Chip Maker Crafts SEPIC Designs for Automotive Lighting

Sep 21, 2005 2:42 PM

Fairchild Semiconductor’s Global Power Resource Design Center in Germany recently completed ballast designs that enable automobile manufacturers to meet the proposed European daytime headlight (daytime running light) safety regulations. The new ballast design uses a SEPIC topology that is well suited to low-voltage dc-dc applications, such as automobile LED-style headlights.

“Fairchild’s Global Power Resource design center in Europe developed a design, using the SEPIC topology, to drive up to seven LEDs with 30-V max output and 350 mA constant current, as well as up to 36 low-power LEDs with 120-V max output with 70 mA constant current output,” said Ole-Peter Brusdal, regional vice president, European Sales and Marketing.

The use of car headlights during the daytime is expected to become mandatory in the European Union under plans being discussed by the European Commission to cut the number of road accidents. Today’s automobiles increasingly use high brightness LEDs of up to 1 W of power. However, daytime headlights typically require five to seven LEDs to comply with the expected new standard. Ideally, these LEDs should be connected in a series to ensure identical current and therefore the brightness of each device. SEPIC topology can transform voltages up as well as down, easily meeting these requirements.

While SEPIC topology is ideal for dc-dc applications, it also is well suited to nonisolated low power ac-dc applications, such as power supplies for industrial controls and white goods. This topology offers cost-effective solutions, achieving an efficiency of about 80%.

“Fairchild is fortunate to have the caliber of talent in Dr. Michael Weirich and his team to develop innovative designs using SEPIC topology in a expansive range of low-voltage applications, such as daytime running headlights, dc-dc converters and off-line ac-dc solutions,” said Brusdal.

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