Patent ID: 7106546

Claim:
A system for controlling the speed of a Voice Coil Motor (VCM) in order to perform the ramp loading of hard disk heads with low noise, the system comprising: a generator for generating a discontinuous PWM drive signal to a power stage including said VCM; a sampling block being clocked by a synchronization signal issued from said generator and receiving a signal related to an electromotive force (Bemf) provided by said VCM; an adder node placed at the sampling block output to add an output from said sampling block to a signal related to a reference electromotive force (Bemf_ref); a filtering block placed downstream of the adder node to receive an output from said adder node and generate a power supply voltage signal; a control block comprising at least one voltage divider and a plurality of controlled switches, said control block being input the voltage signal output from said filtering block and a plurality of control signals issued from said generator to selectively operate said controlled switches and set the value of the power supply signal value of said power stage.