Fault injection in a clock monitor unit

A clock monitor unit comprising:

• logic circuitry configured to operate the clock monitor unit in accordance with a functional operating mode, wherein during the functional operating mode, the clock monitor unit is configured to evaluate whether a frequency of a monitored clock is operating within a specified frequency range;
• clock monitoring control logic configured to evaluate the monitored clock in accordance with the functional operating mode by determining whether counted pulses of the monitored clock are less than or equal to a first pulse count value and greater than or equal to a second pulse count value, wherein during the functional operating mode, the logic circuitry loads into the clock monitoring control logic a high frequency threshold count for the first pulse count value and a low frequency threshold count for the second pulse count value, wherein the high frequency threshold count represents a highest acceptable frequency of the specified frequency range, and wherein the low frequency threshold count represents a lowest acceptable frequency of the specified frequency range;
• and
• logic circuitry configured to operate the clock monitor unit in accordance with a fault injection mode during which the first and second pulse count values are configured by the logic circuitry so that the clock monitoring control logic determines that counted pulses of the monitored clock are both higher than the first pulse count value and lower than the second pulse count value when the clock monitor unit is functioning in accordance with specified operating parameters.