LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 LM2671 SIMPLE SWITCHER(R) Power Converter High Efficiency 500mA Step-Down Voltage Regulator with Features Check for Samples: LM2671 FEATURES 1 * Efficiency up to 96% * Available in SOIC, 8-pin PDIP and WSON Packages * Computer Design Software LM267X Made Simple (version 6.0) * Simple and Easy to Design With * Requires Only 5 external Components * Uses Readily Available Standard Inductors * 3.3V, 5.0V, 12V, and Adjustable Output Versions * Adjustable Version Output Voltage Range: 1.21V to 37V * 1.5% Max Output Voltage Tolerance Over Line and Load Conditions * Ensured 500mA Output Load Current * 0.25 DMOS Output Switch * Wide Input Voltage Range: 8V to 40V * 260 kHz Fixed Frequency Internal Oscillator * TTL Shutdown Capability, Low Power Standby Mode * Soft-Start and Frequency Synchronization * Thermal Shutdown and Current Limit Protection 234 APPLICATIONS * * Simple High Efficiency (>90%) Step-Down (Buck) Regulator Efficient Pre-Regulator for Linear Regulators DESCRIPTION The LM2671 series of regulators are monolithic integrated circuits built with a LMDMOS process. These regulators provide all the active functions for a step-down (buck) switching regulator, capable of driving a 500mA load current with excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5.0V, 12V, and an adjustable output version. Requiring a minimum number of external components, these regulators are simple to use and include patented internal frequency compensation (Patent Nos. 5,382,918 and 5,514,947), fixed frequency oscillator, external shutdown, soft-start, and frequency synchronization. The LM2671 series operates at a switching frequency of 260 kHz, thus allowing smaller sized filter components than what would be needed with lower frequency switching regulators. Because of its very high efficiency (>90%), the copper traces on the printed circuit board are the only heat sinking needed. A family of standard inductors for use with the LM2671 are available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies using these advanced ICs. Also included in the datasheet are selector guides for diodes and capacitors designed to work in switch-mode power supplies. Other features include a ensured 1.5% tolerance on output voltage within specified input voltages and output load conditions, and 10% on the oscillator frequency. External shutdown is included, featuring typically 50 A stand-by current. The output switch includes current limiting, as well as thermal shutdown for full protection under fault conditions. To simplify the LM2671 buck regulator design procedure, there exists computer design software, LM267X Made Simple (version 6.0). 1 2 3 4 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. SIMPLE SWITCHER, WEBENCH are registered trademarks of Texas Instruments. Windows is a registered trademark of Microsoft Corporation. All other 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) 1998-2013, Texas Instruments Incorporated LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com Typical Application Figure 1. Fixed Output Voltage Versions Connection Diagram CB 1 16 VSW * 2 15 VSW * 3 14 VIN SS 4 13 * * 5 12 GND SYNC 6 11 GND * 7 10 FB 8 9 DAP** * ON/OFF * No Connections **Connect to Pins 11, 12 on PCB Figure 2. 16-Lead WSON Surface Mount Package Top View See Package Drawing Number NHN0016A Figure 3. SOIC/PDIP Package 8-Lead Package Top View See Package Drawing Number D0008A/P0008E 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. 2 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 Absolute Maximum Ratings (1) (2) Supply Voltage 45V -0.1V VSH 6V ON/OFF Pin Voltage -1V Switch Voltage to Ground Boost Pin Voltage VSW + 8V -0.3V VFB 14V Feedback Pin Voltage ESD Susceptibility Human Body Model (3) 2 kV Power Dissipation Internally Limited Storage Temperature Range -65C to +150C Lead Temperature D Package Vapor Phase (60s) +215C Infrared (15s) +220C P Package (Soldering, 10s) +260C WSON Package (See AN-1187) Maximum Junction Temperature (1) (2) (3) +150C Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but device parameter specifications may not be ensured under these conditions. 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. The human body model is a 100 pF capacitor discharged through a 1.5 k resistor into each pin. Operating Ratings Supply Voltage 6.5V to 40V -40C TJ +125C Temperature Range Electrical Characteristics LM2671-3.3 Specifications with standard type face are for TJ = 25C, and those in bold type face apply over full Operating Temperature Range. Symbol Parameter Conditions SYSTEM PARAMETERS Test Circuit Figure 22 Typical (1) Min (2) Max (2) Units (3) VOUT Output Voltage VIN = 8V to 40V, ILOAD = 20 mA to 500 mA 3.3 3.251/3.201 3.350/3.399 V VOUT Output Voltage VIN = 6.5V to 40V, ILOAD = 20 mA to 250 mA 3.3 3.251/3.201 3.350/3.399 V Efficiency VIN = 12V, ILOAD = 500 mA 86 (1) (2) (3) % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator performance. When the LM2671 is used as shown in Figure 22 and Figure 23 test circuits, system performance will be as specified by the system parameters section of the Electrical Characteristics. Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 3 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com Electrical Characteristics LM2671-5.0 Symbol Parameter Conditions SYSTEM PARAMETERS Test Circuit Figure 22 Typical (1) Min (2) Max (2) Units (3) VOUT Output Voltage VIN = 8V to 40V, ILOAD = 20 mA to 500 mA 5.0 4.925/4.850 5.075/5.150 V VOUT Output Voltage VIN = 6.5V to 40V, ILOAD = 20 mA to 250 mA 5.0 4.925/4.850 5.075/5.150 V Efficiency VIN = 12V, ILOAD = 500 mA 90 (1) (2) (3) % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator performance. When the LM2671 is used as shown in Figure 22 and Figure 23 test circuits, system performance will be as specified by the system parameters section of the Electrical Characteristics. Electrical Characteristics LM2671-12 Symbol Parameter Conditions SYSTEM PARAMETERS Test Circuit Figure 22 Typical VOUT Output Voltage VIN = 15V to 40V, ILOAD = 20 mA to 500 mA 12 Efficiency VIN = 24V, ILOAD = 500 mA 94 (1) (2) (3) (1) Min (2) Max (2) Units (3) 11.82/11.64 12.18/12.36 V % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator performance. When the LM2671 is used as shown in Figure 22 and Figure 23 test circuits, system performance will be as specified by the system parameters section of the Electrical Characteristics. Electrical Characteristics LM2671-ADJ Symbol Parameter Conditions SYSTEM PARAMETERS Test Circuit Figure 23 VFB VFB (1) (2) (3) 4 Feedback Voltage Feedback Voltage Efficiency Typ (1) Min (2) Max (2) Units (3) VIN = 8V to 40V, ILOAD = 20 mA to 500 mA VOUT Programmed for 5V (see Circuit of Figure 23) 1.210 1.192/1.174 1.228/1.246 V VIN = 6.5V to 40V, ILOAD = 20 mA to 250 mA VOUT Programmed for 5V (see Circuit of Figure 23) 1.210 1.192/1.174 1.228/1.246 V VIN = 12V, ILOAD = 500 mA 90 % Typical numbers are at 25C and represent the most likely norm. All limits ensured at room temperature (standard type face) and at temperature extremes (bold type face). All room temperature limits are 100% production tested. All limits at temperature extremes are ensured via correlation using standard Statistical Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). External components such as the catch diode, inductor, input and output capacitors, and voltage programming resistors can affect switching regulator performance. When the LM2671 is used as shown in Figure 22 and Figure 23 test circuits, system performance will be as specified by the system parameters section of the Electrical Characteristics. Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 All Output Voltage Versions Specifications with standard type face are for TJ = 25C, and those in bold type face apply over full Operating Temperature Range. Unless otherwise specified, VIN = 12V for the 3.3V, 5V, and Adjustable versions and VIN = 24V for the 12V version, and ILOAD = 100 mA. Symbol Parameters Conditions Typ Min Max Units 3.6 mA DEVICE PARAMETERS IQ Quiescent Current VFEEDBACK = 8V For 3.3V, 5.0V, and ADJ Versions 2.5 VFEEDBACK = 15V For 12V Versions 2.5 ON/OFF Pin = 0V 50 100/150 A 1.2/1.25 A 25 A 6 15 mA 0.25 0.40/0.60 275 kHz ISTBY Standby Quiescent Current ICL Current Limit IL Output Leakage Current RDS(ON) Switch On-Resistance ISWITCH = 500 mA fO Oscillator Frequency Measured at Switch Pin 260 D Maximum Duty Cycle 0.8 VIN = 40V, ON/OFF Pin = 0V VSWITCH = 0V VS/D ON/OFF Pin Voltage Thesholds IS/D ON/OFF Pin Current FSYNC Synchronization Frequency VSYNC 225 95 Minimum Duty Cycle Feedback Bias Current 0.62/0.575 1 VSWITCH = -1V, ON/OFF Pin = 0V IBIAS mA VFEEDBACK = 1.3V ADJ Version Only % 0 % 85 nA 1.4 0.8 2.0 ON/OFF Pin = 0V 20 7 37 VSYNC = 3.5V, 50% duty cycle 400 kHz Synchronization Threshold Voltage 1.4 V VSS Soft-Start Voltage 0.63 0.53 0.73 V ISS Soft-Start Current 4.5 1.5 6.9 A JA Thermal Resistance (1) P Package, Junction to Ambient (1) 95 D Package, Junction to Ambient (1) 105 V A C/W Junction to ambient thermal resistance with approximately 1 square inch of printed circuit board copper surrounding the leads. Additional copper area will lower thermal resistance further. See Application Information section in the application note accompanying this datasheet and the thermal model in LM267X Made Simple version 6.0 software. The value J-A for the WSON (NHN) package is specifically dependent on PCB trace area, trace material, and the number of layers and thermal vias. For improved thermal resistance and power dissipation for the WSON package, refer to Application Note AN-1187 SNOA401. Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 5 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics 6 Normalized Output Voltage Line Regulation Figure 4. Figure 5. Efficiency Drain-to-Source Resistance Figure 6. Figure 7. Switch Current Limit Operating Quiescent Current Figure 8. Figure 9. Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 Typical Performance Characteristics (continued) Standby Quiescent Current ON/OFF Threshold Voltage Figure 10. Figure 11. ON/OFF Pin Current (Sourcing) Switching Frequency Figure 12. Figure 13. Feedback Pin Bias Current Peak Switch Current Figure 14. Figure 15. Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 7 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Dropout Voltage--3.3V Option Dropout Voltage--5.0V Option Figure 16. Figure 17. BLOCK DIAGRAM * Patent Number 5,514,947 Patent Number 5,382,918 8 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 Typical Performance Characteristics (Circuit of Figure 22) Continuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 500 mA L = 100 H, COUT = 100 F, COUTESR = 0.1 A: VSW Pin Voltage, 10 V/div. B: Inductor Current, 0.2 A/div C: Output Ripple Voltage, 50 mV/div AC-Coupled Figure 18. Horizontal Time Base: 1 s/div Load Transient Response for Continuous Mode VIN = 20V, VOUT = 5V L = 100 H, COUT = 100 F, COUTESR = 0.1 A: Output Voltage, 100 mV/div, AC-Coupled B: Load Current: 100 mA to 500 mA Load Pulse Figure 20. Horizontal Time Base: 50 s/div Discontinuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 300 mA L = 15 H, COUT = 68 F (2x), COUTESR = 25 m A: VSW Pin Voltage, 10 V/div. B: Inductor Current, 0.5 A/div C: Output Ripple Voltage, 20 mV/div AC-Coupled Figure 19. Horizontal Time Base: 1 s/div Load Transient Response for Discontinuous Mode VIN = 20V, VOUT = 5V, L = 47 H, COUT = 68 F, COUTESR = 50 m A: Output Voltage, 100 mV/div, AC-Coupled B: Load Current: 100 mA to 400 mA Load Pulse Figure 21. Horizontal Time Base: 200 s/div Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 9 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com TEST CIRCUIT AND LAYOUT GUIDELINES CIN - 22 F, 50V Tantalum, Sprague "199D Series" COUT - 47 F, 25V Tantalum, Sprague "595D Series" D1 - 3.3A, 50V Schottky Rectifier, IR 30WQ05F L1 - 68 H Sumida #RCR110D-680L CB - 0.01 F, 50V Ceramic Figure 22. Standard Test Circuits and Layout Guides Fixed Output Voltage Versions CIN - 22 F, 50V Tantalum, Sprague "199D Series" COUT - 47 F, 25V Tantalum, Sprague "595D Series" D1 - 3.3A, 50V Schottky Rectifier, IR 30WQ05F L1 - 68 H Sumida #RCR110D-680L R1 - 1.5 k, 1% CB - 0.01 F, 50V Ceramic For a 5V output, select R2 to be 4.75 k, 1% where VREF = 1.21V Use a 1% resistor for best stability. Figure 23. Standard Test Circuits and Layout Guides Adjustable Output Voltage Versions Application Hints The LM2671 provides all of the active functions required for a step-down (buck) switching regulator. The internal power switch is a DMOS power MOSFET to provide power supply designs with high current capability, up to 0.5A, and highly efficient operation. 10 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 The LM2671 is part of the SIMPLE SWITCHER(R) family of power converters. A complete design uses a minimum number of external components, which have been pre-determined from a variety of manufacturers. Using either this data sheet or TI's WEBENCH(R) design tool, a complete switching power supply can be designed quickly. Also, refer to the LM2670 data sheet for additional applications information. SWITCH OUTPUT This is the output of a power MOSFET switch connected directly to the input voltage. The switch provides energy to an inductor, an output capacitor and the load circuitry under control of an internal pulse-width-modulator (PWM). The PWM controller is internally clocked by a fixed 260kHz oscillator. In a standard step-down application the duty cycle (Time ON/Time OFF) of the power switch is proportional to the ratio of the power supply output voltage to the input voltage. The voltage on the VSW pin cycles between Vin (switch ON) and below ground by the voltage drop of the external Schottky diode (switch OFF). INPUT The input voltage for the power supply is connected to the VIN pin. In addition to providing energy to the load the input voltage also provides bias for the internal circuitry of the LM2671. For ensured performance the input voltage must be in the range of 6.5V to 40V. For best performance of the power supply the VIN pin should always be bypassed with an input capacitor located close to this pin and GND. C BOOST A capacitor must be connected from the CB pin to the VSW pin. This capacitor boosts the gate drive to the internal MOSFET above Vin to fully turn it ON. This minimizes conduction losses in the power switch to maintain high efficiency. The recommended value for C Boost is 0.01F. GROUND This is the ground reference connection for all components in the power supply. In fast-switching, high-current applications such as those implemented with the LM2671, it is recommended that a broad ground plane be used to minimize signal coupling throughout the circuit SYNC This input allows control of the switching clock frequency. If left open-circuited the regulator will be switched at the internal oscillator frequency, typically 260 kHz. An external clock can be used to force the switching frequency and thereby control the output ripple frequency of the regulator. This capability provides for consistent filtering of the output ripple from system to system as well as precise frequency spectrum positioning of the ripple frequency which is often desired in communications and radio applications. This external frequency must be greater than the LM2671 internal oscillator frequency, which could be as high as 275 kHz, to prevent an erroneous reset of the internal ramp oscillator and PWM control of the power switch. The ramp oscillator is reset on the positive going edge of the sync input signal. It is recommended that the external TTL or CMOS compatible clock (between 0V and a level greater than 3V) be ac coupled to the SYNC pin through a 100pF capacitor and a 1K resistor to ground. When the SYNC function is used, current limit frequency foldback is not active. Therefore, the device may not be fully protected against extreme output short circuit conditions. FEEDBACK This is the input to a two-stage high gain amplifier, which drives the PWM controller. Connect the FB pin directly to the output for proper regulation. For the fixed output devices (3.3V, 5V and 12V outputs), a direct wire connection to the output is all that is required as internal gain setting resistors are provided inside the LM2671. For the adjustable output version two external resistors are required to set the dc output voltage. For stable operation of the power supply it is important to prevent coupling of any inductor flux to the feedback input. Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 11 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com ON/OFF This input provides an electrical ON/OFF control of the power supply. Connecting this pin to ground or to any voltage less than 0.8V will completely turn OFF the regulator. The current drain from the input supply when OFF is only 50A. The ON/OFF input has an internal pull-up current source of approximately 20A and a protection clamp zener diode of 7V to ground. When electrically driving the ON/OFF pin the high voltage level for the ON condition should not exceed the 6V absolute maximum limit. When ON/OFF control is not required this pin should be left open. DAP (WSON PACKAGE) The Die Attach Pad (DAP) can and should be connected to the PCB Ground plane/island. For CAD and assembly guidelines refer to Application Note SNOA401. LM2671 Series Buck Regulator Design Procedure (Fixed Output) PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) To simplify the buck regulator design procedure, Texas Instruments is making available computer design software to be used with the SIMPLE SWITCHER line of switching regulators.LM267X Made Simple (version 6.0) is available on Windows(R) 3.1, NT, or 95 operating systems. Given: Given: VOUT = Regulated Output Voltage (3.3V, 5V, or 12V) VOUT = 5V VIN(max) = Maximum DC Input Voltage VIN(max) = 12V ILOAD(max) = Maximum Load Current ILOAD(max) = 500 mA 1. Inductor Selection (L1) 1. Inductor Selection (L1) A. Select the correct inductor value selection guide from Figure 24 A. Use the inductor selection guide for the 5V version shown in and Figure 25 or Figure 26 (output voltages of 3.3V, 5V, or 12V Figure 25. respectively). For all other voltages, see the design procedure for the adjustable version. B. From the inductor value selection guide, identify the inductance region intersected by the Maximum Input Voltage line and the Maximum Load Current line. Each region is identified by an inductance value and an inductor code (LXX). B. From the inductor value selection guide shown in Figure 25, the inductance region intersected by the 12V horizontal line and the 500 mA vertical line is 47 H, and the inductor code is L13. C. Select an appropriate inductor from the four manufacturer's part numbers listed in Table 1. Each manufacturer makes a different style of inductor to allow flexibility in meeting various design requirements. Listed below are some of the differentiating characteristics of each manufacturer's inductors: C. The inductance value required is 47 H. From the table in Table 1, go to the L13 line and choose an inductor part number from any of the four manufacturers shown. (In most instances, both through hole and surface mount inductors are available.) Schott: ferrite EP core inductors; these have very low leakage magnetic fields to reduce electro-magnetic interference (EMI) and are the lowest power loss inductors Renco: ferrite stick core inductors; benefits are typically lowest cost inductors and can withstand E*T and transient peak currents above rated value. Be aware that these inductors have an external magnetic field which may generate more EMI than other types of inductors. Pulse: powered iron toroid core inductors; these can also be low cost and can withstand larger than normal E*T and transient peak currents. Toroid inductors have low EMI. Coilcraft: ferrite drum core inductors; these are the smallest physical size inductors, available only as SMT components. Be aware that these inductors also generate EMI--but less than stick inductors. Complete specifications for these inductors are available from the respective manufacturers. A table listing the manufacturers' phone numbers is located in Table 2. 2. Output Capacitor Selection (COUT) A. Select an output capacitor from the output capacitor table in Table 10. Using the output voltage and the inductance value found in the inductor selection guide, step 1, locate the appropriate capacitor value and voltage rating. 12 2. Output Capacitor Selection (COUT) A. Use the 5.0V section in the output capacitor table in Table 10. Choose a capacitor value and voltage rating from the line that contains the inductance value of 47 H. The capacitance and voltage rating values corresponding to the 47 H inductor are the: Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) The capacitor list contains through-hole electrolytic capacitors from four different capacitor manufacturers and surface mount tantalum capacitors from two different capacitor manufacturers. It is recommended that both the manufacturers and the manufacturer's series that are listed in the table be used. A table listing the manufacturers' phone numbers is located in Table 4. Surface Mount: 68 F/10V Sprague 594D Series. 100 F/10V AVX TPS Series. Through Hole: 68 F/10V Sanyo OS-CON SA Series. 150 F/35V Sanyo MV-GX Series. 150 F/35V Nichicon PL Series. 150 F/35V Panasonic HFQ Series. 3. Catch Diode Selection (D1) A. In normal operation, the average current of the catch diode is the load current times the catch diode duty cycle, 1-D (D is the switch duty cycle, which is approximately the output voltage divided by the input voltage). The largest value of the catch diode average current occurs at the maximum load current and maximum input voltage (minimum D). For normal operation, the catch diode current rating must be at least 1.3 times greater than its maximum average current. However, if the power supply design must withstand a continuous output short, the diode should have a current rating equal to the maximum current limit of the LM2671. The most stressful condition for this diode is a shorted output condition. 3. Catch Diode Selection (D1) A. Refer to the table shown in Table 5. In this example, a 1A, 20V Schottky diode will provide the best performance. If the circuit must withstand a continuous shorted output, a higher current Schottky diode is recommended. B. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. C. Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best performance and efficiency. This Schottky diode must be located close to the LM2671 using short leads and short printed circuit traces. 4. Input Capacitor (CIN) A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground to prevent large voltage transients from appearing at the input. This capacitor should be located close to the IC using short leads. In addition, the RMS current rating of the input capacitor should be selected to be at least 1/2 the DC load current. The capacitor manufacturer data sheet must be checked to assure that this current rating is not exceeded. The curves shown in Figure 28 show typical RMS current ratings for several different aluminum electrolytic capacitor values. A parallel connection of two or more capacitors may be required to increase the total minimum RMS current rating to suit the application requirements. For an aluminum electrolytic capacitor, the voltage rating should be at least 1.25 times the maximum input voltage. Caution must be exercised if solid tantalum capacitors are used. The tantalum capacitor voltage rating should be twice the maximum input voltage. The tables in Recommended Application Voltage for AVX TPS and Sprague 594D Tantalum Chip Capacitors Derated for 85C. show the recommended application voltage for AVX TPS and Sprague 594D tantalum capacitors. It is also recommended that they be surge current tested by the manufacturer. The TPS series available from AVX, and the 593D and 594D series from Sprague are all surge current tested. Another approach to minimize the surge current stresses on the input capacitor is to add a small inductor in series with the input supply line. Use caution when using ceramic capacitors for input bypassing, because it may cause severe ringing at the VIN pin. 4. Input Capacitor (CIN) The important parameters for the input capacitor are the input voltage rating and the RMS current rating. With a maximum input voltage of 12V, an aluminum electrolytic capacitor with a voltage rating greater than 15V (1.25 x VIN) would be needed. The next higher capacitor voltage rating is 16V. The RMS current rating requirement for the input capacitor in a buck regulator is approximately 1/2 the DC load current. In this example, with a 500 mA load, a capacitor with a RMS current rating of at least 250 mA is needed. The curves shown in Figure 28 can be used to select an appropriate input capacitor. From the curves, locate the 16V line and note which capacitor values have RMS current ratings greater than 250 mA. For a through hole design, a 100 F/16V electrolytic capacitor (Panasonic HFQ series, Nichicon PL, Sanyo MV-GX series or equivalent) would be adequate. Other types or other manufacturers' capacitors can be used provided the RMS ripple current ratings are adequate. Additionally, for a complete surface mount design, electrolytic capacitors such as the Sanyo CV-C or CV-BS and the Nichicon WF or UR and the NIC Components NACZ series could be considered. For surface mount designs, solid tantalum capacitors can be used, but caution must be exercised with regard to the capacitor surge current rating and voltage rating. In this example, checking Recommended Application Voltage for AVX TPS and Sprague 594D Tantalum Chip Capacitors Derated for 85C., and the Sprague 594D series datasheet, a Sprague 594D 15 F, 25V capacitor is adequate. 5. Boost Capacitor (CB) This capacitor develops the necessary voltage to turn the switch gate on fully. All applications should use a 0.01 F, 50V ceramic capacitor. 5. Boost Capacitor (CB) For this application, and all applications, use a 0.01 F, 50V ceramic capacitor. 6. Soft-Start Capacitor (CSS - optional) This capacitor controls the rate at which the device starts up. The formula for the soft-start capacitor CSS is: 6. Soft-Start Capacitor (CSS - optional) For this application, selecting a start-up time of 10 ms and using the formula for CSS results in a value of: (1) (2) Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 13 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com PROCEDURE (Fixed Output Voltage Version) EXAMPLE (Fixed Output Voltage Version) where: ISS = Soft-Start Current :4.5 A typical. tSS = Soft-Start Time :Selected. VSSTH = Soft-Start Threshold Voltage :0.63V typical. VOUT = Output Voltage :Selected. VSCHOTTKY = Schottky Diode Voltage Drop :0.4V typical. VIN = Input Voltage :Selected. If this feature is not desired, leave this pin open. With certain softstart capacitor values and operating conditions, the LM2671 can exhibit an overshoot on the output voltage during turn on. Especially when starting up into no load or low load, the softstart function may not be effective in preventing a larger voltage overshoot on the output. With larger loads or lower input voltages during startup this effect is minimized. In particular, avoid using softstart capacitors between 0.033F and 1F. 7. Frequency Synchronization (optional) 7. Frequency Synchronization (optional) The LM2671 (oscillator) can be synchronized to run with an external For all applications, use a 1 k resistor and a 100 pF capacitor for oscillator, using the sync pin (pin 3). By doing so, the LM2671 can the RC filter. be operated at higher frequencies than the standard frequency of 260 kHz. This allows for a reduction in the size of the inductor and output capacitor. As shown in the drawing below, a signal applied to a RC filter at the sync pin causes the device to synchronize to the frequency of that signal. For a signal with a peak-to-peak amplitude of 3V or greater, a 1 k resistor and a 100 pF capacitor are suitable values. INDUCTOR VALUE SELECTION GUIDES (For Continuous Mode Operation) Figure 24. LM2671-3.3 14 Figure 25. LM2671-5.0 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 Figure 26. LM2671-12 Figure 27. LM2671-ADJ Table 1. Inductor Manufacturers' Part Numbers Schott Renco Pulse Engineering Coilcraft Ind. Ref. Desg. Inductan ce (H) Current (A) Through Hole Mount Hole L2 150 0.21 67143920 67144290 RL-5470-4 RL1500-150 PE-53802 PE-53802-S DO1608-154 L3 100 0.26 67143930 67144300 RL-5470-5 RL1500-100 PE-53803 PE-53803-S DO1608-104 L4 68 0.32 67143940 67144310 RL-1284-68-43 RL1500-68 PE-53804 PE-53804-S DO1608-683 L5 47 0.37 67148310 67148420 RL-1284-47-43 RL1500-47 PE-53805 PE-53805-S DO1608-473 L6 33 0.44 67148320 67148430 RL-1284-33-43 RL1500-33 PE-53806 PE-53806-S DO1608-333 L7 22 0.52 67148330 67148440 RL-1284-22-43 RL1500-22 PE-53807 PE-53807-S DO1608-223 L9 220 0.32 67143960 67144330 RL-5470-3 RL1500-220 PE-53809 PE-53809-S DO3308-224 L10 150 0.39 67143970 67144340 RL-5470-4 RL1500-150 PE-53810 PE-53810-S DO3308-154 L11 100 0.48 67143980 67144350 RL-5470-5 RL1500-100 PE-53811 PE-53811-S DO3308-104 L12 68 0.58 67143990 67144360 RL-5470-6 RL1500-68 PE-53812 PE-53812-S DO3308-683 L13 47 0.70 67144000 67144380 RL-5470-7 RL1500-47 PE-53813 PE-53813-S DO3308-473 L14 33 0.83 67148340 67148450 RL-1284-33-43 RL1500-33 PE-53814 PE-53814-S DO3308-333 L15 22 0.99 67148350 67148460 RL-1284-22-43 RL1500-22 PE-53815 PE-53815-S DO3308-223 L18 220 0.55 67144040 67144420 RL-5471-2 RL1500-220 PE-53818 PE-53818-S DO3316-224 L19 150 0.66 67144050 67144430 RL-5471-3 RL1500-150 PE-53819 PE-53819-S DO3316-154 L20 100 0.82 67144060 67144440 RL-5471-4 RL1500-100 PE-53820 PE-53820-S DO3316-104 L21 68 0.99 67144070 67144450 RL-5471-5 RL1500-68 PE-53821 PE-53821-S DO3316-683 Surface Hole Mount Through Surface Through Surface Mount Surface Mount Table 2. Inductor Manufacturers' Phone Numbers Coilcraft Inc. Coilcraft Inc., Europe Pulse Engineering Inc. Pulse Engineering Inc., Europe Renco Electronics Inc. Schott Corp. Phone (800) 322-2645 FAX (708) 639-1469 Phone +44 1236 730 595 FAX +44 1236 730 627 Phone (619) 674-8100 FAX (619) 674-8262 Phone +353 93 24 107 FAX +353 93 24 459 Phone (800) 645-5828 FAX (516) 586-5562 Phone (612) 475-1173 FAX (612) 475-1786 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 15 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com Table 3. Output Capacitor Table Output Capacitor Output Voltage (V) Surface Mount Inductance (H) 3.3 5.0 12 Through Hole Sprague AVX TPS Sanyo OS-CON Sanyo MV-GX Nichicon Panasonic 594D Series Series SA Series Series PL Series HFQ Series (F/V) (F/V) (F/V) (F/V) (F/V) (F/V) 22 120/6.3 100/10 100/10 330/35 330/35 330/35 33 120/6.3 100/10 68/10 220/35 220/35 220/35 47 68/10 100/10 68/10 150/35 150/35 150/35 68 120/6.3 100/10 100/10 120/35 120/35 120/35 100 120/6.3 100/10 100/10 120/35 120/35 120/35 150 120/6.3 100/10 100/10 120/35 120/35 120/35 22 100/16 100/10 100/10 330/35 330/35 330/35 33 68/10 10010 68/10 220/35 220/35 220/35 47 68/10 100/10 68/10 150/35 150/35 150/35 68 100/16 100/10 100/10 120/35 120/35 120/35 100 100/16 100/10 100/10 120/35 120/35 120/35 150 100/16 100/10 100/10 120/35 120/35 120/35 22 120/20 (2x) 68/20 68/20 330/35 330/35 330/35 33 68/25 68/20 68/20 220/35 220/35 220/35 47 47/20 68/20 47/20 150/35 150/35 150/35 68 47/20 68/20 47/20 120/35 120/35 120/35 100 47/20 68/20 47/20 120/35 120/35 120/35 150 47/20 68/20 47/20 120/35 120/35 120/35 220 47/20 68/20 47/20 120/35 120/35 120/35 Table 4. Capacitor Manufacturers' Phone Numbers Nichicon Corp. Panasonic AVX Corp. Sprague/Vishay Sanyo Corp. Phone (847) 843-7500 FAX (847) 843-2798 Phone (714) 373-7857 FAX (714) 373-7102 Phone (845) 448-9411 FAX (845) 448-1943 Phone (207) 324-4140 FAX (207) 324-7223 Phone (619) 661-6322 FAX (619) 661-1055 Table 5. Schottky Diode Selection Table 1A Diodes VR 20V 30V 16 Surface 3A Diodes Through Surface Through Mount Hole Mount Hole SK12 1N5817 SK32 1N5820 B120 SR102 SR302 SK13 1N5818 SK33 1N5821 B130 11DQ03 30WQ03F 31DQ03 MBRS130 SR103 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 Table 5. Schottky Diode Selection Table (continued) 1A Diodes VR Surface 40V 3A Diodes Through Surface Through Mount Hole Mount Hole SK14 1N5819 SK34 1N5822 B140 11DQ04 30BQ040 MBR340 MBRS140 SR104 30WQ04F 31DQ04 10BQ040 MBRS340 SR304 10MQ040 MBRD340 15MQ040 50V SK15 MBR150 SK35 MBR350 B150 11DQ05 30WQ05F 31DQ05 10BQ050 SR105 SR305 Table 6. Diode Manufacturers' Phone Numbers International Rectifier Corp. Motorola, Inc. General Instruments Corp. Diodes, Inc. Phone (310) 322-3331 FAX (310) 322-3332 Phone (800) 521-6274 FAX (602) 244-6609 Phone (516) 847-3000 FAX (516) 847-3236 Phone (805) 446-4800 FAX (805) 446-4850 Figure 28. RMS Current Ratings for Low ESR Electrolytic Capacitors (Typical) Recommended Application Voltage for AVX TPS and Sprague 594D Tantalum Chip Capacitors Derated for 85C. Table 7. AVX TPS Recommended Application Voltage Voltage Rating +85C Rating 3.3 6.3 5 10 10 20 12 25 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 17 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com Table 7. AVX TPS (continued) Recommended Application Voltage Voltage Rating +85C Rating 15 35 Table 8. Sprague 594D Recommended Application Voltage Voltage Rating +85C Rating 2.5 4 3.3 6.3 5 10 8 16 12 20 18 25 24 35 29 50 LM2671 Series Buck Regulator Design Procedure (Adjustable Output) PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) To simplify the buck regulator design procedure, Texas Instrumnets is making available computer design software to be used with the SIMPLE SWITCHER line of switching regulators.LM267X Made Simple is available on (version 6.0) Windows(R)3.1, NT, or 95 operating systems. Given: Given: VOUT = Regulated Output Voltage VOUT = 20V VIN(max) = Maximum Input Voltage VIN(max) = 28V ILOAD(max) = Maximum Load Current ILOAD(max) = 500 mA F = Switching Frequency (Fixed at a nominal 260 kHz). F = Switching Frequency (Fixed at a nominal 260 kHz). 1. Programming Output Voltage (Selecting R1 and R2, as shown in 1. Programming Output Voltage (Selecting R1 and R2, as shown in Figure 23) Figure 23) Use the following formula to select the appropriate resistor values. Select R1 to be 1 k, 1%. Solve for R2. where VREF = 1.21V (3) Select a value for R1 between 240 and 1.5 k. The lower resistor values minimize noise pickup in the sensitive feedback pin. (For the lowest temperature coefficient and the best stability with time, use 1% metal film resistors.) (4) R2 = 1 k (16.53 - 1) = 15.53 k, closest 1% value is 15.4 k. R2 = 15.4 k. (5) 2. Inductor Selection (L1) A. Calculate the inductor Volt * microsecond constant E * T (V * s), from the following formula: 2. Inductor Selection (L1) A. Calculate the inductor Volt * microsecond constant (E * T), (6) (7) where VSAT=internal switch saturation voltage=0.25V and VD = diode forward voltage drop = 0.5V B. Use the E * T value from the previous formula and match it with the E * T number on the vertical axis of the Inductor Value Selection Guide shown in Figure 27. 18 B. E * T = 21.6 (V * s) Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) C. On the horizontal axis, select the maximum load current. C. ILOAD(max) = 500 mA D. Identify the inductance region intersected by the E * T value and the Maximum Load Current value. Each region is identified by an inductance value and an inductor code (LXX). D. From the inductor value selection guide shown in Figure 27, the inductance region intersected by the 21.6 (V * s) horizontal line and the 500 mA vertical line is 100 H, and the inductor code is L20. E. Select an appropriate inductor from the four manufacturer's part numbers listed in Table 1. For information on the different types of inductors, see the inductor selection in the fixed output voltage design procedure. E. From the table in Table 1, locate line L20, and select an inductor part number from the list of manufacturers' part numbers. 3. Output Capacitor SeIection (COUT) 3. Output Capacitor SeIection (COUT) A. Select an output capacitor from the capacitor code selection guide A. Use the appropriate row of the capacitor code selection guide, in in Table 9. Using the inductance value found in the inductor Table 9. For this example, use the 15-20V row. The capacitor code selection guide, step 1, locate the appropriate capacitor code corresponding to an inductance of 100 H is C20. corresponding to the desired output voltage. B. Select an appropriate capacitor value and voltage rating, using the capacitor code, from the output capacitor selection table in Table 10. There are two solid tantalum (surface mount) capacitor manufacturers and four electrolytic (through hole) capacitor manufacturers to choose from. It is recommended that both the manufacturers and the manufacturer's series that are listed in the table be used. A table listing the manufacturers' phone numbers is located in Table 4. B. From the output capacitor selection table in Table 10, choose a capacitor value (and voltage rating) that intersects the capacitor code(s) selected in section A, C20. The capacitance and voltage rating values corresponding to the capacitor code C20 are the: Surface Mount: 33 F/25V Sprague 594D Series. 33 F/25V AVX TPS Series. Through Hole: 33 F/25V Sanyo OS-CON SC Series. 120 F/35V Sanyo MV-GX Series. 120 F/35V Nichicon PL Series. 120 F/35V Panasonic HFQ Series. Other manufacturers or other types of capacitors may also be used, provided the capacitor specifications (especially the 100 kHz ESR) closely match the characteristics of the capacitors listed in the output capacitor table. Refer to the capacitor manufacturers' data sheet for this information. 4. Catch Diode Selection (D1) A. In normal operation, the average current of the catch diode is the load current times the catch diode duty cycle, 1-D (D is the switch duty cycle, which is approximately VOUT/VIN). The largest value of the catch diode average current occurs at the maximum input voltage (minimum D). For normal operation, the catch diode current rating must be at least 1.3 times greater than its maximum average current. However, if the power supply design must withstand a continuous output short, the diode should have a current rating greater than the maximum current limit of the LM2671. The most stressful condition for this diode is a shorted output condition. 4. Catch Diode Selection (D1) A. Refer to the table shown in Table 5. Schottky diodes provide the best performance, and in this example a 1A, 40V Schottky diode would be a good choice. If the circuit must withstand a continuous shorted output, a higher current (at least 1.2A) Schottky diode is recommended. B. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. C. Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best performance and efficiency. The Schottky diode must be located close to the LM2671 using short leads and short printed circuit traces. Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 19 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com PROCEDURE (Adjustable Output Voltage Version) EXAMPLE (Adjustable Output Voltage Version) 5. Input Capacitor (CIN) A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground to prevent large voltage transients from appearing at the input. This capacitor should be located close to the IC using short leads. In addition, the RMS current rating of the input capacitor should be selected to be at least 1/2 the DC load current. The capacitor manufacturer data sheet must be checked to assure that this current rating is not exceeded. The curves shown in Figure 28 show typical RMS current ratings for several different aluminum electrolytic capacitor values. A parallel connection of two or more capacitors may be required to increase the total minimum RMS current rating to suit the application requirements. For an aluminum electrolytic capacitor, the voltage rating should be at least 1.25 times the maximum input voltage. Caution must be exercised if solid tantalum capacitors are used. The tantalum capacitor voltage rating should be twice the maximum input voltage. The tables in Recommended Application Voltage for AVX TPS and Sprague 594D Tantalum Chip Capacitors Derated for 85C. show the recommended application voltage for AVX TPS and Sprague 594D tantalum capacitors. It is also recommended that they be surge current tested by the manufacturer. The TPS series available from AVX, and the 593D and 594D series from Sprague are all surge current tested. Another approach to minimize the surge current stresses on the input capacitor is to add a small inductor in series with the input supply line. Use caution when using ceramic capacitors for input bypassing, because it may cause severe ringing at the VIN pin. 5. Input Capacitor (CIN) The important parameters for the input capacitor are the input voltage rating and the RMS current rating. With a maximum input voltage of 28V, an aluminum electrolytic capacitor with a voltage rating of at least 35V (1.25 x VIN) would be needed. The RMS current rating requirement for the input capacitor in a buck regulator is approximately 1/2 the DC load current. In this example, with a 500 mA load, a capacitor with a RMS current rating of at least 250 mA is needed. The curves shown in Figure 28 can be used to select an appropriate input capacitor. From the curves, locate the 35V line and note which capacitor values have RMS current ratings greater than 250 mA. For a through hole design, a 68 F/35V electrolytic capacitor (Panasonic HFQ series, Nichicon PL, Sanyo MV-GX series or equivalent) would be adequate. Other types or other manufacturers' capacitors can be used provided the RMS ripple current ratings are adequate. Additionally, for a complete surface mount design, electrolytic capacitors such as the Sanyo CV-C or CV-BS and the Nichicon WF or UR and the NIC Components NACZ series could be considered. For surface mount designs, solid tantalum capacitors can be used, but caution must be exercised with regard to the capacitor surge current rating and voltage rating. In this example, checking Recommended Application Voltage for AVX TPS and Sprague 594D Tantalum Chip Capacitors Derated for 85C., and the Sprague 594D series datasheet, a Sprague 594D 15 F, 50V capacitor is adequate. 6. Boost Capacitor (CB) This capacitor develops the necessary voltage to turn the switch gate on fully. All applications should use a 0.01 F, 50V ceramic capacitor. 6. Boost Capacitor (CB) For this application, and all applications, use a 0.01 F, 50V ceramic capacitor. If the soft-start and frequency synchronization features are desired, look at steps 6 and 7 in the fixed output design procedure. Table 9. Capacitor Code Selection Guide (1) Inductance (H) Case Style (1) Output Voltage (V) 22 33 47 68 100 150 220 SM and TH 1.21-2.50 -- -- -- -- C1 C2 C3 SM and TH 2.50-3.75 -- -- -- C1 C2 C3 C3 SM and TH 3.75-5.0 -- -- C4 C5 C6 C6 C6 SM and TH 5.0-6.25 -- C4 C7 C6 C6 C6 C6 SM and TH 6.25-7.5 C8 C4 C7 C6 C6 C6 C6 SM and TH 7.5-10.0 C9 C10 C11 C12 C13 C13 C13 SM and TH 10.0-12.5 C14 C11 C12 C12 C13 C13 C13 SM and TH 12.5-15.0 C15 C16 C17 C17 C17 C17 C17 SM and TH 15.0-20.0 C18 C19 C20 C20 C20 C20 C20 SM and TH 20.0-30.0 C21 C22 C22 C22 C22 C22 C22 TH 30.0-37.0 C23 C24 C24 C25 C25 C25 C25 SM - Surface Mount, TH - Through Hole Table 10. Output Capacitor Selection Table Output Capacitor Cap. Ref. Desg. # 20 Surface Mount Through Hole Sprague AVX TPS Sanyo OS-CON Sanyo MV-GX Nichicon Panasonic 594D Series Series SA Series Series PL Series HFQ Series (F/V) (F/V) (F/V) (F/V) (F/V) (F/V) C1 120/6.3 100/10 100/10 220/35 220/35 220/35 C2 120/6.3 100/10 100/10 150/35 150/35 150/35 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 Table 10. Output Capacitor Selection Table (continued) Output Capacitor Cap. Ref. Desg. # (1) (2) Surface Mount Through Hole Sprague AVX TPS Sanyo OS-CON Sanyo MV-GX Nichicon Panasonic 594D Series Series SA Series Series PL Series HFQ Series (F/V) (F/V) (F/V) (F/V) (F/V) (F/V) C3 120/6.3 100/10 100/35 120/35 120/35 120/35 C4 68/10 100/10 68/10 220/35 220/35 220/35 C5 100/16 100/10 100/10 150/35 150/35 150/35 C6 100/16 100/10 100/10 120/35 120/35 120/35 C7 68/10 100/10 68/10 150/35 150/35 150/35 C8 100/16 100/10 100/10 330/35 330/35 330/35 C9 100/16 100/16 100/16 330/35 330/35 330/35 C10 100/16 100/16 68/16 220/35 220/35 220/35 C11 100/16 100/16 68/16 150/35 150/35 150/35 C12 100/16 100/16 68/16 120/35 120/35 120/35 C13 100/16 100/16 100/16 120/35 120/35 120/35 C14 100/16 100/16 100/16 220/35 220/35 220/35 C15 47/20 68/20 47/20 220/35 220/35 220/35 C16 47/20 68/20 47/20 150/35 150/35 150/35 C17 47/20 68/20 47/20 120/35 120/35 120/35 C18 68/25 (2x) 33/25 47/25 (1) 220/35 220/35 220/35 C19 33/25 33/25 33/25 (1) 150/35 150/35 150/35 33/25 (1) C20 33/25 33/25 120/35 120/35 120/35 C21 33/35 (2x) 22/25 (2) 150/35 150/35 150/35 C22 33/35 22/35 (2) 120/35 120/35 120/35 C23 (2) (2) (2) 220/50 100/50 120/50 C24 (2) (2) (2) 150/50 100/50 120/50 C25 (2) (2) (2) 150/50 82/50 82/50 The SC series of Os-Con capacitors (others are SA series) The voltage ratings of the surface mount tantalum chip and Os-Con capacitors are too low to work at these voltages. Application Information TYPICAL SURFACE MOUNT PC BOARD LAYOUT, FIXED OUTPUT (4X SIZE) CIN - 15 F, 25V, Solid Tantalum Sprague, "594D series" COUT - 68 F, 10V, Solid Tantalum Sprague, "594D series" D1 - 1A, 40V Schottky Rectifier, Surface Mount L1 - 47 H, L13, Coilcraft DO3308 CB - 0.01 F, 50V, Ceramic Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 21 LM2671 SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 www.ti.com TYPICAL SURFACE MOUNT PC BOARD LAYOUT, ADJUSTABLE OUTPUT (4X SIZE) CIN - 15 F, 50V, Solid Tantalum Sprague, "594D series" COUT - 33 F, 25V, Solid Tantalum Sprague, "594D series" D1 - 1A, 40V Schottky Rectifier, Surface Mount L1 - 100 H, L20, Coilcraft DO3316 CB - 0.01 F, 50V, Ceramic R1 - 1k, 1% R2 - Use formula in Design Procedure Figure 29. PC Board Layout Layout is very important in switching regulator designs. Rapidly switching currents associated with wiring inductance can generate voltage transients which can cause problems. For minimal inductance and ground loops, the wires indicated by heavy lines (in Figure 22 and Figure 23) should be wide printed circuit traces and should be kept as short as possible. For best results, external components should be located as close to the switcher IC as possible using ground plane construction or single point grounding. If open core inductors are used, special care must be taken as to the location and positioning of this type of inductor. Allowing the inductor flux to intersect sensitive feedback, IC ground path, and COUT wiring can cause problems. When using the adjustable version, special care must be taken as to the location of the feedback resistors and the associated wiring. Physically locate both resistors near the IC, and route the wiring away from the inductor, especially an open core type of inductor. 22 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 LM2671 www.ti.com SNVS008K - SEPTEMBER 1998 - REVISED APRIL 2013 REVISION HISTORY Changes from Revision J (April 2013) to Revision K * Page Changed layout of National Data Sheet to TI format .......................................................................................................... 22 Submit Documentation Feedback Copyright (c) 1998-2013, Texas Instruments Incorporated Product Folder Links: LM2671 23 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) LM2671LD-ADJ NRND WSON NHN 16 1000 TBD Call TI Call TI -40 to 125 S0008B LM2671LD-ADJ/NOPB ACTIVE WSON NHN 16 1000 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 S0008B LM2671M-12/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 2671 M-12 LM2671M-3.3/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 2671 M3.3 LM2671M-5.0 NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2671 M5.0 LM2671M-5.0/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2671 M5.0 LM2671M-ADJ NRND SOIC D 8 95 TBD Call TI Call TI -40 to 125 2671 MADJ LM2671M-ADJ/NOPB ACTIVE SOIC D 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2671 MADJ LM2671MX-12/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 2671 M-12 LM2671MX-3.3/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 2671 M3.3 LM2671MX-5.0 NRND SOIC D 8 2500 TBD Call TI Call TI -40 to 125 2671 M5.0 LM2671MX-5.0/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2671 M5.0 LM2671MX-ADJ/NOPB ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) SN | CU SN Level-1-260C-UNLIM -40 to 125 2671 MADJ LM2671N-12/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2671 N-12 LM2671N-3.3/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2671 N-3.3 LM2671N-5.0 NRND PDIP P 8 40 TBD Call TI Call TI -40 to 125 LM2671 N-5.0 LM2671N-5.0/NOPB ACTIVE PDIP P 8 40 Green (RoHS & no Sb/Br) SN | CU SN Level-1-NA-UNLIM -40 to 125 LM2671 N-5.0 Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com Orderable Device 1-Nov-2013 Status (1) LM2671N-ADJ/NOPB ACTIVE Package Type Package Pins Package Drawing Qty PDIP P 8 40 Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Green (RoHS & no Sb/Br) SN | CU SN Level-1-NA-UNLIM Op Temp (C) Device Marking (4/5) -40 to 125 LM2671 N-ADJ (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. 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. 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Addendum-Page 2 Samples PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2671LD-ADJ WSON NHN 16 1000 178.0 12.4 5.3 5.3 1.3 8.0 12.0 Q1 LM2671LD-ADJ/NOPB WSON NHN 16 1000 178.0 12.4 5.3 5.3 1.3 8.0 12.0 Q1 LM2671MX-12/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2671MX-3.3/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2671MX-5.0 SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2671MX-5.0/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM2671MX-ADJ/NOPB SOIC D 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 23-Sep-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2671LD-ADJ WSON NHN 16 1000 210.0 185.0 35.0 LM2671LD-ADJ/NOPB WSON NHN 16 1000 213.0 191.0 55.0 LM2671MX-12/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2671MX-3.3/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2671MX-5.0 SOIC D 8 2500 367.0 367.0 35.0 LM2671MX-5.0/NOPB SOIC D 8 2500 367.0 367.0 35.0 LM2671MX-ADJ/NOPB SOIC D 8 2500 367.0 367.0 35.0 Pack Materials-Page 2 MECHANICAL DATA NHN0016A LDA16A (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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