A printhead is provided having fluid ejection nozzles, heaters corresponding to each of the nozzles respectively, with each heater heating printing fluid to cause ejection of a drop of the printing fluid through the corresponding nozzle, and circuitry for generating electrical drive pulses having variable power and length for energizing the heaters. The drive pulses are generated to have less energy than the energy required to heat a volume of the printing fluid equivalent to the drop volume, from the temperature at which the printing fluid enters the printhead to the heterogeneous boiling point of the printing fluid.