Apparatus for detecting clock failure and method therefor

Abstract

A clock failure detection circuit comprises clock failure detection logic having a clock input providing an input clock signal, a counter and a reference clock input providing a reference clock signal to the counter for counting a number of reference clock cycles. The counter comprises a reset input arranged to receive successive reset pulses generated by at least one clock edge of the input clock signal to reset a counter value of the counter. The counter value before reset is used to identify a clock frequency error. A method of detecting a clock failure is also described. By using a counter value based on the reference clock cycles, and a reset trigger based on a clock edge of the input signal, it is possible to identify a clock frequency error in a much shorter time.

Dependencies are inferred from the claim text.