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Power · resistance · capacitance · time

Single-RC thermal step

Inputs

User-entered constant heat-generation step; time-varying loads and duty cycles are not modeled.
User-entered scalar thermal resistance for one ideal path; no hardware or path is derived or selected.
User-entered scalar thermal capacitance for the same one ideal node; mass, material, and geometry are not derived.
User-entered constant reference temperature for this ideal step-response relation.
User-entered elapsed time after the stated constant power step; must be zero or greater.

Results

Literal thermal time constant

100

Literal ideal temperature rise at elapsed time

25.285

Literal ideal node temperature

50.285

Literal ideal steady-state temperature rise

40

τ = R·C; ΔT(t) = P·R·(1 − e^(−t/τ)); Tnode = Tamb + ΔT(t)

A first-pass number, not a code check, certification, or approval. Read the method and its limits below. What this is and is not.

Nearby: Sensible heat · Heat-exchanger ΔTlm · Plane-wall conduction · Thermal radiation exchange

Method

Formula, when it applies, and when it does not

Apply a constant power step to one ideal thermal RC node and report temperature rise and node temperature without selecting cooling hardware.

τ = R·C; ΔT(t) = P·R·(1 − e^(−t/τ)); Tnode = Tamb + ΔT(t)

When

  • Single thermal resistance and capacitance
  • One ideal RC thermal node

Don’t

  • This applies a user-declared constant power step to one ideal thermal RC node. It does not derive resistance or capacitance; determine thermal paths; select a heat sink, TIM, fan, or cooler; model multi-node conduction, convection, radiation, variable power, spatial temperature, material properties, junction limits, capacity, safety, suitability, or approval.
Electronics Cooling thermal RC guidance