Write driver circuit having programmable overshoot and undershoot

In a write current driver circuit including a switching mechanism controlled by complementary first and second input signals to direct write current in opposite directions through a write head between first and second terminals, the improvement of undershoot control circuitry comprising:

• a monitoring circuit for detecting a voltage difference between the first and second terminals;
• an undershoot reduction circuit responsive to the monitoring circuit to add an undershoot reduction current to the write current based on a state of the first and second input signals and a detected voltage difference between the first and second terminals.

A method of increasing overshoot in a write current flowing through a write head between first and second terminals, the method comprising:

• detecting a voltage at the first and second terminals;
• and
• adding an overshoot control current to the write current upon detection of a voltage at one of the first and second terminals below a predetermined threshold.

A method of reducing undershoot in a write current flowing through a write head between first and second terminals in a direction controlled by complementary first and second input signals, the method comprising:

• detecting a voltage difference between the first and second terminals;
• and
• adding an undershoot reduction current to the write current based on a state of the first and second input signals and a detected voltage difference between the first and second terminals.