FB2M5LRR 650 nm 10-250 MBd 50 m LC POF Transceiver w. RSSI

The electrical and optical path supports data rates from 10 to 250 Mbps, while the serial symbol rate depends on the line encoding used. A 100 Mbps Ethernet stream using 4B/5B encoding operates at 125 MBd, whereas a 200 Mbps payload using 8B/10B encoding operates at 250 MBd. This makes 250 MBd the practical upper symbol-rate limit for the intended NRZ applications. When selecting a PHY or FPGA transceiver port, engineers should check the coded line rate rather than relying only on payload throughput. A design exceeding 250 MBd after encoding falls outside the characterised operating range.

Yes, a distance of 50 m over step-index POF is specified at 250 Mbps, but the final reach depends on the complete installation. The transmitter provides an average optical power range of -10 to -2 dBm, while the receiver sensitivity is -24 dBm and its maximum permitted optical input is -2 dBm. Comparing the minimum transmitted power with receiver sensitivity gives a nominal 14 dB optical budget before connector loss, fibre attenuation, bending, contamination, ageing and temperature effects are considered. The link budget should therefore be calculated using the actual cable and connector arrangement. Production hardware should also be tested across the required environmental range.

The data paths should normally be AC coupled so that each side can retain the common-mode voltage required by its own interface. The receiver has a typical common-mode output of 1.25 V, a typical 400 mV peak-to-peak output swing and an 800 mV differential swing. CML circuits generally operate with a 1.5 V common-mode level, while the illustrated LVPECL arrangement shifts the interface to 2 V through a resistor network. RD+ and RD− are internally terminated to 100 Ω, but TD+ and TD− require an external 100 Ω differential resistor. The 100 nF coupling capacitors used for high-speed operation may need to be increased at lower data rates.

The sleep functions reduce standby demand, but their timing must be considered when traffic starts after an idle period. The transmitter has a typical sleep current of 20 µA, the receiver typically draws 7 µA in sleep, and the combined typical value is therefore 27 µA. Transmitter wake-up delay is typically 5 µs and can reach 80 µs, while the receiver enters sleep after 2 seconds and requires 100 µs to wake. The receiver wake threshold lies between -28 and -26 dBm. Intermittent protocols may require a preamble, idle pattern or other valid signalling period before payload data is accepted.

The RSSI pin provides a current related to the average optical power reaching the receiver. Connecting a resistor between RSSI and ground converts this current into an analogue voltage, with 10 kΩ used in the example monitoring circuit. Typical RSSI responsivity is 0.16 A/W, and the available voltage range extends from 0 V to VCC minus 1.5 V. An ADC or comparator can use this signal to identify gradual link loss, contamination or excessive fibre bending before data reception fails. Thresholds should be calibrated in the finished assembly because RSSI is intended for link-health monitoring rather than precision optical-power measurement.

Pins 1 and 12 should connect the EMI shields directly to the signal-ground plane, and both transmitter ground pins must also be connected because they are not internally joined. A continuous, low-inductance ground plane helps limit transmitter-to-receiver crosstalk and external interference. TD+/TD− and RD+/RD− should be routed as controlled-impedance differential pairs with short, matched paths. Supply bypass capacitors should be placed close to the relevant power pins, and the recommended filtering should not be located remotely from the transceiver. The external 100 Ω transmitter termination should also be positioned to minimise stubs and discontinuities.

The component is intended for controlled soldering processes and is not suitable for infrared or vapour-phase reflow. Its maximum soldering condition is 260 °C for 10 seconds, applied once and at least 2.2 mm from the lead root. The MSL 2a classification permits a floor life of 672 hours below 30 °C and 60% relative humidity after the moisture-barrier bag is opened, while dry storage below 10% relative humidity is an alternative. The dust plug should remain installed during soldering, cleaning and drying. Alcohol-based cleaning agents are permitted, but acetone, ethyl acetate, phenol and similar solvents should be excluded from the process.