Ksz80 Ob S4lv02 Datasheet __link__ Here

"OB" is not a standard speed grade or temperature range in official Microchip datasheets. Official suffixes are usually -TLI (Industrial temp, Tape & Reel) or -TR etc. Therefore, "OB" is likely a customer-specific marking or a date/lot identifier.

Search for "S4LV02 configuration" in the OEM’s support portal. If this chip is on a board from Siemens, Wago, Beckhoff, or National Instruments, you need their specific hardware manual, not the PHY datasheet. ksz80 ob s4lv02 datasheet

With that, I can pinpoint the exact datasheet for you. "OB" is not a standard speed grade or