A versatile, intelligent dual-input power management system designed for modern electronics projects
- Overview
- Key Features
- Technical Specifications
- System Architecture
- Design Process
- Simulation Results
- Modularity & Expansion
- PCB Design
- Bill of Materials
- Getting Started
- Assembly Process
- Future Enhancements
- Feedback
The Modular Power Hub is an intelligent power management solution designed to address the growing complexity of powering modern electronics projects. Whether you're building IoT devices, robotics projects, or embedded systems, this hub provides reliable, flexible, and protected power distribution from multiple input sources.
Completed Modular Power Hub after SMD assembly showing component placement and red soldermask
- Eliminates power source uncertainty: Automatically switches between available inputs
- Protects expensive components: Built-in overcurrent, overvoltage, and thermal protection
- Reduces project complexity: Single board handles multiple power requirements
- Enables portable operation: Seamless switching between wall adapters, power banks, and USB sources
- Supports rapid prototyping: Standard voltage rails (5V, 3.3V) for most electronics
- Dual USB Input Support: USB-A and USB-C with automatic priority switching
- Robust Voltage Tolerance: 2.8V - 5.5V input range (handles degraded/non-standard USB sources)
- Smart Source Selection: Prefers higher quality/capacity sources automatically
- Seamless Switching: <50mV voltage dip during source transitions
- Input Protection: Polyfuse overcurrent protection and TVS overvoltage clamping
- 5V Rail: Direct from USB with current limiting and protection
- 3.3V Rail: Clean LDO regulation from LD1117V33
- Current Capacity: Up to 1.2A on 5V rail, 800mA on 3.3V rail
- Low Noise: Proper decoupling and filtering for sensitive analog circuits
- Overcurrent Protection: TPS2115A integrated current limiting
- Overvoltage Protection: TVS0500 diode clamping
- Thermal Protection: PTC polyfuse for fault isolation
- Reverse Polarity Protection: Built into power multiplexer design
- Visual Status Indicators: LEDs show active input source
- Standard Connectors: Industry-standard USB and pin headers
- Compact Form Factor: Optimized for integration into projects
| Parameter | Specification | Notes |
|---|---|---|
| Input Voltage Range | 2.8V - 5.5V | TPS2115A absolute limits |
| Optimal Input Voltage | 4.75V - 5.25V | Design target for full functionality |
| Input Current | Up to 2A per source | Limited by USB spec and connector rating |
| Output Voltage (5V Rail) | Same as selected input | Pass-through architecture |
| 5V Output | 4.9V - 5.1V @ 1.2A | <2% regulation |
| 3.3V Output | 3.25V - 3.35V @ 800mA | <3% regulation, requires ≥4.4V input |
| Switching Time | <1ms | Between input sources |
| Efficiency | >85% | At rated load |
| Operating Temperature | -20°C to +70°C | Commercial grade components |
| Dimensions | 35 × 57.5 mm | Compact PCB optimized for integration |
This power hub is designed and optimized for standard USB 5V operation. While the TPS2115A can handle 2.8V-5.5V inputs, full functionality requires:
- 5V Rail: Input ≥4.75V for optimal regulation and current capacity
- 3.3V Rail: Input ≥4.4V for proper LDO regulation (3.3V + 1.1V dropout)
- Protection Systems: TVS and current limiting calibrated for 5V operation
- LED Indicators: Proper brightness at 5V input levels
At lower input voltages (2.8V-4.5V):
- Reduced Output Voltage: 5V rail follows input voltage
- 3.3V LDO Dropout: May not regulate properly below 4.4V input
- Lower Current Capacity: Reduced performance at voltage extremes
- Protection Thresholds: May not function as designed
Recommendation: Use stable 5V ±5% sources for intended operation
┌─────────────┐ ┌──────────────┐ ┌─────────────┐ ┌──────────────┐
│ USB-A │────│ │────│ Protection │────│ 5V Rail │
│ Input │ │ TPS2115A │ │ (Polyfuse, │ │ (1.2A max) │
└─────────────┘ │ Power │ │ TVS0500) │ └──────────────┘
│ Multiplexer │ └─────────────┘ │
┌─────────────┐ │ │ │
│ USB-C │────│ │ ▼
│ Input │ └──────────────┘ ┌──────────────┐
└─────────────┘ │ LD1117V33 │
│ LDO │
└──────────────┘
│
▼
┌──────────────┐
│ 3.3V Rail │
│ (800mA max) │
└──────────────┘
- TPS2115A: Intelligent power multiplexer with priority control
- LD1117V33: Low-dropout 3.3V linear regulator
- TVS0500: Transient voltage suppressor for overvoltage protection
- Polyfuse: PTC overcurrent protection device
Complete schematic showing power multiplexing, regulation, and protection circuits
- Researched modern USB power delivery standards
- Analyzed typical power consumption patterns of target applications
- Defined protection requirements based on real-world failure modes
- Power Multiplexer: Evaluated TPS2115A vs alternatives (TPS2113, MAX40200)
- LDO Regulator: Selected LD1117V33 for cost/performance balance
- Protection Components: Matched TVS0500 and polyfuse ratings to system requirements
- Passive Components: Calculated optimal decoupling capacitor values
- Circuit Topology: Designed hierarchical power distribution
- Signal Integrity: Proper ground planes and power routing
- Component Placement: Optimized for thermal and electrical performance
- Design Rule Verification: Ensured compliance with USB and safety standards
- Footprint Design: Created accurate land patterns for all SMD components
- Symbol Creation: Designed clear, consistent schematic symbols
- 3D Model Integration: Added realistic component visualization
- Design Rule Setup: Configured manufacturing constraints and clearances
- Layer Stack-up: 2-layer design with dedicated power and ground planes
- Component Placement: Optimized signal flow and thermal management
- Trace Routing: Minimized noise and voltage drop
- Manufacturing Preparation: Generated Gerber files and layout drawings
- SPICE Simulation: Comprehensive circuit analysis using LTSpice
- Thermal Analysis: Verified component temperature rise under load
- Signal Integrity: Checked power rail noise and transient response
- Manufacturing Review: DRC and electrical rule checks
Comprehensive LTSpice simulation and real testing validate design performance:
Simulated Measured
5V Rail Regulation: 4.989V 5.05V (±1.1% regulation)
3.3V Rail Regulation: 3.300V 3.28V (±0.6% regulation)
Current Limit: 1.200A - (as designed)
TVS Current: 0mA - (inactive during normal operation)
MCU Load Profile: 20mA → 80mA (5V), 30mA → 120mA (3.3V)
Voltage Deviation: <20mV on both rails
Recovery Time: <100µs
Switching Time: ~1ms
Voltage Dip: 45mV (0.9% of nominal)
Recovery: Immediate and stable
The modular design allows easy adaptation to different input sources by designing new input boards with the same power interface:
- USB Variants: USB-A, USB-C, Micro-USB, USB-B
- Barrel Jack: 5.5mm x 2.1mm DC barrel connectors for 2.8V-5.5V supplies
- USB-C PD: True USB-C Power Delivery for 9V, 12V, 15V, 20V rails
The TPS2115A's 2.8-5.5V range enables these expansion possibilities with new input board designs
Simply design a new input board with the same power interface
Extend power capabilities with additional converter modules:
- Buck Converters: 12V, 9V, 6V rails for motors and sensors
- Boost Converters: 12V, 15V for analog circuits and displays
- Negative Rails: -5V, -12V for op-amp circuits
- High Current Rails: 3.3V @ 3A for power-hungry applications
- Battery Charging: Li-ion charging with USB-C PD
- Different Connectors: JST, Molex, Phoenix terminals
- Pin Headers: 2.54mm, 1.27mm spacing options
- Modular Stacking: Designed for vertical integration
- Cable Assemblies: Custom wire harnesses
- Board Size: 35 × 57.5 mm (compact form factor)
- Layer Count: 2 layers (Top/Bottom)
- PCB Thickness: 1.6 mm standard
- Ground Plane: Entire bottom layer dedicated as continuous ground plane
- Track Width: Standard KiCad defaults (adequate for <2A current levels)
- Via Size: Standard tenting vias (0.3mm minimum hole size)
- Soldermask: Red for high contrast and easy assembly/debugging
- Surface Finish: HASL with lead for excellent solderability
- Solid Ground Plane: Complete bottom layer ground plane provides:
- Low impedance return path for all signals
- EMI shielding and reduced electromagnetic interference
- Signal integrity protection by minimizing crosstalk and noise
- Thermal dissipation for heat-generating components
- Voltage reference stability for sensitive analog circuits
- 2-Layer Design: Top layer for components and signal routing, bottom layer as dedicated ground plane
- Via Stitching: Strategic ground vias connect top and bottom layers for optimal grounding
- Component Selection: All parts available from major distributors
- Hand Assembly: SMD components sized for manual soldering (0603 and larger)
- Silkscreen Labels: Clear component reference designators for easy identification
- Cost-Effective: 2-layer design optimized for low-cost fabrication
- Gerber Files: Ready for PCB fabrication
- Schematic: Complete electrical design and connections
- PCB Layout: Component placement with reference designators (J1, U1, etc.)
- Bill of Materials: Complete component list with part numbers
2-layer PCB layout showing component placement and routing with bottom ground plane
3D visualization of the PCB design showing component placement and board dimensions
| Component | Part Number | Quantity | Description |
|---|---|---|---|
| U1 | TPS2115ADRBT | 1 | Autoswitching Power Mux |
| U2 | LD1117V33 | 1 | 3.3V LDO Regulator |
| U3 | TVS0500DRVR | 1 | TVS Diode Protection |
| Component | Value | Package | Quantity |
|---|---|---|---|
| C1, C3, C5 | 10µF | 1206 | 3 |
| C2, C4, C6, C8 | 0.1µF | 0603 | 4 |
| C7 | 10µF Tantalum | 1411/3528-21 | 1 |
| R1, R2 | 120Ω | 0603 | 2 |
| R4 | 400Ω | 1206 | 1 |
| Component | Part Number | Quantity | Description |
|---|---|---|---|
| J1 | USB-A Female | 1 | Input Connector |
| J2 | USB-C Female | 1 | Input Connector |
| J3 | Pin Header 1x3 | 1 | GND Output |
| J4 | Pin Header 1x3 | 1 | 3.3V Output |
| J5 | Pin Header 1x3 | 1 | 5V Pin |
| D1, D2 | LED 0603 | 2 | Status Indicators |
Total estimated cost: $12-15 per unit in small quantities
- KiCad 7.0+: For viewing/modifying PCB design
- LTSpice: For circuit simulation
- PCB Manufacturer: JLCPCB, PCBWay, or equivalent
- Component Supplier: DigiKey, Mouser, or equivalent
modular-power-hub/
├── documentation/
│ └── datasheets/ # Component datasheets
├── hardware/
│ ├── schematic/ # KiCad schematic files
│ ├── pcb/ # PCB layout files
│ ├── libraries/ # Custom symbols and footprints
│ └── 3d-models/ # Component 3D models
├── manufacturing/
│ ├── gerbers/ # PCB fabrication files
│ └── bom/ # Bill of materials
├── simulation/
│ ├── ltspice/ # LTSpice simulation files
│ └── results/ # Simulation output data and details
├── LICENSE # MIT License
└── README.md # Project documentation
- Order PCBs: Upload Gerber files to your preferred manufacturer
- Source Components: Use provided BOM for component procurement
- Hand Assembly: Use PCB silkscreen labels (J1, U1, etc.) and schematic for component placement
- Testing: Use provided test procedures to verify functionality
- Integration: Connect to your project using standard interfaces
The board uses surface-mount components for compact design and professional finish. Assembly requires precision but is achievable with proper tools and technique.
- Hot air SMD rework station (temperature controlled)
- Soldering iron with fine tip (for touch-up and through-hole components)
- Solder paste (SAC305 or similar lead-free)
- Flux for improved flow and joint quality
- Tweezers (fine-tip, ESD-safe)
- Magnification (stereo microscope or magnifying glass)
- ESD protection (wrist strap, mat)
- Stencil Method (recommended): Use laser-cut stencil for precise paste application
- Manual Method: Apply small amounts of solder paste to component pads using syringe or fine brush
- Paste Thickness: ~0.1mm (4 mils) for optimal results
- Placement Order: Start with smallest components (0603 resistors/capacitors) first
- Alignment: Use tweezers to carefully position components on paste-covered pads
- Precision: Ensure proper orientation for polarized components (ICs, LEDs, electrolytic capacitors)
- Temperature Profile:
- Preheat: 150°C for 60-90 seconds
- Reflow: 230-245°C for 30-60 seconds
- Cool down naturally
- Airflow: Use low air velocity to prevent component displacement
- Visual Inspection: Watch for proper solder joint formation and component alignment
- Visual Inspection: Check all joints under magnification
- Electrical Testing: Verify continuity and proper component values
- Soldering Iron Touch-up: Fix any cold joints or bridged connections
- Flux Cleaning: Remove flux residue with isopropyl alcohol
- Practice First: If new to SMD soldering, practice on test boards
- Component Orientation: Double-check IC pin 1 marking and LED polarity
- Temperature Control: Use proper temperature profiles to avoid component damage
- Steady Hands: Take breaks to maintain precision during placement
- Documentation: Take photos during assembly for troubleshooting reference
- Visual Inspection: Check for proper component placement and solder joints
- Continuity Testing: Verify ground plane connectivity and power rail isolation
- Power-On Test: Apply 5V input and verify output voltages
- Load Testing: Test with representative loads to verify current capacity
- Switching Test: Verify proper input source switching functionality
- Additional Input Types: Support for even more input types simultaneously by either adding more TPS2115A OR using LTC4412 + PMOS
- Additional Output Options: Support for more output voltage options by adding buck/boost converters
This is a personal portfolio project showcasing hardware design skills. While not actively seeking contributions, I welcome:
- Technical feedback on design decisions and improvements
- Questions about the engineering process or implementation
- Discussion about alternative approaches or optimizations
Feel free to open issues for technical discussions or reach out directly!
This project is licensed under the MIT License - see the LICENSE file for details.
- Texas Instruments: For excellent power management ICs and documentation
- DigiKey: For easy components ordering and datasheet availability
- PCBWay: For amazing PCB board manufacturing
- KiCad Community: For the outstanding open-source EDA tools
- Project Link: https://github.com/NickJiEE/Modular-PowerHub
- Portfolio: https://nickjiee.github.io/
- Email: yji@ieee.org
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