A droop compensation system includes a controlled current source that
provides a scaled model of the PRM output current or VTM input current on
an interface connection. A controlled resistance modeling the VTM
effective series input resistance is connected across the interface
terminal. The voltage developed across the controlled resistance by the
controlled current establishes a correction signal representative of the
VTM droop that is used to adjust the PRM output thereby compensating for
the droop. A VTM control interface provides a mechanism for enabling and
disabling the VTM. The VTM control circuitry may be powered by the
interface connection, allowing the VTM to operate and process power when
the VTM input voltage is below its normal minimum operating voltage,
increasing the VTM dynamic range and allowing "soft start" into a
capacitive load.