Systems and methods for modular power management

Various systems and methods for power management are disclosed herein. For example, a modular, adaptive power management system for use in a hard disk drive system is disclosed. This modular, adaptive power management system includes a hard disk drive controller, a read channel module, a host interface controller and a power manager system. The hard disk controller includes a processor executing firmware, and the host interface controller provides for host access via a host interface. The host interface may be, for example, an ATA interface, a SATA interface, and/or other emerging serial interfaces such as MMC, CE-ATA or SDIO. The power manager system includes a power island register and an oscillation control register. Both the power island register and the oscillation control register are each at least indirectly writable via the firmware and via the host interface. The hard disk controller, the interface controller, the read channel module and the power manager system are implemented across two or more distinct power islands and use two or more distinct clocks. Power to the two or more distinct power islands is at least in part controlled by the power manager system via the power island register, and the two or more distinct clocks are each controlled by the power manager system via the oscillation control register.