Mini UPS 12V Lead-Acid

This project implements a mini uninterruptible power supply (UPS) designed for 12V Lead-Acid AGM/GEL batteries.

Mini UPS 12V Lead-AcidCover
PowerControllerHome Automation
2025-08-26 09:27:16MIT License

PCBA

Design Files

KiCad iconMiniUPS12VLead-Acid.zip1.59MB

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Detailed Description

Mini UPS 12V Lead-Acid | UVP Protector - Buck - Charger - Bypass

This project implements a mini uninterruptible power supply (UPS) designed for 12V Lead-Acid AGM/GEL batteries.
It integrates a dedicated CN3767 lead-acid charger, a PMOS + Schottky bypass circuit, a TPS54360 buck regulator, and an undervoltage protection (UVP) stage to ensure safe battery operation.

The design focuses on maintaining stable 12V output while protecting the battery from undervoltage damage and ensuring correct charging cycles.

🔑 Features

  • Battery chemistry supported: 12V Lead-Acid (AGM, GEL).

  • CN3767-based lead-acid charger with constant-current/constant-voltage (CC/CV) charging.

  • Bypass system:

    • PMOS + Schottky switch circuit.

    • During charging, disconnects the battery from the load to allow proper charging.

    • The load is powered instead by a regulated buck supply.

  • Buck regulator stage:

    • Based on TPS54360 DC/DC converter.

    • Configured to 13.8V output for stable system powering during battery charge.

  • Undervoltage protection (UVP):

    • Implemented with LM393 comparator and TL431 reference.

    • Controls a back-to-back PMOS switch.

    • Cuts off the battery when voltage falls below 11V.

    • Latch-off behavior: system remains disconnected until external power is restored.

  • 2-layer PCB, designed for compact size, thermal management, and robust operation.

📂 Repository structure

  • /schematic/ → Circuit schematic files.

  • /pcb/ → PCB layout files ready for fabrication.

  • /doc/ → Technical notes and design explanation.

  • /img/ → PCB renders and prototype photos.

🔧 Typical applications

  • DIY 12V backup supply for small systems.

  • Router, modem, or IoT device UPS.

  • Low-power embedded controllers requiring uninterrupted 12V operation.

  • Safe battery-powered test benches.

📑 References

📸 Project preview

(Insert here PCB renders and/or real prototype images)

⚖️ License

This project is released under the MIT License.
You are free to use, modify, and distribute it, provided that proper credit is given.