Let%27s delve into the details of clock gating in microcontrollers (MCUs).

1. What is Clock Gating?
- Clock gating is a power-saving technique used in MCUs and other digital circuits.
- It involves selectively enabling or disabling clock signals to specific parts of the circuit based on their activity.
- By turning off clocks to inactive blocks, clock gating reduces dynamic power consumption.

2. How Does Clock Gating Work?
- MCUs developed in the last decade employ extensive clock gating.
- When a specific circuit or peripheral is not needed during a clock cycle, its clock signal is cut off.
- This mode effectively provides clock gating across the entire CPU.
- However, the primary clock (usually the high-frequency oscillator) must continue running to guarantee responsiveness.

3. Benefits of Clock Gating:
- Energy Savings: By disabling clocks to inactive blocks, clock gating reduces power consumption.
- Quick Response: Despite reduced power, the MCU can quickly respond to events.
- Peripheral Autonomy: In standby mode, high-speed peripherals (DMA, serial ports, etc.) can function autonomously.
- RAM Access: RAM remains active, allowing data retrieval by peripherals without CPU intervention.

4. PLLs and Clock Gating:
- Some MCUs use on-chip phase-locked loops (PLLs) to generate various clocks.
- For maximum energy saving, these PLLs are powered down when the driven blocks are inactive.
- PLLs require a constant current to maintain lock, but they take time to stabilize during startup.

5. Overall Impact:
- Clock gating balances responsiveness and energy efficiency.
- It ensures that only necessary components receive clock signals, optimizing MCU performance and power usage.

In summary, clock gating is a fundamental technique that contributes to the energy-efficient operation of MCUs, allowing them to run on limited energy sources for extended periods¹³.


(1) Understanding MCU sleep modes and energy savings. https://www.embedded.com/understanding-mcu-sleep-modes-and-energy-savings/.
(2) Clock Gating - Semiconductor Engineering. https://semiengineering.com/knowledge_centers/low-power/techniques/clock-gating-2/.
(3) . https://bing.com/search?q=clock+gating+in+MCUs.
(4) undefined. https://anysilicon.com/the-ultimate-guide-to-clock-gating/.
(5) undefined. https://www.allaboutcircuits.com/technical-articles/use-of-clock-gating-to-reduce-power-consumption/.
(6) undefined. https://www.nxp.com/docs/en/application-note/AN4503.pdf?&fasp=1&WT_ASSET=Documentation.

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