RC metrics
Time constant τ
0.0100 s
Cutoff frequency
15.9 Hz
90% charge
0.0230 s
99% charge
0.0461 s
RC time constant
Translate resistor-capacitor picks into time-domain intuition.
Applies the classical RC exponential equations: plug in R and C with mixed units and instantly get τ, cutoff frequency, and milestone charge percentages.
0.0100 s
τ
15.9 Hz
f_c
0.0461 s
99% charge
Quick presets
Use presets to sanity-check filter corners in context.
Inputs
Filter hints
Single-pole low-pass magnitude is -3 dB at 15.9 Hz.
Timing cues
Need a specific delay? Multiply τ by desired natural log factor (e.g., 5τ ≈ 99% settle).
Design notes
- Component tolerances stack—spec 1% resistors and C0G/NP0 capacitors for precise filters.
- For active filters, translate the pole frequency directly into op-amp RC pairs.
- High-value resistors increase noise; high-value capacitors increase size—balance per application.
Export τ and fc into your PDN/anti-alias spreadsheets to keep time constants synchronized.