Diodes Incorporated Buck LED drivers, AL8860Q, AL8861Q, and AL8862Q, offer low-cost, robust solutions for driving high-current LEDs in automotive lighting applications. Their hysteretic control scheme and adjustable frequency minimize system size and cost. The AL8862QEV1 evaluation board is used for headlights and taillights, but not optimized to pass CISPR 25 automotive EMC standard. This application note discusses input filters for CISPR 25 Class 4 emissions and board space optimization.