Circuit timing and power analysis are important in various aspects of circuit optimization. In order to solve the problem of finding input vectors to activate worst-case timing or power, a concept called Timed Characteristic Function (TCF) was proposed, which can characterize logical and temporal conditions simultaneously. Traditionally TCF assumes the (one-vector) floating mode of operation. In this paper, we extend TCF for the transition mode and propose an efficient way to construct transition-mode TCF. Also, we apply the TCF concept to the analysis of the Maximum Instantaneous Current (MIC) of a circuit, where transition-mode TCF is used to formulate gates’ switching conditions. The experimental results show that on average, the TCF technique can derive about 60% more accurate results than random simulation does for sequential circuits.