VOICE COIL DRINKER HAVING VARIABLE GAIN IN SEEK AND TRACK FOLLOW MODE

摘要

PURPOSE: To reduce the complexity of a circuit, and to form a driver of a further few circuit hardware by applying a coil current signal having a directional signal. ;CONSTITUTION: A current path is established through one of high voltage side drivers FET 23 and 24, through a voice coil 21, and through selected one of low voltage side drivers FET 27-37 in response to the code bit of head position information. Therefore, currents are allowed to flow from a voltage source VCC through the source drain current path of an FET 24, and through a coil 21 to one or the other of FET 27 and 29. Then, when the FET 27 or an FET 28 is selected, the sum of the resistance values of resistance 40 and 41 is introduced to a circuit. When an FET 29 or 30 is selected, the currents through the coil 21 are allowed to flow only through the resistance 41. Therefore, in a seek mode in which only the resistance 41 is selected, further small output currents can be obtained in response to an input voltage for generating further high currents.;COPYRIGHT: (C)1994,JPO