A switching buck regulator circuit includes an n-type high-side switch.
The driver of the high-side switch employs a boot voltage (Vcboot) as a
power supply. Also, the output current is mirrored to a sense branch. A
current sense voltage is generated employing a transistor in the sense
branch. The current sense voltage is compared to a reference voltage that
is generated employing another transistor having a gate that is coupled
to the gate of the sense branch transistor. A diode (Dp) is coupled
between the gate of the sense branch transistor and the input voltage
(Vin). Another diode (Dc) is coupled between the gate of the sense branch
transistor and Vcboot. When the high-side switch is off, the current
sense voltage is clamped to substantially Vin-V.sub.Dp-V.sub.TN2. When
the high-side switch is on, the gate voltage of the high-side switch is
substantially given by Vcboot-V.sub.Dc.