LOCAL ENGINEERING ESTIMATE

Thermal budget

Estimate a steady-state junction temperature and the remaining heat-sink budget.

FORMULA & LIMITS

Understand the model

Pheat = Pe − Popt; Tj = Ta + Pheat × (Rjc + Rcs + Rsa)

A single-path steady-state estimate, not a validated thermal design. A negative resistance allowance means the chosen limit is infeasible under these assumptions. Use radiant watts, not lumens, for optical output.

Changing an input invalidates the previous result. Check units before calculating again.

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