- Ohm's law
- Power, voltage, current (for DC circuits)
- Voltage, current, phase angle to power (for AC circuits)
- Find a suitable part from the E6/E12/E24-series
- LED resistor calculator
- 3-digit code to capacitance

- Capacitor reactance
- Inductor reactance
- RLC impedance
- Resonant frequency
- RLC circuit resistance for critical damping

- Capacitor DC voltage rise
- Parallel plate capacitance
- Capacitor charge through resistor
- Capacitor discharge through resistor
- Capacitor stored energy
- Tan δ (loss tangent) ↔ ESR
- Capacitor max. dv/dt ↔ max. current

- Two transistor astable multivibrator
- 555 astable frequency/duty cycle
- 555 monostable period
- IR2153/IR21531 frequency
- UC384x frequency
- TL494/KA7500 frequency
- Voltage regulator/stabilizer/converter (e.g. LM317T, MC34063) feedback calculations

- IGBT, MOSFET, diode switching power loss (using E)
- MOSFET switching power loss (using tr, tf)
- IGBT, MOSFET gate driver required power consumption
- IGBT, MOSFET, diode, resistor conduction loss

f | p | n | u | m | c | k | M | G | T | P | |

femto | pico | nano | micro | milli | centi | (none) | kilo | mega | giga | tera | peta |

10^{-15} |
10^{-12} |
10^{-9} |
10^{-6} |
10^{-3} |
10^{-2} |
10^{0} |
10^{3} |
10^{6} |
10^{9} |
10^{12} |
10^{15} |

P = V*I*cos(φ)

Q = V*I*sin(φ)

|S| = V*I

Allowable range: 10pF to 99mF (although capacitors bigger than 10uF usually aren't marked this way)

Letter | B | C | D | F | G | J | K | M | Z |

Tolerance | ±0.1pF | ±0.25pF | ±0.5pF | ±1% | ±2% | ±5% | ±10% | ±20% | +80, -20% |

X

|Z| = sqrt(R

If X

If X

|Z| = 1/sqrt(1/R

φ = arctan(R/(1/(1/X

Q ≤ 0.5 (R/Z

I

V

ratio (dB) = 20*

L = μ

τ = R*C

t

V

τ = R*C

V

E = C*V

τ

t

t

f = 1(t

Schematic

(V

T

No diode parallel to R2: T

Diode parallel to R2 (anode on pin 7): T

T = T

f = 1/T

Duty

f

V

Chip | Voltage |

LM317T | 1.25V |

MC34063 | 1.25V |

LM2576-ADJ | 1.23V |

LM2596-ADJ | 1.23V |

UC384x (V_{FB}) | 2.5V |

The "scaling factor" is not included in the Semikron PDF. According to simulations, if a MOSFET has a certain switching loss with certain gate drive resistance (external+internal gate resistance) and it is doubled, the loss will be also roughly doubled (Ks≈2). The MOSFET coefficients also aren't present in the original PDF and were determined empirically through simulations. Switch and diode losses must be calculated separately.

P

Switch and diode (internal diode - if it conducts) losses must be also calculated separately.

Don't forget to add prefixes, times are usually in nanoseconds.

The gate resistance effect (t

If only a light load is switched at a high frequency, it might be a good idea to add the D-S capacitance discharge loss.

The coefficients were determined theoretically by linearizing the waveform and integrating instantaneous power through the switching times while rising/falling. Select "Custom" in dropdown menus to use custom Kl.

K

E

E

E

P

P

P

Multiply RMS value of sine/triangle by sqrt(2) to get RMS value of half-rectified sine/triangle

Waveform | I_{RMS} | I_{ARV} |

Sine | 0.7071*I_{m} | 0.6366*I_{m} |

Triangle | 0.5774*I_{m} | 0.5*I_{m} |

Square, D=0 to 1 | sqrt(D*I_{high}^{2}+(1-D)*I_{low}^{2}) | D*I_{high}+(1-D)*I_{low} |

Superposed triangle and sine, min. at t=0 | sqrt((0.5372*I_{mt}+0.7071*I_{ms})^2+(0.0699*I_{mt})^2) |
0.6366*I_{ms}+0.5*I_{mt} |

Superposed triangle and sine, tri. +max. at t=0 | sqrt((0.5774*I_{mt})^2+(0.7071*I_{ms})^2) |
* I_{ms}*(0.62+0.2338*(I_{mt}/I_{ms})+0.0403*(I_{mt}/I_{ms})^{2}-0.002*(I_{mt}/I_{ms})^{3}) |

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Function list:

Function list:

- basic calculations (DC power, AC power, LED resistor, Ohm's law, E6/E12/E24 series selector)
- capacitor reactance, inductor reactance, RLC impedance, aperiodicity, resonant frequency calculation
- capacitor dv/dt, maximum current calculation, tan delta to ESR converter
- rise time ↔ bandwidth calculator
- decibel to ratio conversions
- toroid inductance calculator
- capacitor energy and voltage rise
- 555, TL494, UC384x calculator
- MOSFET, IGBT, diode switching and conduction loss calculator