LM27313XMFX/NOPB

Sample & Buy Product Folder Support & Community Tools & Software Technical Documents LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 LM27313/-Q1 1.6-MHz Boost Converter With 30-V Internal FET Switch in SOT-23 1 Features 3 Description • The LM27313/-Q1 switching regulator is a currentmode boost converter with a fixed operating frequency of 1.6 MHz. 1 • • • • • • • • • • LM27313-Q1 is an Automotive-Grade Product that is AEC-Q100 Grade 1 Qualified (–40°C to +125°C Operating Junction Temperature) 30-V DMOS FET Switch 1.6-MHz Switching Frequency Low RDS(ON) DMOS FET Switch Current up to 800 mA Wide Input Voltage Range (2.7 V to 14 V) Low Shutdown Current (< 1 µA) 5-Lead SOT-23 Package Uses Tiny Capacitors and Inductors Cycle-by-Cycle Current Limiting Internally Compensated The use of the SOT-23 package, made possible by the minimal losses of the 800-mA switch, and the small inductors and capacitors result in extremely high power density. The 30-V internal switch makes these solutions perfect for boosting to voltages of 5 V to 28 V. This device has a logic-level shutdown pin that can be used to reduce quiescent current and extend battery life. Protection is provided through cycle-by-cycle current limiting and thermal shutdown. Internal compensation simplifies design and reduces component count. 2 Applications • • • • • Device Information(1) White LED Current Source PDAs and Palm-Top Computers Digital Cameras Portable Phones, Games, and Media Players GPS Devices Typical Application Circuit VIN SHDN R3 51k C1 2.2 PF GND U1 BODY SIZE (NOM) SOT-23 (5) 2.90 mm x 1.60 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Efficiency vs. Load Current SW LM27313 SHDN GND LM27313-Q1 PACKAGE D1 MBR0520 L1/10 PH 5 VIN PART NUMBER LM27313 R1/117k FB R2 13.3k CF 220 pF 12V OUT 260 mA (TYP) C2 4.7 PF 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. LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 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 3 6.1 6.2 6.3 6.4 6.5 6.6 6.7 3 3 4 4 4 5 6 Absolute Maximum Ratings ...................................... ESD Ratings: LM27313 ............................................ ESD Ratings: LM27313-Q1 ...................................... Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics........................................... Typical Characteristics .............................................. Detailed Description .............................................. 8 7.1 Overview ................................................................... 8 7.2 Functional Block Diagram ......................................... 8 7.3 Feature Description................................................... 8 7.4 Device Functional Modes.......................................... 9 8 Application and Implementation ........................ 10 8.1 Application Information............................................ 10 8.2 Typical Applications ................................................ 10 9 Power Supply Recommendations...................... 17 10 Layout................................................................... 17 10.1 Layout Guidelines ................................................. 17 10.2 Layout Example .................................................... 17 10.3 Thermal Considerations ........................................ 17 11 Device and Documentation Support ................. 18 11.1 11.2 11.3 11.4 11.5 Device Support...................................................... Related Links ........................................................ Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 18 18 18 18 18 12 Mechanical, Packaging, and Orderable Information ........................................................... 18 4 Revision History Changes from Revision D (April 2013) to Revision E • Page Added Pin Configuration and Functions section, 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 C (April 2013) to Revision D • 2 Page Changed layout of National Data Sheet to TI format ........................................................................................................... 15 Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 5 Pin Configuration and Functions SOT-23 Package 5-Pin (Top View) Pin Functions PIN NO. (1) NAME I/O (1) DESCRIPTION 1 SW O Drain of the internal FET switch. 2 GND G Analog and power ground. 3 FB I Feedback point that connects to external resistive divider to set VOUT. 4 SHDN I Shutdown control input. Connect to VIN if this feature is not used. 5 VIN I/P Analog and power input. I: Input Pin, O: Output Pin, P: Power Pin, G: Ground Pin 6 Specifications 6.1 Absolute Maximum Ratings (1) (2) MIN MAX UNIT FB Pin Voltage −0.4 6 V SW Pin Voltage −0.4 30 V Input Supply Voltage −0.4 14.5 V Shutdown Input Voltage −0.4 14.5 V 300 °C (Survival) Lead Temp. (Soldering, 5 s) Power Dissipation Internally Limited Storage temperature, Tstg −65 (1) (2) 150 °C 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. 6.2 ESD Ratings: LM27313 VALUE V(ESD) (1) (2) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1) ±2000 Charged device model (CDM), per JEDEC specification JESD22-C101, all pins (2) ±1000 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 3 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 www.ti.com 6.3 ESD Ratings: LM27313-Q1 VALUE Human body model (HBM), per AEC Q100-002 (1) V(ESD) (1) Electrostatic discharge Charged device model (CDM), per AEC Q100-011 UNIT ±2000 Corner pins (1, 3, 4, and 5) ±1000 Other pins ±1000 V AEC Q100-002 indicates HBM stressing is done in accordance with the ANSI/ESDA/JEDEC JS-001 specification. 6.4 Recommended Operating Conditions MIN VIN NOM 2.7 VSW(MAX) VSHDN Junction Temperature, TJ MAX UNIT 14 V 30 V 0 VIN V –40 125 °C 6.5 Thermal Information THERMAL METRIC LM27313, LM27313-Q1 (1) DBV UNIT 5 PINS RθJA Junction-to-ambient thermal resistance 166.3 RθJC(top) Junction-to-case (top) thermal resistance 71.8 RθJB Junction-to-board thermal resistance 28.1 ψJT Junction-to-top characterization parameter 2.1 ψJB Junction-to-board characterization parameter 27.7 RθJC(bot) Junction-to-case (bottom) thermal resistance N/A (1) 4 °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 6.6 Electrical Characteristics Unless otherwise specified: VIN = 5 V, VSHDN = 5 V, IL = 0 mA, and TJ = 25°C. Minimum and Maximum limits are ensured through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only. PARAMETER TEST CONDITIONS VIN Input Voltage −40°C ≤ TJ ≤ +125°C ISW Switch Current Limit See (1) RDS(ON) Switch ON Resistance ISW = 100 mA MIN ISHDN Shutdown Threshold UNIT V 1.25 500 A 650 mΩ 1.5 Device OFF, −40°C ≤ TJ ≤ +125°C Shutdown Pin Bias Current MAX 14 0.80 Device ON, −40°C ≤ TJ ≤ +125°C VSHDN(TH) TYP 2.7 V 0.50 VSHDN = 0 0 VSHDN = 5 V 0 2 µA VSHDN = 5 V, −40°C ≤ TJ ≤ +125°C VFB Feedback Pin Reference Voltage IFB Feedback Pin Bias Current VIN = 3 V VIN = 3 V, −40°C ≤ TJ ≤ +125°C 1.230 1.205 VFB = 1.23 V 60 VSHDN = 5 V, Switching 2.1 VSHDN = 5 V, Switching, −40°C ≤ TJ ≤ +125°C IQ Quiescent Current VSHDN = 5 V, Not Switching fSW Switching Frequency DMAX Maximum Duty Cycle IL Switch Leakage (1) mA 400 500 VSHDN = 0 0.024 2.7 V ≤ VIN ≤ 14 V FB Voltage Line Regulation nA 3.0 VSHDN = 5 V, Not Switching, −40°C ≤ TJ ≤ +125°C ΔVFB/ΔVIN V 1.255 1 0.02 %/V 1.6 −40°C ≤ TJ ≤ +125°C 1.15 −40°C ≤ TJ ≤ +125°C 80% µA 1.90 MHz 88% Not Switching, VSW = 5 V 1 µA Switch current limit is dependent on duty cycle. Limits shown are for duty cycles ≤ 50%. See Figure 15. Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 5 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 www.ti.com 6.7 Typical Characteristics Unless otherwise specified: VIN = 5 V, SHDN pin is tied to VIN, TJ = 25°C. Figure 1. Iq VIN (Active) vs Temperature Figure 2. Oscillator Frequency vs Temperature 88.5 MAX DUTY CYCLE (%) 88.4 88.3 88.2 88.1 88.0 87.9 87.8 -40 -25 0 25 50 75 100 125 o TEMPERATURE ( C) 6 Figure 3. Max. Duty Cycle vs Temperature Figure 4. Feedback Voltage vs Temperature Figure 5. RDS(ON) vs Temperature Figure 6. Current Limit vs Temperature Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 Typical Characteristics (continued) Unless otherwise specified: VIN = 5 V, SHDN pin is tied to VIN, TJ = 25°C. Figure 7. RDS(ON) vs VIN Figure 8. Efficiency vs Load Current (VOUT = 12 V) 100 100 90 90 VIN = 10V VIN = 5V 70 VIN = 3.3V 60 50 40 30 50 40 30 10 10 0 200 400 800 600 1000 VIN = 3.3V 60 20 0 VIN = 5V 70 20 0 VIN = 10V 80 EFFICIENCY (%) EFFICIENCY (%) 80 0 100 200 300 400 500 600 700 LOAD CURRENT (mA) LOAD CURRENT (mA) Figure 9. Efficiency vs Load Current (VOUT = 15 V) Figure 10. Efficiency vs Load Current (VOUT = 20 V) 100 90 VIN = 10V EFFICIENCY (%) 80 70 VIN = 5V 60 50 40 30 20 10 0 0 50 100 150 200 250 300 350 400 LOAD CURRENT (mA) Figure 11. Efficiency vs Load Current (VOUT = 25 V) Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 7 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 www.ti.com 7 Detailed Description 7.1 Overview The LM27313 is a switching converter IC that operates at a fixed frequency of 1.6 MHz using current-mode control for fast transient response over a wide input voltage range and incorporate pulse-by-pulse current limiting protection. Because this is current mode control, a 50-mΩ sense resistor in series with the switch FET is used to provide a voltage (which is proportional to the FET current) to both the input of the pulse width modulation (PWM) comparator and the current limit amplifier. At the beginning of each cycle, the S-R latch turns on the FET. As the current through the FET increases, a voltage (proportional to this current) is summed with the ramp coming from the ramp generator and then fed into the input of the PWM comparator. When this voltage exceeds the voltage on the other input (coming from the Gm amplifier), the latch resets and turns the FET off. Because the signal coming from the Gm amplifier is derived from the feedback (which samples the voltage at the output), the action of the PWM comparator constantly sets the correct peak current through the FET to keep the output voltage in regulation. Q1 and Q2 along with R3 - R6 form a bandgap voltage reference used by the IC to hold the output in regulation. The currents flowing through Q1 and Q2 will be equal, and the feedback loop will adjust the regulated output to maintain this. Because of this, the regulated output is always maintained at a voltage level equal to the voltage at the FB node "multiplied up" by the ratio of the output resistive divider. The current limit comparator feeds directly into the flip-flop, that drives the switch FET. If the FET current reaches the limit threshold, the FET is turned off and the cycle terminated until the next clock pulse. The current limit input terminates the pulse regardless of the status of the output of the PWM comparator. 7.2 Functional Block Diagram 7.3 Feature Description This device is designed as a current mode boost converter for a wide input voltage range. It features a very small package and operates at a high switching frequency. This allows for use of small passive components (inductors and capacitors), enabling small solution size. The device features also logic level shutdown, making it ideal for applications where low power consumption is desired. Control loop compensation is internal and no additional external components are required. Additional protection features are provided by deploying cycle-by-cycle current limiting and thermal shutdown. 8 Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 7.4 Device Functional Modes In normal operational mode, the device regulates output voltage to the value set with resistive divider. In addition, this device has a logic level shutdown pin (SHDN) that allows user to turn the device on/off by driving this pin high/low. Default setup is that this pin is connected to VIN through pullup resistor (typically 50 kΩ). When shutdown pin is low, the device is in shutdown mode consuming typically only 24 nA, making it ideal for applications where low power consumption is desirable. Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 9 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 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 device operates with input voltage in the range of 2.7 V to 14 V and provides regulated output voltage. This device is optimized for high-efficiency operation with minimum number of external components. Also, high switching frequency allows use of small surface mount components, enabling very small solution size. For component selection, refer to Detailed Design Procedure. 8.2 Typical Applications 8.2.1 Application Circuit VIN=5.0 V, VOUT=12.0 V, Iload=250 mA VIN SHDN R3 51k C1 2.2 PF GND D1 MBR0520 L1/10 PH 5 VIN U1 SW LM27313 SHDN GND R1/117k FB R2 13.3k CF 220 pF 12V OUT 260 mA (TYP) C2 4.7 PF Figure 12. Typical Application Circuit Figure 13. Efficiency vs. Load Current 8.2.1.1 Design Requirements The device must be able to operate at any voltage within input voltage range. Load Current must be defined in order to properly size the inductor, input and output capacitors. The 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 startup will depend on the output capacitor selection. More details are provided in Detailed Design Procedure. Device has a shutdown pin (SHDN) that is used to enable and disable device. This pin is active low and should be tied to VIN if not used in application. 10 Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 Typical Applications (continued) 8.2.1.2 Detailed Design Procedure 8.2.1.2.1 Selecting the External Capacitors The LM27313 requires ceramic capacitors at the input and output to accommodate the peak switching currents the part needs to operate. Electrolytic capacitors have resonant frequencies which are below the switching frequency of the device, and therefore can not provide the currents needed to operate. Electrolytics may be used in parallel with the ceramics for bulk charge storage which will improve transient response. When selecting a ceramic capacitor, only X5R and X7R dielectric types should be used. Other types such as Z5U and Y5F have such severe loss of capacitance due to effects of temperature variation and applied voltage, they may provide as little as 20% of rated capacitance in many typical applications. Always consult capacitor manufacturer’s data curves before selecting a capacitor. High-quality ceramic capacitors can be obtained from Taiyo-Yuden, AVX, and Murata. 8.2.1.2.2 Selecting the Output Capacitor A single ceramic capacitor of value 4.7 µF to 10 µF provides sufficient output capacitance for most applications. For output voltages below 10 V, a 10 µF capacitance is required. If larger amounts of capacitance are desired for improved line support and transient response, tantalum capacitors can be used in parallel with the ceramics. Aluminum electrolytics with ultra low ESR such as Sanyo Oscon can be used, but are usually prohibitively expensive. Typical AI electrolytic capacitors are not suitable for switching frequencies above 500 kHz due to significant ringing and temperature rise due to self-heating from ripple current. An output capacitor with excessive ESR can also reduce phase margin and cause instability. 8.2.1.2.3 Selecting the Input Capacitor An input capacitor is required to serve as an energy reservoir for the current which must flow into the inductor each time the switch turns ON. This capacitor must have extremely low ESR and ESL, so ceramic must be used. We recommend a nominal value of 2.2 µF, but larger values can be used. Because this capacitor reduces the amount of voltage ripple seen at the input pin, it also reduces the amount of EMI passed back along that line to other circuitry. 8.2.1.2.4 Feed-Forward Compensation Although internally compensated, the feed-forward capacitor Cf is required for stability (see Equation 1). Adding this capacitor puts a zero in the loop response of the converter. Without it, the regulator loop can oscillate. The recommended frequency for the zero fz should be approximately 8 kHz. Cf can be calculated using the formula: Cf = 1 / (2 x π x R1 x fz) (1) 8.2.1.2.5 Selecting Diodes The external diode used in the typical application should be a Schottky diode. If the switch voltage is less than 15V, a 20V diode such as the MBR0520 is recommended. If the switch voltage is between 15 V and 25 V, a 30V diode such as the MBR0530 is recommended. If the switch voltage exceeds 25V, a 40V diode such as the MBR0540 should be used. The MBR05xx series of diodes are designed to handle a maximum average current of 500 mA. For applications with load currents to 800 mA, a Microsemi UPS5817 can be used. 8.2.1.2.6 Setting the Output Voltage The output voltage is set using the external resistors R1 and R2 (see Equation 2). A value of 13.3 kΩ is recommended for R2 to establish a divider current of approximately 92 µA. R1 is calculated using the formula: R1 = R2 x ( (VOUT / VFB) − 1 ) (2) 8.2.1.2.7 Duty Cycle The maximum duty cycle of the switching regulator determines the maximum boost ratio of output-to-input voltage that the converter can attain in continuous mode of operation. The duty cycle for a given boost application is defined as: Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 11 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 www.ti.com Typical Applications (continued) VOUT + VDIODE - VIN Duty Cycle = VOUT + VDIODE - VSW (3) This applies for continuous mode operation. The equation shown for calculating duty cycle incorporates terms for the FET switch voltage and diode forward voltage. The actual duty cycle measured in operation will also be affected slightly by other power losses in the circuit such as wire losses in the inductor, switching losses, and capacitor ripple current losses from self-heating. Therefore, the actual (effective) duty cycle measured may be slightly higher than calculated to compensate for these power losses. A good approximation for effective duty cycle is: DC (eff) = (1 - Efficiency x (VIN / VOUT)) where • the efficiency can be approximated from the curves provided. (4) 8.2.1.2.8 Inductance Value The first question we are usually asked is: “How small can I make the inductor?” (because they are the largest sized component and usually the most costly). The answer is not simple and involves trade-offs in performance. More inductance means less inductor ripple current and less output voltage ripple (for a given size of output capacitor). More inductance also means more load power can be delivered because the energy stored during each switching cycle is: E = L/2 x (lp)2 where • lp is the peak inductor current. (5) An important point to observe is that the LM27313 will limit its switch current based on peak current. This means that because lp(max) is fixed, increasing L will increase the maximum amount of power available to the load. Conversely, using too little inductance may limit the amount of load current which can be drawn from the output. Best performance is usually obtained when the converter is operated in “continuous” mode at the load current range of interest, typically giving better load regulation and less output ripple. Continuous operation is defined as not allowing the inductor current to drop to zero during the cycle. It should be noted that all boost converters shift over to discontinuous operation as the output load is reduced far enough, but a larger inductor stays “continuous” over a wider load current range. To better understand these tradeoffs, a typical application circuit (5V to 12V boost with a 10 µH inductor) will be analyzed. Because the LM27313 typical switching frequency is 1.6 MHz, the typical period is equal to 1/fSW(TYP), or approximately 0.625 µs. We will assume: VIN = 5 V, VOUT = 12 V, VDIODE = 0.5 V, VSW = 0.5 V. The duty cycle is: Duty Cycle = ((12 V + 0.5 V - 5 V) / (12 V + 0.5 V - 0.5 V)) = 62.5% (6) The typical ON time of the switch is: (62.5% x 0.625 µs) = 0.390 µs (7) It should be noted that when the switch is ON, the voltage across the inductor is approximately 4.5 V. Use the equation: V = L (di/dt) (8) Then, calculate the di/dt rate of the inductor which is found to be 0.45 A/µs during the ON time. Using these facts, we can then show what the inductor current will look like during operation: 12 Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 Typical Applications (continued) Figure 14. 10 µH Inductor Current, 5 V – 12 V Boost During the 0.390-µs ON time, the inductor current ramps up 0.176 A and ramps down an equal amount during the OFF time. This is defined as the inductor “ripple current”. It can also be seen that if the load current drops to about 33 mA, the inductor current will begin touching the zero axis which means it will be in discontinuous mode. A similar analysis can be performed on any boost converter, to make sure the ripple current is reasonable and continuous operation will be maintained at the typical load current values. 8.2.1.2.9 Maximum Switch Current The maximum FET switch current available before the current limiter cuts in is dependent on duty cycle of the application. This is illustrated in Figure 15 which shows typical values of switch current as a function of effective (actual) duty cycle: SWITCH CURRENT LIMIT (mA) 1600 1400 1200 1000 VIN = 5V VIN = 3.3V 800 600 VIN = 2.7V 400 200 0 0 20 40 60 80 100 DUTY CYCLE (%) = [1 - EFF*(VIN/VOUT))] Figure 15. Switch Current Limit vs Duty Cycle 8.2.1.2.10 Calculating Load Current As shown in Figure 14 which depicts inductor current, the load current is related to the average inductor current by the relation: ILOAD = IIND(AVG) x (1 - DC) where • DC is the duty cycle of the application. (9) The switch current can be found by: ISW = IIND(AVG) + ½ (IRIPPLE) (10) Inductor ripple current is dependent on inductance, duty cycle, input voltage and frequency: IRIPPLE = DC x (VIN - VSW) / (fSW x L) (11) Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 13 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 www.ti.com Typical Applications (continued) Combining all terms, we can develop an expression which allows the maximum available load current to be calculated: ILOAD(max) = (1 - DC) x (ISW(max) - DC (VIN - VSW)) 2fL (12) The equation shown to calculate maximum load current takes into account the losses in the inductor or turn-OFF switching losses of the FET and diode. For actual load current in typical applications, we took bench data for various input and output voltages and displayed the maximum load current available for a typical device in graph form: Figure 16. Max. Load Current vs VIN 8.2.1.2.11 Design Parameters VSW and ISW The value of the FET ON voltage (referred to as VSW in the equations) is dependent on load current. A good approximation can be obtained by multiplying the "ON Resistance" of the FET times the average inductor current. FET ON resistance increases at VIN values below 5V, because the internal N-FET has less gate voltage in this input voltage range (see Typical Characteristics). Above VIN = 5 V, the FET gate voltage is internally clamped to 5V. The maximum peak switch current the device can deliver is dependent on duty cycle. The minimum switch current value (ISW) is ensured to be at least 800 mA at duty cycles below 50%. For higher duty cycles, see Typical Characteristics. 8.2.1.2.12 Minimum Inductance In some applications where the maximum load current is relatively small, it may be advantageous to use the smallest possible inductance value for cost and size savings. The converter will operate in discontinuous mode in such a case. The minimum inductance should be selected such that the inductor (switch) current peak on each cycle does not reach the 800 mA current limit maximum. To understand how to do this, an example will be presented. In this example, the LM27313 nominal switching frequency is 1.6 MHz, and the minimum switching frequency is 1.15 MHz. This means the maximum cycle period is the reciprocal of the minimum frequency: TON(max) = 1/1.15M = 0.870 µs (13) Assume: VIN = 5 V, VOUT = 12 V, VSW = 0.2 V, and VDIODE = 0.3 V. The duty cycle is: Duty Cycle = ((12 V + 0.3 V - 5 V) / (12 V + 0.3 V - 0.2 V)) = 60.3% (14) Therefore, the maximum switch ON time is: (60.3% x 0.870 µs) = 0.524 µs 14 Submit Documentation Feedback (15) Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 Typical Applications (continued) An inductor should be selected with enough inductance to prevent the switch current from reaching 800 mA in the 0.524 µs ON time interval (see Figure 17): Figure 17. Discontinuous Design, 5 V – 12 V Boost The voltage across the inductor during ON time is 4.8 V. Minimum inductance value is found by: L = V x (dt/dl) L = 4.8 V x (0.524 µs / 0.8 mA) = 3.144 µH (16) (17) In this case, a 3.3-µH inductor could be used, assuming it provided at least that much inductance up to the 800mA current value. This same analysis can be used to find the minimum inductance for any boost application. 8.2.1.2.13 Inductor Suppliers Some of the recommended suppliers of inductors for this product include, but are not limited to, Sumida, Coilcraft, Panasonic, TDK and Murata. When selecting an inductor, make certain that the continuous current rating is high enough to avoid saturation at peak currents. A suitable core type must be used to minimize core (switching) losses, and wire power losses must be considered when selecting the current rating. 8.2.1.2.14 Shutdown Pin Operation The device is turned off by pulling the shutdown pin low. If this function is not going to be used, the pin should be tied directly to VIN. If the SHDN function will be needed, a pullup resistor must be used to VIN (50 kΩ to 100 kΩ is recommended), or the pin must be actively driven high and low. The SHDN pin must not be left unterminated. 8.2.1.3 Application Curves Figure 18. Typical Startup Waveform for Vin = 3.3 V, Vout = 12 V Figure 19. Typical Startup Waveform for Vin = 5.0 V, Vout = 12 V Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 15 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 www.ti.com Typical Applications (continued) 8.2.2 Application Circuit VIN=5.0V, VOUT=20.0V, Iload=150mA VIN SHDN R3 51k C1 2.2 PF GND D1 MBR0530 L1/10 PH 5 VIN U1 SW R1/205k LM27313 SHDN GND FB R2 13.3k CF 120 pF 20V OUT 130 mA (TYP) C2 4.7 PF Figure 20. Typical Application Circuit Figure 21. Efficiency vs. Load Current 8.2.2.1 Design Requirements See Design Requirements. 8.2.2.2 Detailed Design Procedure See Detailed Design Procedure. 8.2.2.3 Application Curves See Application Curves. 16 Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 LM27313, LM27313-Q1 www.ti.com SNVS487E – DECEMBER 2006 – REVISED JANUARY 2015 9 Power Supply Recommendations The LM27313 is designed to operate from an input voltage supply range from 2.7 V to 14 V. This input supply should be able to withstand the maximum input current and maintain a voltage above 2.7 V. In cases where input supply is located farther away (more than a few inches) from LM27313, additional bulk capacitance may be required in addition to the ceramic bypass capacitors. 10 Layout 10.1 Layout Guidelines High-frequency switching regulators require very careful layout of components in order to get stable operation and low noise. All components must be as close as possible to the LM27313 device. It is recommended that a 4layer PCB be used so that internal ground planes are available. Some additional guidelines to be observed: 1. Keep the path between L1, D1, and C2 extremely short. Parasitic trace inductance in series with D1 and C2 will increase noise and ringing. 2. The feedback components R1, R2 and CF must be kept close to the FB pin of the LM27313 to prevent noise injection on the high impedance FB pin. 3. If internal ground planes are available (recommended) use vias to connect directly to the LM27313 ground at device pin 2, as well as the negative sides of capacitors C1 and C2. 10.2 Layout Example Figure 22. Recommended PCB Component Layout 10.3 Thermal Considerations At higher duty cycles, the increased ON time of the FET means the maximum output current will be determined by power dissipation within the LM27313 FET switch. The switch power dissipation from ON-state conduction is calculated by: PSW = DC x IIND(AVG)2 x RDS(ON) (18) There will be some switching losses as well, so some derating needs to be applied when calculating IC power dissipation. Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 Submit Documentation Feedback 17 LM27313, LM27313-Q1 SNVS487E – DECEMBER 2006 – REVISED JANUARY 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 Related Links The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to sample or buy. Table 1. Related Links PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL DOCUMENTS TOOLS & SOFTWARE SUPPORT & COMMUNITY LM27313 Click here Click here Click here Click here Click here LM27313-Q1 Click here Click here Click here Click here Click here 11.3 Trademarks All trademarks are the property of their respective owners. 11.4 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. 11.5 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. 18 Submit Documentation Feedback Copyright © 2006–2015, Texas Instruments Incorporated Product Folder Links: LM27313 LM27313-Q1 PACKAGE OPTION ADDENDUM www.ti.com 10-Dec-2020 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) LM27313XMF/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 125 SRPB LM27313XMFX/NOPB ACTIVE SOT-23 DBV 5 3000 RoHS & Green SN Level-1-260C-UNLIM -40 to 125 SRPB LM27313XQMF/NOPB ACTIVE SOT-23 DBV 5 1000 RoHS & Green SN Level-1-260C-UNLIM -40 to 125 SD3B LM27313XQMFX/NOPB ACTIVE SOT-23 DBV 5 3000 RoHS & Green SN Level-1-260C-UNLIM -40 to 125 SD3B (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