The Power Management Unit (PMU) is a
microcontroller
A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs (processor cores) along with memory and programmable i ...
that governs
power
Power most often refers to:
* Power (physics), meaning "rate of doing work"
** Engine power, the power put out by an engine
** Electric power
* Power (social and political), the ability to influence people or events
** Abusive power
Power may a ...
functions of digital platforms. This
microchip
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny M ...
has many similar components to the average
computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
, including
firmware
In computing, firmware is a specific class of computer software that provides the low-level control for a device's specific hardware. Firmware, such as the BIOS of a personal computer, may contain basic functions of a device, and may provide h ...
and
software
Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work.
At the lowest programming level, executable code consists ...
,
memory
Memory is the faculty of the mind by which data or information is encoded, stored, and retrieved when needed. It is the retention of information over time for the purpose of influencing future action. If past events could not be remembered, ...
, a
CPU, input/output functions, timers to measure intervals of time, and
analog
Analog or analogue may refer to:
Computing and electronics
* Analog signal, in which information is encoded in a continuous variable
** Analog device, an apparatus that operates on analog signals
*** Analog electronics, circuits which use analog ...
to
digital
Digital usually refers to something using discrete digits, often binary digits.
Technology and computing Hardware
*Digital electronics, electronic circuits which operate using digital signals
**Digital camera, which captures and stores digital i ...
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
*Charging
batteries when necessary
*Controlling power to other
integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
s
*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 the
real-time clock
A real-time clock (RTC) is an electronic device (most often in the form of an integrated circuit) that measures the passage of time.
Although the term often refers to the devices in personal computers, servers and embedded systems, RTCs are pr ...
(RTC)
See also
*
Power management integrated circuit
Power management integrated circuits (power management ICs or PMICs or PMU as unit) are integrated circuits for power management. Although PMIC refers to a wide range of chips (or modules in system-on-a-chip devices), most include several DC/DC ...
(PMIC)
*
System Management Unit The System Management Unit (SMU) is an advanced internal subsystem introduced in late 2004 with the iMac G5 and Power Mac G5 series computers. It manages the functions previously governed by the PMU (Power Management Unit) as well as additional c ...
(SMU)
*
System Management Controller The System Management Controller (SMC) is a subsystem of Intel and Apple processor-based Macintosh computers. It is similar in function to the older SMU, PMU, or UAE of non-Intel Macintosh computers.
Overview
The SMC has roles in controlling ther ...
(SMC)
References
*"Desktop and Portable Systems: Second Edition" Edited by Owen W. Linzmayer {{ISBN, 0-321-33546-5
External links
Resetting the PMU on Macbook and MacbookPro computers- contains general information on the PMU
Apple Inc. hardware
Macintosh computers