Portable data device efficiently utilizing its available power and method thereof

The present invention relates generally to a portable data device efficiently utilizing its available power and method thereof, and in particular, to a portable data device efficiently utilizing its available power by adjusting its clock rate. A portable data device () having a power controller (), a clock generator () and a digital circuit (). The power controller () has an output signal. The output signal is representative of available power. The clock generator () is coupled to the output signal of the power controller () for generating a variable clock rate corresponding to the output signal. The digital circuit () is coupled to the clock generator (), and the digital circuit () is controlled by the variable clock rate.