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Heatsink Thermal Resistance Budget

Online heatsink thermal resistance budget. Positive remaining thermal budget only; airflow conditions must match ratings.

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heatsink thermal resistance budget calculator online

Use heatsink thermal resistance budget online for junction limit C, ambient C, power W, case theta, interface theta. Positive remaining thermal budget only; airflow conditions must match ratings. Ideal nominal component model. Verify topology, operating range, tolerances and ratings against the actual component datasheet.

How to use it

Enter junction limit C. Set ambient C, power W, case theta, interface theta. Select Calculate and check the labeled output. Copy or download the JSON result.

Options and example settings

OptionChoices / valueExample default
junction limit CMain input. Signed finite values. 125
ambient COption. Signed finite values. 40
power WOption. Positive values. 5
case thetaOption. Zero or positive values. 2
interface thetaOption. Zero or positive values. 1

Calculation method

maximum_sink_C_W = positive((junction_limit_C-ambient_C)/power_W-case_theta-interface_theta) (^ means exponentiation; trig functions ending in d use degrees).

Worked examples

Apply heatsink thermal resistance budget to the case below, keeping the displayed units and assumptions. Positive remaining thermal budget only; airflow conditions must match ratings.

Heatsink Thermal Resistance Budget — worked case

Settings: ambient C: 40; power W: 5; case theta: 2; interface theta: 1

Input:

125

Calculated result for these inputs:

Output:

{
  "maximum_sink_C_W": 14
}

Choose the right tool

Match the topology before entering values: series and parallel networks, inverting and noninverting stages, and buck and boost converters use different equations. Component ratings, parasitics, protection and measured conditions require separate review.

Limitations and common mistakes

  • Positive remaining thermal budget only; airflow conditions must match ratings. Ideal nominal component model. Verify topology, operating range, tolerances and ratings against the actual component datasheet.
  • Use the displayed unit in every field. Ratios and percentages are different inputs; percent fields use values such as 25 rather than 0.25.

Frequently asked questions

How can I use heatsink thermal resistance budget calculator online?

Enter junction limit C. Set ambient C, power W, case theta, interface theta. Select Calculate and check the labeled output. Copy or download the JSON result.

Technical references

Where is my input processed?

The bundled tool processes input in your browser. It does not upload tool input to a conversion service. Other site plugins, analytics, advertising and browser extensions may have separate behavior.

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