Patent ID: 7884678

Claim:
Apparatus, comprising: a single-pin input interface, which is operative to sense a voltage across a capacitor of a Resistor-Capacitor (RC) network in which the capacitor is repetitively charging and discharging so that the voltage oscillates as a function of time; a measurement circuit, which is coupled to measure time durations in which the capacitor is charging and in which the sensed voltage lies between first and second predefined thresholds; and a clock generation circuit, which is coupled to generate an output clock signal having a frequency, and to adjust the frequency responsively to the measured time durations, wherein the clock generation circuit comprises: a free-running oscillator, which is operative to generate an initial clock signal at an initial frequency; a frequency divider, which is operative to process the initial clock signal so as to divide the initial frequency by a programmable division ratio to produce the output clock signal; and circuitry, which is coupled to adjust the programmable division ratio responsively to the measured time durations.