSWR = 1/2(VIN x IOUT x FSW x TRISE) PSWF = 1/2(VIN x IOUT x FSW x TFALL) PSW = PSWR + PSWF (23) (24) (25) Another loss is the power required for operation of the internal circuitry: PQ = IQ x VIN (26) IQ is the quiescent operating current, and is typically around 2.5mA for the 0.55MHz frequency option. 12 Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 Typical Application power losses are: Table 1. Power Loss Tabulation VIN 5.0V VOUT 3.3V IOUT 1.25A POUT 4.125W PDIODE 188mW VD 0.45V FSW 550kHz IQ 2.5mA PQ 12.5mW TRISE 4nS PSWR 7mW TFALL 4nS PSWF 7mW RDS(ON) 150m PCOND 156mW INDDCR 70m PIND 110mW D 0.667 PLOSS 481mW 88% PINTERNAL 183mW PCOND + PSW + PDIODE + PIND + PQ = PLOSS PCOND + PSWF + PSWR + PQ = PINTERNAL PINTERNAL = 183mW (27) (28) (29) 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: RT = 'T Power (30) Thermal impedance from the silicon junction to the ambient air is defined as: RTJA = TJ - TA Power (31) 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 etc), and the surrounding circuitry. Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 13 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com Silicon Junction Temperature Determination Method 1: To accurately measure the silicon temperature for a given application, two methods can be used. The first method requires the user to know the thermal impedance of the silicon junction to top case temperature. Some clarification needs to be made before we go any further. 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: TJ - TC R)JC = Power (32) Therefore: Tj = (RJC x PLOSS) + TC (33) From the previous example: Tj = (RJC x PINTERNAL) + TC Tj = 30C/W x 0.189W + TC (34) (35) The second method can give a very accurate silicon junction temperature. The first step is to determine RJA of the application. The LM2831 has over-temperature 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. RTJA = 165 - Ta PINTERNAL (36) 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 3.0cm x 3.0cm. 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 = 189mW (37) 165oC - 144oC = 111o C/W RTJA = 189 mW (38) 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 189mW) = 104C 14 (39) (40) Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 WSON Package Figure 26. Internal WSON Connection For certain high power applications, the PCB land may be modified to a "dog bone" shape (see Figure 27). By increasing the size of ground plane, and adding thermal vias, the RJA for the application can be reduced. FB GND 6 EN 1 2 GND PLANE SW 3 5 VINA 4 VIND Figure 27. 6-Lead WSON PCB Dog Bone Layout Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 15 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com LM2831X Design Example 1 FB EN LM2831 R3 GND L1 VIN VO = 1.2V @ 1.5A SW VIN = 5V R1 C1 D1 C2 R2 Figure 28. LM2831X (1.6MHz): Vin = 5V, Vo = 1.2V @ 1.5A Table 2. Bill of Materials 16 Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI Part Number LM2831X C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22F, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 3.3H, 2.2A TDK VLCF5020T-3R3N2R0-1 R2 15.0k, 1% Vishay CRCW08051502F R1 15.0k, 1% Vishay CRCW08051502F R3 100k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 LM2831X Design Example 2 FB EN LM2831 R3 GND L1 VIN VO = 0.6V @ 1.5A SW VIN = 5V R1 C1 D1 C2 R2 Figure 29. LM2831X (1.6MHz): Vin = 5V, Vo = 0.6V @ 1.5A Table 3. Bill of Materials Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI Part Number LM2831X C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22F, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 3.3H, 2.2A TDK VLCF5020T- 3R3N2R0-1 R2 10.0k, 1% Vishay CRCW08051000F R1 0 R3 100k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 17 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com 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 30. LM2831X (1.6MHz): Vin = 5V, Vo = 3.3V @ 1.5A Table 4. Bill of Materials 18 Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI Part Number LM2831X C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22F, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 2.7H 2.3A TDK VLCF5020T-2R7N2R2-1 R2 10.0k, 1% Vishay CRCW08051002F R1 45.3k, 1% Vishay CRCW08054532F R3 100k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 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 31. LM2831Y (550kHz): Vin = 5V, Vout = 3.3V @ 1.5A Table 5. Bill of Materials Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI Part Number LM2831Y C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22F, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 4.7H 2.1A TDK SLF7045T-4R7M2R0-PF R1 45.3k, 1% Vishay CRCW080545K3FKEA R2 10.0k, 1% Vishay CRCW08051002F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 19 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com 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 32. LM2831Y (550kHz): Vin = 5V, Vout = 1.2V @ 1.5A Table 6. Bill of Materials 20 Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI Part Number LM2831Y C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22F, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 6.8H 1.8A TDK SLF7045T-6R8M1R7 R1 10.0k, 1% Vishay CRCW08051002F R2 10.0k, 1% Vishay CRCW08051002F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 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 33. LM2831Z (3MHz): Vin = 5V, Vo = 3.3V @ 1.5A Table 7. Bill of Materials Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI Part Number LM2831Z C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22F, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 1.6H 2.0A TDK VLCF4018T-1R6N1R7-2 R2 10.0k, 1% Vishay CRCW08051002F R1 45.3k, 1% Vishay CRCW08054532F R3 100k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 21 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com 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 34. LM2831Z (3MHz): Vin = 5V, Vo = 1.2V @ 1.5A Table 8. Bill of Materials 22 Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI Part Number LM2831Z C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22F, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 1.6H, 2.0A TDK VLCF4018T- 1R6N1R7-2 R2 10.0k, 1% Vishay CRCW08051002F R1 10.0k, 1% Vishay CRCW08051002F R3 100k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 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 35. LM2831X (1.6MHz): Vin = 5V, Vo = 1.2V @ 1.5A & 3.3V @1.5A Table 9. Bill of Materials Part ID Part Value Manufacturer Part Number U1, U2 1.5A Buck Regulator TI LM2831X U3 Power on Reset TI LP3470M5X-3.08 C1, C3 Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C2, C4 Output Cap 2x22F, 6.3V, X5R TDK C3216X5ROJ226M C7 Trr delay capacitor TDK D1, D2 Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1, L2 3.3H, 2.2A TDK VLCF5020T-3R3N2R0-1 R2, R4, R5 10.0k, 1% Vishay CRCW08051002F R1, R6 45.3k, 1% Vishay CRCW08054532F R3 100k, 1% Vishay CRCW08051003F Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 23 LM2831 SNVS422C - AUGUST 2006 - REVISED APRIL 2013 www.ti.com LM2831X Buck Converter & Voltage Double Circuit with LDO Follower Design Example 9 VO = 5.0V @ 150mA L2 U2 LDO D2 C6 U1 C3 LM2831 VIN = 5V VIND SW VINA GND C1 EN C5 C4 L1 R1 VO = 3.3V @ 1.5A FB C2 D1 R2 Figure 36. LM2831X (1.6MHz): Vin = 5V, Vo = 3.3V @ 1.5A & LP2986-5.0 @ 150mA Table 10. Bill of Materials 24 Part ID Part Value Manufacturer U1 1.5A Buck Regulator TI LM2831X U2 200mA LDO TI LP2986-5.0 C1, Input Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C2, Output Cap 22F, 6.3V, X5R TDK C3216X5ROJ226M C3 - C6 2.2F, 6.3V, X5R TDK C1608X5R0J225M D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 D2 0.4Vf Schottky 20VR, 500mA ON Semi MBR0520 L2 10H, 800mA CoilCraft ME3220-103 L1 3.3H, 2.2A TDK VLCF5020T-3R3N2R0-1 R2 45.3k, 1% Vishay CRCW08054532F R1 10.0k, 1% Vishay CRCW08051002F Submit Documentation Feedback Part Number Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 LM2831 www.ti.com SNVS422C - AUGUST 2006 - REVISED APRIL 2013 REVISION HISTORY Changes from Revision B (April 2013) to Revision C * Page Changed layout of National Data Sheet to TI format .......................................................................................................... 24 Submit Documentation Feedback Copyright (c) 2006-2013, Texas Instruments Incorporated Product Folder Links: LM2831 25 PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (C) Device Marking (4/5) LM2831XMF/NOPB ACTIVE SOT-23 DBV 5 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SKYB LM2831XMFX/NOPB ACTIVE SOT-23 DBV 5 3000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SKYB LM2831XSD NRND WSON NGG 6 1000 TBD Call TI Call TI -40 to 125 L193B LM2831XSD/NOPB ACTIVE WSON NGG 6 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L193B LM2831XSDX/NOPB ACTIVE WSON NGG 6 4500 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L193B LM2831YMF/NOPB ACTIVE SOT-23 DBV 5 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YMFX/NOPB ACTIVE SOT-23 DBV 5 3000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SKZB LM2831YSD/NOPB ACTIVE WSON NGG 6 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L194B LM2831YSDX/NOPB ACTIVE WSON NGG 6 4500 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L194B LM2831ZMF/NOPB ACTIVE SOT-23 DBV 5 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SLAB LM2831ZMFX/NOPB ACTIVE SOT-23 DBV 5 3000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 SLAB LM2831ZSD/NOPB ACTIVE WSON NGG 6 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L195B LM2831ZSDX/NOPB ACTIVE WSON NGG 6 4500 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L195B (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 23-Oct-2013 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 LM2831YSDX/NOPB WSON NGG 6 4500 330.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1 LM2831ZMF/NOPB SOT-23 DBV 5 1000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2831ZMFX/NOPB SOT-23 DBV 5 3000 178.0 8.4 3.2 3.2 1.4 4.0 8.0 Q3 LM2831ZSD/NOPB WSON NGG 6 1000 178.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1 LM2831ZSDX/NOPB WSON NGG 6 4500 330.0 12.4 3.3 3.3 1.0 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 23-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2831XMF/NOPB SOT-23 DBV 5 1000 210.0 185.0 35.0 LM2831XMFX/NOPB SOT-23 DBV 5 3000 210.0 185.0 35.0 LM2831XSD WSON NGG 6 1000 213.0 191.0 55.0 LM2831XSD/NOPB WSON NGG 6 1000 213.0 191.0 55.0 LM2831XSDX/NOPB WSON NGG 6 4500 367.0 367.0 35.0 LM2831YMF/NOPB SOT-23 DBV 5 1000 210.0 185.0 35.0 LM2831YMFX/NOPB SOT-23 DBV 5 3000 210.0 185.0 35.0 LM2831YSD/NOPB WSON NGG 6 1000 213.0 191.0 55.0 LM2831YSDX/NOPB WSON NGG 6 4500 367.0 367.0 35.0 LM2831ZMF/NOPB SOT-23 DBV 5 1000 210.0 185.0 35.0 LM2831ZMFX/NOPB SOT-23 DBV 5 3000 210.0 185.0 35.0 LM2831ZSD/NOPB WSON NGG 6 1000 213.0 191.0 55.0 LM2831ZSDX/NOPB WSON NGG 6 4500 367.0 367.0 35.0 Pack Materials-Page 2 MECHANICAL DATA NGG0006A SDE06A (Rev A) www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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