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Released by the OSFP MSA, the OSFP-XD (Octal Small Form Factor eXtra Dense) specification defines mechanical, electrical, thermal and optical interface requirements for next-generation ultra-high-density pluggable optical transceivers. Designed for hyperscale data centers and high-speed interconnection, it enables an aggregate port bandwidth up to 3.2 Tb/s and works in conjunction with the CMIS management interface.

Core Positioning

Building upon the standard OSFP footprint, OSFP-XD doubles high-speed lane count from 8 transmit/receive differential pairs to 16 pairs (32 differential lanes in total). It supports peak bandwidth of either 3.2 Tb/s via 224G-PAM4 (16×200 Gb/s) or 1.6 Tb/s via 112G-PAM4 (16×100 Gb/s). A half-populated variant named XD-8 with 8 lanes is also specified, delivering either 1.6 Tb/s or 800 Gb/s throughput.

Mechanical Specifications

OSFP-XD retains the identical module body width as conventional OSFP, but incorporates a double-row 120-contact edge connector internally, broken down as: 80 pins for high-speed signals, 8 power pins, 40 ground pins, 4 low-speed control pins and 4 reserved pins for application or vendor customization. A polarization key is implemented on the rear of the module to prevent damage from incorrect insertion of legacy OSFP into OSFP-XD cages. Multiple heatsink options can be mounted on the top, such as zipper-fin extruded sinks and open-top housings; the bottom surface can be configured flat, finned for airflow or fitted with EMI spring clips. The latching mechanism is mechanically compatible with OSFP. Force limits: maximum insertion force ≤40 N (≤55 N for ride-on heatsink variants) and minimum retention force ≥125 N.

Cage and Connector

Single-row SMT connectors are specified alongside 1×1 and 1×4 cage layouts. Each cage is equipped with EMI springs, ventilation slots, polarization keys, stop shoulders and latch springs. Detailed dimensional rules govern front-panel cutouts and PCB routing including 1×1, back-to-back and 1×4 arrangements; blank port openings must be sealed with dummy plugs to mitigate EMI leakage. A dedicated OSFP-XD-RHS (Ride-on Heatsink) variant stands 10.5 mm tall without on-module integrated cooling and fully relies on cage-mounted heatsinks for thermal dissipation; its stop shoulder is shifted 6 mm forward from standard design to avoid incompatible mating.

Electrical Interface

The 120-pin edge connector provides 16 differential transmit pairs and 16 differential receive pairs for high-speed traffic. Low-speed control signals include SCL/SDA, INT/RSTn (Interrupt/Reset), LPWn/PRSn/ePPS (Low-Power/Module Present/ePPS Clock), with optional ePPS/PTP reference clock support. Eight VCC power pins deliver a total rated current of 20 A (2.5 A per pin) for maximum power exceeding 60 W across eight defined power classes (Class 1~8). Power consumption is capped ≤2 W under low-power mode, while Class 8 high-power modules exceed 14 W. Hot-plug slew rate is restricted to 100 mA/μs.
Thermal Performance
Three case temperature grades are defined: commercial (0~70 °C), extended (-5~85 °C) and industrial (-40~85 °C). Connectors are qualified for a 10-year service life with ambient temperature rise limited to ≤30 °C at 65 °C ambient. Airflow impedance curves are characterized using dedicated test fixtures, with relaxed constraints for low-power modules below 20 W.

Optical Interface

Up to 18 types of optical receptacles are supported: duplex LC, MPO‑12/16, dual-row MPO‑12, MXC, dual MXC, dual Mini-LC, dual LC, dual CS, dual MDC, dual SN, dual MMC, dual SN-MT, quad MDC, quad SN, dual MPO, 8×MDC and 8×SN. Multiple PMD block diagrams for 1600G operation (DR16, DR8, 4FR2, ZR2, 4FR4, 2FR4, 2FR8, FR8) are specified with explicit mapping between electrical lanes and fiber channels.
Reliability & ESD Compliance
Durability requirements: 50 insertion/extraction cycles for modules and 100 cycles for mating connectors and host cages. ESD performance complies with EN61000‑4‑2 (8 kV contact, 15 kV air discharge) and 1000 V HBM.

Summary

By doubling lane density based on baseline OSFP form factor and supporting up to 3.2 Tb/s ultra-high bandwidth, OSFP-XD Rev 1.0 serves as a core interconnection standard for next-generation hyperscale data centers.