Steve:

I don't know about other vendors but Cygnal actually specifies the power consumption of their parts at 32KHz operation. Take the C8051F22x family for instance. With the anlog peripherals shutdown and the CPU active it is specified that operating current is 20 uA. Quite impessive. Click on the graphic below to see an excerpt of the Cygnal data sheet for various current specifications for this part family.


<small>Click to Enlarge</small>


A really advantageous feature of these parts is that they have an onboard oscillator that can be progrgammed to run at 2/4/8/16 MHz. When the processor running at low power mode at 32KHz detects that a short butst time of high horsepower is required then the internal oscillator can be turned on for a short time. Then the calculations are performed and stored and then the system can revert back to the 32KHz mode from the exteral oscillator for Slooow speed and the the internal oscillator turned completely off to save power.

Michael Karas