DN71 ZXSC400 Solution for Luxeon® V Star high powered LED Description This design note shows the ZXSC400 driving a Luxeon® V Star LED. The input voltage ranges from 4.2V to 5.4 V with a maximum output current of 700mA at 5V input. A typical schematic diagram is shown in Figure 1. D1 L1 VIN = 4.4V to 5.4V Q1 C2 U1 C1 VCC VDRIVE Stdn ISENSE GND VFB R4 ZXSC400 C3 R1 Figure 1 R2 R3 Schematic diagram # Ref. Value Part number Manufacturer Comments U1 ZXSC400E6 Zetex LED driver in SOT23-6 Q1 ZXTN25012EFH Zetex Low sat. NPN in SOT23 D1 2A ZHCS2000 Zetex 2A Schottky in SOT23 L1 22H Generic Generic ISAT = 2A R1 18m⍀ Generic Generic 0805 size R2, R3 820m⍀ Generic Generic 0805 size R4 1k⍀ Generic Generic 0805 size C1 22F/10V Generic Generic C2 100F/10V Generic Generic C3 100nF/10V Generic Generic Table 1 Issue 6 - July 2007 © Zetex Semiconductors plc 2007 0805 size Bill of materials 1 www.zetex.com DN71 Typical operating characteristics (For typical application circuit where Tamb = 25°C unless otherwise stated) 100 0.4 Output Current (A) Efficiency (%) 90 80 70 60 50 3.6 3.4 3.2 3 2.8 2.6 2.4 2.2 0.2 0.0 2 3.6 3.4 3.2 Input Voltage (V) 1.6 8 1.2 6 0.8 0.4 0.0 3.4 3.2 3 2.8 2.6 2.4 2.2 2.6 2.4 2.2 2 2.2 2 2 3.6 3.4 3.2 3 2.8 2.6 2.4 Input Voltage (V) Input Voltage vs Input Current Figure 2 4 0 2 Input Voltage (V) www.zetex.com 2.8 Input Voltage vs Output Current Output Voltage (V) Input Current (A) Input Voltage vs Efficiency 3.6 3 Input Voltage (V) Input Voltage vs Output Voltage Performance graphs 2 Issue 6 - July 2007 © Zetex Semiconductors plc 2007 DN71 Intentionally left blank Issue 6 - July 2007 © Zetex Semiconductors plc 2007 3 www.zetex.com DN71 Definitions Product change Zetex Semiconductors reserves the right to alter, without notice, specifications, design, price or conditions of supply of any product or service. Customers are solely responsible for obtaining the latest relevant information before placing orders. Applications disclaimer The circuits in this design/application note are offered as design ideas. It is the responsibility of the user to ensure that the circuit is fit for the user’s application and meets with the user’s requirements. No representation or warranty is given and no liability whatsoever is assumed by Zetex with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Zetex does not assume any legal responsibility or will not be held legally liable (whether in contract, tort (including negligence), breach of statutory duty, restriction or otherwise) for any damages, loss of profit, business, contract, opportunity or consequential loss in the use of these circuit applications, under any circumstances. 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To ensure quality of service and products we strongly advise the purchase of parts directly from Zetex Semiconductors or one of our regionally authorized distributors. For a complete listing of authorized distributors please visit: www.zetex.com/salesnetwork Zetex Semiconductors does not warrant or accept any liability whatsoever in respect of any parts purchased through unauthorized sales channels. ESD (Electrostatic discharge) Semiconductor devices are susceptible to damage by ESD. Suitable precautions should be taken when handling and transporting devices. The possible damage to devices depends on the circumstances of the handling and transporting, and the nature of the device. The extent of damage can vary from immediate functional or parametric malfunction to degradation of function or performance in use over time. Devices suspected of being affected should be replaced. 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Samples may be available “Active” Product status recommended for new designs “Last time buy (LTB)” Device will be discontinued and last time buy period and delivery is in effect “Not recommended for new designs” Device is still in production to support existing designs and production “Obsolete” Production has been discontinued Datasheet status key: “Draft version” This term denotes a very early datasheet version and contains highly provisional information, which may change in any manner without notice. “Provisional version” This term denotes a pre-release datasheet. It provides a clear indication of anticipated performance. However, changes to the test conditions and specifications may occur, at any time and without notice. “Issue” This term denotes an issued datasheet containing finalized specifications. However, changes to specifications may occur, at any time and without notice. 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