Device to prevent undamaged airbag ignition circuits from igniting in the event of an accident by diverting the injection currents

摘要

The invention relates to a protection circuit for a CMOS circuit for a contact (PDH). The CMOS circuit has a p-doped substrate (Sub) and an n-doped N-region (NG), which is electrically connected to an output line (PDCH) and above it to an output transistor (T1H) and the contact (PHD) . The N-region (NG) lies in the p-doped substrate (Sub). The device comprises a switching transistor (T2) and a monitoring device (UVH), the monitoring device (UVH) detecting the potential of the contact (PDH) or a potential derived therefrom and comparing the detected value with a reference value. The monitoring device (UVH) switches on a switching transistor (T2) when the value of the potential of the contact (PDH) is below the reference value. This reference value for the value of the potential of the contact (PDH) is below the value of the potential of the substrate (Sub) and / or below that of the reference potential line (GND). The switching transistor (T2) connects the contact (PDH) with a reference potential line (GND) when it is switched on. The switching transistor (T2) can be the same as the output transistor (T1L).