Patent ID: 6353298
Filing Date: 2002-03-05
Classification: H03F

Abstract:
A circuit for providing drive voltages to a voice coil motor (VCM), said circuit having two driver sets, each driver set having a high side driver and a low side driver, each driver set for connection to respective opposite sides of said VCM, each driver set comprising:first and second SENSEFET devices respectively in said high side driver and said low side driver, each SENSEFET device having a first portion for selectively connecting a side of said VCM to a VCM driving potential and a second portion for sensing a current in said first portion; a circuit for sensing a sense current in said second portion of said SENSEFET device of said low side driver; a circuit for increasing a bias on gates of said SENSEFET device in said low side driver when said sense current falls below a predetermined level; and a circuit for driving a predetermined current in said SENSEFET device of said high side driver when said sense current falls below said predetermined level, wherein a current of at least about said predetermined level always flows in said SENSEFET devices.