Liquid-cooled switch QSFP28 output

Liquid-cooled QSFP28 modules deliver 100 Gbps over four 25 Gbps lanes with enhanced thermal management, enabling high-density switch deployments without thermal throttling. Overview of QSFP28 OutputA QSFP28 (Quad Small Form-Factor Pluggable 28) transceiver provides four lanes, each transmitting at 25. 78125 Gbps using NRZ signaling, combining for a total of 100 Gbps per module ( ).

Liquid-cooled variants are designed to dissipate heat more efficiently, allowing modules to operate at higher power levels or in dense switch environments without exceeding thermal limits ( ). Typical power consumption ranges from 3. 5 W to 4.

5 W, but liquid cooling can maintain stable operation even under maximum load ( ). Signal and Interface ConsiderationsQSFP28 modules interface with switches via CAUI-4 (100G parallel physical interface), which requires careful signal conditioning to maintain low jitter and meet eye mask specifications ( ). Liquid-cooled modules do not alter the electrical output but enable consistent performance by preventing thermal-induced signal degradation.

Each lane's output is referenced to the module's VccTX, VccRX, and GND pins, which are rated for up to 1 A per pin, ensuring reliable power delivery to the optical transmitters ( ).

Thermal and Operational Benefits

Enhanced heat dissipation: Liquid cooling removes heat from the module more efficiently than air cooling, reducing the risk of thermal throttling. Stable output: Maintains consistent optical power and signal integrity across all four channels. High-density deployment: Supports multiple QSFP28 modules in top-of-rack switches without exceeding thermal budgets ( ).

Practical Implications

When deploying liquid-cooled QSFP28 modules: Ensure the switch supports liquid-cooling interfaces and proper coolant flow. Monitor Digital Diagnostic Monitoring (DDM) data for temperature, voltage, and optical power to verify stable operation ( ). Use signal-conditioning devices like linear repeaters or retimers if the switch ASIC-to-module distance exceeds standard PCB channel limits, which can extend reach without compromising output quality ( ).

In summary, liquid-cooled QSFP28 outputs maintain full 100G performance across four 25G lanes while mitigating thermal constraints, making them ideal for high-density, high-performance switch deployments.