Patent ID: 6980383

Claim:
A pole tip protrusion (PTP) test subsystem of a magnetic disk drive for identifying an undesired PTP condition of a head in the disk drive, the subsystem comprising: a PTP stressing mechanism that stresses the head during a PTP test mode to induce a PTP condition, wherein the PTP stressing mechanism increases a data rate of a write operation during the PTP test mode; a disk contact detection circuit that detects when the head contacts a disk of the disk drive; a PTP write current determination circuit that determines a PTP write current level at which the head contacts the disk while the head is stressed during the PTP test mode; a write current limiting mechanism that limits the write current level to a write current limit equal to the determined PTP write current level less a specified margin to provide a buffer against undesired PTP of the head; a write current limit determination mechanism that determines when the write current limit is too low; and a corrective action mechanism that takes corrective action when the write current limit is too low, wherein the corrective action comprises burnishing the head.