Pwm/linear driver for disk drive voice coil actuator

摘要: A voice coil motor (VCM) driver (28) has four field effect transistors (90, 94, 98, 104) connected to a (24) as an H-bridge (Viso). sense resistor (R5) in series with the and (Viso) senses current. feedback amplifier (62) provides signal from voltage developed across (R5). summing junction sums current command signals signal. transconductance loop compensation (56) inverting input junction, non-inverting reference level, output control node. The level is linear differential amplifiers including during drive mode. pulse width modulation (PWM) generator (72) PWM mode applies pulses first one of transistors, polarity circuit (86) responds driving direction by controlling another