Let%27s delve into the details of the brown-out detector (BOD) in microcontrollers (MCUs).
1. What is the Brown-Out Detector (BOD)?
- The BOD is an essential circuit found in many MCUs.
- Its primary function is to monitor the supply voltage (VCC) during operation.
- By comparing the actual VCC level to a fixed trigger level, the BOD determines whether the MCU needs to be put into reset mode to prevent erratic behavior.
2. Why is the BOD Important?
- A "brown-out" occurs when the power supply voltage drops below the level required for reliable operation.
- The BOD protects the MCU from such voltage drops.
- When VCC decreases below the trigger level (VBOT-), the BOD immediately activates a brown-out reset.
- Conversely, when VCC increases above the trigger level (VBOT+), the MCU starts up after a delay counter period (tTOUT).
3. How Does the BOD Work?
- The BOD consists of two stages: the Detector and the Amplifier.
- The Detector monitors the voltage of transistor T1.
- Under normal operation, T1 conducts.
- When VCC drops below the threshold voltage, T1 shuts off.
- The output from the Detector feeds into the ultra-low-power Amplifier stage.
4. BOD Settings and Control:
- The BOD trigger level can be set using BODLEVEL Fuses during device programming.
- Once set, this level remains fixed during application execution.
- Even during sleep modes, the BOD actively monitors the power supply voltage.
- To save power, the BOD can be disabled by software for certain sleep modes.
- Upon wake-up, the BOD automatically re-enables itself.
- Disabling the BOD ensures safe operation if VCC dropped during sleep.
- Wake-up time from sleep mode is approximately 60 μs to verify proper BOD functioning.
5. Additional Information:
- For external brown-out protection, refer to Application Note AN1051¹.
- Remember that the BOD is crucial for maintaining stable MCU operation, especially in challenging voltage conditions.
Remember, the BOD acts as a vigilant guardian, ensuring your MCU operates reliably even when faced with voltage fluctuations! ️<br>
(1) . https://bing.com/search?q=purpose+of+brown-out+detector+in+MCU.
(2) AVR® Device Brown-out Detection (BOD) - Developer Help. https://developerhelp.microchip.com/xwiki/bin/view/products/mcu-mpu/8-bit-avr/structure/bod/.
(3) Microcontroller Brown-out detection - Do It Easy With ScienceProg. https://scienceprog.com/microcontroller-brown-out-detection/.
(4) undefined. https://www.allaboutcircuits.com/technical-articles/what-is-brown-out-reset-microcontroller-prevent-false-power-down/.
(5) undefined. https://ww1.microchip.com/downloads/en/Appnotes/doc4183.pdf.
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