Thunderbolt active cable thermal analysis

Thunderbolt 3 (TBT3) active cable is used for high speed data transmission (2 × 20 Gbps) and high current power delivery (3 amps and 5 amps). Its thermal challenge is to passively dissipate high power from its active components (CDR and SVR) inside the plug and joule heating of high current conductors with very limited outer surface area. A system model including a half TBT3 cable, a mating pair of connectors and a motherboard model are built to investigate ways to meet junction temperature requirement of active components and surface temperature requirements for consumer safety and comfort. The system model of TBT cable includes conduction, convection and radiation and it is validated by comparing simulation results to thermocouple measurements and IR camera readings of cable samples powered up using a system validation board. Once the model is validated, this system model is used to study the impacts of component power levels, cable sizes, plug lengths and motherboard temperatures on the temperature criteria and shows motherboard and cable can be effective heat sinks for active components when designed properly. This makes the model an effective and critical tool to facilitate cable design, and to identify active components power limits. Also, since TBT3 utilizes Type C connector form factor, this model and methodology can be transferred to study other cables with Type C connector as well.