ST8500 Programmable PLC Modem System on Chip STMicroelectronics ST8500 Programmable Power Line Communication (PLC) Modem System on Chip is able to run any PLC protocol up to a 500kHz frequency band. The ST8500 targets CENELEC EN50065, FCC, and ARIB compliant applications supporting all major PLC protocol standards. These standards include ITU G.9904 (PRIME), ITU G.9903 (G3-PLC®), and many other possible PLC protocol specifications and evolutions.