The system management controller (SMC) is responsible for managing the power-related features of Intel-based Macintosh computers. On models that have an Apple T1 or T2 security chip, the SMC is managed by the chip to maintain startup security and prevent unauthorized access.[1][2]

Managed features

  • The power button.
  • Battery and charging.
  • Fans and thermal-management features.
  • Power to the USB ports.
  • Sensors, such as the sudden motion sensor, the ambient light sensor, and keyboard backlighting sensor.
  • Sleep behavior when opening and closing the lid of a notebook computer
  • Status indicator lights, such as sleep status and battery charging status.

Resetting the SMC

If there are power-related issues with a noteook Mac managed by a SMC, the controller can be reset by shutting down, holding down   SHIFT + CONTROL + OPTION   for at least 7 seconds, and then also hold down the power button for at least 10 seconds. The SMC can be reset on a desktop Mac by shutting down, unplugging it from power for at least 15 seconds and then plugging it back in for at least 5 seconds before turning it back on. This process does not affect data stored in NVRAM or PRAM.

Newer Macs based on the Apple M1 processor do not contain a SMC that can be reset in this manner.[3]

References

  1. About Startup Security Utility, Apple Support. 2021-01-11.
  2. Examined: The new MacBook Pro Touch Bar and Apple's T1 authentication chip by Mike Wuerthele, AppleInsider. 2016-10-28.
  3. How to reset the SMC on an M1 or Intel Mac by David Price, Macworld. 2021-02-04.

External links

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