Voice coil driver with variable gain in seek and track-follow modes

摘要

A driver circuit for providing drive current to a coil for positioning a read/write head of a memory disk system and method are presented. The driver circuit includes a pair of high side driver transistors having current paths connected between respective terminals of the coil and a voltage source, a first pair of low side driver transistors having current paths connected between respective terminals of the coil and a first voltage sense node, and a second pair of low side driver transistors having current paths connected between respective terminals of the coil and a second voltage sense node. A first sense resistor is connected between the first and second voltage sense nodes, and a second sense resistor is connected between the second sense node and a reference potential. A first set of selection switches operates to select one of the pair of high side driver transistors and one transistor of each of the first and second pairs of the low side driver transistors to establish a current path through the selected transistors and the coil in response to a direction signal. A second set of selection switches operates to select one or the other of the selected low side driver. transistors in response to a seek and track-follow mode selection signal. A circuit is also provided for applying a coil current signal to a low side driver transistor selected by the first and second sets of selection switches.