The need to consume less power and provide extended battery life is critical for today’s mobile devices. SATA has supported power management since its inception and manufacturers quickly adopted these recommendations to minimize system power consumption, especially for mobile products. However, to meet the ever more aggressive power/battery life requirements in this new environment, the SATA interface is continuing to evolve.
The original reduced power modes for the SATA interface are Partial and Slumber. In Partial mode, some logic is powered off, but must be able to come up to full operation within 10 microseconds. Slumber mode further reduces power, but can take as long as 10 milliseconds to become fully operational.
While the SATA specification defines power management for the SATA interface itself, the INCITS T13 committee (www.t13.org) AT Attachment - ATA/ATAPI Command Set specifies power management within the device behind the interface. This may involve powering off non-interface electronics or spinning down the disks, in the case of an HDD.
DevSleep provides yet another level of power management via a SATA interface signal that instructs the device to enter a mode where the device is almost completely shut down, resulting in less power consumption than Slumber mode. This feature enables devices to be always on and always connected without unnecessarily reducing battery life.
SATA allows interface power management to be Host Initiated (HIPM) or Device Initiated (DIPM), thus providing the flexibility to optimize the SATA components for a wide range of usages and applications.
SATA power management is pervasive in HDDs and SSDs, but is not limited to these types of products. One such example is the SATA Zero-Power Optical Disk Drive (ODD) feature, which eliminates the power consumption of an idle SATA ODD, resulting in overall system power reduction.