Concept of Low Power
In the design of embedded systems, low power design is a challenge that many designers must face. This is because embedded systems are widely used in portable and mobile products, which often do not have a constant power supply and rely on batteries for power. Therefore, designers consider every detail to reduce power consumption in order to extend battery life as much as possible.
As a result, most chips will have low power modes. From the perspective of MCUs, the performance of low power MCUs is generally measured by the following parameters:
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What is the working current consumed by the MCU in deep sleep mode, typically measured in microamperes?
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How long does it take for the MCU to wake up from deep sleep mode and enter high-speed operation, measured in microseconds?
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What is the current consumption during high-speed operation, measured in microamperes per megahertz (uA/MHz)?
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Can unused functions within the MCU be completely turned off to prevent additional energy consumption?
MCUs that possess the above characteristics can generally be classified as low power MCUs.
Low power MCUs typically remain in sleep mode, maintaining a state that can be awakened. After each wake-up, they quickly resolve issues and then immediately return to sleep mode.
For example, with a CR2032 battery that has a standard capacity of 200 milliamp-hours, if the current consumption is only 1 microampere, theoretically, it can remain in standby for many years. The calculation formula is as follows:
200mAh/1uA=200mAh/0.001mA=200000H=approximately 8333 days or about 22.8 years
Therefore, a sleep current of no more than 1 microampere is considered quite good.
This current is not necessarily better the lower it is. Because excessively low standby current has no practical significance, and this current cannot be infinitely small. To maintain stable operation, a small amount of current must always be consumed. Making it too small can actually hinder operational stability.
Taking a domestic low power MCU as an example, let’s look at the CW32L situation.
The CW32L is a low power series MCU from Wuhan Xinyuan Semiconductor Co., Ltd. The CW32L series MCUs have a minimum sleep current of 450 nanoamperes, which has been verified through precise practical testing by the Xinyuan Semiconductor team, ensuring stability and reliability across the full temperature range under this process.
In the next issue, we will analyze the selection of the CW32L series chips and how to obtain development boards, materials, and support.
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