A switching regulator provides programming output current control through
a single input terminal by modifying the reference voltage in the control
loop of the switching regulator. The switching regulator includes a first
input terminal receiving a program input voltage indicative of a desired
output current, a voltage divider receiving a first reference voltage and
providing a second reference voltage at a first node between the first
and second resistors and a third reference voltage at a second node
between the second and third resistors, and a precision active pulldown
circuit coupled to receive the program input voltage and operative to
pull down the second reference voltage at the first node in response to
the program input voltage. In operation, the third reference voltage is
used in the control loop of the switching regulator to control the output
current of the switching regulator in response to the program input
voltage.