An integrated circuit device having an internal clock oscillator that is synchronized to an external frequency reference, said integrated circuit device comprising: a digital processor; a clock oscillator supplying a clock signal to said digital processor; a counter having a clock input (clk) coupled to the clock oscillator, wherein the counter counts periods of the clock oscillator; a frequency adjustment controller having a count input, a reference count input, an external frequency reference input, a reset output, a frequency increment output (inc), a frequency decrement output (dec), and a disable input for enabling and disabling operation thereof coupled to said digital processor; and an oscillator tuning circuit, the oscillator tuning circuit having frequency increase and decrease inputs coupled to the frequency increment and decrement outputs (inc, dec), respectively, of the frequency adjustment controller; the oscillator tuning circuit is coupled to the clock oscillator, wherein the clock oscillator frequency is determined by the oscillator tuning circuit; wherein the frequency adjustment controller is enabled by means of said digital processor when an external frequency reference is available, and wherein the frequency adjustment controller compares the count from the counter with a reference count at the reference count input when a reference frequency period is finished, the reference frequency period is from the external frequency reference coupled to the external frequency reference input of the frequency adjustment controller, wherein the reference count is provided by the digital processor or programmed into said integrated circuit device at a time of manufacture; wherein: if the reference count is greater than the count then the frequency adjustment controller causes the oscillator tuning circuit to increase the clock oscillator frequency, if the reference count is less than the count then the frequency adjustment controller causes the oscillator tuning circuit to decrease the clock oscillator frequency, if the reference count is substantially the same as the count then the frequency adjustment controller does nothing to the oscillator tuning circuit and the clock oscillator frequency remains at substantially the same frequency; and thereafter the frequency adjustment controller resets the counter count. a digital processor; a clock oscillator supplying a clock signal to said digital processor; a counter having a clock input (clk) coupled to the clock oscillator, wherein the counter counts periods of the clock oscillator; a frequency adjustment controller having a count input, a reference count input, an external frequency reference input, a reset output, a frequency increment output (inc), a frequency decrement output (dec), and a disable input for enabling and disabling operation thereof coupled to said digital processor; and an oscillator tuning circuit, the oscillator tuning circuit having frequency increase and decrease inputs coupled to the frequency increment and decrement outputs (inc, dec), respectively, of the frequency adjustment controller; the oscillator tuning circuit is coupled to the clock oscillator, wherein the clock oscillator frequency is determined by the oscillator tuning circuit; wherein the frequency adjustment controller is enabled by means of said digital processor when an external frequency reference is available, and wherein the frequency adjustment controller compares the count from the counter with a reference count at the reference count input when a reference frequency period is finished, the reference frequency period is from the external frequency reference coupled to the external frequency reference input of the frequency adjustment controller, wherein the reference count is provided by the digital processor or programmed into said integrated circuit device at a time of manufacture; wherein: if the reference count is greater than the count then the frequency adjustment controller causes the oscillator tuning circuit to increase the clock oscillator frequency, if the reference count is less than the count then the frequency adjustment controller causes the oscillator tuning circuit to decrease the clock oscillator frequency, if the reference count is substantially the same as the count then the frequency adjustment controller does nothing to the oscillator tuning circuit and the clock oscillator frequency remains at substantially the same frequency; and thereafter the frequency adjustment controller resets the counter count. if the reference count is greater than the count then the frequency adjustment controller causes the oscillator tuning circuit to increase the clock oscillator frequency, if the reference count is less than the count then the frequency adjustment controller causes the oscillator tuning circuit to decrease the clock oscillator frequency, if the reference count is substantially the same as the count then the frequency adjustment controller does nothing to the oscillator tuning circuit and the clock oscillator frequency remains at substantially the same frequency; and thereafter the frequency adjustment controller resets the counter count.