| 摘要 |
<p>A voice coil motor (VCM) driver (28) has four field effect transistors (90, 94, 98, 104) connected to a motor coil (24) as an H-bridge (Viso). A sense resistor (R5) in series with the coil (24) and the H-bridge (Viso) senses coil current. A feedback amplifier (62) provides a feedback signal from a voltage developed across the sense resistor (R5). A summing junction sums current command signals with the feedback signal. A transconductance loop compensation amplifier (56) 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 (56) including the four field effect transistors during a linear drive mode. A pulse width modulation (PWM) generator (72) connected to the output 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 (86) responds to a driving current direction signal by controlling another one of the four field effect transistors during the PWM drive mode.</p> |
