Electronic circuit arrangement for switching an electrical load in a fail safe manner

Abstract

An electronic circuit arrangement for switching an electrical load disposed intermediate a power source and a ground includes a combinatorial logic block for receiving and processing at least one condition signal and for generating a first enabling signal. A biasing element generates a bias voltage upon receiving the first enabling signal. A first switch disposed intermediate the electrical load and the power source conducts upon application of the bias voltage enabling passage of an electrical supply current from the power source to the electrical load. A fail-safe circuit operation is achieved with the use of a microprocessor which generates a second enabling signal feeding into the biasing element and a second switch disposed intermediate the electrical load and the ground and which conducts upon application of a third enabling signal from the microprocessor thus enabling passage of the electrical supply current to ground. First and second feedback circuits monitor the state of the electrical load and provide status feedback to the microprocessor which is adapted for annunciating a fault condition.