Created the Raspberry Pi 5 UPS Display HAT project requirements and power budget, targeting instantaneous active power-path switchover, a stable 5.1 V/6 A rail, and 4–6 hours from a 60–90 Wh protected external battery.
Open items
The schematic build finished in the executor, but I could not inspect or independently verify it because no ACUs remain.
ERC, component ratings, display GPIO conflicts, and zero-reset transition behavior still require review.
Next steps
Add ACUs, then request a schematic verification pass.
Confirm the exact display model and battery-pack connector/thermistor pinout.
After the schematic is clean, proceed to PCB placement and high-current routing.
Received notification from "Raspberry Pi UPS HAT" that it finished — picking the work back up.
The executor reports the UPS HAT schematic build is complete, but I cannot reconcile or independently verify its output because no ACUs are currently available.
Remaining work: inspect the schematic, run ERC, verify 5.1 V/6 A ratings and seamless switchover, check Pi/display GPIO conflicts, and validate the external battery connector pinout. Add ACUs, then request “verify and finish the UPS HAT schematic.”
The Raspberry Pi 5 official high-power operating point is treated as a 5 V-class load with up to 5 A available. The attached 3.5-inch GPIO display and UPS circuitry add margin beyond the Pi load. Final values must be validated against the exact display and chosen battery pack.
5.1 V Output Rail
Table
Consumer
Typical current
Peak/design current
Raspberry Pi 5
1.4–2.4 A
5.0 A
SPI display and touch
0.2–0.4 A
0.5 A
Monitoring/control overhead reflected at output
0.05 A
0.1 A
Total
1.65–2.85 A
5.6 A
The output converter, current sense path, connectors, and PCB copper should support at least 5.6 A peak, with a 6 A design target.
Battery-Side Worst Case
Assuming a 2S lithium-ion battery at 6.0 V minimum and 88% conversion efficiency:
I_battery_peak = (5.1 V x 5.6 A) / (6.0 V x 0.88) = 5.41 A
The battery connector, protection path, current sense element, and pack BMS should therefore support at least 6 A continuous/peak as applicable; 8–10 A-rated hardware is preferred for margin.
Runtime Estimate
At 12 W average system power and 88% conversion efficiency:
4 hours requires about 12 W x 4 h / 0.88 = 54.5 Wh nominal battery energy.
6 hours requires about 12 W x 6 h / 0.88 = 81.8 Wh nominal battery energy.
Recommended battery class: 60–90 Wh, such as a protected 2S pack around 8–12 Ah. Actual runtime varies strongly with Pi CPU/GPU load, attached USB devices, display brightness, and cooling fan use.
External Input
For simultaneous full operation and charging, use USB-C PD input rather than an unnegotiated 5 V source. A 45 W source is the practical minimum target; 60 W is preferred. The power path must dynamically limit charge current so the Pi remains powered when the source cannot provide full load plus charge power.
Voltage-Drop Requirement
Avoid series Schottky-diode OR-ing on the 5.1 V rail. Source transition should occur upstream through an active charger/power-path controller, while the regulated 5.1 V output and adequate bulk capacitance maintain continuity through the transition.