LM2745-19AEVAL

www.ti.com Table of Contents User’s Guide LM2745 Buck Controller Evaluation Module User's Guide Table of Contents 1 Introduction.............................................................................................................................................................................2 2 Specifics Of The Board.......................................................................................................................................................... 2 3 Feature Options...................................................................................................................................................................... 2 4 Specification Summary.......................................................................................................................................................... 3 5 Performance Characteristics – Efficiency............................................................................................................................3 6 Switch Node Voltage and Output Voltage Ripple.................................................................................................................4 7 Load Transient Response...................................................................................................................................................... 5 8 Bill of Materials....................................................................................................................................................................... 6 9 PCB Layout..............................................................................................................................................................................8 10 Revision History................................................................................................................................................................... 9 Trademarks All trademarks are the property of their respective owners. SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated 1 Introduction www.ti.com 1 Introduction This user's guide describes the LM2745 printed circuit board (PCB) design and provides an example typical application circuit. The LM2745 is a voltage mode PWM buck controller that implements synchronous rectification. It provides a low-cost, high power density, and efficient point of load solution. In steady state operation, the LM2745 is always synchronous, even at no load, simplifying the compensation design. The LM2745 ensures a smooth and controlled start-up when the output is pre-biased. The current limit protection does not require a current limit resistor in the power path, but is achieved by sensing the voltage VDS across the low side MOSFET. Though the control sections of the IC are rated for 3 V to 6 V (VCC), the driver sections are designed to accept input supply rails (VIN) as high as 14 V. 2 Specifics Of The Board This demo board targets the fixed and mobile telecommunications, industrial electronics, and distributed power markets. The demo board has a VIN range of 8 V to 14 V and a LDO regulator, the LP2937, powers VCC by regulating a 5-V output voltage. The LM2745 regulates to an output range of 1.2 V to 3.3 V at 19 A with a switching frequency of 300 kHz. The demo board is optimized for the previously mentioned parameters, thus for additional design modifications, refer to the Design Consideration section of the LM2745/48 Synch Buck Controller w/ Pre-Bias Startup & Optional Clock Synchronization data sheet. The PCB is designed on four layers. The top and bottom layers are 2-oz. copper and the two inner layers are 1-oz. copper. The board measures 2.19 inch × 1.03 inch × 0.41 inch (56 mm × 26.2 mm × 10.3 mm) (l × w × h) on a FR4 laminate. 3 Feature Options When the tracking feature of the LM2745 is required for use, remove the jumper that connects the soft-start capacitor, C10, and connect the resistor divider, on designators R13 and R14 (see Figure 3-1). The Track terminal has been provided for the user's connecting convenience. The demo board is synchronize ready, just connect an external clock to the SYNC terminal. Note Increasing the switching frequency results in a lower inductor current ripple and input and output voltage ripple (if the component values are kept the same). Monitor the MOSFET junction temperature since switching losses will increase, and do not exceed the maximum junction temperature of the MOSFET. Refer to the MOSFET manufacturer data sheet for the maximum junction temperature specification and heat sinking guidelines. Connects SoftStart Capacitor SJ1 SJ1 Connects Tracking Resistors Figure 3-1. Soft-Start and Tracking Jumper 2 LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback www.ti.com Specification Summary 4 Specification Summary • • • • • • • • • • • • • • Space saving footprint Wide ambient temperature range: –40°C to 65°C Input voltage range: 8 V to 14 V Adjustable output voltage: 1.2 V to 3.3 V No minimum load requirement Remote ON/OFF Power-good signal Fixed switching frequency: 300 kHz Switching frequency synchronize range 250 kHz to 1 MHz Current limit protection Controller power supply start-up tracking function Start-up with a pre-biased output load Adjustable soft start Small size: 2.19 inch × 1.03 inch × 0.41 inch (56 mm × 26.2 mm × 10.3 mm) 5 Performance Characteristics – Efficiency Figure 5-1. Efficiency vs. Load Current VOUT = 3.3 V, fSW = 300 kHz SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated 3 Switch Node Voltage and Output Voltage Ripple www.ti.com 6 Switch Node Voltage and Output Voltage Ripple 4 Figure 6-1. VIN = 8 V, VOUT = 3.3 V, ILOAD = 100 mA, fSW = 300 kHz, 20-MHz Bandwidth Limit Figure 6-2. VIN = 8 V, VOUT = 3.3 V, ILOAD = 19 A, fSW = 300 kHz, 20-MHz Bandwidth Limit Figure 6-3. VIN = 14 V, VOUT = 3.3 V, ILOAD = 100 mA, fSW = 300 kHz, 20-MHz Bandwidth Limit Figure 6-4. VIN = 14 V, VOUT = 3.3 V, ILOAD = 19 A, fSW = 300 kHz, 20-MHz Bandwidth Limit LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback www.ti.com Load Transient Response 7 Load Transient Response 5A/DIV 2A/DIV 50 mV/DIV 50 mV/DIV 100 µs/DIV 100 µs/DIV Figure 7-1. VIN = 14 V, VOUT = 3.3 V ILOAD = 2A to 10A, CH1: VOUT, CH2: ILOAD Figure 7-2. VIN = 14 V, VOUT = 3.3 V, ILOAD = 11 A to 19 A, CH1: VOUT, CH2: ILOAD 5A/DIV 2A/DIV 100 mV/DIV 100 mV/DIV 100 µs/DIV 100 µs/DIV Figure 7-3. VIN = 8 V, VOUT = 3.3 V, ILOAD = 2 A to 10 Figure 7-4. VIN = 8 V, VOUT = 3.3 V, ILOAD = 11 A to 19 A, CH1: VOUT, CH2: ILOAD A, CH1: VOUT, CH2: ILOAD SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated 5 Bill of Materials www.ti.com 8 Bill of Materials Table 8-1. Bill of Materials for LM2745 POL EVB (VIN: 8 V to 14 V, VOUT: 3.3 V, 19 A) Location 6 Part Number Type Size Parameters Qty Vendor U1 LM2745 Syn. Buck Controller TSSOP-14 VIN: 4.5 V–5.5 V 1 NSC U2 LM27937IMP-5.0 Linear Regulator 5 V,500 mA SOT-223 5 V, 500 mA 1 NSC L1 SER2010-202ML Inductor 2 μH, 27 A, 0.852 mΩ 1 Coilcraft Q1-2 IRF6633 N-MOSFET DirectFET-MP 20 V, 16 A, 4.1 mΩ, 11 nC 2 Vishay Q3 IRF6609 N-MOSFET DirectFET-MT 20 V, 150 A, 2 mΩ, 46 nC 1 Vishay D1 SL22-E3/2C Schottky Diode SMB 20 V, 2 A 1 Vishay D2 MBRS0520 Schottky Diode SOD123 20 V, 0.5 A 1 Vishay C1, 2 GRM32ER61C226KE20L Ceramic Capacitor 1210 22 µF, 25 V, X7R, 5% 2 Murata C3, 11 GRM319R71H104KA01B Ceramic Capacitor 1206 100 nF, 25 V, X7R, 10% 2 Murata C14 GRM319R71H474KA01B Ceramic Capacitor 1206 470 nF, 25 V, X7R, 10% 1 Murata C9 GRM1885C1H1210JA01 Ceramic Capacitor 0603 120 pF, 50 V, C0G, 5% 1 Murata C6 GRM188R71H222KA01 Ceramic Capacitor 0603 2.2 nF, 50 V, X7R, 10% 1 Murata C7 GRM1885C1H101JA01 Ceramic Capacitor 0603 100 pF, 50 V, C0G, 5% 1 Murata C8 GRM188R71H332KA01 Ceramic Capacitor 0603 3.3 nF, 50 V, X7R, 10% 1 Murata C10 GRM188R71H153KA01 Ceramic Capacitor 0603 15 nF, 50 V, X7R, 10% 1 Murata C12 GRM40X7R472K25 Ceramic Capacitor 0805 470 nF, 25 V, X7R, 10% 1 Murata C13 12066D226MAT Ceramic Capacitor 1206 22 µF, 6.3 V, X5R, 20% 1 AVX C4, 5 6SVPC220M OS-CON C6 220 µF, 6.3 V, 20% 2 Sanyo R1,18 CRCW06030R00F Chip Resistor 0603 0Ω 2 Vishay R2 CRCW06032151F Chip Resistor 0603 2.15 k, 1% 1 Vishay R3, R17 CRCW06031002F Chip Resistor 0603 10 k, 1% 2 Vishay R4 CRCW06032211F Chip Resistor 0603 2.21 k, 1% 1 Vishay R10, 11 CRCW06031003F Chip Resistor 0603 100 k, 1% 2 Vishay R5, 6, 8 CRCW06032R21F Chip Resistor 0603 2.21 Ω, 1% 3 Vishay R7, 9 CRCW06034702F Chip Resistor 0603 47 k, 1% 2 Vishay R12 CRCW06038451F Chip Resistor 0603 8.45 k, 1% 1 Vishay R15 CRCW06031821F Chip Resistor 0603 1.82 k, 1% 1 Vishay R16 CRCW060310R0F Chip Resistor 0603 10 Ω, 1% 1 Vishay — — F-Pin — — Pin 90 deg., SIP, 6 way 8 Pitch: 2.54 mm LM2745 Buck Controller Evaluation Module User's Guide 1 SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated www.ti.com Bill of Materials SJ2 U2 LM2937 VOUT C13 R18 VIN C12 GND R16 C11 D2 VIN C14 R6 R17 R11 C2 U1 C1 R5 BOO T SD SD PWGD Q1 HG VCC LM2745 PWGD Q2 R7 VOUT L1 R15 ISEN C7 SYNC FREQ/SYNC LG R8 Q3 R10 PGND SS/TRACK D1 + C5 + + C4 C3 R9 SGND PGND EAO R13 FB TRACK R14 C9 SJ1 C6 R2 R3 C8 R12 C10 TRIM R4 SENSE Figure 8-1. 300 kHz Demo Board Schematic SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated 7 PCB Layout www.ti.com 9 PCB Layout Figure 9-1. Top Silkscreen Figure 9-2. Top Copper Layer Figure 9-3. Bottom Silkscreen 8 LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback www.ti.com Revision History Figure 9-4. Bottom Copper Layer Figure 9-5. Internal Layer-1 (GND Copper) Figure 9-6. Internal Layer-2 (GND Copper) 10 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision A (May 2013) to Revision B (February 2022) Page • Updated the numbering format for tables, figures, and cross-references throughout the document. ................2 • Updated the user's guide title............................................................................................................................. 2 SNVA213B – MAY 2007 – REVISED FEBRUARY 2022 Submit Document Feedback LM2745 Buck Controller Evaluation Module User's Guide Copyright © 2022 Texas Instruments Incorporated 9 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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