LM27342MYEVAL

www.ti.com Table of Contents User’s Guide LM27341 Step-Down Converter Evaluation Module User's Guide Table of Contents 1 Introduction.............................................................................................................................................................................2 2 Evaluation Board Schematic................................................................................................................................................. 3 3 Powering and Loading Considerations................................................................................................................................ 4 3.1 Quick Start Procedure........................................................................................................................................................4 3.2 Starting Up......................................................................................................................................................................... 4 3.3 Overcurrent Protection....................................................................................................................................................... 4 3.4 Synchronization..................................................................................................................................................................4 3.5 Adjusting the Output Voltage..............................................................................................................................................4 4 Performance Characteristics.................................................................................................................................................5 5 Layout and Bill of Materials................................................................................................................................................... 6 6 PCB Layout..............................................................................................................................................................................7 7 Revision History......................................................................................................................................................................8 List of Figures Figure 4-1. Conversion Efficiency Versus Output Current........................................................................................................... 5 Figure 4-2. Output Voltage During a Typical Start-Up Sequence................................................................................................ 5 Figure 6-1. Top Layer and Overlay.............................................................................................................................................. 7 Figure 6-2. Internal Layer 1......................................................................................................................................................... 7 Figure 6-3. Internal Layer 2......................................................................................................................................................... 8 Figure 6-4. Bottom Layer............................................................................................................................................................. 8 List of Tables Table 5-1. Bill of Materials............................................................................................................................................................6 Trademarks All trademarks are the property of their respective owners. SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 LM27341 Step-Down Converter Evaluation Module User's Guide Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated 1 Introduction www.ti.com 1 Introduction The LM27342 demonstration board is designed to provide the power supply design engineer with a fully functional regulator design, which can be synchronized to an external clock between 1000 kHz and 2350 kHz. The evaluation board provides a 3.3-V output with a 2-A current capability. The wide input voltage ranges from 5 V to 20 V. Without an external synchronization signal, the design operates at 2000 kHz, reducing the solution size and keeping switching noise out of the AM radio band. The printed circuit board (PCB) consists of four layers of copper on FR4 material. There is a ground plane on the internal layer directly beneath the LM27342, and a ground plane on the bottom layer. The LM27342 is thermally tied to the ground planes by thermal vias directly underneath the device. The second internal layer is tied half to VIN and half to VOUT. This application report contains the evaluation board schematic, a quick setup procedure, and a bill-of-materials (BOM). For complete circuit design information, see the LM27341/LM27342/LM27341Q/LM27342Q 2 MHz 1.5A/2A Wide Input Range Step-Down DCDC Regulator with Frequency Synchronization data sheet. The performance of the evaluation board is as follows: • • • • • 2 Input range: 5 V to 20 V Output voltage: 3.3 V Output current: 0 A to 2 A Frequency of operation: 1000 kHz to 2350 kHz Board size: 1.1 inches × 1.3 inches LM27341 Step-Down Converter Evaluation Module User's Guide SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated www.ti.com Evaluation Board Schematic 2 Evaluation Board Schematic SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 LM27341 Step-Down Converter Evaluation Module User's Guide Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated 3 Powering and Loading Considerations www.ti.com 3 Powering and Loading Considerations Read this entire page prior to attempting to power the evaluation board. 3.1 Quick Start Procedure 1. Set the bench power supply current limit to 2 A. Set the power supply voltage to 12 V. Turn off the power supply output. Connect the power supply to the LM27342 demo board. Positive connection to VIN and negative connection to GND. 2. Connect a load, as high as 2 A, to the VOUT terminal. Positive connection to VOUT and negative connection to GND. 3. Connect a signal generator to provide a synchronization signal to the SYNC terminal. Positive connection to SYNC and negative connection to GND. 4. The EN pin should be left open for normal operation. 5. Turn on the bench power supply with no load applied to the LM27342. VOUT should be in regulation with a nominal 3.3-V output. 6. Slowly increase the load while monitoring the output voltage, VOUT should remain in regulation with a nominal 3.3-V output as the load is increased up to 2 A. 7. Slowly sweep the input voltage from 5 V to 20 V and back to 12 V, VOUT should remain in regulation with a nominal 3.3-V output. 8. Turn on the signal generator, and synchronize the LM27342 to a 3.3-V square wave at 1 MHz. VOUT should remain in regulation with a nominal 3.3-V output. Monitor SYNC and SW to observe the synchronization behavior. 3.2 Starting Up The EN pin is tied to VIN to simplify start up. The pullup resistor allows the power supply design engineer to toggle EN independently, if desired, and observe the start-up behavior of the LM27342. 3.3 Overcurrent Protection The evaluation board is configured with overcurrent protection. The inductor current is limited to 4.0 A (maximum). 3.4 Synchronization A SYNC pin has been provided on the evaluation board. This pin can be used to synchronize the regulator to an external clock or multiple evaluation boards can be synchronized together by connecting their SYNC pins together. Refer to the LM27342 data sheet for complete information 3.5 Adjusting the Output Voltage The output voltage is set using the following equation where R2 is connected between the FB pin and GND, and R1 is connected between VOUT and FB. (1) Adjusting the output voltage will affect the performance of the LM27342. In addition, output capacitors might not be rated for the new output voltage. Refer to the LM27342 data sheet for more information. 4 LM27341 Step-Down Converter Evaluation Module User's Guide SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated www.ti.com Performance Characteristics 4 Performance Characteristics Efficiency Plots Figure 4-1 shows the conversion efficiency versus output current for several input voltage conditions. Figure 4-1. Conversion Efficiency Versus Output Current Turn-On Waveform When applying power to the LM27342 evaluation board a soft-start sequence occurs. Figure 4-2 shows the output voltage during a typical start-up sequence. Output Current = 1A Figure 4-2. Output Voltage During a Typical Start-Up Sequence SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 LM27341 Step-Down Converter Evaluation Module User's Guide Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated 5 Layout and Bill of Materials www.ti.com 5 Layout and Bill of Materials The bill of materials is shown in Table 5-1, including the manufacturer and part number. Table 5-1. Bill of Materials 6 Part Name Part ID Part Value Part Number Manufacturer Buck Regulator U1 2A Buck Regulator LM27342 Texas Instruments CIN CIN 10 µF TMK325B7106MM-T Taiyo Yuden CBOOST CB 0.1 µF C0603C104K8RACTU Kemet COUT COUT 22 µF GRM32ER71A226KE20L Murata COUT2 COUT2 22 µF GRM32ER71A226KE20L Murata Catch Diode D1 Schottky Diode, Vf = 0.32 V CMS06 Toshiba Inductor L1 2.7 µH CDRH5D18BHHPNP-2R7M Sumida Feedback Resistor R1 430 Ω MCR03EZPFX4300 Rohm Feedback Resistor R2 187 Ω MCR03EZPFX1870 Rohm Pullup Resistor REN 4.7 kΩ MCR03EZPFX4701 Rohm Pulldown Resistor R_S 4.7 kΩ MCR03EZPFX4701 Rohm Connectors VIN, GND, GND, VOUT, EN, SYNC Turret 160-2043-02-01-00 Cambion Test Point SW Miniature Test Point 5000 Keystone LM27341 Step-Down Converter Evaluation Module User's Guide SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated www.ti.com PCB Layout 6 PCB Layout Figure 6-1. Top Layer and Overlay Figure 6-2. Internal Layer 1 SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 LM27341 Step-Down Converter Evaluation Module User's Guide Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated 7 Revision History www.ti.com Figure 6-3. Internal Layer 2 Figure 6-4. Bottom Layer 7 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision A (April 2013) to Revision B (December 2021) Page • Updated the numbering format for tables, figures, and cross-references throughout the document. ................2 • Updated the user's guide title ............................................................................................................................ 2 • Edited user's guide for clarity..............................................................................................................................2 8 LM27341 Step-Down Converter Evaluation Module User's Guide SNVA381B – NOVEMBER 2008 – REVISED DECEMBER 2021 Submit Document Feedback Copyright © 2021 Texas Instruments Incorporated IMPORTANT NOTICE AND DISCLAIMER TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCE DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS” AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD PARTY INTELLECTUAL PROPERTY RIGHTS. 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