How to prevent a smart controller (PAC) from crashing due to voltage drops or interruptions?

Ensuring the PAC (Power Actuator) does not crash during voltage dips and interruptions requires attention to both hardware and software.

On the hardware side, the power supply design utilizes a wide input range (e.g., 85-264VAC) switching power supply and increases the energy storage capacitor (e.g., 1000μF) to maintain short-term power supply. Critical circuits (such as the CPU and memory) use LDO (Low Voltage Regulator) staged voltage and include a power-down detection circuit to trigger a reset.

On the software side, a watchdog timer is enabled, and the system saves its state to non-volatile memory upon detecting a voltage dip.

Testing is conducted according to IEC61000-4-11/29, applying a voltage dip to 70% of the rated value for 10 cycles, followed by a 5ms interrupt; the system should not restart or should recover its state after restarting. Through this design, the PAC can withstand voltage anomalies, increasing its MTBF to 100,000 hours.