UPS PCB Design

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I can’t execute research or start building the schematic right now because AI features are unavailable due to no available ACUs. No changes have been made to the empty project yet.
At a high level, your UPS should be partitioned like this:
Diagram



  
    
  
  
    
  






















220 VAC Input
Fuse, MOV, NTC, EMI Filter
Isolated AC-DC Supply<br/>~15 V to 16 V, >=120 W
Power-Path / Ideal-Diode ORing
12 V 7 Ah SLA Battery
Battery Fuse + Reverse Protection + UVLO
12 V to 13.3 V Boost Converter<br/>>=7 A Output
13.3 V DC Output, 7 A
SLA Charger / Float Regulator<br/>13.8 V Float
Output Current Limit / eFuse
Recommended starting architecture:
  • AC front end: Use an off-the-shelf certified isolated AC-DC module/supply rather than designing offline 220 VAC directly on the PCB. Target 15–16 VDC, ≥120 W, preferably 150 W margin.
  • AC-to-load regulation: Use a high-current buck regulator from the AC-DC rail to generate 13.3 V / 7 A.
    • Candidate controllers: TI LM5146, TI LM25116, Analog LTC3891/LTC3895.
  • Battery charger: SLA float charger set to about 13.8 V, with current limiting appropriate for a 7 Ah battery.
    • Candidate ICs/controllers: TI BQ24450, UC3906, or a discrete CC/CV charger using a buck controller.
  • Battery backup boost stage: Boost 10.5–13.8 V battery voltage to regulated 13.3 V / 7 A.
    • This is high current: battery input current can exceed 10 A near UVLO.
    • Candidate controllers: TI LM5122, TI LM5155, Analog LTC3786, LT3757A.
  • Power-path switchover: Use ideal-diode ORing / MOSFET power muxing so the load remains powered when AC disappears.
    • Candidate ICs: TI LM74700-Q1, LTC4359, LTC4416/LTC4417 depending topology.
  • Battery UVLO: Disable the boost stage around 10.5 V to protect the SLA battery.
    • Can be implemented with the boost controller EN/UVLO divider or a supervisor/comparator such as TLV3012, TLV6700, or LM393.
  • Output protection: Add fuse/eFuse/current-limit protection on the 13.3 V output.
    • Candidate ICs: TI TPS25947/TPS25982, LTC4368, or a high-current fuse plus TVS depending cost and reset behavior.
  • Battery protection: Add inline battery fuse, reverse-polarity MOSFET, TVS, and connector rated for >15 A surge.
Important design note: this is a mains-connected 220 VAC product, so isolation, creepage/clearance, fuse selection, enclosure, earth strategy, and certification are safety-critical. I strongly recommend starting with a certified AC-DC brick/module and keeping hazardous AC off the low-voltage UPS PCB unless you’re designing to IEC/UL requirements.
What remains:
  • Select exact ICs/modules after checking availability, datasheets, efficiency, thermal limits, and cost.
  • Define battery charge current target.
  • Decide whether the 220 VAC AC-DC stage is on-board or an external certified supply.
  • Build the schematic power tree, protection, charger, boost, and ORing stages once ACUs are available.
Use external AC-DC
Set charge current
Find suitable ICs
Calculate power budget
Save requirements note
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