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ThePower Management Unit (PMU) is amicrocontroller that governspower functions of digital platforms. Thismicrochip has many similar components to the averagecomputer, includingfirmware andsoftware,memory, aCPU, input/output functions, timers to measure intervals of time, andanalog todigital converters to measure the voltages of the main battery or power source of the computer. The PMU is one of the few items to remain active even when the computer is completely shut down, powered by the backup battery.

For portable computers, the PMU is responsible for coordinating many functions, including:

• Monitoring power connections and battery charges
• Chargingbatteries when necessary
• Controlling power to otherintegrated circuits
• Shutting down unnecessary system components when they are left idle
• Controlling sleep and power functions (On and Off)
• Managing the interface for built in keypad and touchpads on portable computers
• Regulating thereal-time clock (RTC)

• Power management integrated circuit (PMIC)
• System Management Unit (SMU)
• System Management Controller (SMC)

• "Desktop and Portable Systems: Second Edition" Edited by Owen W. Linzmayer.ISBN 0-321-33546-5.

• Resetting the PMU on Macbook and MacbookPro computers – contains general information on the PMU

• Apple Inc. hardware
• Macintosh computers

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