METHOD FOR DETERMINING CHARGING CAPACITANCE OF CAPACITOR

The present invention provides a method of determining a charging capacitance of a capacitor in an air bag system using a bus system. The method is a method of determining a charging capacitance of a capacitor in which a charging capacitance of a capacitor required for activating an air bag system normally is obtained from the following formula (I). C = 2E/V (In the formula, C represents a capacitor charging capacitance, V represents a charging voltage, and E represents the minimum ignition energy required for making the heat generating portion of the igniter generate heat to ignite a priming, which is obtained by the following formula (II): E = Imin x (Rmax + r1 + r2) x T + w x 10 Imin: the minimum ignition current value (A) Rmax: the maximum resistance value of the heat generating portion ( OMEGA ) r1: an ON resistance value of the switching circuit (the maximum ON resistance value at 150 DEG C) ( OMEGA ) r2: a resistance value of the other elements ( OMEGA ) T: a time period in which a current flows in the heat generating portion (sec) w: a power consumed by the whole integrated circuit when the switching circuit is OFF)