Engineering Design Suiteby EETech
Technical Resources

Background reading for the calculators in this suite

Vendor-neutral explainers, formula derivations, and the engineering reasoning behind each tool's defaults.

Calculator Reference Notes

  • Temperature coefficient modeling
    Why the linear TCR model is enough for most practical work — and when it isn't.
  • Ohm's law and power dissipation
    Foundational relationships used across nearly every other calculator in the suite.
  • Color-code conventions across IEC 60062
    4, 5, and 6-band axial markings with tolerance and TC bands.
  • Ferrite bead behavior at high frequency
    Why a bead is not a resistor and why a single number on a datasheet is misleading.

Formula Library

  • Arrhenius temperature acceleration
    The 10 °C rule, its derivation, and its limitations for aluminum electrolytics.
  • Beta vs. Steinhart–Hart for NTCs
    When the simpler Beta model is sufficient and when extended models are needed.
  • Adiabatic vs. steady-state thermal models
    Approaches for sizing resistors under pulse and continuous current.

Engineering Background

  • Current-sense topologies
    Low-side, high-side, in-line, and isolated current sensing for power electronics.
  • Pulse-handling fundamentals
    Single-pulse, repetitive-pulse, and surge classifications for resistive elements.
  • EMI filtering with passive components
    Choosing between beads, common-mode chokes, and π-filters.

Glossary

  • TCR, ppm/°C, and tolerance
    Plain-language definitions of the terms used across the calculator inputs.
  • θ_JA, θ_JC, and SOA
    Thermal resistance and safe operating area terminology.
  • Beta value, B25/85, and R25
    Common shorthand on NTC thermistor datasheets.
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