An Online UPS Card (Uninterruptible Power Supply Card) is an essential electronic module that forms the core of an online UPS system, designed to provide seamless and reliable backup power to critical electrical and electronic equipment. It continuously conditions incoming AC power and converts it to DC to charge the battery, while simultaneously feeding power to the inverter, which generates a clean and stable AC output. In the event of a power failure, the online UPS card instantly switches to battery power without any interruption, ensuring that connected systems such as servers, medical devices, industrial controllers, and communication equipment remain operational. Featuring advanced microcontroller-based control, high-speed switching, and built-in fault protection, the UPS card enhances power quality by filtering out voltage spikes, surges, noise, and frequency variations.