A drive arrangement for activating a car safety device activation element

摘要

A drive arrangement for activating a car safety device activation element (201), such as an air bag, comprises a drive circuit (203)which is coupled to the car safety device activation element (201). The drive circuit generates an activation signal which activates the car safety device. The arrangement includes a power supply transistor (215) which is coupled in series with a power supply input of the drive circuit (203) and an energy reservoir such as a capacitor (213). The arrangement further comprises control means (217) which controls the supply voltage to the drive circuit (203) by controlling the power supply transistor (215)to operate in an active region to provide a voltage drop during activation of the car safety device activation element (201). Hence, a significant voltage drop and thus energy dissipation may be moved from the drive circuit (203) to the power supply transistor (215). The drive circuit may therefore be reduced in size and the power supply transistor may be implemented in a cheap technology suitable for energy dissipation. <IMAGE>