Regulating current output from a buck converter without external current sensing

A step-down (buck) switching regulator regulates output current without sensing a current external to a converter integrated circuit. The regulator generates a set current that is indicative of a predetermined current level to which the output current is regulated. The regulator generates a sense current whose magnitude is proportional to an inductor current flowing through a power switch during an on time. During a first time period, the sense current is less than the set current. During a second time period, the sense current is greater than the set current. The output current of the regulator is maintained at the predetermined current level such that the first time period is equal to the second time period when the output current equals the predetermined current level. The set current is compared to the sense current in circuitry inside a bootstrap power generator whose voltage fluctuates with the voltage across the inductor.