Finisar FCLF8521P2BTL Network Transceiver Module Networking

Finisar’s FCLF8520P2BTL, FCLF8521P2BTL and FCLF8522P2BTL 1000BASE-T Copper Small
Form Pluggable (SFP) transceivers are based on the SFP Multi Source Agreement (MSA). They
are compatible with the Gigabit Ethernet and 1000BASE-T standards as specified in IEEE Std
802.3. They are RoHS compliant and lead-free per Directive 2002/95/EC and Finisar Application
Note AN-2038. The 1000BASE-T physical layer IC (PHY) can be accessed via I2C, allowing
access to all PHY settings and features.

The FCLF8520P2BTL uses the SFP’s RX_LOS pin for link indication, and 1000BASE-X auto-
negotiation should be disabled on the host system. The FCLF8521P2BTL is compatible with
1000BASE-X auto-negotiation, but does not have a link indication feature (RX_LOS is internally
grounded). See AN-2036, “Frequently Asked Questions Regarding Finisar’s 1000BASE-T SFPs”,
for a more complete explanation on the differences between the two models and details on
applications issues for the products. The FCLF8522 shall support both RX_LOS pin for link
indication and 1000BASE-X auto-negotiation.