A power circuit and a charge pumping circuit add one control switch of
small size to control a power transistor, and save one switch of large
area and one capacitor of large area as compared with a conventional
power circuit and a conventional charge pumping circuit. The power
circuit includes a power processing circuit, a linear voltage-regulating
switch, and a capacitor. The linear voltage-regulating switch includes a
power transistor and a control switch. The control switch has a first end
coupled to a gate of the power transistor and a second end coupled to one
of a drain and a source of the power transistor. When the control switch
is "on", the power transistor is "off". When the control switch is "off",
the voltage on the drain of the power transistor is maintained at a
predetermined value by the linear voltage-regulating switch.