PWM/linear driver for disk drive voice coil actuator
US5838515A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 30, 1996 |
| Grant date | Nov 17, 1998 |
| Priority date | — |
| Expiry date | Apr 30, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03F3/2173
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A voice coil motor (VCM) driver has four field effect transistors connected to a motor coil as an H-bridge. A sense resistor in series with the coil and the H-bridge senses coil current. A feedback amplifier provides a feedback signal from a voltage developed across the sense resistor. A summing junction sums current command signals with the feedback signal. A transconductance loop compensation amplifier has an inverting input connected to the summing junction, has a non-inverting input connected to a reference level, and has an output control signal node. The control level is connected to control linear transconductance differential driver amplifiers including the four field effect transistors during a linear drive mode. A pulse width modulation (PWM) generator connected to the output control signal node generates variable duty cycle pulses related to the control level during a PWM drive mode applies the pulses to a first one of the four field effect transistors, and a polarity control circuit responds to a driving current direction signal by controlling another one of the four field effect transistors during the PWM drive mode.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.