A voltage regulator control integrated circuit includes constituent parts including an error amplifier circuit, a comparator circuit, a compensation signal generator circuit, an oscillator/one-shot circuit, a latch, and a current sense circuit. In a first example, the integrated circuit is operable in a first mode and in a second mode. In the first mode, the various parts are configured and interconnected in such a way that they operate together as a valley current mode regulator control circuit. In the second mode, the various parts are configured and interconnected in such a way that they operate together as a current-mode constant on-time mode regulator control circuit. In another example, a voltage regulator control integrated circuit has the same basic constituent parts and is operable in a first mode as a peak current mode regulator control circuit, or in a second mode as a constant off-time time mode regulator control circuit.