Product Folder Order Now Support & Community Tools & Software Technical Documents LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 LM2678 SIMPLE SWITCHER(R) High Efficiency 5-A Step-Down Voltage Regulator 1 Features 3 Description * * The LM2678 series of regulators are monolithic integrated circuits which provide all of the active functions for a step-down (buck) switching regulator capable of driving up to 5-A loads with excellent line and load regulation characteristics. High efficiency (>90%) is obtained through the use of a low ONresistance DMOS power switch. The series consists of fixed output voltages of 3.3 V, 5 V, and 12 V and an adjustable output version. 1 * * * * * * * * Efficiency Up to 92% Simple and Easy to Design Using Off-the-Shelf External Components 120-m DMOS Output Switch 3.3-V, 5-V, and 12-V Fixed Output and Adjustable (1.2 V to 37 V) Versions 50-A Standby Current When Switched OFF 2% Maximum Output Tolerance Over Full Line and Load Conditions Wide Input Voltage Range: 8 V to 40 V 260-kHz Fixed Frequency Internal Oscillator -40 to 125C Operating Junction Temperature Range Create a Custom Design Using the LM2678 With the WEBENCH(R) Power Designer 2 Applications * * * Simple-to-Design, High Efficiency (>90%) StepDown Switching Regulators Efficient System Preregulator for Linear Voltage Regulators Battery Chargers The SIMPLE SWITCHER(R) concept provides for a complete design using a minimum number of external components. A high fixed frequency oscillator (260 kHz) allows the use of physically smaller sized components. A family of standard inductors for use with the LM2678 are available from several manufacturers to greatly simplify the design process. The LM2678 series also has built-in thermal shutdown, current limiting, and an ON/OFF control input that can power down the regulator to a low 50A quiescent current standby condition. The output voltage is ensured to a 2% tolerance. The clock frequency is controlled to within a 11% tolerance. Device Information(1) PART NUMBER LM2678 PACKAGE BODY SIZE (NOM) TO-263 (7) 10.10 mm x 8.89 mm TO-220 (7) 14.986 mm x 10.16 mm VSON (14) 6.00 mm x 5.00 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Typical Application 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. LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com Table of Contents 1 2 3 4 5 6 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 4 6.1 6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 4 4 4 5 5 5 6 6 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics - 3.3 V .............................. Electrical Characteristics - 5 V ................................. Electrical Characteristics - 12 V ............................... Electrical Characteristics - Adjustable...................... Electrical Characteristics - All Output Voltage Versions ..................................................................... 6.10 Typical Characteristics ............................................ 7 6 7 Detailed Description ............................................ 10 7.1 Overview ................................................................. 10 7.2 Functional Block Diagram ....................................... 10 7.3 Feature Description................................................. 10 7.4 Device Functional Modes........................................ 11 8 Application and Implementation ........................ 12 8.1 Application Information............................................ 12 8.2 Typical Application .................................................. 14 9 Power Supply Recommendations...................... 26 10 Layout................................................................... 26 10.1 Layout Guidelines ................................................. 26 10.2 Layout Example .................................................... 27 11 Device and Documentation Support ................. 28 11.1 11.2 11.3 11.4 11.5 11.6 11.7 Custom Design With WEBENCH(R) Tools ............. Related Documentation......................................... Receiving Notification of Documentation Updates Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 28 28 28 28 28 28 28 12 Mechanical, Packaging, and Orderable Information ........................................................... 29 12.1 VSON Package Devices ....................................... 29 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision J (June 2016) to Revision K Page * Deleted RADJ = 5.6 k .......................................................................................................................................................... 6 * Deleted and updated with new values for Min, Typ and Max ............................................................................................... 6 * Deleted and updated with new values for Min and Max ....................................................................................................... 6 * Changed soft-start pin to ON/OFF pin.................................................................................................................................... 6 * Changed to 200 A from 1.5 mA............................................................................................................................................ 6 * Changed typ and max values to 16 and 15 mA ..................................................................................................................... 6 Changes from Revision I (April 2013) to Revision J Page * Added 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 * Removed all references to Computer Design Software LM267X Made Simple (Version 6.0).............................................. 1 Changes from Revision H (April 2013) to Revision I * 2 Page Changed layout of National Data Sheet to TI format ........................................................................................................... 29 Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 5 Pin Configuration and Functions KTW Package 7-Pin TO-263 Top View NDZ Package 7-Pin TO-220 Top View Not to scale ON/OFF 6 FB 5 NC 4 GND 3 CB 2 Input 1 Switch_output 1 2 3 4 5 6 7 7 Switch_output Input CB GND NC FB ON/OFF Not to scale NHM Package 14-Pin VSON Top View NC 1 14 Switch_output Input 2 13 Switch_output Input 3 12 Switch_output CB 4 11 NC NC 5 10 NC NC 6 9 GND FB 7 8 ON/OFF DAP Not to scale DAP connect to pin 9 Pin Functions PIN NAME I/O DESCRIPTION TO-263, TO-220 VSON Switch output 1 12, 13, 14 O Source pin of the internal high-side FET. This is a switching node. Attached this pin to an inductor and the cathode of the external diode. Input 2 2, 3 I Supply input pin to collector pin of high-side FET. Connect to power supply and input bypass capacitors CIN. Path from VIN pin to high frequency bypass CIN and GND must be as short as possible. CB 3 4 I Boot-strap capacitor connection for high-side driver. Connect a high-quality 100-nF capacitor from CB to VSW Pin. GND 4 9 -- FB 6 7 I Feedback sense input pin. Connect to the midpoint of feedback divider to set VOUT for ADJ version or connect this pin directly to the output capacitor for a fixed output version. ON/OFF 7 8 I Enable input to the voltage regulator. High = ON and low = OFF. Pull this pin high or float to enable the regulator. NC 5 1, 5, 6, 10, 11 -- Power ground pins. Connect to system ground. Ground pins of CIN and COUT. Path to CIN must be as short as possible. No connect pins. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 3 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) (2) MIN MAX UNIT 45 V -0.1 6 V -1 VIN V VSW + 8 V 14 V Input supply voltage Soft-start pin voltage Switch voltage to ground (3) Boost pin voltage Feedback pin voltage -0.3 Power dissipation Soldering temperature Internally limited Wave (4 s) 260 Infrared (10 s) 240 Vapor phase (75 s) 219 Storage temperature, Tstg (1) (2) (3) -65 C 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. The absolute maximum specification of the Switch Voltage to Ground applies to DC voltage. An extended negative voltage limit of -10 V applies to a pulse of up to 20 ns, -6 V of 60 ns and -3 V of up to 100 ns. 6.2 ESD Ratings V(ESD) (1) (2) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) (2) VALUE UNIT 2000 V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. ESD was applied using the human-body model, a 100-pF capacitor discharged through a 1.5-k resistor into each pin. 6.3 Recommended Operating Conditions Supply voltage Junction temperature, TJ 4 Submit Documentation Feedback MIN MAX 8 40 UNIT V -40 125 C Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 6.4 Thermal Information LM2678 THERMAL METRIC (1) RJA Junction-to-ambient thermal resistance (2) (3) (4) (5) (6) (7) (8) KTW (TO-263) NHM (VSON) 7 PINS 7 PINS 14 PINS -- -- See (2) 65 See (3) 45 -- -- See (4) -- 56 -- See (5) -- 35 -- See (6) -- 26 -- See (7) -- -- 55 See (8) -- -- 29 2 2 -- RJC(top) Junction-to-case (top) thermal resistance (1) NDZ (TO-220) UNIT C/W C/W For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. Junction to ambient thermal resistance (no external heat sink) for the 7-lead TO-220 package mounted vertically, with 1/2 inch leads in a socket, or on a PCB with minimum copper area. Junction to ambient thermal resistance (no external heat sink) for the 7-lead TO-220 package mounted vertically, with 1/2 inch leads soldered to a PCB containing approximately 4 square inches of (1 oz.) copper area surrounding the leads. Junction to ambient thermal resistance for the 7-lead DDPAK mounted horizontally against a PCB area of 0.136 square inches (the same size as the DDPAK package) of 1 oz. (0.0014 in. thick) copper. Junction to ambient thermal resistance for the 7-lead DDPAK mounted horizontally against a PCB area of 0.4896 square inches (3.6 times the area of the DDPAK package) of 1 oz. (0.0014 in. thick) copper. Junction to ambient thermal resistance for the 7-lead DDPAK mounted horizontally against a PCB copper area of 1.0064 square inches (7.4 times the area of the DDPAK 3 package) of 1 oz. (0.0014 in. thick) copper. Additional copper area reduces thermal resistance further. Junction to ambient thermal resistance for the 14-lead VSON mounted on a PCB copper area equal to the die attach paddle. Junction to ambient thermal resistance for the 14-lead VSON mounted on a PCB copper area using 12 vias to a second layer of copper equal to die attach paddle. Additional copper area will reduce thermal resistance further. For layout recommendations, see AN-1187 Leadless Leadfram Package (LLP). 6.5 Electrical Characteristics - 3.3 V Specifications apply for TA = TJ = 25C and RADJ = 5.6 k (unless otherwise noted). PARAMETER VOUT Output voltage VIN = 8 V to 40 V, 100 mA IOUT 5 A Efficiency VIN = 12 V, ILOAD = 5 A (1) (2) MIN (1) TYP (2) TJ = 25C 3.234 3.3 TJ = -40C to 125C 3.201 TEST CONDITIONS MAX (1) UNIT 3.366 3.399 V 82% All room temperature limits are 100% tested during production with TA = TJ = 25C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). Typical values are determined with TA = TJ = 25C and represent the most likely norm. 6.6 Electrical Characteristics - 5 V Specifications apply for TA = TJ = 25C and RADJ = 5.6 k (unless otherwise noted). PARAMETER TEST CONDITIONS TJ = 25C VOUT Output voltage VIN = 8 V to 40 V, 100 mA IOUT 5 A Efficiency VIN = 12 V, ILOAD = 5 A (1) (2) TJ = -40C to 125C MIN (1) TYP (2) 4.9 5 4.85 MAX (1) UNIT 5.1 5.15 V 84% All room temperature limits are 100% tested during production with TA = TJ = 25C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). Typical values are determined with TA = TJ = 25C and represent the most likely norm. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 5 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com 6.7 Electrical Characteristics - 12 V Specifications apply for TA = TJ = 25C and RADJ = 5.6 k (unless otherwise noted). PARAMETER VOUT Output voltage VIN = 15 V to 40 V, 100 mA IOUT 5 A Efficiency VIN = 24 V, ILOAD = 5 A (1) (2) MIN (1) TYP (2) MAX (1) TJ = 25C 11.76 12 12.24 TJ = -40C to 125C 11.64 TEST CONDITIONS UNIT V 12.36 92% All room temperature limits are 100% tested during production with TA = TJ = 25C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). Typical values are determined with TA = TJ = 25C and represent the most likely norm. 6.8 Electrical Characteristics - Adjustable Specifications apply for TA = TJ = 25C and RADJ = 5.6 k (unless otherwise noted). PARAMETER VFB Feedback voltage Efficiency VIN = 12 V, ILOAD = 5 A (1) (2) MIN (1) TYP (2) MAX (1) TJ = 25C 1.186 1.21 1.234 TJ = -40C to 125C 1.174 TEST CONDITIONS VIN = 8 V to 40 V, 100 mA IOUT 5 A VOUT programmed for 5 V UNIT 1.246 V 84% All room temperature limits are 100% tested during production with TA = TJ = 25C. All limits at temperature extremes are specified through correlation using standard Quality Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL). Typical values are determined with TA = TJ = 25C and represent the most likely norm. 6.9 Electrical Characteristics - All Output Voltage Versions Specifications are for TA = TJ = 25C, VIN = 12 V for the 3.3-V, 5-V, and adjustable versions, and VIN = 24 V for the 12-V version (unless otherwise noted). PARAMETER TEST CONDITIONS IQ Quiescent current VFEEDBACK = 8 V for 3.3-V, 5-V, and adjustable versions, VFEEDBACK = 15 V for 12-V version ISTBY Standby quiescent current ON/OFF pin = 0 V ICL Current limit IL Output leakage current VIN = 40 V, ON/OFF pin = 0 V RDS(ON) Switch ON-Resistance ISWITCH = 5 A fO Oscillator frequency Measured at switch pin D Duty cycle IBIAS Feedback bias current VON/OFF ON/OFF threshold voltage ION/OFF ON/OFF input current 6 MIN TJ = 25C TYP MAX 4.2 6 50 100 TJ = -40C to 125C TJ = 25C TJ = -40C to 125C 150 6.1 7 5.75 VSWITCH = 0 V VSWITCH = -1 V 16 TJ = 25C 0.12 TJ = -40C to 125C 91% Minimum duty cycle 0% VFEEDBACK = 1.3 V (adjustable version only) 0.14 0.8 TJ = 25C TJ = -40C to 125C Submit Documentation Feedback kHz nA 1.4 TJ = -40C to 125C ON/OFF input = 0 V A 85 TJ = 25C A mA 280 Maximum duty cycle A 15 260 225 mA 200 0.225 TJ = 25C TJ = -40C to 125C 8.3 8.75 UNIT 2 20 45 V A Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 6.10 Typical Characteristics Figure 1. Normalized Output Voltage Figure 2. Line Regulation Figure 3. Efficiency vs Input Voltage Figure 4. Efficiency vs ILOAD Figure 5. Switch Current Limit Figure 6. Operating Quiescent Current Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 7 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com Typical Characteristics (continued) Figure 7. Standby Quiescent Current Figure 8. ON/OFF Threshold Voltage Figure 9. ON/OFF Pin Current (Sourcing) Figure 10. Switching Frequency Continuous Mode Switching Waveforms, VIN = 20 V, VOUT = 5 V, ILOAD = 5 A, L = 10 H, COUT = 400 F, COUTESR = 13 m A. VSW pin voltage = 10 V/div B. Inductor current = 2 A/div C. Output ripple voltage = 20 mV/div AC-coupled Figure 11. Feedback Pin Bias Current 8 Submit Documentation Feedback Figure 12. Horizontal Time Base: 1 s/div Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 Typical Characteristics (continued) Discontinuous Mode Switching Waveforms, VIN = 20 V, VOUT = 5 V, ILOAD = 500 mA, L = 10 H, COUT = 400 F, COUTESR = 13 m A. VSW pin voltage = 10 V/div B. Inductor current = 1 A/div C. Output ripple voltage = 20 mV/div AC-coupled Load Transient Response for Continuous Mode, VIN = 20 V, VOUT = 5 V, L = 10 H, COUT = 400 F, COUTESR = 13 m A. Output voltage = 100 mV/div, AC-coupled B. Load current = 500-mA to 5-A load pulse Figure 13. Horizontal Time Base: 1 s/div Figure 14. Horizontal Time Base: 100 s/div Load Transient Response for Discontinuous Mode, VIN = 20 V, VOUT = 5 V, vs L = 10 H, COUT = 400 F, COUTESR = 13 m A. Output voltage = 100 mV/div, AC-coupled B. Load current = 200-mA to 3-A load pulse Figure 15. Horizontal Time Base: 200 s/div Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 9 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com 7 Detailed Description 7.1 Overview The LM2678 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 5 A, and highly efficient operation. The LM2678 is part of the SIMPLE SWITCHER(R) family of power converters. The design support WEBENCH, can also be used to provide instant component selection, circuit performance calculations for evaluation, a bill of materials component list and a circuit schematic for LM2678. 7.2 Functional Block Diagram 7.3 Feature Description 7.3.1 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 260-kHz 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 pin 1 switches between Vin (switch ON) and below ground by the voltage drop of the external Schottky diode (switch OFF). 10 Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 Feature Description (continued) 7.3.2 Input The input voltage for the power supply is connected to pin 2. In addition to providing energy to the load the input voltage also provides bias for the internal circuitry of the LM2678. For ensured performance the input voltage must be in the range of 8 V to 40 V. For best performance of the power supply the input pin must always be bypassed with an input capacitor located close to pin 2. 7.3.3 C Boost A capacitor must be connected from pin 3 to the switch output, pin 1. 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 0.01 F. 7.3.4 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 LM2678, TI recommends that a broad ground plane be used to minimize signal coupling throughout the circuit. 7.3.5 Feedback This is the input to a two-stage high gain amplifier, which drives the PWM controller. It is necessary to connect pin 6 to the actual output of the power supply to set the DC output voltage. For the fixed output devices (3.3-V, 5V and 12-V outputs), a direct wire connection to the output is all that is required as internal gain setting resistors are provided inside the LM2678. 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. 7.3.6 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 0.8 V is completely turn OFF the regulator. The current drain from the input supply when OFF is only 50 A. Pin 7 has an internal pullup current source of approximately 20 A and a protection clamp Zener diode of 7 V to ground. When electrically driving the ON/OFF pin the high voltage level for the ON condition should not exceed the 6 V absolute maximum limit. When ON/OFF control is not required pin 7 should be left open circuited. 7.4 Device Functional Modes 7.4.1 Shutdown Mode The ON/OFF pin provides electrical ON and OFF control for the LM2678. When the voltage of this pin is lower than 1.4 V, the device enters shutdown mode. The typical standby current in this mode is 45 A. 7.4.2 Active Mode When the voltage of the ON/OFF pin is higher than 1.4 V, the device starts switching and the output voltage rises until it reaches a normal regulation voltage. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 11 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 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 8.1.1 Design Considerations Power supply design using the LM2678 is greatly simplified by using recommended external components. A wide range of inductors, capacitors, and Schottky diodes from several manufacturers have been evaluated for use in designs that cover the full range of capabilities (input voltage, output voltage, and load current) of the LM2678. A simple design procedure using nomographs and component tables provided in this data sheet leads to a working design with very little effort. The individual components from the various manufacturers called out for use are still just a small sample of the vast array of components available in the industry. While these components are recommended, they are not exclusively the only components for use in a design. After a close comparison of component specifications, equivalent devices from other manufacturers could be substituted for use in an application. Important considerations for each external component and an explanation of how the nomographs and selection tables were developed follows. 8.1.2 Inductor The inductor is the key component in a switching regulator. For efficiency the inductor stores energy during the switch ON time and then transfers energy to the load while the switch is OFF. Nomographs are used to select the inductance value required for a given set of operating conditions. The nomographs assume that the circuit is operating in continuous mode (the current flowing through the inductor never falls to zero). The magnitude of inductance is selected to maintain a maximum ripple current of 30% of the maximum load current. If the ripple current exceeds this 30% limit the next larger value is selected. The inductors offered have been specifically manufactured to provide proper operation under all operating conditions of input and output voltage and load current. Several part types are offered for a given amount of inductance. Both surface mount and through-hole devices are available. The inductors from each of the three manufacturers have unique characteristics. * Renco: ferrite stick core inductors; benefits are typically lowest cost and can withstand ripple and transient peak currents above the rated value. These inductors have an external magnetic field, which may generate EMI. * Pulse Engineering: powdered iron toroid core inductors; these also can withstand higher than rated currents and, being toroid inductors, have low EMI. * Coilcraft: ferrite drum core inductors; these are the smallest physical size inductors and are available only as surface mount components. These inductors also generate EMI but less than stick inductors. 8.1.3 Output Capacitor The output capacitor acts to smooth the DC output voltage and also provides energy storage. Selection of an output capacitor, with an associated equivalent series resistance (ESR), impacts both the amount of output ripple voltage and stability of the control loop. The output ripple voltage of the power supply is the product of the capacitor ESR and the inductor ripple current. The capacitor types recommended in the tables were selected for having low ESR ratings. In addition, both surface mount tantalum capacitors and through-hole aluminum electrolytic capacitors are offered as solutions. 12 Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 Application Information (continued) Impacting frequency stability of the overall control loop, the output capacitance, in conjunction with the inductor, creates a double pole inside the feedback loop. In addition the capacitance and the ESR value create a zero. These frequency response effects together with the internal frequency compensation circuitry of the LM2678 modify the gain and phase shift of the closed-loop system. As a general rule for stable switching regulator circuits it is desired to have the unity gain bandwidth of the circuit to be limited to no more than one-sixth of the controller switching frequency. With the fixed 260-kHz switching frequency of the LM2678, the output capacitor is selected to provide a unity gain bandwidth of 40 kHz maximum. Each recommended capacitor value has been chosen to achieve this result. In some cases multiple capacitors are required either to reduce the ESR of the output capacitor, to minimize output ripple (a ripple voltage of 1% of VOUT or less is the assumed performance condition), or to increase the output capacitance to reduce the closed loop unity gain bandwidth (to less than 40 kHz). When parallel combinations of capacitors are required it has been assumed that each capacitor is the exact same part type. The RMS current and working voltage (WV) ratings of the output capacitor are also important considerations. In a typical step-down switching regulator, the inductor ripple current (set to be no more than 30% of the maximum load current by the inductor selection) is the current that flows through the output capacitor. The capacitor RMS current rating must be greater than this ripple current. The voltage rating of the output capacitor should be greater than 1.3 times the maximum output voltage of the power supply. If operation of the system at elevated temperatures is required, the capacitor voltage rating may be de-rated to less than the nominal room temperature rating. Careful inspection of the manufacturer's specification for de-rating of working voltage with temperature is important. 8.1.4 Input Capacitor Fast changing currents in high current switching regulators place a significant dynamic load on the unregulated power source. An input capacitor helps to provide additional current to the power supply as well as smooth out input voltage variations. Like the output capacitor, the key specifications for the input capacitor are RMS current rating and working voltage. The RMS current flowing through the input capacitor is equal to one-half of the maximum DC load current so the capacitor should be rated to handle this. Paralleling multiple capacitors proportionally increases the current rating of the total capacitance. The voltage rating should also be selected to be 1.3 times the maximum input voltage. Depending on the unregulated input power source, under light load conditions the maximum input voltage could be significantly higher than normal operation and should be considered when selecting an input capacitor. The input capacitor must be placed very close to the input pin of the LM2678. Due to relative high current operation with fast transient changes, the series inductance of input connecting wires or PCB traces can create ringing signals at the input terminal which could possibly propagate to the output or other parts of the circuitry. It may be necessary in some designs to add a small valued (0.1 F to 0.47 F) ceramic type capacitor in parallel with the input capacitor to prevent or minimize any ringing. 8.1.5 Catch Diode When the power switch in the LM2678 turns OFF, the current through the inductor continues to flow. The path for this current is through the diode connected between the switch output and ground. This forward biased diode clamps the switch output to a voltage less than ground. This negative voltage must be greater than -1 V so a low voltage drop (particularly at high current levels) Schottky diode is recommended. Total efficiency of the entire power supply is significantly impacted by the power lost in the output catch diode. The average current through the catch diode is dependent on the switch duty cycle (D) and is equal to the load current times (1-D). Use of a diode rated for much higher current than is required by the actual application helps to minimize the voltage drop and power loss in the diode. During the switch ON time the diode will be reversed biased by the input voltage. The reverse voltage rating of the diode must be at least 1.3 times greater than the maximum input voltage. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 13 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com Application Information (continued) 8.1.6 Boost Capacitor The boost capacitor creates a voltage used to overdrive the gate of the internal power MOSFET. This improves efficiency by minimizing the ON-resistance of the switch and associated power loss. For all applications it is recommended to use a 0.01-F, 50-V ceramic capacitor. 8.1.7 Additional Application Information When the output voltage is greater than approximately 6 V, and the duty cycle at minimum input voltage is greater than approximately 50%, the designer should exercise caution in selection of the output filter components. When an application designed to these specific operating conditions is subjected to a current limit fault condition, it may be possible to observe a large hysteresis in the current limit. This can affect the output voltage of the device until the load current is reduced sufficiently to allow the current limit protection circuit to reset itself. Under current limiting conditions, the LM267x is designed to respond in the following manner: 1. At the moment when the inductor current reaches the current limit threshold, the ON-pulse is immediately terminated. This happens for any application condition. 2. However, the current limit block is also designed to momentarily reduce the duty cycle to below 50% to avoid subharmonic oscillations, which could cause the inductor to saturate. 3. Thereafter, once the inductor current falls below the current limit threshold, there is a small relaxation time during which the duty cycle progressively rises back above 50% to the value required to achieve regulation. If the output capacitance is sufficiently large, it may be possible that as the output tries to recover, the output capacitor charging current is large enough to repeatedly re-trigger the current limit circuit before the output has fully settled. This condition is exacerbated with higher output voltage settings because the energy requirement of the output capacitor varies as the square of the output voltage (1/2 CV2), thus requiring an increased charging current. A simple test to determine if this condition might exist for a suspect application is to apply a short circuit across the output of the converter, and then remove the shorted output condition. In an application with properly selected external components, the output will recover smoothly. Practical values of external components that have been experimentally found to work well under these specific operating conditions are COUT = 47 F, L = 22 H. It should be noted that even with these components, for a device's current limit of ICLIM, the maximum load current under which the possibility of the large current limit hysteresis can be minimized is ICLIM/2. For example, if the input is 24 V and the set output voltage is 18 V, then for a desired maximum current of 1.5 A, the current limit of the chosen switcher must be confirmed to be at least 3 A. Under extreme overcurrent or short circuit conditions, the LM267X employs frequency foldback in addition to the current limit. If the cycle-by-cycle inductor current increases above the current limit threshold (due to short circuit or inductor saturation for example) the switching frequency is automatically reduced to protect the IC. Frequency below 100 kHz is typical for an extreme short-circuit condition. 8.2 Typical Application 8.2.1 All Output Voltage Versions Figure 16. Typical Application for All Output Voltage Versions 14 Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 Typical Application (continued) 8.2.1.1 Design Requirements Select the power supply operating conditions and the maximum output current and follow below procedures to find the external components for LM2678. 8.2.1.2 Detailed Design Procedure 8.2.1.2.1 Custom Design With WEBENCH(R) Tools Click here to create a custom design using the LM2678 device with the WEBENCH(R) Power Designer. 1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements. 2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial. 3. Compare the generated design with other possible solutions from Texas Instruments. The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time pricing and component availability. In most cases, these actions are available: * Run electrical simulations to see important waveforms and circuit performance * Run thermal simulations to understand board thermal performance * Export customized schematic and layout into popular CAD formats * Print PDF reports for the design, and share the design with colleagues Get more information about WEBENCH tools at www.ti.com/WEBENCH. Using the nomographs and tables in this data sheet (or use the available design software at www.ti.com) a complete step-down regulator can be designed in a few simple steps. Step 1: Define the power supply operating conditions: * Required output voltage * Maximum DC input voltage * Maximum output load current Step 2: Set the output voltage by selecting a fixed output LM2678 (3.3-V, 5-V, or 12-V applications) or determine the required feedback resistors for use with the adjustable LM2678-ADJ Step 3: Determine the inductor required by using one of the four nomographs, Figure 17 through Figure 20. Table 3 provides a specific manufacturer and part number for the inductor. Step 4: Using Table 5 (fixed output voltage) or Table 9 (adjustable output voltage), determine the output capacitance required for stable operation. Table 1 provides the specific capacitor type from the manufacturer of choice. Step 5: Determine an input capacitor from Table 5 for fixed output voltage applications. Use Table 1 to find the specific capacitor type. For adjustable output circuits select a capacitor from Table 1 with a sufficient working voltage (WV) rating greater than VIN max, and an RMS current rating greater than one-half the maximum load current (2 or more capacitors in parallel may be required). Step 6: Select a diode from Table 4. The current rating of the diode must be greater than ILOAD max and the reverse voltage rating must be greater than VIN maximum. Step 7: Include a 0.01-F, 50-V capacitor for CBOOST in the design. 8.2.1.2.2 Capacitor Selection Guides Table 1. Input and Output Capacitor Codes - Surface Mount CAPACITOR REFERENCE CODE SURFACE MOUNT AVX TPS SERIES SPRAGUE 594D SERIES KEMET T495 SERIES C (F) WV (V) Irms (A) C (F) WV (V) Irms (A) C (F) WV (V) Irms (A) C1 330 6.3 1.15 120 6.3 1.1 100 6.3 0.82 C2 100 10 1.1 220 6.3 1.4 220 6.3 1.1 Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 15 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com Typical Application (continued) Table 1. Input and Output Capacitor Codes - Surface Mount (continued) CAPACITOR REFERENCE CODE 16 SURFACE MOUNT AVX TPS SERIES SPRAGUE 594D SERIES KEMET T495 SERIES C (F) WV (V) Irms (A) C (F) WV (V) Irms (A) C (F) WV (V) Irms (A) C3 220 10 1.15 68 10 1.05 330 6.3 1.1 C4 47 16 0.89 150 10 1.35 100 10 1.1 C5 100 16 1.15 47 16 1 150 10 1.1 C6 33 20 0.77 100 16 1.3 220 10 1.1 C7 68 20 0.94 180 16 1.95 33 20 0.78 C8 22 25 0.77 47 20 1.15 47 20 0.94 C9 10 35 0.63 33 25 1.05 68 20 0.94 C10 22 35 0.66 68 25 1.6 10 35 0.63 C11 -- -- -- 15 35 0.75 22 35 0.63 C12 -- -- -- 33 35 1 4.7 50 0.66 C13 -- -- -- 15 50 0.9 -- -- -- Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 Table 2. Input and Output Capacitor Codes - Through Hole CAPACITOR REFERENCE CODE THROUGH HOLE SANYO OS-CON SA SERIES SANYO MV-GX SERIES NICHICON PL SERIES PANASONIC HFQ SERIES C (F) WV (V) Irms (A) C (F) WV (V) Irms (A) C (F) WV (V) Irms (A) C (F) WV (V) C1 47 6.3 1 1000 6.3 0.8 680 10 0.8 82 35 Irms (A) 0.4 C2 150 6.3 1.95 270 16 0.6 820 10 0.98 120 35 0.44 C3 330 6.3 2.45 470 16 0.75 1000 10 1.06 220 35 0.76 C4 100 10 1.87 560 16 0.95 1200 10 1.28 330 35 1.01 C5 220 10 2.36 820 16 1.25 2200 10 1.71 560 35 1.4 C6 33 16 0.96 1000 16 1.3 3300 10 2.18 820 35 1.62 C7 100 16 1.92 150 35 0.65 3900 10 2.36 1000 35 1.73 C8 150 16 2.28 470 35 1.3 6800 10 2.68 2200 35 2.8 0.36 C9 100 20 2.25 680 35 1.4 180 16 0.41 56 50 C10 47 25 2.09 1000 35 1.7 270 16 0.55 100 50 0.5 C11 -- -- -- 220 63 0.76 470 16 0.77 220 50 0.92 C12 -- -- -- 470 63 1.2 680 16 1.02 470 50 1.44 C13 -- -- -- 680 63 1.5 820 16 1.22 560 50 1.68 C14 -- -- -- 1000 63 1.75 1800 16 1.88 1200 50 2.22 C15 -- -- -- -- -- -- 220 25 0.63 330 63 1.42 C16 -- -- -- -- -- -- 220 35 0.79 1500 63 2.51 C17 -- -- -- -- -- -- 560 35 1.43 -- -- -- C18 -- -- -- -- -- -- 2200 35 2.68 -- -- -- C19 -- -- -- -- -- -- 150 50 0.82 -- -- -- C20 -- -- -- -- -- -- 220 50 1.04 -- -- -- C21 -- -- -- -- -- -- 330 50 1.3 -- -- -- C22 -- -- -- -- -- -- 100 63 0.75 -- -- -- C23 -- -- -- -- -- -- 390 63 1.62 -- -- -- C24 -- -- -- -- -- -- 820 63 2.22 -- -- -- C25 -- -- -- -- -- -- 1200 63 2.51 -- -- -- Table 3. Inductor Manufacturer Part Numbers INDUCTOR REFERENCE NUMBER INDUCTANCE (H) CURRENT (A) L23 33 L24 22 L25 RENCO PULSE ENGINEERING THROUGH HOLE SURFACE MOUNT 1.35 RL-5471-7 1.65 RL-1283-22-43 15 2 L29 100 L30 L31 COILCRAFT THROUGH HOLE SURFACE MOUNT SURFACE MOUNT RL1500-33 PE-53823 PE-53823S DO3316-333 RL1500-22 PE-53824 PE-53824S DO3316-223 RL-1283-15-43 RL1500-15 PE-53825 PE-53825S DO3316-153 1.41 RL-5471-4 RL-6050-100 PE-53829 PE-53829S DO5022P-104 68 1.71 RL-5471-5 RL6050-68 PE-53830 PE-53830S DO5022P-683 47 2.06 RL-5471-6 RL6050-47 PE-53831 PE-53831S DO5022P-473 L32 33 2.46 RL-5471-7 RL6050-33 PE-53932 PE-53932S DO5022P-333 L33 22 3.02 RL-1283-22-43 RL6050-22 PE-53933 PE-53933S DO5022P-223 L34 15 3.65 RL-1283-15-43 -- PE-53934 PE-53934S DO5022P-153 L38 68 2.97 RL-5472-2 -- PE-54038 PE-54038S -- L39 47 3.57 RL-5472-3 -- PE-54039 PE-54039S -- L40 33 4.26 RL-1283-33-43 -- PE-54040 PE-54040S -- L41 22 5.22 RL-1283-22-43 -- PE-54041 P0841 -- L44 68 3.45 RL-5473-3 -- PE-54044 -- -- L45 10 4.47 RL-1283-10-43 -- -- P0845 DO5022P-103HC L46 15 5.6 RL-1283-15-43 -- -- P0846 DO5022P-153HC L47 10 5.66 RL-1283-10-43 -- -- P0847 DO5022P-103HC L48 47 5.61 RL-1282-47-43 -- -- P0848 -- L49 33 5.61 RL-1282-33-43 -- -- P0849 -- Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 17 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com Table 4. Schottky Diode Selection Table SURFACE MOUNT REVERSE VOLTAGE (V) 20 5 A OR MORE SK32 -- SK33 30 30WQ03F 40 50 or more THROUGH HOLE 3A MBRD835L 3A 5 A OR MORE 1N5820 -- SR302 1N5821 -- 31DQ03 SK34 MBRD1545CT 1N5822 1N5825 30BQ040 6TQ045S MBR340 MBR745 30WQ04F -- 31DQ04 80SQ045 MBRS340 -- SR403 6TQ045 MBRD340 -- -- -- SK35 -- MBR350 -- 30WQ05F -- 31DQ05 -- -- -- SR305 -- 8.2.1.3 Application Curves For continuous mode operation 18 Figure 17. LM2678-3.3 Figure 18. LM2678-5 Figure 19. LM2678-12 Figure 20. LM2678-Adjustable Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 8.2.2 Fixed Output Voltage Design Example Figure 21. Basic Circuit for Fixed Output Voltage Applications 8.2.2.1 Detailed Design Procedure A system logic power supply bus of 3.3 V is to be generated from a wall adapter which provides an unregulated DC voltage of 13 V to 16 V. The maximum load current is 4 A. Through-hole components are preferred. Step 1: Operating conditions are: * VOUT = 3.3 V * VIN max = 16 V * ILOAD max = 4 A Step 2: Select a LM2678 3.3-V. The output voltage has a tolerance of 2% at room temperature and 3% over the full operating temperature range. Step 3: Use the nomograph for the 3.3-V device, Figure 17. The intersection of the 16-V horizontal line (Vin max) and the 4-A vertical line (Iload max) indicates that L46, a 15-H inductor, is required. From Table 3, L46 in a through-hole component is available from Renco with part number RL-1283-15-43. Step 4: Use Table 5 to determine an output capacitor. With a 3.3-V output and a 15-H inductor there are four through-hole output capacitor solutions with the number of same type capacitors to be paralleled and an identifying capacitor code given. Table 1 provides the actual capacitor characteristics. Any of the following choices work in the circuit: * 2 x 220-F, 10-V Sanyo OS-CON (code C5) * 2 x 820-F, 16-V Sanyo MV-GX (code C5) * 1 x 3900-F, 10-V Nichicon PL (code C7) * 2 x 560-F, 35-V Panasonic HFQ (code C5) Step 5: Use Table 5 to select an input capacitor. With 3.3-V output and 15 H there are three through-hole solutions. These capacitors provide a sufficient voltage rating and an RMS current rating greater than 2 A (1/2 Iload max). Again using Table 1 for specific component characteristics the following choices are suitable: * 2 x 680-F, 63-V Sanyo MV-GX (code C13) * 1 x 1200-F, 63-V Nichicon PL (code C25) * 1 x 1500-F, 63-V Panasonic HFQ (code C16) Step 6: From Table 4 a 5-A or more Schottky diode must be selected. For through-hole components only 40-V rated diodes are indicated and 4 part types are suitable: * 1N5825 * MBR745 * 80SQ045 * 6TQ045 Step 7: A 0.01-F capacitor is used for CBOOST. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 19 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com 8.2.2.1.1 Capacitor Selection Table 5. Output Capacitors for Fixed Output Voltage Application--Surface Mount (1) (2) SURFACE MOUNT OUTPUT VOLTAGE (V) INDUCTANCE (H) 3.3 5 12 (1) (2) AVX TPS SERIES SPRAGUE 594D SERIES KEMET T495 SERIES NO. C CODE NO. C CODE NO. C CODE 10 5 C1 5 C1 5 C2 15 4 C1 4 C1 4 C3 22 3 C2 2 C7 3 C4 33 1 C1 2 C7 3 C4 10 4 C2 4 C6 4 C4 15 3 C3 2 C7 3 C5 22 3 C2 2 C7 3 C4 33 2 C2 2 C3 2 C4 47 2 C2 1 C7 2 C4 10 4 C5 3 C6 5 C9 15 3 C5 2 C7 4 C9 22 2 C5 2 C6 3 C8 33 2 C5 1 C7 3 C8 47 2 C4 1 C6 2 C8 68 1 C5 1 C5 2 C7 100 1 C4 1 C5 1 C8 No. represents the number of identical capacitor types to be connected in parallel. C Code indicates the Capacitor Reference number in Table 1 and Table 2 for identifying the specific component from the manufacturer. Table 6. Output Capacitors for Fixed Output Voltage Application--Through Hole (1) (2) THROUGH HOLE OUTPUT VOLTAGE (V) 3.3 5 12 (1) (2) 20 INDUCTAN CE (H) SANYO OS-CON SA SERIES SANYO MV-GX SERIES NICHICON PL SERIES PANASONIC HFQ SERIES NO. C CODE NO. C CODE NO. C CODE NO. C CODE 10 2 C5 2 C6 1 C8 2 C6 15 2 C5 2 C5 1 C7 2 C5 22 1 C5 1 C10 1 C5 1 C7 33 1 C5 1 C10 1 C5 1 C7 10 2 C4 2 C5 1 C6 2 C5 15 1 C5 1 C10 1 C5 1 C7 22 1 C5 1 C9 1 C5 1 C5 33 1 C4 1 C5 1 C4 1 C4 47 1 C4 1 C4 1 C2 2 C4 10 2 C7 1 C10 1 C14 2 C4 15 1 C8 1 C6 1 C17 1 C5 22 1 C7 1 C5 1 C13 1 C5 33 1 C7 1 C4 1 C12 1 C4 47 1 C7 1 C3 1 C11 1 C3 68 1 C6 1 C2 1 C10 1 C3 100 1 C6 1 C2 1 C9 1 C1 No. represents the number of identical capacitor types to be connected in parallel. C Code indicates the Capacitor Reference number in Table 1 and Table 2 for identifying the specific component from the manufacturer. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 Table 7. Input Capacitors for Fixed Output Voltage Application--Surface Mount (1) (2) (3) SURFACE MOUNT OUTPUT VOLTAGE (V) INDUCTANCE (H) 3.3 5 12 (1) (2) (3) (4) AVX TPS SERIES SPRAGUE 594D SERIES KEMET T495 SERIES NO. C CODE NO. C CODE NO. 10 3 C7 2 C10 3 C9 15 See (4) See (4) 3 C13 4 C12 22 See (4) See (4) 2 C13 3 C12 33 See (4) (4) 2 C13 3 C12 10 3 C4 2 C6 3 C9 15 4 C9 3 C12 4 C10 22 See (4) See (4) 3 C13 4 C12 33 See (4) See (4) 2 C13 3 C12 47 See (4) See (4) 1 C13 2 C12 10 4 C9 2 C10 4 C10 15 4 C8 2 C10 4 C10 22 4 C9 3 C12 4 C10 33 See (4) See (4) 3 C13 4 C12 47 See (4) (4) 2 C13 3 C12 68 See (4) See (4) 2 C13 2 C12 100 See (4) See (4) 1 C13 2 C12 See See C CODE No. represents the number of identical capacitor types to be connected in parallel. C Code indicates the Capacitor Reference number in Table 1 and Table 2 for identifying the specific component from the manufacturer. Assumes worst case maximum input voltage and load current for a given inductance value. Check voltage rating of capacitors to be greater than application input voltage. Table 8. Input Capacitors for Fixed Output Voltage Application--Through Hole (1) (2) (3) THROUGH HOLE OUTPUT VOLTAGE (V) INDUCTAN CE (H) SANYO OS-CON SA SERIES NO. 3.3 5 12 (1) (2) (3) (4) SANYO MV-GX SERIES C CODE NO. NICHICON PL SERIES PANASONIC HFQ SERIES C CODE NO. C CODE NO. C CODE 10 2 C9 2 C8 1 C18 1 C8 15 See (4) See (4) 2 C13 1 C25 1 C16 22 See (4) See (4) 1 C14 1 C24 1 C16 33 See (4) (4) 1 C14 1 C24 1 C16 10 2 C7 2 C8 1 C25 1 C8 15 See (4) See (4) 2 C8 1 C25 1 C8 22 See (4) (4) 2 C13 1 C25 1 C16 33 See (4) See (4) 1 C14 1 C23 1 C13 47 See (4) See (4) 1 C12 1 C19 1 C11 10 2 C10 2 C8 1 C18 1 C8 C8 See See 15 2 C10 2 C8 1 C18 1 22 See (4) See (4) 2 C8 1 C18 1 C8 33 See (4) See (4) 2 C12 1 C24 1 C14 47 See (4) See (4) 1 C14 1 C23 1 C13 68 See (4) See (4) 1 C13 1 C21 1 C15 100 See (4) See (4) 1 C11 1 C22 1 C11 No. represents the number of identical capacitor types to be connected in parallel. C Code indicates the Capacitor Reference number in Table 1 and Table 2 for identifying the specific component from the manufacturer. Assumes worst case maximum input voltage and load current for a given inductance value. Check voltage rating of capacitors to be greater than application input voltage. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 21 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com 8.2.3 Adjustable Output Design Example Figure 22. Basic Circuit for Adjustable Output Voltage Applications 8.2.3.1 Detailed Design Procedure In this example it is desired to convert the voltage from a two battery automotive power supply (voltage range of 20 V to 28 V, typical in large truck applications) to the 14.8-VDC alternator supply typically used to power electronic equipment from single battery 12-V vehicle systems. The load current required is 3.5 A maximum. It is also desired to implement the power supply with all surface mount components. Step 1: Operating conditions are: * VOUT = 14.8 V * VIN max = 28 V * ILOAD max = 3.5 A Step 2: Select an LM2678S-ADJ. To set the output voltage to 14.9-V two resistors need to be chosen (R1 and R2 in Figure 22). For the adjustable device the output voltage is set by Equation 1. where * VFB is the feedback voltage of typically 1.21 V (1) A recommended value to use for R1 is 1k. In this example then R2 is determined with Equation 2. where * R2 = 11.23 k (2) The closest standard 1% tolerance value to use is 11.3 k. This sets the nominal output voltage to 14.88 V which is within 0.5% of the target value. Step 3: To use the nomograph for the adjustable device, Figure 20, requires a calculation of the inductor Volt * microsecond constant (E * T expressed in V * S) from Equation 3. where * 22 VSAT is the voltage drop across the internal power switch which is Rds(ON) times Iload Submit Documentation Feedback (3) Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 In this example this would be typically 0.12 x 3.5 A or 0.42 V and VD is the voltage drop across the forward biased Schottky diode, typically 0.5 V. The switching frequency of 260 kHz is the nominal value to use to estimate the ON time of the switch during which energy is stored in the inductor. For this example, E * T is found with Equation 4 and Equation 5. (4) (5) Using Figure 20, the intersection of 27 V * S horizontally and the 3.5 A vertical line (ILOAD max) indicates that L48 , a 47-H inductor, or L49, a 33-H inductor could be used. Either inductor will be suitable, but for this example selecting the larger inductance results in lower ripple current. From Table 3, L48 in a surface mount component is available from Pulse Engineering with part number P0848. Step 4: Use Table 9 to determine an output capacitor. With a 14.8-V output the 12.5 to 15 V row is used and with a 47-H inductor there are three surface mount output capacitor solutions. Table 1 provides the actual capacitor characteristics based on the C Code number. Any of the following choices can be used: * 1 x 33-F, 20-V AVX TPS (code C6) * 1 x 47-F, 20-V Sprague 594 (code C8) * 1 x 47-F, 20-V Kemet T495 (code C8) NOTE When using the adjustable device in low voltage applications (less than 3-V output), if the nomograph Figure 20 selects an inductance of 22 H or less Table 9 and Table 10 do not provide an output capacitor solution. With these conditions the number of output capacitors required for stable operation becomes impractical. TI recommends using either a 33-H or 47-H inductor and the output capacitors from Table 9 and Table 10. Step 5: An input capacitor for this example requires at least a 35-V WV rating with an RMS current rating of 1.75 A (1/2 IOUT max). Table 1 shows that C12, a 33-F, 35-V capacitor from Sprague, has the highest voltage and current rating of the surface mount components and that two of these capacitor in parallel are adequate. Step 6: From Table 4 a 5-A or more Schottky diode must be selected. For surface mount diodes with a margin of safety on the voltage rating one of two diodes can be used: * MBRD1545CT * 6TQ045S Step 7: A 0.01-F capacitor is used for CBOOST. 8.2.3.1.1 Capacitor Selection Table 9. Output Capacitors for Adjustable Output Voltage Applications--Surface Mount (1) (2) SURFACE MOUNT OUTPUT VOLTAGE (V) 1.21 to 2.5 2.5 to 3.75 3.75 to 5 (1) (2) (3) INDUCTANCE (H) AVX TPS SERIES SPRAGUE 594D SERIES KEMET T495 SERIES NO. C CODE NO. C CODE NO. C CODE 33 (3) 7 C1 6 C2 7 C3 47 (3) 5 C1 4 C2 5 C3 (3) 4 C1 3 C2 4 C3 47 (3) 3 C1 2 C2 3 C3 22 4 C1 3 C2 4 C3 33 3 C1 2 C2 3 C3 47 2 C1 2 C2 2 C3 33 No. represents the number of identical capacitor types to be connected in parallel. C Code indicates the Capacitor Reference number in Table 1 and Table 2 for identifying the specific component from the manufacturer. Set to a higher value for a practical design solution. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 23 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com Table 9. Output Capacitors for Adjustable Output Voltage Applications--Surface Mount(1)(2) (continued) SURFACE MOUNT OUTPUT VOLTAGE (V) 5 to 6.25 6.25 to 7.5 7.5 to 10 10 to 12.5 12.5 to 15 15 to 20 20 to 30 30 to 37 24 INDUCTANCE (H) AVX TPS SERIES SPRAGUE 594D SERIES KEMET T495 SERIES NO. C CODE NO. C CODE NO. C CODE 22 3 C2 3 C3 3 C4 33 2 C2 2 C3 2 C4 47 2 C2 2 C3 2 C4 68 1 C2 1 C3 1 C4 22 3 C2 1 C4 3 C4 33 2 C2 1 C3 2 C4 47 1 C3 1 C4 1 C6 68 1 C2 1 C3 1 C4 33 2 C5 1 C6 2 C8 47 1 C5 1 C6 2 C8 68 1 C5 1 C6 1 C8 100 1 C4 1 C5 1 C8 33 1 C5 1 C6 2 C8 47 1 C5 1 C6 2 C8 68 1 C5 1 C6 1 C8 100 1 C5 1 C6 1 C8 33 1 C6 1 C8 1 C8 47 1 C6 1 C8 1 C8 68 1 C6 1 C8 1 C8 100 1 C6 1 C8 1 C8 33 1 C8 1 C10 2 C10 47 1 C8 1 C9 2 C10 68 1 C8 1 C9 2 C10 100 1 C8 1 C9 1 C10 33 2 C9 2 C11 2 C11 47 1 C10 1 C12 1 C11 68 1 C9 1 C12 1 C11 100 1 C9 1 C12 1 C11 10 4 C13 8 C12 15 3 C13 5 C12 22 2 C13 4 C12 1 C13 3 C12 47 1 C13 2 C12 68 1 C13 2 C12 33 No values available Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 Table 10. Output Capacitors for Adjustable Output Voltage Applications--Through Hole (1) (2) THROUGH HOLE OUTPUT VOLTAGE (V) 1.21 to 2.5 2.5 to 3.75 3.75 to 5 5 to 6.25 6.25 to 7.5 7.5 to 10 10 to 12.5 12.5 to 15 15 to 20 20 to 30 30 to 37 (1) (2) (3) INDUCTANCE (H) SANYO OS-CON SA SERIES SANYO MV-GX SERIES NICHICON PL SERIES PANASONIC HFQ SERIES NO. C CODE NO. C CODE NO. C CODE NO. C CODE 33 (3) 2 C3 5 C1 5 C3 3 C (3) 2 C2 4 C1 3 C3 2 C5 33 (3) 1 C3 3 C1 3 C1 2 C5 47 (3) 1 C2 2 C1 2 C3 1 C5 22 1 C3 3 C1 3 C1 2 C5 33 1 C2 2 C1 2 C1 1 C5 47 1 C2 2 C1 1 C3 1 C5 22 1 C5 2 C6 2 C3 2 C5 33 1 C4 1 C6 2 C1 1 C5 47 1 C4 1 C6 1 C3 1 C5 68 1 C4 1 C6 1 C1 1 C5 22 1 C5 1 C6 2 C1 1 C5 33 1 C4 1 C6 1 C3 1 C5 47 1 C4 1 C6 1 C1 1 C5 68 1 C4 1 C2 1 C1 1 C5 33 1 C7 1 C6 1 C14 1 C5 47 1 C7 1 C6 1 C14 1 C5 68 1 C7 1 C2 1 C14 1 C2 100 1 C7 1 C2 1 C14 1 C2 33 1 C7 1 C6 1 C14 1 C5 47 1 C7 1 C2 1 C14 1 C5 47 68 1 C7 1 C2 1 C9 1 C2 100 1 C7 1 C2 1 C9 1 C2 33 1 C9 1 C10 1 C15 1 C2 47 1 C9 1 C10 1 C15 1 C2 68 1 C9 1 C10 1 C15 1 C2 100 1 C9 1 C10 1 C15 1 C2 33 1 C10 1 C7 1 C15 1 C2 47 1 C10 1 C7 1 C15 1 C2 68 1 C10 1 C7 1 C15 1 C2 100 1 C10 1 C7 1 C15 1 C2 33 1 C7 1 C16 1 C2 47 1 C7 1 C16 1 C2 1 C7 1 C16 1 C2 68 No values available 100 1 C7 1 C16 1 C2 10 1 C12 1 C20 1 C10 15 1 C11 1 C20 1 C11 22 1 C11 1 C20 1 C10 33 No values available 1 C11 1 C20 1 C10 47 1 C11 1 C20 1 C10 68 1 C11 1 C20 1 C10 No. represents the number of identical capacitor types to be connected in parallel. C Code indicates the Capacitor Reference number in Table 1 and Table 2 for identifying the specific component from the manufacturer. Set to a higher value for a practical design solution. Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 25 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com 9 Power Supply Recommendations The LM2678 is designed to operate from an input voltage supply up to 40 V. This input supply must be well regulated and able to withstand maximum input current and maintain a stable voltage. 10 Layout 10.1 Layout Guidelines Board layout is critical for the proper operation of switching power supplies. First, the ground plane area must be sufficient for thermal dissipation purposes. Second, appropriate guidelines must be followed to reduce the effects of switching noise. Switch mode converters are very fast switching devices. In such cases, the rapid increase of input current combined with the parasitic trace inductance generates unwanted L di/dt noise spikes. The magnitude of this noise tends to increase as the output current increases. This noise may turn into electromagnetic interference (EMI) and can also cause problems in device performance. Therefore, take care in layout to minimize the effect of this switching noise. The most important layout rule is to keep the AC current loops as small as possible. Figure 23 shows the current flow in a buck converter. The top schematic shows a dotted line which represents the current flow during the top switch ON-state. The middle schematic shows the current flow during the top switch OFF-state. The bottom schematic shows the currents referred to as AC currents. These AC currents are the most critical because they are changing in a very short time period. The dotted lines of the bottom schematic are the traces to keep as short and wide as possible. This will also yield a small loop area reducing the loop inductance. To avoid functional problems due to layout, review the PCB layout example. Best results are achieved if the placement of the LM2679 device, the bypass capacitor, the Schottky diode, RFBB, RFBT, and the inductor are placed as shown in the example. Note that, in the layout shown, R1 = RFBB and R2 = RFBT. It is also recommended to use 2-oz. copper boards or heavier to help thermal dissipation and to reduce the parasitic inductances of board traces. See AN-1229 SIMPLE SWITCHER(R) PCB Layout Guidelines for more information. Figure 23. Typical Current Flow in Buck Regulator 26 Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 10.2 Layout Example Figure 24. Top Layer Foil Pattern of Printed-Circuit Board Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 27 LM2678 SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 www.ti.com 11 Device and Documentation Support 11.1 Custom Design With WEBENCH(R) Tools Click here to create a custom design using the LM2678 device with the WEBENCH(R) Power Designer. 1. Start by entering the input voltage (VIN), output voltage (VOUT), and output current (IOUT) requirements. 2. Optimize the design for key parameters such as efficiency, footprint, and cost using the optimizer dial. 3. Compare the generated design with other possible solutions from Texas Instruments. The WEBENCH Power Designer provides a customized schematic along with a list of materials with real-time pricing and component availability. In most cases, these actions are available: * Run electrical simulations to see important waveforms and circuit performance * Run thermal simulations to understand board thermal performance * Export customized schematic and layout into popular CAD formats * Print PDF reports for the design, and share the design with colleagues Get more information about WEBENCH tools at www.ti.com/WEBENCH. 11.2 Related Documentation For related documentation see the following: * AN-1187 Leadless Leadfram Package (LLP) (SNOA401) * AN-1229 SIMPLE SWITCHER(R) PCB Layout Guidelines (SNVA054) 11.3 Receiving Notification of Documentation Updates To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper right corner, click on Alert me to register and receive a weekly digest of any product information that has changed. For change details, review the revision history included in any revised document. 11.4 Community Resources The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. TI E2ETM Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 11.5 Trademarks E2E is a trademark of Texas Instruments. SIMPLE SWITCHER, WEBENCH are registered trademarks of Texas Instruments. All other trademarks are the property of their respective owners. 11.6 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. 11.7 Glossary SLYZ022 -- TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 28 Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 LM2678 www.ti.com SNVS029K - MARCH 2000 - REVISED FEBRUARY 2017 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. 12.1 VSON Package Devices The LM2678 is offered in the 14-pin VSON surface mount package to allow for a significantly decreased footprint with equivalent power dissipation compared to the DDPAK. For details on mounting and soldering specifications, refer to AN-1187 Leadless Leadfram Package (LLP). Submit Documentation Feedback Copyright (c) 2000-2017, Texas Instruments Incorporated Product Folder Links: LM2678 29 PACKAGE OPTION ADDENDUM www.ti.com 2-Sep-2017 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) LM2678S-12 NRND DDPAK/ TO-263 KTW 7 45 TBD Call TI Call TI -40 to 125 LM2678 S-12 LM2678S-12/NOPB ACTIVE DDPAK/ TO-263 KTW 7 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-12 LM2678S-3.3 NRND DDPAK/ TO-263 KTW 7 45 TBD Call TI Call TI -40 to 125 LM2678 S-3.3 LM2678S-3.3/NOPB ACTIVE DDPAK/ TO-263 KTW 7 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-3.3 LM2678S-5.0 NRND DDPAK/ TO-263 KTW 7 45 TBD Call TI Call TI -40 to 125 LM2678 S-5.0 LM2678S-5.0/NOPB ACTIVE DDPAK/ TO-263 KTW 7 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-5.0 LM2678S-ADJ NRND DDPAK/ TO-263 KTW 7 45 TBD Call TI Call TI -40 to 125 LM2678 S-ADJ LM2678S-ADJ/NOPB ACTIVE DDPAK/ TO-263 KTW 7 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-ADJ LM2678SD-12 NRND VSON NHM 14 250 TBD Call TI Call TI -40 to 125 S0003BB LM2678SD-12/NOPB ACTIVE VSON NHM 14 250 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 S0003BB LM2678SD-3.3/NOPB ACTIVE VSON NHM 14 250 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 S0003CB LM2678SD-5.0/NOPB ACTIVE VSON NHM 14 250 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 S0003DB LM2678SD-ADJ NRND VSON NHM 14 250 TBD Call TI Call TI -40 to 125 S0003EB LM2678SD-ADJ/NOPB ACTIVE VSON NHM 14 250 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 S0003EB LM2678SDX-3.3/NOPB ACTIVE VSON NHM 14 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 S0003CB LM2678SDX-5.0/NOPB ACTIVE VSON NHM 14 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 S0003DB LM2678SDX-ADJ/NOPB ACTIVE VSON NHM 14 2500 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 S0003EB LM2678SX-12/NOPB ACTIVE DDPAK/ TO-263 KTW 7 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-12 Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 2-Sep-2017 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) LM2678SX-3.3/NOPB ACTIVE DDPAK/ TO-263 KTW 7 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-3.3 LM2678SX-5.0/NOPB ACTIVE DDPAK/ TO-263 KTW 7 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-5.0 LM2678SX-ADJ NRND DDPAK/ TO-263 KTW 7 500 TBD Call TI Call TI -40 to 125 LM2678 S-ADJ LM2678SX-ADJ/NOPB ACTIVE DDPAK/ TO-263 KTW 7 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2678 S-ADJ LM2678T-12/NOPB ACTIVE TO-220 NDZ 7 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2678 T-12 LM2678T-3.3/NOPB ACTIVE TO-220 NDZ 7 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2678 T-3.3 LM2678T-5.0 NRND TO-220 NDZ 7 45 TBD Call TI Call TI -40 to 125 LM2678 T-5.0 LM2678T-5.0/NOPB ACTIVE TO-220 NDZ 7 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2678 T-5.0 LM2678T-ADJ NRND TO-220 NDZ 7 45 TBD Call TI Call TI -40 to 125 LM2678 T-ADJ LM2678T-ADJ/NOPB ACTIVE TO-220 NDZ 7 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2678 T-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) 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 <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Addendum-Page 2 Samples PACKAGE OPTION ADDENDUM www.ti.com (4) 2-Sep-2017 There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 3 PACKAGE MATERIALS INFORMATION www.ti.com 24-Aug-2017 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 LM2678SD-12 VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SD-12/NOPB VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SD-3.3/NOPB VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SD-5.0/NOPB VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SD-ADJ VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SD-ADJ/NOPB VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SDX-3.3/NOPB VSON NHM 14 2500 330.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SDX-5.0/NOPB VSON NHM 14 2500 330.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SDX-ADJ/NOPB VSON NHM 14 2500 330.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2678SX-12/NOPB DDPAK/ TO-263 KTW 7 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2678SX-3.3/NOPB DDPAK/ TO-263 KTW 7 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2678SX-5.0/NOPB DDPAK/ TO-263 KTW 7 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2678SX-ADJ DDPAK/ TO-263 KTW 7 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2678SX-ADJ/NOPB DDPAK/ TO-263 KTW 7 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 24-Aug-2017 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2678SD-12 VSON NHM 14 250 210.0 185.0 35.0 LM2678SD-12/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2678SD-3.3/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2678SD-5.0/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2678SD-ADJ VSON NHM 14 250 210.0 185.0 35.0 LM2678SD-ADJ/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2678SDX-3.3/NOPB VSON NHM 14 2500 367.0 367.0 35.0 LM2678SDX-5.0/NOPB VSON NHM 14 2500 367.0 367.0 35.0 LM2678SDX-ADJ/NOPB VSON NHM 14 2500 367.0 367.0 35.0 LM2678SX-12/NOPB DDPAK/TO-263 KTW 7 500 367.0 367.0 45.0 LM2678SX-3.3/NOPB DDPAK/TO-263 KTW 7 500 367.0 367.0 45.0 LM2678SX-5.0/NOPB DDPAK/TO-263 KTW 7 500 367.0 367.0 45.0 LM2678SX-ADJ DDPAK/TO-263 KTW 7 500 367.0 367.0 45.0 LM2678SX-ADJ/NOPB DDPAK/TO-263 KTW 7 500 367.0 367.0 45.0 Pack Materials-Page 2 MECHANICAL DATA KTW0007B TS7B (Rev E) BOTTOM SIDE OF PACKAGE www.ti.com MECHANICAL DATA NHM0014A SRC14A (Rev A) www.ti.com MECHANICAL DATA NDZ0007B TA07B (Rev E) www.ti.com IMPORTANT NOTICE Texas Instruments Incorporated (TI) reserves 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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Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright (c) 2017, Texas Instruments Incorporated Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Texas Instruments: LM2678S-12 LM2678S-12/NOPB LM2678S-3.3 LM2678S-3.3/NOPB LM2678S-5.0 LM2678S-5.0/NOPB LM2678S-ADJ LM2678S-ADJ/NOPB LM2678SD-12 LM2678SD-12/NOPB LM2678SD-3.3 LM2678SD-3.3/NOPB LM2678SD-5.0 LM2678SD-5.0/NOPB LM2678SD-ADJ LM2678SD-ADJ/NOPB LM2678SDX-12 LM2678SDX12/NOPB LM2678SDX-3.3 LM2678SDX-3.3/NOPB LM2678SDX-5.0 LM2678SDX-5.0/NOPB LM2678SDX-ADJ LM2678SDX-ADJ/NOPB LM2678SX-12/NOPB LM2678SX-3.3 LM2678SX-3.3/NOPB LM2678SX-5.0 LM2678SX5.0/NOPB LM2678SX-ADJ LM2678SX-ADJ/NOPB LM2678T-12 LM2678T-12/NOPB LM2678T-3.3 LM2678T3.3/NOPB LM2678T-5.0 LM2678T-5.0/NOPB LM2678T-ADJ LM2678T-ADJ/NOPB