Patent ID: 8797667

Claim:
A disk drive comprising: a disk; a head actuated over the disk, the head comprising a touchdown sensor comprising a resistance; a fly height actuator; and control circuitry operable to: apply a fly height control signal to the fly height actuator to control a fly height of the head; configure the fly height control signal to substantially zero and apply a bias signal at a reference value to the touchdown sensor at a reference temperature and measure a corresponding reference resistance of the touchdown sensor; estimate an operating resistance of the touchdown sensor at a predetermined operating temperature of the touchdown sensor based on the reference resistance, the reference temperature, and a thermal coefficient of resistance (TCR) of the touchdown sensor, wherein the TCR specifies a change in temperature of the touchdown sensor relative to a change in the resistance of the touchdown sensor; and configure the fly height control signal to achieve a target fly height of the head and generate an operating value for the bias signal by adjusting the bias signal until a measured interim resistance of the touchdown sensor substantially equals the operating resistance.