The present invention relates generally to integrated circuits, and, more particularly, to a microcontroller that has multiple power modes.
A microcontroller unit (MCU) is a type of integrated circuit (IC) that has a plurality of components such as multiple processor cores and peripherals. MCUs are designed for specific applications and often are part of specific systems, such as automotive electronics systems and wireless communication devices. An MCU used in an automotive system may include multiple processor cores and peripherals such as timers, dynamic and static random access memories (DRAM and SRAM), DRAM and SRAM controllers, a flash memory and controller, a controller area network (CAN) and a local interconnect network (LIN). For example, if the MCU is used for displaying vehicle data such as tire pressure, and cabin and ambient temperatures on a multi-information display, the multiple processor cores communicate with the DRAM in which an operating system is stored, and a flash memory in which the vehicle data is stored. The flash memory receives the vehicle data from components external to the MCU by way of the peripherals such as the CAN and the LIN, which manage communications between the flash memory and the external components. The multiple processor cores control the CAN and the LIN to enable communications.
To reduce the overall power consumed, the MCU is operable in multiple power modes like high and low power modes. For example, when the automobile is parked and powered off (i.e., not in use), applications such as radio, power windows and the multi-information display, are not required. Thus, to reduce power consumption of the MCU, the MCU operates in the low power mode and the multiple processor cores and the peripherals that handle the aforementioned applications (i.e., the DRAM controller, the DRAM, the flash memory and controller, and the CAN and the LIN) are powered off. However, peripherals such as the timers, the SRAM controller and the SRAM are active because they are used to retain an operating state of the MCU. Such peripherals are classified as being in a low power domain. Since the multiple processor cores are power-gated in the low power mode, the low power domain is left without control.
When the applications such as the multi-information display, the radio and the power-windows are needed, the MCU exits the low power mode and begins operating in the high power mode. The multiple processor cores and the peripherals (i.e., the DRAM controller, the DRAM, the flash memory and controller, and the CAN and the LIN) then are powered on, and classified as being high power domains. The multiple processor cores control the peripherals in the high and low power domains in the high power mode. However, in the high power mode, since both the high and low power domains are operational, the power consumption of the MCU is high.
When the MCU is in the high power mode, the high and low power domains receive a first supply voltage from a first voltage regulator. When the MCU is in the low power mode, the first voltage regulator is powered off and a second voltage regulator is turned on, and the low power domain is disconnected from the first voltage regulator and connected to the second voltage regulator using a switch. Thus, when the MCU is in the low power mode, it is not possible to control the components of the low power domain. Further, if only the CAN and the LIN are required to be active, the entire high power domain must be powered and the MCU has to toggle between the low and high power modes, which increases the average power consumption of the MCU. Since the MCU receives power from the car battery, the increased average power consumption drains the battery faster.
Therefore it would be advantageous to have a microcontroller that operates in multiple power modes including high and low power modes, but allows for controlled operation in the low power mode, and yet has low average power consumption.