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It is the time required to charge the capacitor, through the resistor, from an initial charge voltage of zero to approximately 63.2% of the value of an applied DC voltage, or to discharge the capacitor through the same resistor to approximately 36.8% of its initial charge voltage.
These equations can be rewritten in terms of charge and current using the relationships C = Q / V and V = IR (see Ohm's law). Thus, the voltage across the capacitor tends towards V as time passes, while the voltage across the resistor tends towards 0, as shown in the figures. This is in keeping with the intuitive point that the ...
A simple resistor–capacitor circuit demonstrates charging of a capacitor. A series circuit containing only a resistor, a capacitor, a switch and a constant DC source of voltage V 0 is known as a charging circuit. [32]
The diode and the switch are simplified as either a short circuit when they are on or by an open circuit when they are off. When in the off-state, the capacitor C is charged by the input source through the inductor L 1. When in the on-state, the capacitor C transfers the energy to the output capacitor through the inductance L 2.
Instantaneous current declines to steady-state current as the capacitor reaches full charge. In the case of open circuit, the capacitor will be charged to the peak AC voltage (one cannot actually charge a capacitor with AC line power, so this refers to a varying but unidirectional voltage; e.g., the voltage output from a rectifier).
The energy (measured in joules) stored in a capacitor is equal to the work required to push the charges into the capacitor, i.e. to charge it. Consider a capacitor of capacitance C, holding a charge +q on one plate and −q on the other.
Since none of the original charge is lost, the final state of the capacitors will be as described above, with half the initial voltage on each capacitor. Since in this state the two capacitors together are left with half the energy, regardless of the amount of resistance half of the initial energy will be dissipated as heat in the wire resistance.
The entire wire capacitance is applied to the gate output, and the delay through the wire itself is ignored. Elmore delay [5] is a simple approximation, often used where speed of calculation is important but the delay through the wire itself cannot be ignored. It uses the R and C values of the wire segments in a simple calculation.