AURA SOM/AURA Hardware/Power modes

History
Issue Date	Notes
2023/09/14	First Release

Power modes

AURA SOM includes the i.MX93 SOC which supports innovative power management. As written in its Fact Sheet:

The i.MX 93 applications processors implement NXP’s innovative energy flex architecture where power and clock frequency of heterogenous domains such as the application domain (Cortex-A55s), real-time domain (Cortex-M33, peripherals) and flex domains (NPU, DDR, etc.) can be individually controlled to provide the maximum flexibility to achieve the lowest power consumption possible tuned to use cases.

Mode definition

AURA (i.MX93-based) supports the following power modes:

• RUN mode: all external power rails are on, the Cortex®-A55 is active and running; other internal modules can be on/off based on application.
• Low Power RUN mode: is defined as a very low power run mode with all external power rails are on. In this mode, all the unnecessary power domain (MIX) can be off, except AONMIX and the internal modules required, such as OSC24M/PLL. Cortex-M33 CPU in AONMIX handles all the computing and data processing. Cortex-A55 is power down and DRAM can be in self-refresh/retention mode.
• IDLE mode: This mode is defined as a mode, which the Cortex®-A55 can automatically enter when there is no thread running and all high-speed devices are not active. The Cortex®-A55 can be put into power gated state but with L3 data retained, DRAM and the bus clock are reduced.
• SUSPEND mode: is defined as the most power saving mode where all the clocks are off (including the Cortex®-M33 CPU), all the unnecessary power supplies are off and all power gateable portions of the SoC are power gated. The Cortex®-A55 CPU are fully power gated, all internal digital logic and analog circuit that can be powered down will be off, and all PHYs are power gated. DRAM is set at self-refresh/retention mode
• BBSM mode: also called RTC mode. Only the power for the BBSM domain remains on to keep RTC and BBSM logic alive
• OFF mode: all power rails are off

Low power modes

The IDLE, SUSPEND, and BBSM mode are defined as low power: the main subsystems which are involved in the different power status are the following ones

• Cortex®-A55 CPU0 and CPU1, L3 cache, DRAM controller and PHY, SYSTEM_PLL 1/2/3, XTAL, RTC, module clocks, Edgelock Secure Enclave, GPIO Wakeup, RTC Wakeup, USB Wakeup, other wakeup

All the subsystems are OFF in every low power mode except in the following cases:

• IDLE
  • ON:L3 cache, DRAM controller and PHY, SYSTEM_PLL 1/2/3, XTAL, RTC, module clocks, Edgelock Secure Enclave, GPIO Wakeup, RTC Wakeup, USB Wakeup, other wakeup
  • external DRAM in self-refresh
  • DRAM, NOC, AXI clocks are running
• SUSPEND
  • ON: RTC, Edgelock Secure Enclave, GPIO Wakeup, RTC Wakeup
  • external DRAM in self-refresh
• BBSM
  • ON: RTC, Edgelock Secure Enclave, RTC Wakeup

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