Trim circuitry and method for accuracy improvement in current se

Details Trim circuitry and method for accuracy improvement in current se Trim circuitry and method for accuracy improvement in current se

1997-09-22

2000-11-21

Ometz, David L.

Dynamic magnetic information storage or retrieval

Automatic control of a recorder mechanism

Controlling the head

318439, 330253, 330257, G11B 555, G11B 2112, H02P 500, H03F 316

Patent

active

061511862

ABSTRACT:
A circuit (10) and method for providing a drive current to a voice coil (20) to position a head (13) of a disk drive (14) includes driver circuitry (68, 70) for controlling currents flowing in the voice coil (20) and at least one sense current circuit (92), which may include FET devices (112, 114, 116, 118), for sensing and controlling the currents in a current path (26) of the driver circuit (10). Programmable circuitry (170) is connected to adjust at least one of the sense current circuits (112, 114 or 116, 118) to control a current flowing through the voice coil (20) to position the head (13) to a desired location. A trim capability is implemented by providing one or more trim FETs (145-148, 155-158) that are selectively connectable in parallel with current mirroring FETs (120, 126), which may be, for example, FETs connected to mirror a current in one of the current flow paths (26) of the drive circuit (10). By such selective connection, an effective channel width provided by the FET devices (120, 145-148 or 126, 155-158) can be selectively provided, thereby enabling the current in the voice coil (20), and therefore the position of the head (13) controlled by the voice coil (20) to be adjustable.

REFERENCES:
patent: 5113147 (1992-05-01), Klein
patent: 5191297 (1993-03-01), Penman et al.
patent: 5416646 (1995-05-01), Shirai
patent: 5444579 (1995-08-01), Klein et al.
patent: 5455816 (1995-10-01), Bitting
patent: 5493189 (1996-02-01), Ling et al.
patent: 5867001 (1999-02-01), Lagerquist et al.
patent: 5877914 (1999-03-01), Gontowski, Jr.

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