Microcontroller power management method - Power Circuit - Circuit Diagram

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Nuvotech's NUC1xx includes NUC101, NUC100, NUC120, NUC130 and NUC140. It is a 32-bit microcontroller (MCU) with ARM Cortex-M0 as the core. It can reach the operating frequency of 50MHz through different clock settings. However, in the case of general simple control or low system load, the CPU does not need to perform the required amount of calculation at the highest operating clock. At this time, you can use the control of the system clock to reduce the clock to save power.

Another situation is that the CPU can enter the Idle or Power Down mode because it waits for the next job or only needs to work for a long time. After a certain time or when a specific event occurs, it will be woken up. Processing of related events. At the same time, if there are no system modules in the system, you can also turn them off to save unnecessary power consumption. This article describes the principles of various power saving methods and provides examples of related examples.

Switch system module

In the Nunning Technology NUC1xx, in order to save power, when a system module is not in use, its input clock can be turned off, so that it enters the off mode, thereby achieving power saving effect. In NUC1xx, almost all system modules can be turned off separately. These modules include: Watch Dog Timer, RTC, Timer0~3, I2C0~1, SPI0~3, UART0~2, PWM0~7, CAN, USB, ADC, ACMP, PS2, PDMA, Flash ISP. However, not every module contains all the module functions. For example, the CAN module only has this function in NUC130 and NUC140. For details, please refer to the related files of each chip.

The relevant power consumption of each module is shown in Table 1.

Nuvoton Technology NUC1xx achieves the purpose of shutting down each module by turning off the clocks of each module. Therefore, to close the module, the relevant clock control buffer must be set. The NUX1xx provides the AHBCLK Register and the APBCLK Register to control the switches of the various modules listed above.

System clock setting

The power consumption of Nuvotech's NUC1xx itself has a lot to do with its running clock. If the running clock is high, the power consumption is high, otherwise it is more power-saving, but at the same time the CPU may not be able to load a large number of operations. Therefore, if you want to balance a large number of calculations and power saving, you must be able to adjust the CPU's working clock according to the actual needs, in order to achieve the best operational efficiency.

The NUC1xx has a built-in PLL that can generate the clock required by the system using an external 12MHz crystal or an internal 22M oscillator. The clock generated by the PLL can be used as the operating frequency of the CPU after proper frequency division. In addition, NUC1xx also provides direct supply to the CPU operating frequency via an external 32KHz crystal or an internal 10KHz oscillator. Therefore, the NUC1xx provides great flexibility in setting the operating clock.