The RTL8201/RTL8201BL is a single-port Phyceiver with an MII (Media Independent Interface)/SNI(Serial Network Interface). It implements all 10/100M Ethernet Physical-layer functions including the Physical Coding Sublayer (PCS), Physical Medium Attachment (PMA), Twisted Pair Physical Medium Dependent Sublayer (TP-PMD), 10Base-Tx Encoder/Decoder and Twisted Pair Media Access Unit (TPMAU). A PECL interface is supported to connect with an external 100Base-FX fiber optical transceiver. The chip is fabricated with an advanced CMOS process to meet low voltage and low power requirements. The RTL8201BL can be used as a Network Interface Adapter, MAU, CNR, ACR, Ethernet Hub, Ethernet Switch. Additionally, it can be used in any embedded system with an Ethernet MAC that needs a twisted pair physical connection or fiber PECL interface to external 100Base-FX optical transceiver module.