Power Semiconductors & Thermal
Every power semiconductors & thermal calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
11 calculators in this section
- Component Derating CalculatorDerating is running a part below its rating so that it survives. The factors live in documents this page will not reproduce, so you type in your own — and what you get back is the arithmetic a single-factor calculation misses: the manufacturer's own temperature curve has already taken part of the rating away before your factor is applied, and the two compound.
- Conduction-Cooled Electronics CalculatorIn vacuum there is no convection. A board that runs cool on the bench cooks in orbit, because the whole heat path is conduction through the copper into a frame or wedge-lock rail, plus a little radiation. This computes the resistance of each segment, the rise at each, the junction temperature, and the share of the heat that actually leaves by radiation.
- Diode Power Loss CalculatorEstimate a rectifier or freewheel diode's losses — conduction, reverse recovery and leakage — and its junction temperature, using either a single forward voltage or the threshold-plus-resistance model from the datasheet.
- Enclosure Fan Airflow Calculator (CFM)How much air a sealed-but-vented enclosure needs to carry its own heat away: Q = P ÷ (ρ·c_p·ΔT), derived rather than quoted, with the altitude and inlet-temperature corrections that the familiar 3.16·W/ΔT°F shortcut leaves out — and the fan-curve derating that is the reason a fan never delivers its rated CFM.
- ESD and TVS Protection CalculatorThe peak current an electrostatic discharge delivers, the voltage the TVS actually clamps to at that current rather than at the data sheet's test current, and then the part that catches people: the inductive drop in the loop the current takes, which for a nanosecond edge is usually far larger than the clamp itself.
- Heatsink Thermal Resistance CalculatorThe heatsink a power transistor, regulator or diode needs: the maximum sink-to-ambient thermal resistance (θSA) from the power, temperatures, θJC and the mounting interface — and the junction temperature and margin with the heatsink you pick.
- MOSFET Gate Driver Calculator (Power and Gate Resistor)Gate-drive power from Qg, Vgs and the switching frequency — and, more usefully, how it splits between the driver's own output resistance, your external gate resistor and the MOSFET's internal gate resistance, because only the first of those heats the driver. With the peak source and sink currents, the turn-on time the Miller charge and your Rg actually give, the driver's junction temperature, and the bootstrap capacitor for a high-side stage.
- MOSFET Loss CalculatorEstimate a switching MOSFET's conduction, switching and output-capacitance losses from datasheet values, the gate-drive power, and the junction temperature from θJA or θJC + θCS + θSA.
- MOSFET Output Characteristics CalculatorDrain current against drain-source voltage for a MOSFET at two gate voltages, with a resistive load line drawn across them and the operating point where they cross. The square-law model, stated with its limits — a modern power MOSFET is not a square-law device and its datasheet curve is the truth — plus the dissipation at the operating point and whether it sits in the constant-current region, which is where MOSFETs die.
- RC Snubber CalculatorSize the R and C across a switching device or a relay contact from figures you can actually measure: the ringing frequency on a scope, and the same frequency again with a known capacitor added. That gives the parasitic capacitance and the loop inductance, and from those the snubber capacitor, the resistor that damps the ring hardest, the damping the pair achieves, the peak voltage they save and the watts the resistor has to take.
- Switching Device Load Locus CalculatorThe path a hard-switched device traces in the voltage-current plane over one cycle, drawn against the safe operating area you type in from its datasheet. At turn-off the current holds while the voltage rises, then falls at full voltage — out to the top-right corner. At turn-on the opposite diode's reverse recovery adds a current spike while the voltage is still up. Both corners are where devices die.