A Practical Guide to Selecting the Right Bare Board Power Supply

The selection process begins with a clear and detailed specification of your electrical needs.

Input Voltage Range: Determine the source-is it a universal AC mains (85-264 VAC), a stable 48V telecom bus, or a fluctuating battery source (e.g., 9-36 VDC)? Ensure the selected module can handle your input range, including any anticipated transients or surges.

Output Power & Current: Calculate the total power required by your load. Critically, do not select a module that operates at its maximum rated power. Derate by at least 20-30% to ensure long-term reliability and better thermal performance. Analyze both continuous and peak current demands.

Efficiency: Efficiency is not just a number; it's a primary driver of thermal management. A module with 94% efficiency will generate significantly less heat than one at 88%, simplifying cooling and improving system longevity. Always examine the efficiency curve across your expected load range.

Output Voltage Ripple & Noise: For sensitive loads like FPGAs, analog sensors, or RF circuits, low output noise is critical. High ripple can compromise signal integrity. Check the datasheet for peak-to-peak ripple specifications and ensure they meet your system's noise immunity requirements.

The "bare board" design means you, the system integrator, are responsible for its physical and thermal environment.

Form Factor & Mounting: Precisely measure the available PCB area and height clearance. Verify the module's footprint, mounting hole locations, and the height of its tallest component. Ensure your design can accommodate it without interference.

Thermal Management: This is often the most critical challenge. How will heat be dissipated?

Conduction Cooling: The most common method. The module is secured to the system's chassis or a heatsink using thermal interface materials (TIMs). The datasheet's thermal derating curve is essential-it shows the maximum power the module can deliver at a given ambient temperature or baseplate temperature.

Forced Air Cooling: If using airflow, verify the required Linear Feet per Minute (LFM) or CFM to achieve the rated performance. A module requiring 400 LFM may not be suitable for a sealed, fanless enclosure.

Integrating a bare board shifts the burden of final product certification onto your shoulders.

Safety Standards (IEC/UL/EN 62368-1): While the bare board itself may not be fully certified, it must be designed to meet the required safety standards. You must verify that the PCB layout provides sufficient creepage and clearance distances for your input voltage level to pass the final product safety audit.

Electromagnetic Compatibility (EMC): Check if the module includes built-in input filtering to mitigate conducted emissions. If not, you will need to design an external filter on your main board to comply with standards like CISPR 32, adding complexity and cost.

Protection Features: A robust module should include:

Overcurrent Protection (OCP)

Overvoltage Protection (OVP)

Overtemperature Protection (OTP) - crucial as thermal conditions are system-dependent.

Control & Monitoring: Features like a Power Good signal, remote On/Off control, and digital interfaces (PMBus) for voltage/current/temperature monitoring are valuable for advanced system management.

The supplier's expertise and support are as important as the module's specifications.

Quality and Longevity: Choose a manufacturer with a proven track record of quality and reliability. Request metrics like Mean Time Between Failures (MTBF).

Documentation and Support: Comprehensive datasheets, application notes, and Gerber files are invaluable. Responsive technical support can resolve integration issues quickly.

Customization Capability: For high-volume projects or unique requirements, the ability to customize parameters like output voltage, PCB shape, or connector types can be a decisive advantage.