Led Lighting Spd Design Installation Guide Page 18 LED Lighting SPD Design & Installation Guide

LED Lighting Surge Protection Modules Design and Installation Guide 2015 Littelfuse LED Lighting SPD Module Design and Installation Guide www.littelfuse.com The following steps summarize a design process that helps ensure enough inductance is present between the SPD MOVs and the one in the driver: 1. MOV1 and MOV2 need to be coordinated so that most of surge current/energy flows through MOV1. 2. Select MOVs with V M of MOV1 V M of MOV2, where V M is the Maximum Continuous Operating Voltage. 3. Select MOVs with V C of MOV1 V C of MOV2, where V C is the Maximum Clamping Voltage. 4. V MOV1 = V MOV2 + L (di/dt) 5. Inductance L may be added in series with the SPD. Increasing inductance L will result in better coordination as MOV1 absorbs the higher surge energy 6. Refer to the embedded links in the SPD blocks of Figure 17 for MOV technical information. See the Littelfuse Varistor Ordering Information Diagram for details on constructing a part number. The Littelfuse Application Team has years of expertise in such coordination requirements and has helped many customers optimize their circuit reliability while meeting surge immunity requirements. Power Supply Unit Design Considerations (Fuse, Equivalent Resistance, TVS Diode) Although an SPD module is designed to absorb most of the surge energy produced by a lightning strike, some residual energy can enter the LED driver and cause damage to the components inside it ( Figure 18 ). To minimize the damage, always consider an LED driver design that works in cooperation with the SPD module so less energy can enter the LED driver. Power Supply Unit Design Considerations 18

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