Abstract: A power supply may include multiple converters connected in parallel. The power supply may detect a signal that indicates how much power a device uses. Based on the signal, a converter controller may determine which of the multiple converters to activate or deactivate to supply enough power to meet the power load of the device and to operate the highest efficiency possible. The amount of power output from the power supply may be the sum of the power output by each of the converters that is activated. The power supply may use the multiple converters to operate at high efficiency throughout a wide range of power load levels. Such a power supply may achieve a haystack (i.e., near flat) power efficiency curve throughout a large part of its operating range.