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  "assumptions": [
    "Steady-state lumped thermal resistance",
    "Rθ constant (not Zth(t))",
    "θJA is an effective / application value, not a JEDEC-board package constant",
    "θJC+θCS+θSA is a single series path; parallel PCB/package paths are ignored",
    "P is device dissipation converted to heat"
  ],
  "limitations": [
    "Steady-state lumped Rθ only; not Zth(t) or CFD",
    "θJA and θJC+θCS+θSA are exclusive models — mixing them is CONFLICTING_INPUTS",
    "Required mode reports θSA,max, not total θJA",
    "θCA / Rth_HS are rejected: θCA already includes the ambient-side path",
    "Parallel PCB/package heat-flow paths are ignored on the explicit stack",
    "P is device dissipation converted to heat, not load or output power",
    "θSA,max ≤ 0 returns HEATSINK_INFEASIBLE and is not a purchasable heatsink"
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  "boundary_conditions": [
    "P < 0 → VALUE_MUST_BE_NON_NEGATIVE",
    "Required mode P ≤ 0 → VALUE_MUST_BE_POSITIVE",
    "Tj_max ≤ Ta in required mode → VALUE_OUT_OF_RANGE",
    "Rth_CA or Rth_HS → CONFLICTING_INPUTS",
    "Mixed θJA and stack fields → CONFLICTING_INPUTS",
    "θSA,max ≤ 0 → warning HEATSINK_INFEASIBLE (result still returned)"
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  "sources": [
    {
      "title": "JEDEC JESD51 series — Integrated Circuits Thermal Measurement Method",
      "section": "Junction-to-ambient and junction-to-case thermal metrics on specified test boards",
      "supports": "Tj = Ta + P·θJA as a thermal-metric estimate; θJA is test-condition specific",
      "kind": "standard",
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    {
      "title": "Analog Devices — Practical Design Techniques for Power and Thermal Management",
      "section": "Section 8, Fig. 8.50 — junction → case → case-to-sink → sink-to-ambient",
      "url": "https://www.analog.com/media/en/training-seminars/design-handbooks/Practical-Design-Techniques-Power-Thermal/Section8.pdf",
      "supports": "θJA = θJC + θCS + θSA; required θSA,max = (Tj,max−Ta)/P − θJC − θCS",
      "kind": "reference",
      "accessed": "2026-09-14"
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    {
      "title": "Texas Instruments SPRA953 — Semiconductor and IC Package Thermal Metrics",
      "section": "RθJA, RθJC, and application dependence of junction-to-ambient metrics",
      "url": "https://www.ti.com/lit/pdf/spra953",
      "supports": "θJA is not a universal equivalent of the explicit case/heatsink stack",
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      "section": "θCA is case-to-ambient (all case-to-ambient paths); θJA = θJC + θCA",
      "url": "https://www.analog.com/en/resources/technical-articles/thermal-characterization-of-ic-packages.html",
      "supports": "Do not add θCA to θSA — θCA already includes the ambient-side path",
      "kind": "reference",
      "accessed": "2026-09-14"
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