PowerBox PCB

PowerBox

An all-in-one power solution for cyberdecks and portable embedded systems.

PowerBox is my custom-designed PCB that handles USB-C Power Delivery input, dual-cell lithium battery management, balance charging, and regulated power output, all in a single compact board. Designed to push up to 36W of power to whatever you throw at it.

Overview

PowerBox was built to power DIY cyberdecks and portable computing projects that need more juice than a standard battery banks can provide.

Components

PowerBox is built around 7 core subsystems:

1. USB-C Power Delivery Input

A USB-C port paired with a PD sink controller that negotiates 12V from a PD-capable charger. At full load the circuit can draw up to 36W which is well beyond what standard 5V USB can supply.

2. Dual Buck DC-DC Converters (×2)

Two TPS54620 synchronous step-down converters provide regulated output voltages. The TPS54620 is a 6A, 17V capable device giving plenty of headroom for demanding loads.

3. Ideal Diode Circuits (×2)

When USB-C power is present, the battery-fed bucks are switched off to prevent backfeeding the charger. This creates a condition where the buck converter inputs can see negative voltages which is outside their rated range. The ideal diode circuits clamp this safely, acting as electronic diodes with near-zero forward voltage drop.

4. BMS Circuit (DW01A)

A battery management system built around the DW01A which is a popular and proven lithium-ion protection IC. Handles over-charge, over-discharge, and short-circuit protection for the cell pack.

5. 2S Balance Charger (BQ2588RGER)

A proper 2-series balance charger using TI's BQ2588RGER, capable of up to 2A charge current. Keeps both cells at equal state-of-charge for longevity and safety.

PCB

The PCB design files are in the PowerBox_PCB/ directory. Output gerbers and fabrication files are in Output/.

Design Logic

USB-C PD (12V, 36W)
        │
        ├──► Buck 1 (TPS54620) ──► Ideal Diode ──► Output Rail A
        │
        ├──► Buck 2 (TPS54620) ──► Ideal Diode ──► Output Rail B
        │
        └──► BQ2588RGER Balance Charger ──► 2S Li-Ion Pack
                                                  │
                                              DW01A BMS
                                                  │
                                            Battery Output

Why did I choose 36W / USB-C PD?

A 2S lithium pack needs to charge while simultaneously powering the system. At full system load, 15W standard USB-C isn't enough, it can't even charge an open MacBook. Requesting 12V via PD and pulling up to 3A gives the 36W headroom needed to charge the battery and run the load at the same time.

Why two cells?

More cells = more capacity. More capacity = the circuit can sustain high loads without the cells entering stress territory. A single-cell design at 36W draw would be asking for trouble (and possibly a fire).

Repository Structure

PowerBox/
├── Notes/           # Design notes and calculations
├── Output/          # Gerber files and fabrication outputs
├── Parts/           # Bill of materials and component info
└── PowerBox_PCB/    # KiCad / PCB design files

Key ICs

Zine

License

See LICENSE for details.

Built by Alvin-Alford