Short-circuit energy

The short-circuit contribution (for a output falling transition) is given by:

$$E_{sc} = \int_{t_0}^{\tau_o} V_{D}I_{D} \;dt$$

where $I_{D}$ is the p-MOSFET current flowing through the p-MOSFET that has a changing gate voltage, during the output falling; of course all the p-MOSFETs among this one and the output node must be on to have this contribution of power dissipation. So if we neglect the little discharging of the source voltage of this MOSFET, we can easily calculate the short-circuit energy, calculating the current flowing.

A similar equation can be written for the n-MOS network.

Since voltage swings, internal currents and capacitances are known from the delay analysis, the power supply dissipation does not require additional computations.