A system that sources a heater, comprising: a heating resistor; a switch coupled between a power source and the heating resistor, the switch configured to source the heating resistor at an input voltage (V IN) from the power source; and a root mean square pulse width modulation controller coupled to the switch, wherein the RMS PWM controller is configured to generate a RMS PWM control signal to control the switch, wherein the RMS PWM controller includes: a ramp generator operable to generate a ramping signal; a first clock operable to generate a fixed frequency clocking signal; a second clock operable to generate a variable ramp control signal from the ramping signal and the fixed frequency clocking signal, wherein a frequency of the variable ramp control signal is controlled by the fixed frequency clocking signal, and wherein a slope of the variable ramp control signal is controlled by the ramping signal; wherein the RMS PWM control signal operates the switch to provide power to the heating resistor at a first duty cycle corresponding to the magnitude of a first input voltage (V IN), wherein the slope of the variable ramp control signal is set to a first value corresponding to the first input voltage (V IN) while at the first duty cycle; wherein the RMS PWM control signal operates the switch to provide power to the heating resistor at a second duty cycle corresponding to the magnitude of a second input voltage (V IN), wherein the slope of the variable ramp control signal is set to a second value corresponding to the second input voltage (V IN) while at the second duty cycle; and wherein varying the slope of the variable ramp control signal between the first duty cycle and the second duty cycle causes the power provided to the heating resistor at the first duty cycle to be the same as the power provided to the heating resistor at the second duty cycle. a heating resistor; a switch coupled between a power source and the heating resistor, the switch configured to source the heating resistor at an input voltage (V IN) from the power source; and a root mean square pulse width modulation controller coupled to the switch, wherein the RMS PWM controller is configured to generate a RMS PWM control signal to control the switch, wherein the RMS PWM controller includes: a ramp generator operable to generate a ramping signal; a first clock operable to generate a fixed frequency clocking signal; a second clock operable to generate a variable ramp control signal from the ramping signal and the fixed frequency clocking signal, wherein a frequency of the variable ramp control signal is controlled by the fixed frequency clocking signal, and wherein a slope of the variable ramp control signal is controlled by the ramping signal; a ramp generator operable to generate a ramping signal; a first clock operable to generate a fixed frequency clocking signal; a second clock operable to generate a variable ramp control signal from the ramping signal and the fixed frequency clocking signal, wherein a frequency of the variable ramp control signal is controlled by the fixed frequency clocking signal, and wherein a slope of the variable ramp control signal is controlled by the ramping signal; wherein the RMS PWM control signal operates the switch to provide power to the heating resistor at a first duty cycle corresponding to the magnitude of a first input voltage (V IN), wherein the slope of the variable ramp control signal is set to a first value corresponding to the first input voltage (V IN) while at the first duty cycle; wherein the RMS PWM control signal operates the switch to provide power to the heating resistor at a second duty cycle corresponding to the magnitude of a second input voltage (V IN), wherein the slope of the variable ramp control signal is set to a second value corresponding to the second input voltage (V IN) while at the second duty cycle; and wherein varying the slope of the variable ramp control signal between the first duty cycle and the second duty cycle causes the power provided to the heating resistor at the first duty cycle to be the same as the power provided to the heating resistor at the second duty cycle.