D-fend™ is the industry's first all-digital, programmable loudspeaker protection and attenuation circuit designed to solve the age-old problems associated with protecting loudspeakers from excessive power conditions. With on-board digital filtering, D-fend™ provides multiple frequency dependent thresholds and independent attack/release timing parameters. This enables the designer to use D-fend™ technology prior to passive filtration, and allows increased sensitivity in specific frequency bands such as woofer over-excursion bands or high frequency peak damage regions.