Newly-Patented Converter Switches in a Microsecond from Standby to Any LoadSeptember 14, 2006 by Jeff Shepard
Using the switched current technology with switched charge, Edward Herbert, an independent inventor, has introduced a converter where the output can go from 0 Volts, 0 Amps to any output voltage (VID) and any load current in less than a microsecond, and it can go from any VID, any load current to 0 volts, 0 amps just as fast. Herbert was granted U. S. Patent No. 7,098,638 on August 29, 2006. Claimed to be "true digital power conversion," this topology builds on the switched-current technology and extends its application to the processor itself.
The greatest waste of power in a processor is the loss due to the leakage current when the processor is idle. By reducing the core voltage to zero, all of that power can be saved. This was not possible until now, as the processor has to be "ready," and it took too long to restore the voltage. The switched-current power converter has very fast dynamic response for changes in current from no load to full load and back again in the time that it takes to turn a MOSFET on, then off again. The recently-issued patent shows how to use "passive ballasting" to divide a constant current into a large number of smaller constant currents. The ballasting is very small parallel inductors, and the self-inductance of parallel circuit board traces is sufficient for most applications.
"The parasitic impedance of the interposer limits the dynamic response of an external power supply. Using the totem-pole power converter for processors, the impedance of the interposer is no longer a problem; it becomes part of the solution," Herbert stated. "For a number of reasons, the preferred location for the power control circuitry is on the processor die itself, or as close to it as possible."