LM3405AXMYEVAL

User's Guide SNVA370B – October 2008 – Revised May 2013 AN-1899 LM3405A VSSOP Evaluation Board 1 Introduction This evaluation board converts an input voltage of 5V to 18V, and can illuminate up to four 750 mA LEDs using the LM3405A VSSOP 1.6 MHz LED Driver samples. A bill of materials included describes the parts used on this evaluation board. A schematic and layout have also been included with measured performance characteristics of the evaluation board. 2 LM3405A VSSOP Evaluation Board Schematic D3 D2 C4 D4 LED + L1 R2 C3 LM3405A VIN R3 5 4 6 3 7 2 8 1 D1 C2 LED DIMM eMSOP8 C1 R1 Figure 1. LM3405A VSSOP Evaluation Board Schematic All trademarks are the property of their respective owners. SNVA370B – October 2008 – Revised May 2013 Submit Documentation Feedback AN-1899 LM3405A VSSOP Evaluation Board Copyright © 2008–2013, Texas Instruments Incorporated 1 LM3405A VSSOP Pin-Out 3 www.ti.com LM3405A VSSOP Pin-Out FB 1 8 EN/DIM GND 2 7 GND NC 3 6 VIN BOOST 4 5 SW Figure 2. 8-Pin VSSOP Pin Out 4 Four Methods of Deriving VBOOST The standard evaluation board derives VBOOST voltage using the “Shunt Zener” configuration, shown in Figure 1. Depending on the specific application, VBOOST voltage can be derived by loading and no-loading external components on the evaluation PCB. The following four schematics show methods to derive VBOOST. 4.1 VBOOST Derived from Shunt Zener Configuration This configuration, Figure 3, is recommended for distributed input voltages that have a wide voltage variation. The shunt zener acts as basic voltage regulator for the VBOOST voltage. D4 should have a typical value of 3.6V to 5.1V, R2 = (VIN - Vzener)/4 mA, C4 = 0.10 µF. D3 D2 C4 D4 LED + L1 R2 C3 LM3405A VIN R3 5 4 6 3 7 2 8 1 D1 C2 LED DIMM eMSOP8 C1 R1 Figure 3. VBOOST Derived from Shunt Zener Configuration 2 AN-1899 LM3405A VSSOP Evaluation Board SNVA370B – October 2008 – Revised May 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Four Methods of Deriving VBOOST www.ti.com 4.2 VBOOST Derived from VOUT Use this configuration, Figure 4, for output voltages (VLED) that are between 3V and 5.5V. D3 LED + L1 C3 LM3405A 5 4 6 3 7 2 8 1 D1 LED VIN R3 LED DIMM eMSOP8 C1 R1 Figure 4. VBOOST Derived from VOUT SNVA370B – October 2008 – Revised May 2013 Submit Documentation Feedback AN-1899 LM3405A VSSOP Evaluation Board Copyright © 2008–2013, Texas Instruments Incorporated 3 Four Methods of Deriving VBOOST 4.3 www.ti.com VBOOST Derived from VIN Use this configuration, Figure 5, for input voltages that are between 3V and 5.5V. D2 LED+ L1 C3 LM3405A VIN R3 5 4 6 3 7 2 8 1 D1 C2 LED LEDDIMM eMSOP8 C1 R1 Figure 5. VBOOST Derived from VIN 4 AN-1899 LM3405A VSSOP Evaluation Board SNVA370B – October 2008 – Revised May 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Four Methods of Deriving VBOOST www.ti.com 4.4 VBOOST Derived from External Supply This method of deriving the VBOOST voltage, Figure 6, is recommended if the distributed voltage used for point of load regulation is greater than 5V, but there is access to an external voltage between 3V and 5V. The typical current draw from the external supply would be approximately 2.50 mA. 5.5V >VEXTERNAL > 3V External Supply D2 LED + L1 LM3405A C3 5 4 6 3 7 2 8 1 D1 C2 LEDs VIN R3 LED DIMM eMSOP8 C1 R1 Figure 6. VBOOST Derived from External Supply SNVA370B – October 2008 – Revised May 2013 Submit Documentation Feedback AN-1899 LM3405A VSSOP Evaluation Board Copyright © 2008–2013, Texas Instruments Incorporated 5 PCB Top Layer 5 www.ti.com PCB Top Layer Figure 7. Layout, Top Layer Figure 8. Layout, Bottom Layer 6 AN-1899 LM3405A VSSOP Evaluation Board SNVA370B – October 2008 – Revised May 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Bill of Materials www.ti.com 6 Bill of Materials Table 1. Bill of Materials Part ID Part Value Manufacturer Part Number U1 1A Buck LED Driver VSSOP Texas Instruments LM3405A C1, Input Cap 10 µF, 25V, X5R (1210) TDK C3225X5R1E106M C2, Output Cap 4.7 µF, 25V, X5R (1206) TDK C3216X5R1E475M C3 2.2 µF (0805) TDK C2012X5R1E225M C2012X5R1E105M C4 1.0 µF (0805) TDK D1, Catch Diode 0.3Vf Schottky 1.5A, 30VR TOSHIBA CRS08 D2 SOT23 Schottky Vishay BAT54-V D3 SOT23 Schottky Vishay BAT54-V (No Load) D4 4.3V Zenner SOT23 Vishay BZX84C4V3-V L1 4.7 µH, 1.5A, CoilCraft MOS6020-472MLB R1 267 mΩ (1206) Vishay R2 1 kΩ, 1% Vishay CRCW08051001F R3 10.0 kΩ, 1% Vishay CRCW08051002F SNVA370B – October 2008 – Revised May 2013 Submit Documentation Feedback AN-1899 LM3405A VSSOP Evaluation Board Copyright © 2008–2013, Texas Instruments Incorporated 7 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. 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