Patent ID: 6185488
Filing Date: 2001-02-06
Classification: B60R,G01R,H01L

Abstract:
A diagnosing apparatus for a passenger protective system comprising:a squib for activating the passenger protective system;a power transistor connected in series to at last one end of the squib to supply an igniting current to the squib, wherein the power transistor is made up of a plurality of transistor cells formed on a single substrate and connected in parallel, at least one of the plurality of transistor cells including a check transistor that allows a current less than that needed to ignite the squib to flow into the squib when the check transistor is turned on; anddiagnosing means for diagnosing the power transistor based on a potential of the squib when the check transistor is turned on and at least one other of the plurality of transistor cells is turned off;wherein each of the transistor cells has a drain region, a source region, a gate region and a gate electrode provided above the gate region, andwherein the check transistor is provided by separating the gate electrode of the at least one of the plurality of transistor cells into two sections, a first section being the gate electrode of the check transistor and the second section being the gate electrode for other than the check transistor, the first and second sections being connected separately from one another.