Product Folder Sample & Buy Technical Documents Support & Community Tools & Software LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 LM2576xx Series SIMPLE SWITCHER(R) 3-A Step-Down Voltage Regulator 1 Features 3 Description * The LM2576 series of regulators are monolithic integrated circuits that provide all the active functions for a step-down (buck) switching regulator, capable of driving 3-A load with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V, 5 V, 12 V, 15 V, and an adjustable output version. 1 * * * * * * * * * 3.3-V, 5-V, 12-V, 15-V, and Adjustable Output Versions Adjustable Version Output Voltage Range,1.23 V to 37 V (57 V for HV Version) 4% Maximum Over Line and Load Conditions Specified 3-A Output Current Wide Input Voltage Range: 40 V Up to 60 V for HV Version Requires Only 4 External Components 52-kHz Fixed-Frequency Internal Oscillator TTL-Shutdown Capability, Low-Power Standby Mode High Efficiency Uses Readily Available Standard Inductors Thermal Shutdown and Current Limit Protection 2 Applications * * * * Simple High-Efficiency Step-Down (Buck) Regulator Efficient Preregulator for Linear Regulators On-Card Switching Regulators Positive-to-Negative Converter (Buck-Boost) Requiring a minimum number of external components, these regulators are simple to use and include fault protection and a fixed-frequency oscillator. The LM2576 series offers a high-efficiency replacement for popular three-terminal linear regulators. It substantially reduces the size of the heat sink, and in some cases no heat sink is required. A standard series of inductors optimized for use with the LM2576 are available from several different manufacturers. This feature greatly simplifies the design of switch-mode power supplies. Other features include a 4% tolerance on output voltage within specified input voltages and output load conditions, and 10% on the oscillator frequency. External shutdown is included, featuring 50-A (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under fault conditions. Device Information(1) PART NUMBER LM2576 LM2576HV PACKAGE BODY SIZE (NOM) TO-220 (5) 10.16 mm x 8.51 mm DDPAK/TO-263 (5) 10.16 mm x 8.42 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Fixed Output Voltage Version Typical Application Diagram 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. LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 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 4 5 5 5 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: 15 V ................................. Electrical Characteristics: Adjustable Output Voltage ....................................................................... 6.10 Electrical Characteristics: All Output Voltage Versions ..................................................................... 6.11 Typical Characteristics ............................................ 7 6 6 8 Detailed Description ............................................ 12 7.1 Overview ................................................................. 12 7.2 Functional Block Diagram ....................................... 12 7.3 Feature Description................................................. 12 7.4 Device Functional Modes........................................ 14 8 Application and Implementation ........................ 15 8.1 Application Information............................................ 15 8.2 Typical Applications ................................................ 19 9 Power Supply Recommendations...................... 24 10 Layout................................................................... 25 10.1 10.2 10.3 10.4 Layout Guidelines ................................................. Layout Example .................................................... Grounding ............................................................. Heat Sink and Thermal Considerations ................ 25 26 26 26 11 Device and Documentation Support ................. 28 11.1 11.2 11.3 11.4 11.5 11.6 11.7 Device Support .................................................... Documentation Suuport ........................................ Related Links ........................................................ Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 28 29 29 29 29 29 29 12 Mechanical, Packaging, and Orderable Information ........................................................... 30 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (April 2013) to Revision D 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 * Moved the thermal resistance data from the Electrical Characteristics: All Output Voltage Versions table to the Thermal Information table....................................................................................................................................................... 4 Changes from Revision B (April 2013) to Revision C * 2 Page Changed layout of National Data Sheet to TI format ............................................................................................................. 3 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 5 Pin Configuration and Functions KC Package 5-Pin TO-220 Top View KTT Package 5-PIN DDPAK/TO-263 Top View DDPAK/TO-263 (S) Package 5-Lead Surface-Mount Package Top View Pin Functions PIN NO. NAME I/O (1) DESCRIPTION 1 VIN I Supply input pin to collector pin of high-side transistor. 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. 2 OUTPUT O Emitter pin of the power transistor. This is a switching node. Attached this pin to an inductor and the cathode of the external diode. 3 GROUND -- Ground pin. Path to CIN must be as short as possible. 4 FEEDBACK 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. 5 ON/OFF I Enable input to the voltage regulator. High = OFF and low = ON. Connect to GND to enable the voltage regulator. Do not leave this pin float. -- TAB -- (1) Connected to GND. Attached to heatsink for thermal relief for TO-220 package or put a copper plane connected to this pin as a thermal relief for DDPAK package. I = INPUT, O = OUTPUT Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 3 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings over the recommended operating junction temperature range of -40C to 125C (unless otherwise noted) (1) (2) MIN Maximum supply voltage 45 LM2576HV 63 ON /OFF pin input voltage Output voltage to ground MAX LM2576 (Steady-state) Power dissipation V -1 V Internally Limited -65 Storage temperature, Tstg (2) V -0.3V V +VIN Maximum junction temperature, TJ (1) UNIT 150 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 TI Sales Office/ Distributors for availability and specifications. 6.2 ESD Ratings V(ESD) (1) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) VALUE UNIT 2000 V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions over the recommended operating junction temperature range of -40C to 125C (unless otherwise noted) Temperature LM2576, LM2576HV Supply voltage MIN MAX UNIT -40 125 C LM2576 40 LM2576HV 60 V 6.4 Thermal Information LM2576, LM2576HV THERMAL METRIC (1) (2) (3) KTT (TO-263) KC (TO-220) UNIT 5 PINS 5 PINS RJA Junction-to-ambient thermal resistance 42.6 32.4 C/W RJC(top) Junction-to-case (top) thermal resistance 43.3 41.2 C/W RJB Junction-to-board thermal resistance 22.4 17.6 C/W JT Junction-to-top characterization parameter 10.7 7.8 C/W JB Junction-to-board characterization parameter 21.3 17 C/W RJC(bot) Junction-to-case (bottom) thermal resistance 0.4 0.4 C/W (1) (2) (3) 4 For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report, SPRA953 and the Using New Thermal Metrics applications report, SBVA025. The package thermal impedance is calculated in accordance with JESD 51-7 Thermal Resistances were simulated on a 4-layer, JEDEC board. Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 6.5 Electrical Characteristics: 3.3 V Specifications are for TJ = 25C (unless otherwise noted). PARAMETER TEST CONDITIONS SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32 (1) TYP MAX UNIT 3.234 3.3 3.366 V 3.3 3.432 Output Voltage VIN = 12 V, ILOAD = 0.5 A Circuit of Figure 26 and Figure 32 TJ = 25C 3.168 Output Voltage: LM2576 6 V VIN 40 V, 0.5 A ILOAD 3 A Circuit of Figure 26 and Figure 32 Applies over full operating temperature range 3.135 TJ = 25C 3.168 Output Voltage: LM2576HV 6 V VIN 60 V, 0.5 A ILOAD 3 A Circuit of Figure 26 and Figure 32 Applies over full operating temperature range 3.135 Efficiency VIN = 12 V, ILOAD = 3 A VOUT MIN (1) 3.465 3.3 V 3.45 3.482 V 75% External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical Characteristics: All Output Voltage Versions. 6.6 Electrical Characteristics: 5 V Specifications are for TJ = 25C for the Figure 26 and Figure 32 (unless otherwise noted). PARAMETER TEST CONDITIONS MIN TYP MAX 4.9 5 5.1 4.8 5 5.2 UNIT SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32 (1) VOUT Output Voltage VIN = 12 V, ILOAD = 0.5 A Circuit of Figure 26 and Figure 32 VOUT 0.5 A ILOAD 3 A, 8 V VIN 40 V Circuit of Figure 26 and Figure 32 TJ = 25C Output Voltage LM2576 VOUT 0.5 A ILOAD 3 A, 8 V VIN 60 V Circuit of Figure 26 and Figure 32 TJ = 25C Output Voltage LM2576HV Efficiency VIN = 12 V, ILOAD = 3 A (1) Applies over full operating temperature range Applies over full operating temperature range 4.75 4.8 5.25 5 5.225 V V 4.75 5.275 V 77% External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical Characteristics: All Output Voltage Versions. 6.7 Electrical Characteristics: 12 V Specifications are for TJ = 25C (unless otherwise noted). PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 11.76 12 12.24 V 11.52 12 12.48 SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32 (1) VOUT Output Voltage VIN = 25 V, ILOAD = 0.5 A Circuit of Figure 26 and Figure 32 VOUT 0.5 A ILOAD 3 A, 15 V VIN 40 V Circuit of Figure 26 and Figure 32 and TJ = 25C Output Voltage LM2576 VOUT 0.5 A ILOAD 3 A, 15 V VIN 60 V Circuit of Figure 26 and Figure 32 TJ = 25C Output Voltage LM2576HV Efficiency VIN = 15 V, ILOAD = 3 A (1) Applies over full operating temperature range Applies over full operating temperature range 11.4 11.52 12.6 12 11.4 V 12.54 12.66 V 88% External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical Characteristics: All Output Voltage Versions. Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 5 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 6.8 Electrical Characteristics: 15 V over operating free-air temperature range (unless otherwise noted). PARAMETER TEST CONDITIONS SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32 VOUT Output Voltage VIN = 25 V, ILOAD = 0.5 A Circuit of Figure 26 and Figure 32 VOUT 0.5 A ILOAD 3 A, 18 V VIN 40 V Circuit of Figure 26 and Figure 32 TJ = 25C Output Voltage LM2576 VOUT 0.5 A ILOAD 3 A, 18 V VIN 60 V Circuit of Figure 26 and Figure 32 TJ = 25C Output Voltage LM2576HV Efficiency VIN = 18 V, ILOAD = 3 A (1) MIN TYP MAX UNIT 14.7 15 15.3 V 14.4 15 15.6 (1) Applies over full operating temperature range 14.25 15.75 14.4 Applies over full operating temperature range 15 15.68 V 14.25 15.83 V 88% External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical Characteristics: All Output Voltage Versions. 6.9 Electrical Characteristics: Adjustable Output Voltage over operating free-air temperature range (unless otherwise noted). PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 1.217 1.23 1.243 V 1.193 1.23 1.267 SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32 (1) VOUT Feedback voltage VIN = 12 V, ILOAD = 0.5 A VOUT = 5 V, Circuit of Figure 26 and Figure 32 VOUT 0.5 A ILOAD 3 A, 8 V VIN 40 V VOUT = 5 V, Circuit of Figure 26 and Figure 32 TJ = 25C Feedback Voltage LM2576 VOUT 0.5 A ILOAD 3 A, 8 V VIN 60 V VOUT = 5 V, Circuit of Figure 26 and Figure 32 TJ = 25C Feedback Voltage LM2576HV Efficiency VIN = 12 V, ILOAD = 3 A, VOUT = 5 V (1) Applies over full operating temperature range 1.18 1.193 Applies over full operating temperature range 1.28 1.23 1.18 V 1.273 1.286 V 77% External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical Characteristics: All Output Voltage Versions. 6.10 Electrical Characteristics: All Output Voltage Versions over operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS SYSTEM PARAMETERS TEST CIRCUIT Figure 26 and Figure 32 Ib Feedback Bias Current fO Oscillator Frequency (3) (1) (2) (3) 6 VOUT = 5 V (Adjustable Version Only) MIN TYP (1) MAX UNIT (2) TJ = 25C 100 Applies over full operating temperature range 500 TJ = 25C 47 Applies over full operating temperature range 42 50 nA 52 58 63 kHz All limits specified at room temperature (25C) unless otherwise noted. All room temperature limits are 100% production tested. All limits at temperature extremes are specified through correlation using standard Statistical Quality Control (SQC) methods. External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance. When the LM2576/LM2576HV is used as shown in Figure 26 and Figure 32, system performance is as shown in Electrical Characteristics: All Output Voltage Versions. The oscillator frequency reduces to approximately 11 kHz in the event of an output short or an overload which causes the regulated output voltage to drop approximately 40% from the nominal output voltage. This self protection feature lowers the average power dissipation of the IC by lowering the minimum duty cycle from 5% down to approximately 2%. Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Electrical Characteristics: All Output Voltage Versions (continued) over operating free-air temperature range (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TJ = 25C VSAT Saturation Voltage DC Max Duty Cycle (ON) (5) ICL Current Limit (4) (3) IL Output Leakage Current IQ Quiescent Current (6) ISTBY Standby Quiescent Current IOUT = 3 A TYP (1) MAX 1.4 Applies over full operating temperature range (4) 93% 98% 4.2 5.8 Applies over full operating temperature range 3.5 Output = 0 V Output = -1 V Output = -1 V 2 (6) (7) 1.8 2 TJ = 25C ON /OFF Pin = 5 V (OFF) UNIT 6.9 7.5 V A 7.5 30 mA 5 10 mA 50 200 A ON /OFF CONTROL TEST CIRCUIT Figure 26 and Figure 32 VOUT = 0 V VIH ON /OFF Pin Logic Input Level VIL IIH IIL (4) (5) (6) (7) ON /OFF Pin Input Current VOUT = Nominal Output Voltage TJ = 25C 2.2 Applies over full operating temperature range 2.4 TJ = 25C 1.4 V 1.2 Applies over full operating temperature range 1 0.8 V ON /OFF Pin = 5 V (OFF) 12 30 A ON /OFF Pin = 0 V (ON) 0 10 A Output pin sourcing current. No diode, inductor or capacitor connected to output. Feedback pin removed from output and connected to 0V. Feedback pin removed from output and connected to +12 V for the Adjustable, 3.3-V, and 5-V versions, and +25 V for the 12-V and 15V versions, to force the output transistor OFF. VIN = 40 V (60 V for high voltage version). Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 7 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 6.11 Typical Characteristics (Circuit of Figure 26 and Figure 32) 8 Figure 1. Normalized Output Voltage Figure 2. Line Regulation Figure 3. Dropout Voltage Figure 4. Current Limit Figure 5. Quiescent Current Figure 6. Standby Quiescent Current Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Typical Characteristics (continued) (Circuit of Figure 26 and Figure 32) Figure 7. Oscillator Frequency Figure 8. Switch Saturation Voltage Figure 10. Minimum Operating Voltage Figure 9. Efficiency Figure 11. Quiescent Current vs Duty Cycle Figure 12. Feedback Voltage vs Duty Cycle Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 9 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com Typical Characteristics (continued) (Circuit of Figure 26 and Figure 32) Figure 13. Minimum Operating Voltage Figure 14. Quiescent Current vs Duty Cycle Figure 15. Feedback Voltage vs Duty Cycle Figure 16. Feedback Pin Current VOUT = 15 V A: Output Pin Voltage, 50 V/div B: Output Pin Current, 2 A/div If the DDPAK/TO-263 package is used, the thermal resistance can be C: Inductor Current, 2 A/div reduced by increasing the PCB copper area thermally connected to the package. Using 0.5 square inches of copper area, JA is 50C/W, D: Output Ripple Voltage, 50 mV/div, AC-Coupled with 1 square inch of copper area, JA is 37C/W, and with 1.6 or Horizontal Time Base: 5 s/div more square inches of copper area, JA is 32C/W. Figure 18. Switching Waveforms Figure 17. Maximum Power Dissipation (DDPAK/TO-263) 10 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Typical Characteristics (continued) (Circuit of Figure 26 and Figure 32) Figure 19. Load Transient Response Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 11 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 7 Detailed Description 7.1 Overview The LM2576 SIMPLE SWITCHER(R) regulator is an easy-to-use, non-synchronous step-down DC-DC converter with a wide input voltage range from 40 V to up to 60 V for a HV version. It is capable of delivering up to 3-A DC load current with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V, 5 V, 12 V, 15 V, and an adjustable output version. The family requires few external components, and the pin arrangement was designed for simple, optimum PCB layout. 7.2 Functional Block Diagram 3.3 V R2 = 1.7 k 5 V, R2 = 3.1 k 12 V, R2 = 8.84 k 15 V, R2 = 11.3 k For ADJ. Version R1 = Open, R2 = 0 Patent Pending 7.3 Feature Description 7.3.1 Undervoltage Lockout In some applications it is desirable to keep the regulator off until the input voltage reaches a certain threshold. Figure 20 shows an undervoltage lockout circuit that accomplishes this task, while Figure 21 shows the same circuit applied to a buck-boost configuration. These circuits keep the regulator off until the input voltage reaches a predetermined level. VTH VZ1 + 2VBE(Q1) 12 Submit Documentation Feedback (1) Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Feature Description (continued) Complete circuit not shown. Figure 20. Undervoltage Lockout for Buck Circuit Complete circuit not shown (see Figure 24). Figure 21. Undervoltage Lockout for Buck-Boost Circuit 7.3.2 Delayed Start-Up The ON /OFF pin can be used to provide a delayed start-up feature as shown in Figure 22. With an input voltage of 20 V and for the part values shown, the circuit provides approximately 10 ms of delay time before the circuit begins switching. Increasing the RC time constant can provide longer delay times. But excessively large RC time constants can cause problems with input voltages that are high in 60-Hz or 120-Hz ripple, by coupling the ripple into the ON /OFF pin. 7.3.3 Adjustable Output, Low-Ripple Power Supply Figure 23 shows a 3-A power supply that features an adjustable output voltage. An additional LC filter that reduces the output ripple by a factor of 10 or more is included in this circuit. Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 13 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com Feature Description (continued) Complete circuit not shown. Figure 22. Delayed Start-Up Figure 23. 1.2-V to 55-V Adjustable 3-A Power Supply With Low Output Ripple 7.4 Device Functional Modes 7.4.1 Shutdown Mode The ON/OFF pin provides electrical ON and OFF control for the LM2576. When the voltage of this pin is higher than 1.4 V, the device is in shutdown mode. The typical standby current in this mode is 50 A. 7.4.2 Active Mode When the voltage of the ON/OFF pin is below 1.2 V, the device starts switching, and the output voltage rises until it reaches the normal regulation voltage. 7.4.3 Current Limit The LM2576 device has current limiting to prevent the switch current from exceeding safe values during an accidental overload on the output. This current limit value can be found in Electrical Characteristics: All Output Voltage Versions under the heading of ICL. The LM2576 uses cycle-by-cycle peak current limit for overload protection. This helps to prevent damage to the device and external components. The regulator operates in current limit mode whenever the inductor current exceeds the value of ICL given in Electrical Characteristics: All Output Voltage Versions. This occurs if the load current is greater than 3 A, or the converter is starting up. Keep in mind that the maximum available load current depends on the input voltage, output voltage, and inductor value. The regulator also incorporates short-circuit protection to prevent inductor current run-away. When the voltage on the FB pin (ADJ) falls below about 0.58 V the switching frequency is dropped to about 11 kHz. This allows the inductor current to ramp down sufficiently during the switch OFF-time to prevent saturation. 14 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 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 Input Capacitor (CIN) To maintain stability, the regulator input pin must be bypassed with at least a 100-F electrolytic capacitor. The capacitor's leads must be kept short, and placed near the regulator. If the operating temperature range includes temperatures below -25C, the input capacitor value may need to be larger. With most electrolytic capacitors, the capacitance value decreases and the ESR increases with lower temperatures and age. Paralleling a ceramic or solid tantalum capacitor increases the regulator stability at cold temperatures. For maximum capacitor operating lifetime, the RMS ripple current rating of the capacitor must be greater than: (2) 8.1.2 Inductor Selection All switching regulators have two basic modes of operation: continuous and discontinuous. The difference between the two types relates to the inductor current, whether it is flowing continuously, or if it drops to zero for a period of time in the normal switching cycle. Each mode has distinctively different operating characteristics, which can affect the regulator performance and requirements. The LM2576 (or any of the SIMPLE SWITCHER(R) family can be used for both continuous and discontinuous modes of operation. The inductor value selection guides in Figure 27 through Figure 31 are designed for buck regulator designs of the continuous inductor current type. When using inductor values shown in the inductor selection guide, the peak-to-peak inductor ripple current is approximately 20% to 30% of the maximum DC current. With relatively heavy load currents, the circuit operates in the continuous mode (inductor current always flowing), but under light load conditions, the circuit is forced to the discontinuous mode (inductor current falls to zero for a period of time). This discontinuous mode of operation is perfectly acceptable. For light loads (less than approximately 300 mA), it may be desirable to operate the regulator in the discontinuous mode, primarily because of the lower inductor values required for the discontinuous mode. The selection guide chooses inductor values suitable for continuous mode operation, but if the inductor value chosen is prohibitively high, the designer should investigate the possibility of discontinuous operation. Inductors are available in different styles such as pot core, toriod, E-frame, bobbin core, and so on, as well as different core materials, such as ferrites and powdered iron. The bobbin core is the least expensive type, and consists of wire wrapped on a ferrite rod core. This type of construction makes for an inexpensive inductor; however, because the magnetic flux is not completely contained within the core, the bobbin core generates more electromagnetic interference (EMI). This EMI can cause problems in sensitive circuits, or can give incorrect scope readings because of induced voltages in the scope probe. The inductors listed in the selection chart include ferrite pot core construction for AIE, powdered iron toroid for Pulse Engineering, and ferrite bobbin core for Renco. Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 15 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com Application Information (continued) An inductor must not operate beyond its maximum-rated current because it may saturate. When an inductor begins to saturate, the inductance decreases rapidly, and the inductor begins to look mainly resistive (the DC resistance of the winding), causing the switch current to rise very rapidly. Different inductor types have different saturation characteristics, and this must be considered when selecting an inductor. The inductor manufacturer's data sheets include current and energy limits to avoid inductor saturation. 8.1.3 Inductor Ripple Current When the switcher is operating in the continuous mode, the inductor current waveform ranges from a triangular to a sawtooth type of waveform (depending on the input voltage). For a given input voltage and output voltage, the peak-to-peak amplitude of this inductor current waveform remains constant. As the load current rises or falls, the entire sawtooth current waveform also rises or falls. The average DC value of this waveform is equal to the DC load current (in the buck regulator configuration). If the load current drops to a low enough level, the bottom of the sawtooth current waveform reaches zero, and the switcher changes to a discontinuous mode of operation. This is a perfectly acceptable mode of operation. Any buck switching regulator (no matter how large the inductor value is) is forced to run discontinuous if the load current is light enough. 8.1.4 Output Capacitor An output capacitor is required to filter the output voltage and is needed for loop stability. The capacitor must be placed near the LM2576 using short PCB traces. Standard aluminum electrolytics are usually adequate, but TI recommends low ESR types for low output ripple voltage and good stability. The ESR of a capacitor depends on many factors, including: the value, the voltage rating, physical size, and the type of construction. In general, low value or low voltage (less than 12 V) electrolytic capacitors usually have higher ESR numbers. The amount of output ripple voltage is primarily a function of the ESR (Equivalent Series Resistance) of the output capacitor and the amplitude of the inductor ripple current (IIND). See Inductor Ripple Current. The lower capacitor values (220 F to 1000 F) allows typically 50 mV to 150 mV of output ripple voltage, while larger-value capacitors reduces the ripple to approximately 20 mV to 50 mV. Output Ripple Voltage = (IIND) (ESR of COUT) (3) To further reduce the output ripple voltage, several standard electrolytic capacitors may be paralleled, or a higher-grade capacitor may be used. Such capacitors are often called high-frequency, low-inductance, or lowESR. These reduces the output ripple to 10 mV or 20 mV. However, when operating in the continuous mode, reducing the ESR below 0.03 can cause instability in the regulator. Tantalum capacitors can have a very low ESR, and must be carefully evaluated if it is the only output capacitor. Because of their good low temperature characteristics, a tantalum can be used in parallel with aluminum electrolytics, with the tantalum making up 10% or 20% of the total capacitance. The ripple current rating of the capacitor at 52 kHz should be at least 50% higher than the peak-to-peak inductor ripple current. 8.1.5 Catch Diode Buck regulators require a diode to provide a return path for the inductor current when the switch is off. This diode must be placed close to the LM2576 using short leads and short printed-circuit traces. Because of their fast switching speed and low forward voltage drop, Schottky diodes provide the best efficiency, especially in low output voltage switching regulators (less than 5 V). Fast-recovery, high-efficiency, or ultra-fast recovery diodes are also suitable, but some types with an abrupt turnoff characteristic may cause instability and EMI problems. A fast-recovery diode with soft recovery characteristics is a better choice. Standard 60-Hz diodes (for example, 1N4001 or 1N5400, and so on) are also not suitable. See Table 3 for Schottky and soft fastrecovery diode selection guide. 16 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Application Information (continued) 8.1.6 Output Voltage Ripple and Transients The output voltage of a switching power supply contains a sawtooth ripple voltage at the switcher frequency, typically about 1% of the output voltage, and may also contain short voltage spikes at the peaks of the sawtooth waveform. The output ripple voltage is due mainly to the inductor sawtooth ripple current multiplied by the ESR of the output capacitor (see Inductor Selection). The voltage spikes are present because of the fast switching action of the output switch, and the parasitic inductance of the output filter capacitor. To minimize these voltage spikes, special low inductance capacitors can be used, and their lead lengths must be kept short. Wiring inductance, stray capacitance, as well as the scope probe used to evaluate these transients, all contribute to the amplitude of these spikes. An additional small LC filter (20 H and 100 F) can be added to the output (as shown in Figure 23) to further reduce the amount of output ripple and transients. A 10 x reduction in output ripple voltage and transients is possible with this filter. 8.1.7 Feedback Connection The LM2576 (fixed voltage versions) feedback pin must be wired to the output voltage point of the switching power supply. When using the adjustable version, physically locate both output voltage programming resistors near the LM2576 to avoid picking up unwanted noise. Avoid using resistors greater than 100 k because of the increased chance of noise pickup. 8.1.8 ON /OFF INPUT For normal operation, the ON /OFF pin must be grounded or driven with a low-level TTL voltage (typically below 1.6 V). To put the regulator into standby mode, drive this pin with a high-level TTL or CMOS signal. The ON /OFF pin can be safely pulled up to +VIN without a resistor in series with it. The ON /OFF pin must not be left open. 8.1.9 Inverting Regulator Figure 24 shows a LM2576-12 in a buck-boost configuration to generate a negative 12-V output from a positive input voltage. This circuit bootstraps the ground pin of the regulator to the negative output voltage, then by grounding the feedback pin, the regulator senses the inverted output voltage and regulates it to -12 V. For an input voltage of 12 V or more, the maximum available output current in this configuration is approximately 700 mA. At lighter loads, the minimum input voltage required drops to approximately 4.7 V. The switch currents in this buck-boost configuration are higher than in the standard buck-mode design, thus lowering the available output current. Also, the start-up input current of the buck-boost converter is higher than the standard buck-mode regulator, and this may overload an input power source with a current limit less than 5 A. Using a delayed turn-on or an undervoltage lockout circuit (described in Negative Boost Regulator) would allow the input voltage to rise to a high enough level before the switcher would be allowed to turn on. Because of the structural differences between the buck and the buck-boost regulator topologies, the buck regulator design procedure section can not be used to select the inductor or the output capacitor. The recommended range of inductor values for the buck-boost design is between 68 H and 220 H, and the output capacitor values must be larger than what is normally required for buck designs. Low input voltages or high output currents require a large value output capacitor (in the thousands of micro Farads). The peak inductor current, which is the same as the peak switch current, can be calculated in Equation 4: where * fosc = 52 kHz (4) Under normal continuous inductor current operating conditions, the minimum VIN represents the worst case. Select an inductor that is rated for the peak current anticipated. Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 17 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com Application Information (continued) Figure 24. Inverting Buck-Boost Develops -12 V Also, the maximum voltage appearing across the regulator is the absolute sum of the input and output voltage. For a -12-V output, the maximum input voltage for the LM2576 is +28 V, or +48 V for the LM2576HV. 8.1.10 Negative Boost Regulator Another variation on the buck-boost topology is the negative boost configuration. The circuit in Figure 25 accepts an input voltage ranging from -5 V to -12 V and provides a regulated -12-V output. Input voltages greater than -12 V causes the output to rise above -12 V, but does not damage the regulator. + Feedback VIN 1 LM2576-12 COUT 4 Output 2200 PF LOW ESR 2 + CIN 3 GND 5 ON/OFF 1N5820 100 PF -VIN VOUT = -12V 100 PH -5V to -12V Copyright (c) 2016, Texas Instruments Incorporated Typical Load Current 400 mA for VIN = -5.2 V 750 mA for VIN = -7 V Heat sink may be required. Figure 25. Negative Boost Because of the boosting function of this type of regulator, the switch current is relatively high, especially at low input voltages. Output load current limitations are a result of the maximum current rating of the switch. Also, boost regulators can not provide current-limiting load protection in the event of a shorted load, so some other means (such as a fuse) may be necessary. 18 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 8.2 Typical Applications 8.2.1 Fixed Output Voltage Version CIN -- 100-F, 75-V, Aluminum Electrolytic COUT -- 1000-F, 25-V, Aluminum Electrolytic D1 -- Schottky, MBR360 L1 -- 100 H, Pulse Eng. PE-92108 R1 -- 2 k, 0.1% R2 -- 6.12 k, 0.1% Figure 26. Fixed Output Voltage Versions 8.2.1.1 Design Requirements Table 1 lists the design parameters of this example. Table 1. Design Parameters DESIGN PARAMETER Regulated Output Voltage EXAMPLE VALUE 5V (3.3 V, 5 V, 12 V, or 15 V), VOUT Maximum Input Voltage, VIN(Max) 15 V Maximum Load Current, ILOAD(Max) 3A 8.2.1.2 Detailed Design Procedure 8.2.1.2.1 Inductor Selection (L1) 1. Select the correct Inductor value selection guide from Figure 27, Figure 28, Figure 29, or Figure 30. (Output voltages of 3.3 V, 5 V, 12 V or 15 V respectively). For other output voltages, see the design procedure for the adjustable version. Use the selection guide shown in Figure 28. 2. From the inductor value selection guide, identify the inductance region intersected by VIN(Max) and ILOAD(Max), and note the inductor code for that region. From the selection guide, the inductance area intersected by the 15-V line and 3-A line is L100. 3. Identify the inductor value from the inductor code, and select an appropriate inductor from the table shown in Figure 27. Part numbers are listed for three inductor manufacturers. The inductor chosen must be rated for operation at the LM2576 switching frequency (52 kHz) and for a current rating of 1.15 x ILOAD. For additional inductor information, see Inductor Selection. Inductor value required is 100 H from the table in Figure 27. Choose AIE 415-0930, Pulse Engineering PE92108, or Renco RL2444. 8.2.1.2.2 Output Capacitor Selection (COUT) 1. The value of the output capacitor together with the inductor defines the dominate pole-pair of the switching regulator loop. For stable operation and an acceptable output ripple voltage, (approximately 1% of the output voltage) TI recommends a value between 100 F and 470 F. We choose COUT = 680-F to 2000-F standard aluminum electrolytic. Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 19 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 2. The voltage rating of the capacitor must be at least 1.5 times greater than the output voltage. For a 5-V regulator, a rating of at least 8 V is appropriate, and a 10-V or 15-V rating is recommended. Capacitor voltage rating = 20 V. Higher voltage electrolytic capacitors generally have lower ESR numbers, and for this reason it may be necessary to select a capacitor rated for a higher voltage than would normally be needed. 8.2.1.2.3 Catch Diode Selection (D1) 1. The catch-diode current rating must be at least 1.2 times greater than the maximum load current. Also, 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 LM2576. The most stressful condition for this diode is an overload or shorted output condition. For this example, a 3-A current rating is adequate. 2. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. Use a 20-V 1N5823 or SR302 Schottky diode, or any of the suggested fast-recovery diodes shown in Table 3. 8.2.1.2.4 Input Capacitor (CIN) An aluminum or tantalum electrolytic bypass capacitor located close to the regulator is needed for stable operation. A 100-F, 25-V aluminum electrolytic capacitor located near the input and ground pins provides sufficient bypassing. 8.2.1.3 Application Curves 20 Figure 27. LM2576(HV)-3.3 Figure 28. LM2576(HV)-5.0 Figure 29. LM2576(HV)-12 Figure 30. LM2576(HV)-15 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Figure 31. LM2576(HV)-ADJ 8.2.2 Adjusted Output Voltage Version where VREF = 1.23 V, R1 between 1 k and 5 k Figure 32. Adjustable Output Voltage Version 8.2.2.1 Design Requirements Table 2 lists the design parameters of this example. Table 2. Design Parameters DESIGN PARAMETER EXAMPLE VALUE Regulated Output Voltage, VOUT 10 V Maximum Input Voltage, VIN(Max) 25 V Maximum Load Current, ILOAD(Max) 3A Switching Frequency, F Fixed at 52 kHz Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 21 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 8.2.2.2 Detailed Design Procedure 8.2.2.2.1 Programming Output Voltage Select R1 and R2, as shown in Figure 32. Use Equation 5 to select the appropriate resistor values. (5) R1 can be between 1k and 5k. (For best temperature coefficient and stability with time, use 1% metal film resistors) (6) (7) R2 = 1 k (8.13 - 1) = 7.13 k, closest 1% value is 7.15 k 8.2.2.2.2 Inductor Selection (L1) 1. Calculate the inductor Volt * microsecond constant, E * T (V * s), from Equation 8: (8) Calculate E * T (V * s) (9) 2. 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 31. E * T = 115 V * s 3. On the horizontal axis, select the maximum load current. ILOAD(Max) = 3 A 4. Identify the inductance region intersected by the E * T value and the maximum load current value, and note the inductor code for that region. Inductance Region = H150 5. Identify the inductor value from the inductor code, and select an appropriate inductor from the table shown in Table 4. Part numbers are listed for three inductor manufacturers. The inductor chosen must be rated for operation at the LM2576 switching frequency (52 kHz) and for a current rating of 1.15 x ILOAD. For additional inductor information, see Inductor Selection. Inductor Value = 150 H Choose from AIE part #415-0936, Pulse Engineering part #PE-531115, or Renco part #RL2445. 8.2.2.2.3 Output Capacitor Selection (COUT) 1. The value of the output capacitor together with the inductor defines the dominate pole-pair of the switching regulator loop. For stable operation, the capacitor must satisfy : yields capacitor values between 10 F and 2200 F that satisfies the loop requirements for stable operation. But to achieve an acceptable output ripple voltage, (approximately 1% of the output voltage) and transient response, the output capacitor may need to be several times larger than yields. However, for acceptable output ripple voltage select 22 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 COUT 680 F COUT = 680-F electrolytic capacitor 2. The capacitor's voltage rating must be at last 1.5 times greater than the output voltage. For a 10-V regulator, a rating of at least 15 V or more is recommended. Higher voltage electrolytic capacitors generally have lower ESR numbers, and for this reason it may be necessary to select a capacitor rate for a higher voltage than would normally be needed. 8.2.2.2.4 Catch Diode Selection (D1) 1. The catch-diode current rating must be at least 1.2 times greater than the maximum load current. Also, if the power supply design must withstand a continuous output short, the diode must have a current rating equal to the maximum current limit of the LM2576. The most stressful condition for this diode is an overload or shorted output. See Table 3. For this example, a 3.3-A current rating is adequate. 2. The reverse voltage rating of the diode should be at least 1.25 times the maximum input voltage. Use a 30-V 31DQ03 Schottky diode, or any of the suggested fast-recovery diodes in Table 3. 8.2.2.2.5 Input Capacitor (CIN) An aluminum or tantalum electrolytic bypass capacitor located close to the regulator is needed for stable operation. A 100-F aluminum electrolytic capacitor located near the input and ground pins provides sufficient bypassing. Table 3. Diode Selection Guide SCHOTTKY VR 3A FAST RECOVERY 4 A to 6 A 3A 4 A to 6 A The following diodes are all rated to 100-V 31DF1 HER302 The following diodes are all rated to 100-V 50WF10 MUR410 HER602 1N5820 20 V MBR320P 1N5823 SR302 1N5821 MBR330 30 V 50WQ03 1N5824 31DQ03 SR303 1N5822 MBR340 50WQ04 1N5825 MBR340 40 V 31DQ04 SR304 MBR350 50 V 31DQ05 50WQ05 SR305 MBR360 60 V 50WR06 50SQ060 DQ06 SR306 Table 4. Inductor Selection by Manufacturer's Part Number (1) (2) (3) INDUCTOR CODE INDUCTOR VALUE SCHOTT (1) PULSE ENG. (2) RENCO (3) L47 47 H 671 26980 PE-53112 RL2442 L68 68 H 671 26990 PE-92114 RL2443 L100 100 H 671 27000 PE-92108 RL2444 L150 150 H 671 27010 PE-53113 RL1954 L220 220 H 671 27020 PE-52626 RL1953 L330 330 H 671 27030 PE-52627 RL1952 Schott Corporation, (612) 475-1173, 1000 Parkers Lake Road, Wayzata, MN 55391. Pulse Engineering, (619) 674-8100, P.O. Box 12235, San Diego, CA 92112. Renco Electronics Incorporated, (516) 586-5566, 60 Jeffryn Blvd. East, Deer Park, NY 11729. Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 23 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com Table 4. Inductor Selection by Manufacturer's Part Number (continued) INDUCTOR CODE INDUCTOR VALUE SCHOTT (1) PULSE ENG. (2) RENCO (3) L470 470 H 671 27040 PE-53114 RL1951 L680 680 H 671 27050 PE-52629 RL1950 H150 150 H 671 27060 PE-53115 RL2445 H220 220 H 671 27070 PE-53116 RL2446 H330 330 H 671 27080 PE-53117 RL2447 H470 470 H 671 27090 PE-53118 RL1961 H680 680 H 671 27100 PE-53119 RL1960 H1000 1000 H 671 27110 PE-53120 RL1959 H1500 1500 H 671 27120 PE-53121 RL1958 H2200 2200 H 671 27130 PE-53122 RL2448 9 Power Supply Recommendations As in any switching regulator, layout is very important. Rapidly switching currents associated with wiring inductance generate voltage transients which can cause problems. For minimal inductance and ground loops, the length of the leads indicated by heavy lines should be kept as short as possible. Single-point grounding (as indicated) or ground plane construction should be used for best results. When using the adjustable version, physically locate the programming resistors near the regulator, to keep the sensitive feedback wiring short. 24 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 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 33 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 also yields 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 LM2576 device, the bypass capacitor, the Schottky diode, RFBB, RFBT, and the inductor are placed as shown in Figure 34.TI also recommends using 2-oz copper boards or heavier to help thermal dissipation and to reduce the parasitic inductances of board traces. See application note AN-1229 SIMPLE SWITCHER(R) PCB Layout Guidelines (SNVA054) for more information. Figure 33. Current Flow in Buck Application Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 25 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 10.2 Layout Example Figure 34. LM2576xx Layout Example 10.3 Grounding To maintain output voltage stability, the power ground connections must be low-impedance (see Figure 26 and Figure 32). For the 5-lead TO-220 and DDPAK/TO-263 style package, both the tab and pin 3 are ground and either connection may be used, as they are both part of the same copper lead frame. 10.4 Heat Sink and Thermal Considerations In many cases, only a small heat sink is required to keep the LM2576 junction temperature within the allowed operating range. For each application, to determine whether or not a heat sink is required, the following must be identified: 1. Maximum ambient temperature (in the application). 2. Maximum regulator power dissipation (in application). 3. Maximum allowed junction temperature (125C for the LM2576). For a safe, conservative design, a temperature approximately 15C cooler than the maximum temperatures must be selected. 4. LM2576 package thermal resistances JA and JC. Total power dissipated by the LM2576 can be estimated in Equation 10: PD = (VIN)(IQ) + (VO/VIN)(ILOAD)(VSAT) where * * * 26 IQ (quiescent current) and VSAT can be found in Typical Characteristics shown previously, VIN is the applied minimum input voltage, VO is the regulated output voltage, and ILOAD is the load current. Submit Documentation Feedback (10) Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Heat Sink and Thermal Considerations (continued) The dynamic losses during turnon and turnoff are negligible if a Schottky type catch diode is used. When no heat sink is used, the junction temperature rise can be determined by Equation 11: TJ = (PD) (JA) (11) To arrive at the actual operating junction temperature, add the junction temperature rise to the maximum ambient temperature. TJ = TJ + TA (12) If the actual operating junction temperature is greater than the selected safe operating junction temperature determined in step 3, then a heat sink is required. When using a heat sink, the junction temperature rise can be determined by Equation 13: TJ = (PD) (JC + interface + Heat sink) (13) The operating junction temperature is: TJ = TA + TJ (14) As in Equation 14, if the actual operating junction temperature is greater than the selected safe operating junction temperature, then a larger heat sink is required (one that has a lower thermal resistance). Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 27 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 11 Device and Documentation Support 11.1 Device Support 11.1.1 Device Nomenclature 11.1.1.1 Definition of Terms BUCK REGULATOR A switching regulator topology in which a higher voltage is converted to a lower voltage. Also known as a step-down switching regulator. BUCK-BOOST REGULATOR A switching regulator topology in which a positive voltage is converted to a negative voltage without a transformer. DUTY CYCLE (D) Ratio of the output switch's on-time to the oscillator period. (15) CATCH DIODE OR CURRENT STEERING DIODE The diode which provides a return path for the load current when the LM2576 switch is OFF. EFFICIENCY () The proportion of input power actually delivered to the load. (16) CAPACITOR EQUIVALENT SERIES RESISTANCE (ESR) The purely resistive component of a real capacitor's impedance (see Figure 35). It causes power loss resulting in capacitor heating, which directly affects the capacitor's operating lifetime. When used as a switching regulator output filter, higher ESR values result in higher output ripple voltages. Figure 35. Simple Model of a Real Capacitor Most standard aluminum electrolytic capacitors in the 100 F-1000 F range have 0.5 to 0.1 ESR. Higher-grade capacitors (low-ESR, high-frequency, or low-inductance) in the 100 F to 1000 F range generally have ESR of less than 0.15. EQUIVALENT SERIES INDUCTANCE (ESL) The pure inductance component of a capacitor (see Figure 35). The amount of inductance is determined to a large extent on the capacitor's construction. In a buck regulator, this unwanted inductance causes voltage spikes to appear on the output. OUTPUT RIPPLE VOLTAGE The AC component of the switching regulator's output voltage. It is usually dominated by the output capacitor's ESR multiplied by the inductor's ripple current (IIND). The peak-to-peak value of this sawtooth ripple current can be determined by reading Inductor Ripple Current. CAPACITOR RIPPLE CURRENT RMS value of the maximum allowable alternating current at which a capacitor can be operated continuously at a specified temperature. STANDBY QUIESCENT CURRENT (ISTBY) Supply current required by the LM2576 when in the standby mode (ON /OFF pin is driven to TTL-high voltage, thus turning the output switch OFF). INDUCTOR RIPPLE CURRENT (IIND) The peak-to-peak value of the inductor current waveform, typically a sawtooth waveform when the regulator is operating in the continuous mode (vs. discontinuous mode). CONTINUOUS/DISCONTINUOUS MODE OPERATION Relates to the inductor current. In the continuous mode, the inductor current is always flowing and never drops to zero, vs. the discontinuous mode, where the inductor current drops to zero for a period of time in the normal switching cycle. INDUCTOR SATURATION The condition which exists when an inductor cannot hold any more magnetic flux. 28 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV LM2576, LM2576HV www.ti.com SNVS107D - JUNE 1999 - REVISED MAY 2016 Device Support (continued) When an inductor saturates, the inductor appears less inductive and the resistive component dominates. Inductor current is then limited only by the DC resistance of the wire and the available source current. OPERATING VOLT MICROSECOND CONSTANT (E*Top) The product (in VoIt*s) of the voltage applied to the inductor and the time the voltage is applied. This E*Top constant is a measure of the energy handling capability of an inductor and is dependent upon the type of core, the core area, the number of turns, and the duty cycle. 11.2 Documentation Suuport 11.2.1 Related Documentation For related documentation, see the following: AN-1229 SIMPLE SWITCHER(R) PCB Layout Guidelines (SNVA054) 11.3 Related Links The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to sample or buy. Table 5. Related Links PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL DOCUMENTS TOOLS & SOFTWARE SUPPORT & COMMUNITY LM2576 Click here Click here Click here Click here Click here LM2576HV Click here Click here Click here Click here Click here 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 is a registered trademark 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. Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV Submit Documentation Feedback 29 LM2576, LM2576HV SNVS107D - JUNE 1999 - REVISED MAY 2016 www.ti.com 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. 30 Submit Documentation Feedback Copyright (c) 1999-2016, Texas Instruments Incorporated Product Folder Links: LM2576 LM2576HV 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) LM2576HVS-12 NRND DDPAK/ TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576 HVS-12 P+ LM2576HVS-12/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-12 P+ LM2576HVS-3.3/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-3.3 P+ LM2576HVS-5.0 NRND DDPAK/ TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576 HVS-5.0 P+ LM2576HVS-5.0/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-5.0 P+ LM2576HVS-ADJ NRND DDPAK/ TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576 HVS-ADJ P+ LM2576HVS-ADJ/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-ADJ P+ LM2576HVSX-12 NRND DDPAK/ TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2576 HVS-12 P+ LM2576HVSX-12/NOPB ACTIVE DDPAK/ TO-263 KTT 5 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-12 P+ LM2576HVSX-3.3/NOPB ACTIVE DDPAK/ TO-263 KTT 5 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-3.3 P+ LM2576HVSX-5.0 NRND DDPAK/ TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2576 HVS-5.0 P+ LM2576HVSX-5.0/NOPB ACTIVE DDPAK/ TO-263 KTT 5 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-5.0 P+ LM2576HVSX-ADJ NRND DDPAK/ TO-263 KTT 5 500 TBD Call TI Call TI -40 to 125 LM2576 HVS-ADJ P+ LM2576HVSX-ADJ/NOPB ACTIVE DDPAK/ TO-263 KTT 5 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576 HVS-ADJ P+ LM2576HVT-12 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576HVT -12 P+ LM2576HVT-12/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT-12/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM Addendum-Page 1 LM2576HVT -12 P+ -40 to 125 LM2576HVT -12 P+ 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) LM2576HVT-15/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576HVT -15 P+ LM2576HVT-15/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT -15 P+ LM2576HVT-15/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576HVT -15 P+ LM2576HVT-5.0 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576HVT -5.0 P+ LM2576HVT-5.0/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576HVT -5.0 P+ LM2576HVT-5.0/LF02 ACTIVE TO-220 NEB 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT -5.0 P+ LM2576HVT-5.0/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT -5.0 P+ LM2576HVT-5.0/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576HVT -5.0 P+ LM2576HVT-ADJ NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576HVT -ADJ P+ LM2576HVT-ADJ/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576HVT -ADJ P+ LM2576HVT-ADJ/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576HVT -ADJ P+ LM2576HVT-ADJ/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576HVT -ADJ P+ LM2576S-12 NRND DDPAK/ TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576S -12 P+ LM2576S-12/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S -12 P+ LM2576S-3.3/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S -3.3 P+ LM2576S-5.0 NRND DDPAK/ TO-263 KTT 5 45 TBD Call TI Call TI -40 to 125 LM2576S -5.0 P+ LM2576S-5.0/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S -5.0 P+ LM2576S-ADJ/NOPB ACTIVE DDPAK/ TO-263 KTT 5 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S -ADJ P+ Addendum-Page 2 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) LM2576SX-3.3/NOPB ACTIVE DDPAK/ TO-263 KTT 5 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S -3.3 P+ LM2576SX-5.0/NOPB ACTIVE DDPAK/ TO-263 KTT 5 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S -5.0 P+ LM2576SX-ADJ/NOPB ACTIVE DDPAK/ TO-263 KTT 5 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2576S -ADJ P+ LM2576T-12 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576T -12 P+ LM2576T-12/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576T -12 P+ LM2576T-12/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T -12 P+ LM2576T-12/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T-15/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T-15/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T-3.3/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T-3.3/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T -3.3 P+ LM2576T-5.0 NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576T -5.0 P+ LM2576T-5.0/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI LM2576T -5.0 P+ LM2576T-5.0/LF02 ACTIVE TO-220 NEB 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T -5.0 P+ LM2576T-5.0/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T -5.0 P+ LM2576T-5.0/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T -5.0 P+ LM2576T-ADJ NRND TO-220 KC 5 45 TBD Call TI Call TI -40 to 125 LM2576T -ADJ P+ LM2576T-ADJ/LB03 NRND TO-220 NDH 5 45 TBD Call TI Call TI Addendum-Page 3 -40 to 125 LM2576T -12 P+ LM2576T -15 P+ -40 to 125 LM2576T -15 P+ LM2576T -3.3 P+ LM2576T -ADJ P+ Samples PACKAGE OPTION ADDENDUM www.ti.com Orderable Device 2-Sep-2017 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) LM2576T-ADJ/LF02 ACTIVE TO-220 NEB 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T -ADJ P+ LM2576T-ADJ/LF03 ACTIVE TO-220 NDH 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM LM2576T -ADJ P+ LM2576T-ADJ/NOPB ACTIVE TO-220 KC 5 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2576T -ADJ P+ (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. (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. 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 4 Samples PACKAGE OPTION ADDENDUM www.ti.com 2-Sep-2017 Addendum-Page 5 PACKAGE MATERIALS INFORMATION www.ti.com 18-Jan-2016 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ LM2576HVSX-12 DDPAK/ TO-263 KTT 5 500 330.0 24.4 LM2576HVSX-12/NOPB DDPAK/ TO-263 KTT 5 500 330.0 LM2576HVSX-3.3/NOPB DDPAK/ TO-263 KTT 5 500 DDPAK/ TO-263 KTT 5 LM2576HVSX-5.0/NOPB DDPAK/ TO-263 KTT DDPAK/ TO-263 LM2576HVSX-ADJ/NOPB DDPAK/ TO-263 LM2576HVSX-5.0 LM2576HVSX-ADJ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 10.75 14.85 5.0 16.0 24.0 Q2 24.4 10.75 14.85 5.0 16.0 24.0 Q2 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2576SX-3.3/NOPB DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2576SX-5.0/NOPB DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 LM2576SX-ADJ/NOPB DDPAK/ TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 18-Jan-2016 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2576HVSX-12 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576HVSX-12/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576HVSX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576HVSX-5.0 DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576HVSX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576HVSX-ADJ DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576HVSX-ADJ/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576SX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576SX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2576SX-ADJ/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 Pack Materials-Page 2 MECHANICAL DATA NEB0005B www.ti.com PACKAGE OUTLINE KC0005A TO-220 - 16.51 mm max height SCALE 0.850 TO-220 4.83 4.06 10.67 9.65 3.05 2.54 B 1.40 1.14 A 6.86 5.69 3.71-3.96 8.89 6.86 (6.275) 12.88 10.08 OPTIONAL CHAMFER 16.51 MAX 2X (R1) OPTIONAL 9.25 7.67 C (4.25) PIN 1 ID (OPTIONAL) NOTE 3 14.73 12.29 1 5X 0.25 5 0.61 0.30 1.02 0.64 C A B 3.05 2.03 4X 1.7 6.8 1 5 4215009/A 01/2017 NOTES: 1. All controlling linear dimensions are in inches. Dimensions in brackets are in millimeters. Any dimension in brackets or parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. Shape may vary per different assembly sites. www.ti.com EXAMPLE BOARD LAYOUT KC0005A TO-220 - 16.51 mm max height TO-220 4X (1.45) PKG 0.07 MAX ALL AROUND 0.07 MAX ALL AROUND METAL TYP (1.45) PKG (2) 4X (2) 1 (R0.05) TYP 5X ( 1.2) SOLDER MASK OPENING, TYP (1.7) TYP 5 FULL R TYP (6.8) LAND PATTERN NON-SOLDER MASK DEFINED SCALE:12X 4215009/A 01/2017 www.ti.com MECHANICAL DATA NDH0005D www.ti.com MECHANICAL DATA KTT0005B TS5B (Rev D) BOTTOM SIDE OF PACKAGE 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. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. 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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: LM2576T-15 LM2576T-15/LB03 LM2576T-15/LF03 LM2576T-15/NOPB LM2576T-3.3 LM2576T-3.3/LB03 LM2576T-3.3/LF03 LM2576T-3.3/NOPB LM2576T-5.0 LM2576T-5.0/LB03 LM2576T-5.0/LF02 LM2576T-5.0/LF03 LM2576T-5.0/NOPB LM2576T-ADJ LM2576T-ADJ/LB02 LM2576T-ADJ/LB03 LM2576T-ADJ/LF02 LM2576TADJ/LF03 LM2576T-ADJ/NOPB LM2576S-12 LM2576S-12/NOPB LM2576S-3.3 LM2576S-3.3/NOPB LM2576S-5.0 LM2576S-5.0/NOPB LM2576S-ADJ LM2576S-ADJ/NOPB LM2576SX-3.3 LM2576SX-3.3/NOPB LM2576SX-5.0 LM2576SX-5.0/NOPB LM2576SX-ADJ LM2576SX-ADJ/NOPB LM2576T-12 LM2576T-12/LB03 LM2576T-12/LF03 LM2576T-12/NOPB