High-Efficiency Power Adapter Solution

The STR-A6069H + STR-SR3010 solution can achieve up to 90-91% efficiency at full load for 5V output applications. The actual efficiency depends on transformer design, synchronous MOSFET selection, and operating conditions. At 115VAC input, efficiency is typically 89-90%. At 230VAC input, efficiency can reach 90-91% due to lower primary current. Light load efficiency is also excellent due to frequency foldback and burst mode operation. The synchronous rectifier contributes 3-5% efficiency improvement compared to diode rectification.

Expect 89-91% efficiency depending on input voltage and design optimization. Contact us for efficiency optimization guidance.

Transformer selection involves several parameters: Core size (EE16 for up to 30W), turns ratio (based on input/output voltages), primary inductance (calculated for desired switching frequency), and winding construction (for low leakage inductance and good coupling). The turns ratio is typically 15-20:1 for 5V output from universal input. Primary inductance of 1-2mH is typical for 65kHz operation. Work with transformer suppliers who can provide designs optimized for your specific requirements. Starrystone Tech can recommend qualified suppliers.

EE16 core for up to 30W. Work with qualified suppliers. Contact us for recommendations.

EMI design considerations include: Input filter design with common mode choke and X/Y capacitors

Proper PCB layout with minimized switching loops

Snubber circuits across primary MOSFET and secondary rectifier

Shielding techniques if needed

and Grounding design to reduce common mode noise. The quasi-resonant operation of STR-A6069H inherently reduces EMI compared to fixed-frequency PWM. Conducted EMI testing should be performed early to identify any issues before finalizing the design.

Design EMI filter from the start. Test early to identify issues. We can provide EMI design guidance.

Thermal optimization involves: Selecting low-loss components (especially synchronous MOSFET)

Designing adequate copper area for heat spreading

Using thermal vias to inner layers

Positioning heat-generating components for airflow

and Considering enclosure design for heat dissipation. The synchronous rectifier MOSFET typically generates the most heat - select a device with low RDS(on) and adequate package thermal capability. Test under worst-case conditions (maximum load, highest ambient temperature) to verify thermal performance.

Focus on synchronous MOSFET selection and PCB thermal design. Test under worst-case conditions.

Power adapters typically require multiple safety certifications: UL 60950-1 or UL 62368-1 for USA, CE marking with EN 60950-1 or EN 62368-1 for Europe, CCC for China, and PSE for Japan. Energy efficiency certifications include DoE Level VI for USA and CoC Tier 2 for Europe. The design should incorporate appropriate creepage and clearance distances, isolation barriers, and protection against electric shock. Starrystone Tech reference designs incorporate safety considerations, but final certification is the manufacturer's responsibility.

Plan for required certifications early. Engage with testing labs during development. We can provide guidance.

Yes, the solution can be adapted for different output voltages (typically 5V to 24V). Modifications include: Adjusting transformer turns ratio for the new output voltage

Selecting appropriate synchronous rectifier MOSFET voltage rating

Updating feedback resistor divider for voltage regulation

Adjusting output capacitor voltage rating

and Potentially modifying snubber circuits. Higher output voltages may require different transformer core sizes. Our FAE team can provide guidance for specific voltage modifications.

Solution can be adapted for 5V-24V outputs. Contact us for specific voltage modifications.