Littelfuse HF Suffix
A question has been asked regarding the difference between Littelfuse part numbers with and without the HF suffix. Historically this suffix called out Halogen Free however many of their products moved to this being standard thus dropping the HF suffix.
For example noted on an older 2010 datasheet for
Littelfuse PolyFuse Resettable PTC series 1812L
" Effective September 15, 2009 onward, all 1812L PTC products will be manufactured Halogen Free (HF). Existing Non-Halogen Free 1812L PTC products will continue to be
sold until supplies are depleted. Effective January 1, 2010, all 1812L PTC product will be manufactured and sold as Halogen Free by default, and the “HF” part number suffix
code will be discontinued – Refer to Part Ordering Number System and Packaging Options sections for additional information. "