Data storage device measuring air bearing resonant frequency to calibrate fly height touchdown power

A data storage device comprising:

• a disk surface;
• a head actuated over the disk surface, wherein the head comprises a plurality of elements including a write assist element and a fly height actuator;
• and
• control circuitry configured to:
• control a bias signal applied to the write assist element such that the write assist element is unprotruded;
• while the write element is substantially unprotruded, measure an air bearing resonant frequency (ABRF) of the head and disk surface;
• control the bias signal applied to the write assist element such that the write assist element protrudes toward the disk surface;
• and
• while the write assist element protrudes toward the disk surface, excite the head at the measured ABRF in order to calibrate a control signal applied to the fly height actuator during write operations.

A data storage device comprising:

• a disk surface;
• a head actuated over the disk surface, wherein the head comprises a plurality of elements including a write assist element and a fly height actuator;
• a means for controlling a bias signal applied to the write assist element such that the write assist element is substantially unprotruded;
• while the write element is substantially unprotruded, a means for measuring an air bearing resonant frequency (ABRF) of the head and disk surface;
• a means for controlling the bias signal applied to the write assist element such that the write assist element protrudes toward the disk surface;
• and
• while the write assist element protrudes toward the disk surface, a means for exciting the head at the measured ABRF and detecting the head touching down onto the disk surface.