LM3495EVAL/NOPB

www.ti.com Table of Contents User’s Guide LM3495 Buck Controller Evaluation Module User's Guide Table of Contents 1 Specifications Of The Board..................................................................................................................................................2 2 Example Circuit.......................................................................................................................................................................2 3 Powering The Converter........................................................................................................................................................ 2 4 Enabling The Converter......................................................................................................................................................... 2 5 Testing The Converter............................................................................................................................................................ 3 6 SKIP/PWM................................................................................................................................................................................3 7 MOSFET Footprints................................................................................................................................................................ 3 8 Permanent Components........................................................................................................................................................ 3 9 Additional Footprints..............................................................................................................................................................4 10 Complete Circuit Schematic................................................................................................................................................ 5 11 Connection Diagrams...........................................................................................................................................................6 12 Typical Performance Waveforms........................................................................................................................................ 7 13 Bill of Materials (BOM)........................................................................................................................................................10 14 PCB Layout..........................................................................................................................................................................11 15 Revision History................................................................................................................................................................. 14 Trademarks All trademarks are the property of their respective owners. SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 LM3495 Buck Controller Evaluation Module User's Guide Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated 1 Specifications Of The Board www.ti.com 1 Specifications Of The Board The evaluation board has been designed to test various circuits using the LM3495 buck regulator controller. Figure 10-1 shows a complete schematic for all components. The board has four layers, consisting of signal/ power traces on the top and bottom, one internal ground plane, and an internal split power plane. The top and bottom planes are 1-oz. copper, internal planes are 1/2 oz., and the board is 62-mil FR4 laminate. 2 Example Circuit The example circuit that comes on the evaluation board steps input voltages of 12 V ±10% down to 1.2 V at currents up to 10 A with a switching frequency of 500 kHz. The measured efficiency of the converter is 86% at an output current of 7 A. Figure 2-1. Efficiency for VIN = 12 V 3 Powering The Converter The example circuit for the LM3495 evaluation board is optimized to run at inputs of 12 V, however the circuit will operate with input voltages ranging from 2.9 V to 18.0 V connected between the ‘VIN’ and ‘GND’ terminals at the top of the board. Fixed loads, resistors, and variable electronic loads can be connected between the ‘Vo’ and ‘GND’ terminals. Table 13-1 lists all the components used in the example circuit. 4 Enabling The Converter The SPDT switch ON/OFF controls the state of the converter while power is applied to the input terminals. While in the OFF position the COMP/SD* pin of the LM3495 is grounded, the output is disabled, and the IC enters a low power state. While in the ON position the output voltage is regulated and is capable of delivering current to a load connected at the output terminals. 2 LM3495 Buck Controller Evaluation Module User's Guide SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated www.ti.com Testing The Converter 5 Testing The Converter Figure 11-1 shows a block diagram of connections for making measurements of efficiency. The wires used for making connections at both the input and output should be rated to at least 10 A of continuous current and should be no longer than is needed for convenient testing. A series ammeter capable of measuring 10 A or more should be used for both the input and the output lines. Dedicated voltmeters should be connected with their positive and negative leads right at the four power terminals at the top of the evaluation board. This measurement technique minimizes the voltage loss in the wires that connect the evaluation board to the input power supply and the electronic load. Output voltage ripple measurements should be taken directly across the 100-nF ceramic capacitor, Cox, placed right between the output terminals. Care must be taken to minimize the loop area between the oscilloscope probe tip and the ground lead. One method to minimize this loop is to remove the spring tip and ‘pigtail’ ground lead of the probe and then wind bare wire around the probe shaft. The bare wire should contact the ground of the probe and the end of the wire can then contact the ground side of Cox. Figure 11-2 shows a diagram of this method. An oscilloscope probe modified as described above can also be used to measure the switch node voltage, LG pin voltage, and HG pin voltage (all three with respect to ground) using the 40-mil diameter hole pairs labeled “+ SW –“, “+ LG –“, and “+ HG –“, respectively. 6 SKIP/PWM A second SPDT switch labeled SKIP/FPWM determines that control scheme the LM3495 uses at low output currents. When set to SKIP, the converter saves energy during light loads (approximately 100 mA or less) by using the body diode of the low-side FET, as well as leaving the high-side FET off if possible. When the switch is set to FPWM, the LM3495 forces both top and bottom FETs to switch during every cycle, regardless of the load current. 7 MOSFET Footprints The LM3495 evaluation board has footprints for single N-MOSFETs with SO-8 packages and standard pinouts. These footprints can also accept newer MOSFET packages that are compatible with SO-8 footprints. See Figure 7-1. Q1 is the high-side FET and Q2 low-side FET. S D S D SO-8 S D G D Figure 7-1. SO-8 MOSFET Pinout 8 Permanent Components The following components should remain the same for any new circuits evaluated on the LM3495 evaluation board: Name Value Cb 0.1 µF Cf 1 µF Cdd 2.2 µF SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 LM3495 Buck Controller Evaluation Module User's Guide Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated 3 Additional Footprints www.ti.com 9 Additional Footprints A 100-pF ceramic capacitor should be placed at position Dsync whenever the LM3495 runs without an external clock. When an external clock is used, Dsync should be removed and a 100-pF ceramic capacitor placed at Csync. The 0-Ω resistor J1 connects the TRACK pin and VDD pins of the LM3495 together. It should be removed only when the tracking function is used. The 0-Ω resistor J2 connects the VIN and VLIN5 terminals of the LM3495 together. This resistor should be used only when the input voltage is 5.5 V or less to provide maximum MOSFET gate drive. The 0-Ω resistor J3 connects the ‘VIN’ terminal to the VIN pin of the LM3495. This resistor should be removed only for testing of the input current draw of the LM3495 IC. The 0-Ω resistor Rbst can be replaced with a higher value resistor to limit the current drawn by the BOOST pin. This slows the high-side FET gate drive rise time and can reduce ringing on the switch node. Care must be taken, as slowing the gate drive too much can cause shoot-through current. Components Rt1 and Rt2 are used if the output of the converter is tracking another supply during start-up. For this application, the output of the external supply should be connected to the TRACK IN terminal. When the tracking feature is not used, the track pin should be connected to the VDD pin by placing a 0-Ω resistor in position J2. Components Rsnb and Csnb can be used to filter ringing on the switch node. D2 provides a position for a diode to go in parallel with Q2. In circuits with output currents of approximately 5 A or less, a Schottky diode at D2 can improve the efficiency of the converter. 4 LM3495 Buck Controller Evaluation Module User's Guide SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated www.ti.com Complete Circuit Schematic 10 Complete Circuit Schematic J3 CDD CF VLIN5 1 PF 2.2 PF D1 J2 LIN J1 TRACK IN RT2 13 9 VIN TRACK Vin 14 CB BOOST RT1 SYNC IN 1 VLIN5 RBST 2 8 FREQ/SYNC + CIN1 + CIN2 0.1 PF Q1 HG CSYNC CINX 3 SW/CSH DSYNC RFRQ LM3495 LG 6 SKIP/FPWM 5 L1 RLIM Vo ILIM 15 FPWM 4 Q2 + C O1 + C O2 COX RSNB COMP/SD ON/OFF CSNB RLG CSL 11 D2 16 FB CC1 CC2 10 SNS SGND 7 12 PGND RC1 RFB2 RFB1 Figure 10-1. Circuit Schematic SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 LM3495 Buck Controller Evaluation Module User's Guide Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated 5 Connection Diagrams www.ti.com 11 Connection Diagrams Ammeter Ammeter A + 50W , 10 A Electronic Load A + 18V , 6A Power Supply - Vo Voltmeter GND GND Vin V V Voltmeter LM3495 Evaluation Board Figure 11-1. Efficiency Measurement Setup Oscilloscope Vo GND Cox Figure 11-2. Output Voltage Ripple Measurement Setup 6 LM3495 Buck Controller Evaluation Module User's Guide SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated www.ti.com Typical Performance Waveforms 12 Typical Performance Waveforms Figure 12-1. Switch Node Voltage (VIN = 12 V, VO = 1.2 V, IO = 5 A) Figure 12-2. Switch Node Voltage (VIN = 12 V, VO = 1.2 V, IO = 5 A) SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 LM3495 Buck Controller Evaluation Module User's Guide Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated 7 Typical Performance Waveforms www.ti.com Figure 12-3. Output Voltage Ripple, AC Coupled (VIN = 12 V, VO = 1.2 V, IO = 5 A) Figure 12-4. Load Transient Response (VIN = 12 V, VO = 1.2 V, IO = 0 A to 4 A) 8 LM3495 Buck Controller Evaluation Module User's Guide SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated www.ti.com Typical Performance Waveforms Figure 12-5. Load Transient Response (VIN = 12 V, VO = 1.2 V, IO = 4 A to 0 A) SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 LM3495 Buck Controller Evaluation Module User's Guide Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated 9 Bill of Materials (BOM) www.ti.com 13 Bill of Materials (BOM) Table 13-1. Bill of Materials (BOM) 10 Qty ID Part Number Type Size Parameters Vendor 1 U1 LM3495 Synchronous Controller TSSOP-16 1 Q1 HAT2198R N-MOSFET SO-8 30 V, 9.6 mΩ 11 nC Renesas 1 Q2 HAT2165H N-MOSFET LFPAK 30 V 3.4 mΩ, 33 nC Renesas 1 D1 MBR0530 Schottky Diode SMA 30 V, 0.5 A Vishay 1 L1 RLF12560T-1R0N140 Inductor 12.5x12.8 x6.0mm 1 µH, 14 A, 3 mΩ TDK 1 Cin C3225X5R1E226M Capacitor 1210 22 µF, 25 V TDK 2 Co1, Co2 C3225X5R0J107M Capacitor 1210 100 µF, 6.3 V, 1 mΩ TDK 1 Cf C3216X7R1E105M Capacitor 1206 1 µF, 25 V TDK TI 1 Cdd C3216X7R1E225M Capacitor 1206 2.2 µF, 25 V TDK 2 Cb, Cinx VJ1206Y104KXXAT Capacitor 1206 100 nF, 10% Vishay 1 Cc1 VJ1206Y103KXXAT Capacitor 1206 10 nF, 10% Vishay 3 Cc2, Csync, Dsync VJ1206A101KXXAT Capacitor 1206 100 pF, 10% Vishay 1 Cox VJ0805Y104KXXAT Capacitor 805 100 nF, 10% Vishay 3 Rbst, J1, J3 CRCW08050R00F Resistor 805 0Ω Vishay 1 Lin CRCW25120R00F Resistor 2512 0Ω Vishay 1 Rc1 CRCW12061501F Resistor 1206 1.5 kΩ, 1% Vishay 2 Rfb1, Rfb2 CRCW12061002F Resistor 1206 10 kΩ, 1% Vishay 1 Rfrq CRCW12065492F Resistor 1206 54.9 kΩ, 1% Vishay 1 Rlg CRCW12061R00F Resistor 1206 1 Ω, 1% Vishay 1 Rlim CRCW12063321F Resistor 1206 3.32 kΩ, 1% Vishay 2 SKIP/FPWM ON/OFF NKK A12AB SPST 5 Vo, GND1 GND2, GND3 Vin Newark 40F6004 Terminal Silver 0.094” Cambion 4 SYNC IN GND4, GND5 TRACK IN Newark 94F1478 Terminal Silver 0.062” Keystone LM3495 Buck Controller Evaluation Module User's Guide NKK SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated www.ti.com PCB Layout 14 PCB Layout Figure 14-1. Top Layer and Top Overlay SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 LM3495 Buck Controller Evaluation Module User's Guide Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated 11 PCB Layout www.ti.com Figure 14-2. Bottom Layer 12 LM3495 Buck Controller Evaluation Module User's Guide SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated www.ti.com PCB Layout Figure 14-3. Internal Layer 1 SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 LM3495 Buck Controller Evaluation Module User's Guide Submit Document Feedback Copyright © 2022 Texas Instruments Incorporated 13 Revision History www.ti.com Figure 14-4. Internal Layer 2 15 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision B (April 2013) to Revision C (February 2022) Page • Updated the numbering format for tables, figures, and cross-references throughout the document. ................2 • Updated the user's guide title............................................................................................................................. 2 14 LM3495 Buck Controller Evaluation Module User's Guide SNVA149C – MARCH 2006 – REVISED FEBRUARY 2022 Submit Document Feedback Copyright © 2022 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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