Vishay TSFF Series IR Emitting Diodes. The TSFF family, from Vishay Semiconductors, are high speed Infrared (IR) emitting diodes. With a peak wavelength of 870nm, these IREDs use double hetero (DH) technology. Suitable applications for the TSFF family of IREDs includes; IR video data transmission, free air data transmission and smoke automatic fire detectors.. Features of the TSFF family of IR emitting diodes: T-1 3/4 (5mm) through-hole packages High reliability High radiant power High radiant intensity Low forward voltage Peak wavelength: 870nm