Measurement of the write current of a current mode write driver while engaged in the writing process

A disk drive device for performing data read and write operations to a disk storage media, said disk drive including a current mode driver circuit for writing data through a write head, the current mode driver circuit including one or more current mirror circuits for providing a current output in proportion to current through said write head during a write operation, the drive device comprising:

• means for converting said current mirror circuit current output into a first voltage;
• means for generating a second voltage representing a reference current;
• and,
• means for comparing said first voltage value to said second voltage and generating an output signal indicating a ratio of said first and second voltages, said ratio being a measure of said current output of said current mirror circuit.

A tape drive device for performing data read and write operations to a tape storage media, said tape drive including a current mode driver circuit for writing data through a write head, the current mode driver circuit including one or more current mirror circuits for providing a current output in proportion to current through said write head during a write operation, the drive device comprising:

• means for converting said current mirror circuit current output into a first voltage;
• means for generating a second voltage representing a reference current;
• and,
• means for comparing said first voltage value to said second voltage and generating an output signal indicating a ratio of said first and second voltages, said ratio being a measure of said current output of said current mirror circuit.