Control circuits that employ time-based current control methods for switching
voltage regulators are provided. The control circuit includes a current estimation
circuit and optionally, a transfer function circuit. The current estimation circuit
generates estimates of regulator output current as function of switch period for
use as a threshold indicative of peak current limit. This arrangement eliminates
the need for error amplifiers to provide effective current mode control. The absence
of error amplifiers allows fabrication of switching regulators on smaller die areas
and provides switching regulators with reduced power consumption.