Patent ID: 8180520

Claim:
An electronic safing system, comprising: a safing sensor which detects a physical quantity responsive to a collision and outputs a voltage according to a detected result; a comparing circuit including a voltage dividing circuit and a comparator, wherein the voltage dividing circuit sets a reference voltage and is provided by a plurality of resistors connected in a series circuit, which has an end connected to a power source and another end connected to a ground, and wherein the comparator compares the voltage output from the safing sensor with the reference voltage set by the voltage dividing circuit, and outputs a signal according to a comparison result; and a microcomputer which determines, based on the voltage output from the safing sensor and the signal output from the comparing circuit, whether a collision occurs, wherein the safing sensor has an output terminal, which is connected to an input terminal of the comparing circuit; wherein the microcomputer has an A/D port, which is connected to the input terminal of the comparing circuit and the output terminal of the safing sensor, and is settable an input and an output in a selectable manner according to an internal register; wherein the microcomputer sets the A/D port settable the input and the output to be an output port, and outputs a predetermined voltage for a diagnosis from the A/D port settable the input and the output, when the comparing circuit is diagnosed; wherein the microcomputer diagnoses the comparing circuit according to the signal output from the comparing circuit; and wherein the microcomputer switches the A/D port settable the input and the output to be an input port, and inputs the voltage output from the safing sensor, when the microcomputer determines in the diagnosis that the comparing circuit is in a normal condition.