Disk drive comprising depletion mode MOSFETs for protecting a head from electrostatic discharge

An electrostatic discharge (ESD) protection circuit for protecting a head actuated over a disk in a disk drive, the head comprising a first head terminal and a second head terminal, the ESD protection circuit comprising a first depletion mode metal oxide semiconductor field effect transistor (MOSFET) and a second depletion mode MOSFET, each depletion mode MOSFET comprising a gate terminal and a first and second transistor terminals, wherein:

• (a) the first transistor terminal of the first depletion mode MOSFET is coupled to the first head terminal;
• (b) the second transistor terminal of the first depletion mode MOSFET is coupled to ground;
• (c) the first transistor terminal of the second depletion mode MOSFET is coupled to the second head terminal;
• (d) the second transistor terminal of the second depletion mode MOSFET is coupled to ground;
• and
• (e) the gate terminals are coupled to ground through a resistive element to turn on the first and second depletion mode MOSFETs while the disk drive is powered down, thereby grounding the first and second head terminals to protect the head from ESD.

A head for use in a disk drive comprising a disk, the head comprising a first head terminal and a second head terminal, the head comprising a silicon integrated circuit including an electrostatic discharge (ESD) protection circuit comprising a first depletion mode metal oxide semiconductor field effect transistor (MOSFET) and a second depletion mode MOSFET, each depletion mode MOSFET comprising a gate terminal and a first and second transistor terminals, wherein:

• (a) the first transistor terminal of the first depletion mode MOSFET is coupled to the first head terminal;
• (b) the second transistor terminal of the first depletion mode MOSFET is coupled to ground;
• (c) the first transistor terminal of the second depletion mode MOSFET is coupled to the second head terminal;
• (d) the second transistor terminal of the second depletion mode MOSFET is coupled to ground;
• and
• (e) the gate terminals are coupled to ground through a resistive element to turn on the first and second depletion mode MOSFETs while the disk drive is powered down, thereby grounding the first and second head terminals to protect the head from ESD.

A method of protecting a head in a disk drive from electrostatic discharge (ESD), the head comprising a first head terminal and a second head terminal, the method comprising the steps of:

• (a) coupling a first transistor terminal of a first depletion mode metal oxide semiconductor field effect transistor (MOSFET) to the first head terminal;
• (b) coupling a second transistor terminal of the first depletion mode MOSFET to ground;
• (c) coupling a first transistor terminal of a second depletion mode MOSFET to the second head terminal;
• (d) coupling a second transistor terminal of the second depletion mode MOSFET to ground;
• and
• (e) coupling a gate terminal of the first and second depletion mode MOSFETs to ground through a resistive element to turn on the first and second depletion mode MOSFETs while the disk drive is powered down, thereby grounding the first and second head terminals to protect the head from ESD.