A control source and drivers for a thermal actuator fly height controlled
heads in a disk drive system includes provisions for driving a heater
element to dissipate various levels of power, and thus actuate the head
by a desired amount, depending on whether the head is in a write mode or
a read mode. Further, overshoot and undershoot are achieved as desired by
providing initial values and equilibrium values and through the use of a
control capacitor to provide a time constant to the drive signal to the
heater element.