A switching regulator having a control circuit that automatically senses when
a
low power mode should be initiated without the use of expensive external components
nor an extensive amount of external components is disclosed herein. The switching
regulator includes an input switching device, a driver, an inductor, a first output
switching device, a second output switching device and an output node. The control
circuit includes a low power switching device connected to the output node and
the second end of the inductor. An amplifier connects the low power switching device
and the first output switching device. A first current mirror couples to the amplifier
to mirror the difference between the output current through the output load and
the current supplied at the second end of the inductor. A second current mirror
couples to the first current mirror to mirror the current difference through a
current source and a capacitor connected in parallel across the current source.
A comparator compares the voltage generated by the capacitor with a predetermined
voltage source. A first and second AND gate couples to the comparator. The output
of the first AND gate provides a entry signal that initiates the low power mode
for the switching regulator. The second AND gate couples to receive this entry
signal. The output of the first AND gate provides a exit signal that indicates
when the switching regulator is not in low power mode. The first AND gate couples
to receive this exit signal.