LMR10510YMFX

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LMR10510 SIMPLE SWITCHER ® 5.5Vin, 1A Step-Down Voltage Regulator in SOT-23 and LLP Literature Number: SNVS727A

October 31, 2011 SIMPLE SWITCHER® 5.5Vin, 1A Step-Down Voltage Regulator in SOT-23 and LLP

Features

■ Input voltage range of 3V to 5.5V ■ Output voltage range of 0.6V to 4.5V ■ Output current up to 1A ■ 1.6MHz (LMR10510X) and 3 MHz (LMR10510Y) switching frequencies ■ Low shutdown Iq, 30 nA typical ■ Internal soft-start ■ Internally compensated ■ Current-Mode PWM operation ■ Thermal shutdown ■ SOT23-5 (2.92 x 2.84 x 1 mm) and LLP-6 (3 x 3 x 0.8 mm) packaging ■ Fully enabled for WEBENCH® Power Designer Performance Benefits ■ Extremely easy to use ■ Tiny overall solution reduces system cost

Applications

■ Point-of-Load Conversions from 3.3V, and 5V Rails ■ Space Constrained Applications ■ Battery Powered Equipment ■ Industrial Distributed Power Applications ■ Power Meters ■ Portable Hand-Held Instruments System Performance Efficiency vs Load Current - "X" VIN = 5V 100EFFICIENCY (%) LOAD CURRENT (A) 1.8Vout3.3Vout 30165696 Efficiency vs Load Current - "Y" VIN = 5V 100EFFICIENCY (%) LOAD CURRENT (A) 1.8Vout3.3Vout 30165697 Typical Application 30165664 © 2011 Texas Instruments Incorporated 301656 www.ti.com LMR10510 SIMPLE SWITCHER® 5.5Vin, 1A Step-Down Voltage Regulator in SOT-23 and LLP

Ordering Information

Option Package Type NSC Package Drawing Top Mark Supplied As LMR10510XMFE 1.6MHz SOT23-5 MF05A SH7B 250 units Tape and Reel LMR10510XMF 1000 units Tape and Reel LMR10510XMFX 3000 units Tape and Reel LMR10510YMFE 3MHz SH9B 250 units Tape and Reel LMR10510YMF 1000 units Tape and Reel LMR10510YMFX 3000 units Tape and Reel LMR10510YSDE LLP-6 SDE06A L268B 250 units Tape and Reel LMR10510YSD 1000 units Tape and Reel LMR10510YSDX 4500 units Tape and Reel www.ti.com 2 LMR10510

Pin Descriptions 5-Pin SOT23 Pin Name Function 1 SW Switch node. Connect to the inductor and catch diode. 2 GND Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin. 3 FB Feedback pin. Connect to external resistor divider to set output voltage. 4 EN Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VIN + 0.3V. 5 VIN Input supply voltage. Pin Descriptions 6-Pin LLP Pin Name Function 1 FB Feedback pin. Connect to external resistor divider to set output voltage. 2 GND Signal and power ground pin. Place the bottom resistor of the feedback network as close as possible to this pin. 3 SW Switch node. Connect to the inductor and catch diode. 4 VIND Power Input supply. 5 VINA Control circuitry supply voltage. Connect VINA to VIND on PC board. 6 EN Enable control input. Logic high enables operation. Do not allow this pin to float or be greater than VINA + 0.3V. DAP Die Attach Pad Connect to system ground for low thermal impedance, but it cannot be used as a primary GND connection. 3 www.ti.com LMR10510

Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. 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 (Note 2) 150°C Storage Temperature −65°C to +150°C For soldering specifications: see product folder at www.national.com and www.national.com/ms/MS/MS-SOLDERING.pdf Operating Ratings VIN 3V to 5.5V Junction Temperature −40°C to +125°C Electrical Characteristics (Note 3), (Note 4) 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 guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. Symbol Parameter Conditions Min Typ Max Units VFB Feedback Voltage 0.588 0.600 0.612 V ΔVFB/VIN Feedback Voltage Line Regulation VIN = 3V to 5V 0.02 %/V IB Feedback Input Bias Current 0.1 100 nA UVLO Undervoltage Lockout VIN Rising 2.73 2.90 V VIN Falling 1.85 2.3 UVLO Hysteresis 0.43 V DMAX Maximum Duty Cycle LMR10510-X 86 94 %LMR10510-Y 82 90 DMIN Minimum Duty Cycle LMR10510-X 5 %LMR10510-Y 7 RDS(ON) Switch On Resistance LLP-6 Package 150 mΩSOT23-5 Package 130 195 ICL Switch Current Limit VIN = 3.3V 1.2 1.75 A VEN_TH Shutdown Threshold Voltage 0.4 VEnable Threshold Voltage 1.8 ISW Switch Leakage 100 nA IEN Enable Pin Current Sink/Source 100 nA IQ Quiescent Current (switching) LMR10510X VFB = 0.55 3.3 5 mA LMR10510Y VFB = 0.55 4.3 6.5 mA Quiescent Current (shutdown) All Options VEN = 0V 30 nA www.ti.com 4 LMR10510

Symbol Parameter Conditions Min Typ Max Units θJA Junction to Ambient

0 LFPM Air Flow (Note 5)

θJC Junction to Case LLP-6 Package 18 °C/WSOT23-5 Package 80 TSD Thermal Shutdown Temperature 165 °C Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Range indicates conditions for which the device is intended to be functional, but does not guarantee specfic performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. Note 2: Thermal shutdown will occur if the junction temperature exceeds the maximum junction temperature of the device. Note 3: Min and Max limits are 100% production tested at 25°C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control (SQC) methods. Limits are used to calculate National’s Average Outgoing Quality Level (AOQL). Note 4: Typical numbers are at 25°C and represent the most likely parametric norm. Note 5: Applies for packages soldered directly onto a 3” x 3” PC board with 2oz. copper on 4 layers in still air. 5 www.ti.com LMR10510

Typical Performance Characteristics Unless stated otherwise, all curves taken at VIN = 5.0V with configuration in typical application circuit shown in Figure 3. TJ = 25° C, unless otherwise specified. η vs Load "X" Vin = 5V, Vo = 1.8V & 3.3V 100EFFICIENCY (%) LOAD CURRENT (A) 1.8Vout3.3Vout 30165696 η vs Load "Y" Vin = 5V, Vo = 3.3V & 1.8V 100EFFICIENCY (%) LOAD CURRENT (A) 1.8Vout3.3Vout 30165697 η vs Load "X and Y" Vin = 3.3V, Vo = 1.8V 100EFFICIENCY (%) LOAD CURRENT (A) LMR10510YLMR10510X 30165698 Load Regulation Vin = 3.3V, Vo = 1.8V (All Options) 30165683 www.ti.com 6 LMR10510

Vin = 5V, Vo = 1.8V (All Options) 30165684 Load Regulation Vin = 5V, Vo = 3.3V (All Options) 30165685 Oscillator Frequency vs Temperature - "X" 30165624 Oscillator Frequency vs Temperature - "Y" 30165636 Current Limit vs Temperature Vin = 3.3V 30165686 RDSON vs Temperature (LLP-6 Package) 30165687 7 www.ti.com LMR10510

RDSON vs Temperature (SOT23-5 Package) 30165688 LMR10510X IQ (Quiescent Current) 30165628 LMR10510Y IQ (Quiescent Current) 30165637 Line Regulation Vo = 1.8V, Io = 500mA 30165653 VFB vs Temperature 30165627 www.ti.com 8 LMR10510

(Vin = 5V, Vo = 1.2V @ 1A) 30165656 Phase Plot vs Frequency (Vin = 5V, Vo = 1.2V @ 1A) 30165657 Simplified Block Diagram 30165604 FIGURE 1. 9 www.ti.com LMR10510

is included, featuring an ultra-low stand-by current of 30 nA. put switch turns off until the next switching cycle begins. to maintain a constant output voltage. FIGURE 2. Typical Waveforms a controlled fashion, which helps reduce inrush current.

vide better operating efficiency. For recommended inductors see Example Circuits. INPUT CAPACITOR An input capacitor is necessary to ensure that V IN does not drop excessively during switching transients. The primary specifications of the input capacitor are capacitance, voltage, RMS current rating, and ESL (Equivalent Series Inductance). The recommended input capacitance is 22 µF.The input volt- age 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 (I RMS-IN) must be greater than: Neglecting inductor ripple simplifies the above equation to: 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 effec- tive cross sectional area of the current path. A large leaded capacitor will have high ESL and a 0805 ceramic chip capac- itor will have very low ESL. At the operating frequencies of the LMR10510, leaded capacitors may have an ESL so large that the resulting impedance (2 πfL) will be higher than that re- quired 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. Con- sult capacitor manufacturer datasheets to see how rated capacitance varies over operating conditions. OUTPUT CAPACITOR The output capacitor is selected based upon the desired out- put ripple and transient response. The initial current of a load transient is provided mainly by the output capacitor. The out- put ripple of the converter is: When using MLCCs, the ESR is typically so low that the ca- pacitive 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 LMR10510, there is really no need to review any other ca- pacitor 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 capaci- tances in the inductor to the output. A ceramic capacitor will bypass this noise while a tantalum will not. Since the output capacitor is one of the two external components that control the stability of the regulator control loop, most applications will require a minimum of 22 µF of output capacitance. Capaci- tance often, but not always, can be increased significantly with little detriment to the regulator stability. Like the input ca- pacitor, 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) The reverse breakdown rating of the diode must be at least the maximum input voltage plus appropriate margin. To im- prove 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 10kΩ. When designing a unity gain converter (Vo = 0.6V), R1 should be between 0Ω and 100Ω, and R2 should be equal or greater than 10kΩ. VREF = 0.60V PCB LAYOUT CONSIDERATIONS When planning layout there are a few things to consider when trying to achieve a clean, regulated output. The most impor- tant consideration is the close coupling of the GND connec- tions of the input capacitor and the catch diode D1. These ground ends should be close to one another and be connect- ed to the GND plane with at least two through-holes. Place these components as close to the IC as possible. Next in im- portance 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 V OUT 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 for further considerations and the LMR10510 demo board as an example of a good layout. www.ti.com 12 LMR10510

Calculating Efficiency, and Junction Temperature The complete LMR10510 DC/DC converter efficiency can be calculated in the following manner. Or Calculations for determining the most significant power loss- es 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): VSW is the voltage drop across the internal PFET when it is on, and is equal to: VSW = IOUT x RDSON VD is the forward voltage drop across the Schottky catch diode. It can be obtained from the diode manufactures Elec- trical Characteristics section. If the voltage drop across the inductor (VDCR) is accounted for, the equation becomes: The conduction losses in the free-wheeling Schottky diode are calculated as follows: PDIODE = VD x IOUT x (1-D) Often this is the single most significant power loss in the cir- cuit. 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 The LMR10510 conduction loss is mainly associated with the internal PFET: If the inductor ripple current is fairly small, the conduction losses can be simplified to: PCOND = IOUT2 x RDSON x D 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 Another loss is the power required for operation of the internal circuitry: PQ = IQ x VIN IQ is the quiescent operating current, and is typically around 3.3mA for the 1.6MHz frequency option. Typical Application power losses are: Power Loss Tabulation VIN 5.0V VOUT 3.3V POUT 3.3W IOUT 1.0A VD 0.45V PDIODE 150mW FSW 1.6MHz IQ 3.3mA PQ 17mW TRISE 4nS PSWR 16mW TFALL 4nS PSWF 16mW RDS(ON) 150mΩ PCOND 100mW INDDCR 70mΩ PIND 70mW D 0.667 PLOSS 369mW η 88% PINTERNAL 149mW ΣPCOND + PSW + PDIODE + PIND + PQ = PLOSS ΣPCOND + PSWF + PSWR + PQ = PINTERNAL PINTERNAL = 149mW Thermal Definitions TJ = Chip junction temperature TA = Ambient temperature RθJC = Thermal resistance from chip junction to device case RθJA = Thermal resistance from chip junction to ambient air Heat in the LMR10510 due to internal power dissipation is removed through conduction and/or convection. Conduction: Heat transfer occurs through cross sectional ar- eas of material. Depending on the material, the transfer of heat can be considered to have poor to good thermal con- ductivity 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: 13 www.ti.com LMR10510

Physical Dimensions inches (millimeters) unless otherwise noted 5-Lead SOT-23 Package 6-Lead LLP Package 17 www.ti.com LMR10510

LMR10510 SIMPLE SWITCHER® 5.5Vin, 1A Step-Down Voltage Regulator in SOT-23 and LLP TI/NATIONAL INTERIM IMPORTANT NOTICE Texas Instruments has purchased National Semiconductor. As of Monday, September 26th, and until further notice, products sold or advertised under the National Semiconductor name or logo, and information, support and interactions concerning such products, remain subject to the preexisting National Semiconductor standard terms and conditions of sale, terms of use of website, and Notices (and/or terms previously agreed in writing with National Semiconductor, where applicable) and are not subject to any differing terms and notices applicable to other TI components, sales or websites. To the extent information on official TI and National websites and business social networking media, etc., pertains to both TI and National-branded products, both companies' instructions, warnings and limitations in the above-referenced terms of use apply. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Applications Audio www.ti.com/audio Communications and Telecom www.ti.com/communications Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps DLP® Products www.dlp.com Energy and Lighting www.ti.com/energy DSP dsp.ti.com Industrial www.ti.com/industrial Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical Interface interface.ti.com Security www.ti.com/security Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics- defense Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video RFID www.ti-rfid.com Wireless www.ti.com/wireless-apps RF/IF and ZigBee® Solutions www.ti.com/lprf TI E2E Community Home Page e2e.ti.com Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright© 2011 Texas Instruments Incorporated www.ti.com

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