Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - DC/DC voltage regulator Holder SOT 23 5

GND

= 5V

= 3.3V @ 1.5A

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,

• Space Saving SOT-23 Package

PWM step-down DC/DC converter in a 5 pin SOT-23

• Input Voltage Range of 3.0V to 5.5V

and a 6 Pin WSON package. It provides all the active

• Output Voltage Range of 0.6V to 4.5V

functions to provide local DC/DC conversion with fast

transient response and accurate regulation in the

• 1.5A Output Current

smallest possible PCB area. With a minimum of

• High Switching Frequencies

external components, the LM2831 is easy to use. The

– 1.6MHz (LM2831X)

ability to drive 1.5A loads with an internal 130 mΩ

PMOS switch using state-of-the-art 0.5 µm BiCMOS

– 0.55MHz (LM2831Y)

technology results in the best power density

– 3.0MHz (LM2831Z)

available. The world-class control circuitry allows on-

• 130mΩ PMOS Switch

times as low as 30ns, thus supporting exceptionally

high frequency conversion over the entire 3V to 5.5V

• 0.6V, 2% Internal Voltage Reference

input operating range down to the minimum output

• Internal Soft-Start

voltage of 0.6V. Switching frequency is internally set

• Current Mode, PWM Operation

to 550 kHz, 1.6 MHz, or 3.0 MHz, allowing the use of

• Thermal Shutdown

extremely small surface mount inductors and chip

capacitors. Even though the operating frequency is

• Over Voltage Protection

high, efficiencies up to 93% are easy to achieve.

External shutdown is included, featuring an ultra-low

APPLICATIONS

stand-by current of 30 nA. The LM2831 utilizes

• Local 5V to Vcore Step-Down Converters

current-mode control and internal compensation to

provide high-performance regulation over a wide

• Core Power in HDDs

range of operating conditions. Additional features

• Set-Top Boxes

include internal soft-start circuitry to reduce inrush

• USB Powered Devices

current, pulse-by-pulse current limit, thermal

shutdown, and output over-voltage protection.

• DSL Modems

Typical Application Circuit

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.

2All 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.

Summary of content (33 pages)

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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.
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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.
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LM2831 www.ti.com SNVS422C – AUGUST 2006 – REVISED APRIL 2013 Operating Ratings VIN 3V to 5.5V −40°C to +125°C Junction Temperature Electrical Characteristics VIN = 5V unless otherwise indicated under the Conditions column. Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C. Minimum and Maximum limits are specified through test, design, or statistical correlation.
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LM2831 SNVS422C – AUGUST 2006 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this datasheet. TJ = 25°C, unless otherwise specified. η vs Load "X" Vin = 5V, Vo = 1.8V & 3.3V η vs Load - "Y" Vin = 5V, Vo = 3.3V & 1.8V Figure 3. Figure 4. η vs Load "Z" Vin = 5V, Vo = 3.3V & 1.8V η vs Load "X, Y and Z" Vin = 3.3V, Vo = 1.8V Figure 5. Figure 6.
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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 = 25°C, 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.
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LM2831 SNVS422C – AUGUST 2006 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) All curves taken at VIN = 5.0V with configuration in typical application circuit shown in Applications Information section of this datasheet. TJ = 25°C, unless otherwise specified. RDSON vs Temperature (SOT-23 Package) LM2831X IQ (Quiescent Current) 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 (ºC) Figure 15. Figure 16.
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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 = 25°C, unless otherwise specified. Gain vs Frequency (Vin = 5V, Vo = 1.2V @ 1A) Phase Plot vs Frequency (Vin = 5V, Vo = 1.2V @ 1A) Figure 21. Figure 22.
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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.
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LM2831 www.ti.com SNVS422C – AUGUST 2006 – REVISED APRIL 2013 CURRENT LIMIT The LM2831 uses cycle-by-cycle current limiting to protect the output switch. During each switching cycle, a current limit comparator detects if the output switch current exceeds 2.5A (typ), and turns off the switch until the next switching cycle begins. THERMAL SHUTDOWN Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature exceeds 165°C.
PAGE 10
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.
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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.
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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.
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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) 150mΩ PCOND 156mW INDDCR 70mΩ PIND 110mW D 0.
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LM2831 SNVS422C – AUGUST 2006 – REVISED APRIL 2013 www.ti.com Silicon Junction Temperature Determination Method 1: To accurately measure the silicon temperature for a given application, two methods can be used. The first method requires the user to know the thermal impedance of the silicon junction to top case temperature. Some clarification needs to be made before we go any further. RθJC is the thermal impedance from all six sides of an IC package to silicon junction.
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LM2831 www.ti.com SNVS422C – AUGUST 2006 – REVISED APRIL 2013 WSON Package Figure 26. Internal WSON Connection For certain high power applications, the PCB land may be modified to a "dog bone" shape (see Figure 27). By increasing the size of ground plane, and adding thermal vias, the RθJA for the application can be reduced. FB GND 6 EN 1 2 GND PLANE SW 3 5 VINA 4 VIND Figure 27.
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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 22µF, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22µF, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.
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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 22µF, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22µF, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 3.
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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 22µF, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22µF, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.
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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 22µF, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22µF, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.
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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 22µF, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22µF, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.
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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 22µF, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22µF, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 L1 1.
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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 22µF, 6.3V, X5R TDK C3216X5ROJ226M C3216X5ROJ226M C2, Output Cap 2x22µF, 6.3V, X5R TDK D1, Catch Diode 0.3Vf Schottky 1.
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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.
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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.
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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 ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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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.
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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.
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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.
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MECHANICAL DATA NGG0006A SDE06A (Rev A) www.ti.
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