Disk drive with reduced power modes

摘要

A method for controlling a rotating disk magnetic data storage device employing several reduced power modes which are automatically entered and exited under the control of the rotating disk device microcontroller. Two modes are provided which are fully responsive to host computer commands, and are thereby transparent to the host computer user, all providing significant power savings. An additional full power down mode is provided which can be initiated by a command from the host computer user, wherein the operational state parameters of the rotating disk device are stored in the host computer until the host computer powers on the device. At this time the stored state parameter are restored into the rotating disk device allowing it to resume its operational state immediately prior to the power suspension. Additionally, a reduced power startup procedure is provided where a low current start is first attempted, which will be successful in a high percentage of attempts, followed by a higher current attempt if the first attempt is unsuccessful. A portion of the drive circuitry is disabled during the startup procedure to further save energy.