Tools
Each one names the standard it implements and the assumptions it makes. An uncited calculator is just a number generator.
| Sym | Tool | Solves for | Basis |
|---|---|---|---|
| w | Trace width | mils / mm | IPC-2221 |
| R | Resistor decoder | ohms | IEC 60062 / 60063 |
| fc | RC filter | hertz | First-order passive |
| Z0 | Microstrip impedance | ohms | IPC-2141 |
| Vo | Voltage divider | volts | Ohm's law |
| e% | Baud rate error | per cent | Integer-divisor UART |
| Iv | Via | amps / ohms / K/W | IPC-2221 / IPC-6012 |
| Rp | I²C pull-up | ohms | NXP UM10204 |
| CL | Crystal load | picofarads | TI SWRA372; ST AN2867 |
| Rs | LED resistor | ohms | Ohm's law |
| C | Capacitor code | farads | IEC 60062 / EIA-198 |
| t | Battery runtime | hours / days | Time-weighted average |
| |Z| | Decoupling | ohms vs hertz | Series RLC / target impedance |
| RT | RS-485 bus | termination / bias | TIA-485 / TI SLLA272 |
| Zb | Ferrite bead filter | dB vs hertz | Würth ANP045 / TI SLYT740 |
| 555 | 555 timer | hertz / seconds | TI LM555 datasheet |
| E96 | E-series finder | ohms / ratios | IEC 60063 |
| AWG | Wire gauge | volts / ohms | AWG · NASA NESC |
| RC | RC snubber | ohms / farads | TI SLYT465 |
| Csh | ADC charge bucket | ns / pF | TI SBAA286 |
| Vos | Op-amp DC error | µV / mV | TI SBOA590 |
| Vcl | TVS clamping | volts / verdict | TI SLLA305 |
| ppm | Crystal ppm budget | ppm / s per day | TI SLLA122 |
| I²t | Fusing current | amps / mil | Onderdonk (estimate) |
| Tj | LDO thermal | °C / cm² | TI AN-2020 |
| ΔV | Buck ripple | mA / mV | TI SLVA630 / SNVA559 |
| L | Buck inductor | µH | TI SNVA559 / SLUP123 |
| D | Boost converter | A / µH | TI SLVA372 |
| τ | Capacitor charge time | ms | Würth SN015 |
| N | Transformer turns ratio | V / Ω | TI SLUP123 |
| θ | Heat sink | K/W | TI SPRA953 |
| nF | Capacitance converter | pF / nF / µF | BIPM SI Brochure |
| X | Reactance | Ω | Würth ANP109 / ADI MT-101 |
| f₀ | LC resonance | Hz | Würth ANP062 / TI SNVA871 |
| V_O | LM317 | V / Ω | TI LM317 datasheet |
| G | Op amp gain | V/V / dB | TI SBOA092 / SLOA011 |
| dB | dB and dBm | dB / dBm / W | BIPM SI Brochure / Infineon AP24026 |
| PWM | PWM to voltage | V / mV | TI SPRAA88 |
| C | Supercapacitor backup | F / s | Abracon, Designing with Supercapacitors |
| R_B | Transistor base resistor | Ω | Nexperia BJT Application Handbook |
| C | Smoothing capacitor | µF / V | TI UCC28740, TIDUB51 |
| Z0 | Coplanar waveguide | ohms | Sandia SAND2017-12410J |
| V_HYS | Comparator hysteresis | V / Ω | TI SBOA313, SNOA997 |
| P_D | MOSFET power loss | W / °C | TI SLYT664 |
| R_F | Transimpedance amplifier | Ω / F | TI SBOA268, SBOA122 |
| SR | Slew rate | V/µs / Hz | TI SLOA011 |
| e_n | Johnson noise | V / dB | TI SLVA043 |
| D | Buck-boost converter | H / A | TI SLVA535 |
| L | Air-core inductor | µH / turns | NBS Scientific Paper 169 |
| E | Thermocouple | mV / °C | NIST Monograph 175 |
| R_T | PT100 RTD | Ω / °C | TI SBAA275, IEC 60751 |
| I | 4–20 mA scaling | mA / % | TI SLAA866, SLYT847 |
| V_O | Wheatstone bridge | V / Ω | TI SLOA034 |
| dB | Attenuator pad | Ω / dB | Skyworks 200312E, Maxim AN972 |
| VSWR | VSWR and return loss | dB / Γ | Keysight AN 1449-3, Huber+Suhner |
| Z0 | Coax impedance | ohms | Huber+Suhner, R&S 1MA99 |
| δ | Skin depth | µm / Ω | TI SLUP197, NBS SP 169 |
| NF | Noise figure | dB / K | Keysight AN 57-1 |
| G | Instrumentation amplifier gain | Ω / V/V | TI INA128, ADI AD620 |
| PLL | PLL loop filter | F / Ω | TI SNAA106C (Banerjee) |
| ∫ | Op-amp integrator | F / Hz | TI SBOA275, SBOA276 |
| f0 | RC oscillator | Hz / Ω | TI SLOA060, AN-31 |
| Σ | Summing amplifier | V / Ω | TI SBOA272, AN-31 |
| fa | Aliasing | Hz | ADI MT-002 |
| 2V | Charge pump | V / F | TI LM2662 |
| I | Constant current source | A / Ω | TI SBOA325, SBOA436, LM317 |
| V_KA | TL431 shunt regulator | V / Ω | TI TL431 datasheet |
| dB | RF link budget | dB / m | ITU-R P.525 |
| Z | Impedance matching | H / F | Silicon Labs AN1275 |
| N | Toroid inductor | turns / µH | TDK (EPCOS) ferrites |
| ESR | Capacitor ESR | Ω / W | Vishay, TDK, KEMET |
| L | Wire inductance | nH | NBS Scientific Paper 169 |
| M | Mutual inductance | nH / k | NBS Scientific Paper 169 |
| Lc | Critical length | mm / verdict | TI AN-807 / IPC-2141 |
| Q | Active filter | R and C values | TI SLOA049 |
| Rg | Gate resistor | ohms | TI SLUA618 / SLUP170 |
| SNR | ADC noise floor | dB | ADI MT-001 / MT-003 |
| I₁ | Current divider | amps | Kirchhoff / Ohm's law |
| Vsw | Relay coil suppression | volts | TE 13C3264 / Omron |
| Ipk | Inrush current limiter | ohms | Ametherm 24002 / TDK / TI SLVA156 |
| τ | Switch debounce | ms | Würth SN015 / SN74HC14 |
| Vdo | LDO dropout | volts | TI SLVA207 / SLVA079 |
| Rpu | Pull-up / pull-down | ohms | TI SLVA485 / SDAA246 |
| 120Ω | CAN bus termination | metres | TI SLLA486 / SLLA270 |
| Vgs | MOSFET level shifter | volts | Nexperia AN10441 / UM10204 |
| f_ring | Probe loading | MHz | Tektronix ABCs of Probes |
| Riso | Op amp capacitive load | ohms | TI SBOA418 / SBOA626 |
| λ/40 | Bypass placement | mm | Xilinx XAPP623 / TI SLOA069 |
| ePAD | Exposed pad stencil | mm | TI SLUA271 / SNVA183 |
| LSB | ADC / DAC resolution | volts | TI SLAA013 |
| Cboot | Bootstrap capacitor | farads | TI SLUA887 |
| Rsense | Current sense resistor | ohms | TI SBOA197 / Vishay 30405 |
| Vf·I | Reverse polarity | watts | TI SLVAE57B |
| CC/CV | Li-ion charge | hours | TI SLAA287 / SSZTA38 |
| B | NTC thermistor | ohms | TDK / Vishay NTC notes |
| Np:Ns | Flyback transformer | henries | TI SNVA866 / SLUP254 |