Load-control backup signal generation circuit

摘要

In a case in which a malfunction occurs in a control processor which operates according to a predetermined program, a load-control backup signal generation circuit supplies a backup control signal to a switch of a load connected to an output of the control processor. The load-control backup signal generation circuit includes: a watchdog input terminal to which a watchdog signal periodically output from the control processor is input; a pulse count unit which counts a clock pulse generated with a constant period and which controls a count state of the clock pulse according to a signal input to the watchdog input terminal; and a signal selection unit which selects, from a plurality of options, a predetermined condition for causing a backup signal output unit to generate the backup control signal, based on a count output signal of a plurality of bits output from the pulse count unit.

主权项

1. A load-control backup signal generation circuit which, in a case in which a malfunction occurs in a control processor which operates according to a predetermined program, generates and supplies a backup control signal to a switch of a load connected to an output of the control processor, said load-control backup signal generation circuit comprising:
a watchdog input terminal to which a watchdog signal periodically output from the control processor is input; a pulse count circuit which counts a clock pulse generated with a constant period and which controls a count state of the clock pulse according to a signal input to the watchdog input terminal; a signal selection circuit which selects, from a plurality of options, a predetermined condition for generating the backup control signal, based on a count output signal of a plurality of bits output from the pulse control circuit; and a latch circuit comprising a D input terminal connected to a power supply line and a latch input connected to an output of the signal selection circuit to receive an output signal of the signal selection circuit, the latch circuit outputting the backup control signal based on the power supply line in response to the output signal latching the latching circuit.