Calculate the time it takes to charge a capacitor to the level of the input voltage.
Vc = Vi (1-e-t/τ)
- Vi = Input Voltage
- τ = time constant
- Vc = voltage at the capacitor at time t
time constant τ = RC, where R is resistance and C is capacitance.
At t = 5*RC = 5τ (or 5 time constants),
Vc/Vi = (1-e-5) = 0.9933
In other words, at t = 5τ, the capacitor voltage reaches 99.33% of the input voltage.
For R = 1 kΩ and C = 1 nF, the capacitor charging time is 5 µs.
Capacitor Discharge Time – How long does it take for a cap to discharge to a final voltage level?