What is PMU (PMIC)

What is PMU (PMIC)

PMU (Power Management Unit) is a power management unit, a highly integrated power management solution for portable applications, that is, the traditional Discrete power management chips, for example, low-voltage differential linear voltage regulators (LVS) and DC/DC converters (DC/DC), but now they are all integrated into the Power Management Unit (PMU) of mobile phones, in this way, higher power conversion efficiency and lower power consumption can be achieved, and fewer components can be used to reduce the board-level space, reducing the cost.

PMU is an integrated power management unit for Consumer Electronics (mobile phones, MP4, GPS, PDAs, and so on, it can provide all power supplies with different voltage levels required by the main chip, and provide different cell phone work units with the same voltage, such as processors, RF devices, and camera modules, enable these units to work properly. Power Management, charging control, and switch control circuit are integrated as needed by the main chip. Including adaptive USB-compatible PWM charger, multi-channel DC converter (buckdc-dcconverter), multi-channel Linear Voltage Regulator (ldos), charge pump, RTC circuit, motor drive circuit, LCD Backlight Drive Circuit, keyboard Backlight Drive Circuit, keyboard controller, voltage/current/temperature, and other multi-channel 12-bitadc, as well as multi-channel configurable gpio. In addition, protection circuits such as over/under voltage (OVP/UVP), over temperature (OTP), and over current (OCP) are integrated. Advanced PMU allows safe and transparent power distribution between USB and external AC adapters, lithium batteries, and application system loads. Dynamic Power Supply Path Management
(Dppm) shared between system and battery chargingAC AdapterCurrent, and automatically reduces the charging current when the system load increases.Adjust the relationship between the charging current and the system current distribution to maximize the normal operation of the system,When charging through the USB port, if the input voltage falls below the threshold to prevent the USB port from crashing, the input voltage-based Dynamic Power Management (IDPM) reduces the input current. When the adapter cannot provide peak system current, the Power Path architecture also allows the battery to compensate for this type of system current requirement.

LVS is a voltage regulator that uses a low working pressure difference to adjust the output voltage through negative feedback so that it remains unchanged. If the pressure difference is small, use the ldos, with the shutdown function to facilitate power management. Large Pressure Difference or high efficiency with DC-DC.

Various voltage sources are provided as required by the system, which are required for voltage adjustment. In addition, these power supplies can also be turned on and off in sync with functions to support Voltage Field switching.

PMU is generally customized with the master chip. Because it must work with the CPU power-on sequence. The power-on sequence of some voltages and the interval between them have a sequential relationship and time requirements. This is a good mask. PMU is actually a dedicated power controller with a mask program. 32.768khz crystals and M crystals are required. The STANDBY state is 32.768khz crystals, and the normal operation is M.
Back to the battery PMIC into the STANDBY state, PMU by 32.768khz crystal to provide the clock, press the power button to trigger the boot, the installation of customized boot sequence will correspond to the DC-DC open, M master clock operation, after the CPU power is normal, the output settings to the CPU, the output reset signal to the CPU, release the reset signal, CPU start. The CPU output ps_hold signal puts PMIC in the working state. (When the instance is shut down, the CPU will hold the ps_hold power down and the PMIC will be shut down)

After the CPU is working properly, you can use the I2C interface to control each module of PMIC. For example, when the system changes the frequency, the core voltage must be adjusted to the corresponding voltage at Different Operating frequencies. RTC time settings and alarm clock. At the same time, PMIC can generate an interrupt signal to the CPU for exception events, and the CPU can then interrupt the processing.

The more PMIC power supply, the smaller the power supply to the system module, and the smaller the power supply to each module, the more power consumption.