Schematic RC time constant: 1K * 1u = 1ms, Vc = V1 * [1 – exp(-t/RC)] When t = 1RC, Vc = 0.63V1 = 3.15V; When t = 2RC, Vc = 0.86V1 = 4.30V; When t = 3RC, Vc = 0.95V1 = 4.75V; Recommendation: A tool for calculating time constant Device information: Device Model Element Signal source V1 VPULSE/ SOURCE Resistor R1 R/ ANALOG Capacitor C1 C/ ANALOG GND 0 Signal source description: V1: Starting voltage V2: Pulse voltage TD: Delay time, set 1ms here for easy observation TR: Rise time, set 0.5us here TF: Fall time, no need to set PW: Pulse width, no need to set, that is, the pulse width is unlimited PER: Pulse period, no need to set Simulation Results Simulation settings: Add Trace: Add Toggle Curse, Mark Label, Text Label: It can be seen that one time constant corresponds to a voltage of 3.1612V; two time constants correspond to a voltage of 4.3232V; three time constants correspond to a voltage of 4.7510V, which is similar to the theoretical calculation.