On-chip watchdog circuit

A common feature in conventional micro-controllers and microprocessors is a watchdog function circuit. Typically, the watchdog function circuit includes circuitry that monitors error signals from various self-testing functions of the micro-controller or microprocessor. The self-testing functions can include, for example, a counter overflow bit, a checksum discrepancy computational bit or other test function. The watchdog function circuit provides an enable signal that is actively updated based on the completion of the various self-testing functions of the micro-controller or microprocessor. If one or more of the self-testing functions fail, the enable signal from the watchdog function circuit is required to change state in a fail-safe manner. An on-chip watchdog circuit () is provided that generates an output signal () when an error signal () generated by a circuit under test () is detected. The on-chip watchdog circuit () comprises a logic gate () that is connected to a clock signal and receives a signal in response to the error signal generated by the circuit under test (). A gate output circuit () is connected to an output of the logic gate (). An RC circuit () is connected to the gate output circuit (). A comparator () is connected to the RC circuit (). The comparator () is also connected to a voltage divider () and provides the output signal () in response to the error signal () generated by the circuit under test (), and the on-chip watchdog circuit () and the circuit under test () are integrated on a same semiconductor microchip.