33.2.3 Power Management

The Flash system supports multiple power modes for reducing or managing power. These include auto standby, Flash power-down, and controlling power during sleep.

Flash Auto Standby

The Flash panel enters a Standby mode automatically after a read or write operation. Each Flash panel enters its Auto-Standby mode independently of the other. After a read request completes as defined by the read access time (TACC), the panel enters Auto-Standby mode. For writes/erases this after the recovery time. When a panel is in this mode read and write requests incur no access time penalty.

Flash Hibernate

The Flash panel supports Flash Hibernate mode, which cuts power to most of the panel’s circuits. This substantially reduces the power consumption of Flash systems. Flash Hibernate affects both panels.

Flash Hibernate mode incurs an entry and exit delay, TDPDS and TDPDH, respectively. When in Flash Hibernate mode all Flash operations are suspended; however, the Flash control system automatically wakes up the panels on a request (read or write). The panels are not automatically put back into Hibernate after a wakeup event. If the interrupt causes a wakeup to sleepwalking the panels return the mode selected by CTRLB.SLP.

See Power Mode in Standby Sleep for manual entry and exit of Flash Hibernate.

Sleep Interaction

The Flash system holds off entry into sleep modes lower than Idle Sleep to cleanly stop Flash operations. The following operations delay entry into sleep:

  • In-progress read from any source (system, CRC, and so on)
  • Flash mode change (that is, High Temp, wake from Flash Hibernate)
  • Requested program or erase operation, and so on
Note: Row programming and erase operations can significantly delay entry into a sleep mode.

Entry into Idle Sleep mode does not cause a Flash mode change. Clocks in the Flash system stop automatically when they are not needed for operation.

Entry into Standby Sleep mode can cause a Flash mode change. The Flash can be setup to enter Auto-Standby or Flash Hibernate. If Flash Hibernate is selected there is the option to wakeup to Auto-Standby or remain in Flash Hibernate until the first access. Waking up to Auto-Standby provides the fastest initial access to the Flash system.

See Power Mode in Standby Sleep for power mode control of the Flash on entry and exit of system Standby Sleep.