Cosel AC-DC Power Supply Selection Guide
This technical reference document provides detailed information about cosel product specifications, characteristics, and performance parameters. Use this information to support your design and analysis activities.
Electrical characteristics are specified over the operating temperature range unless otherwise noted. Parameters are guaranteed by design, testing, or statistical analysis. Typical values is the most likely parametric norm at 25°C.
Thermal characteristics require careful attention during system design. The junction-to-ambient thermal resistance depends on the mounting configuration, PCB copper area, and airflow conditions. Use thermal simulation tools to predict operating temperatures under actual conditions.
Reliability data is based on accelerated life testing and field failure analysis. Mean time between failures (MTBF) calculations follow industry-standard methodologies. Contact BeiLuo for detailed reliability reports and qualification data.
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Frequently Asked Questions
1. How much power headroom should I include?
Include 20-30% power headroom above your calculated maximum load. This provides margin for: Component variations and tolerances; Transient loads and startup currents; Future expansion and feature additions; Reliable operation below maximum stress. For critical applications or harsh environments, consider 50% headroom. Operating at lower load percentages improves reliability and extends operating life. Always check derating curves for high temperature operation.
2. What is the difference between peak and continuous power?
Continuous power is the maximum power the supply can deliver indefinitely under specified conditions. Peak power is a higher power level available for short durations (typically seconds to minutes). Peak power capability is useful for: Motor starting and acceleration; Capacitor charging; Pulsed loads; Transient conditions. Important considerations: Duty cycle must be within specified limits; Average power must not exceed continuous rating; Thermal management must handle peak dissipation; Some supplies may require minimum load after peak. Check datasheets for specific peak power ratings and timing.
3. How do I calculate inrush current?
Inrush current calculation considers: Input capacitance: Larger capacitors cause higher inrush; Input voltage: Higher voltage causes higher inrush; ESR: Lower ESR allows higher peak current; Temperature: Cold components may have higher inrush. Typical inrush currents: Small supplies (<50W): 10-30A peak; Medium supplies (50-300W): 30-100A peak; Large supplies (>300W): 50-200A peak. Mitigation methods: NTC thermistors (lower cold resistance); Active inrush limiting circuits; Sequential startup of multiple supplies; Circuit breakers with inrush tolerance. Contact our FAE team for inrush calculations for your specific application.
4. What cooling method should I use?
Cooling method selection depends on: Power level: Higher power requires more cooling; Enclosure: Sealed enclosures limit cooling options; Environment: Dust, moisture affect cooling choices; Noise: Fans add noise and maintenance; Reliability: Passive cooling is more reliable. Cooling options: Natural convection: Simple, reliable, limited to ~100W; Forced air: Higher power capability, adds noise and maintenance; Conduction: Heat sink or chassis mounting; Liquid cooling: Highest power density, complex. Always follow manufacturer thermal guidelines and verify with thermal testing. Contact our FAE team for thermal design assistance.
5. How do I ensure EMC compliance?
Ensuring EMC compliance involves: Input filtering: Use Cosel EMI filters or add external filtering; Layout: Minimize loop areas, separate noisy and sensitive traces; Grounding: Single point ground, avoid ground loops; Shielding: Enclosure and cable shielding as needed; Decoupling: Adequate output capacitors for load transients. Conducted emissions: Typically 150kHz - 30MHz; Use input filters meeting CISPR 32/EN 55032; Radiated emissions: Typically 30MHz - 1GHz; Proper enclosure and cable routing. Cosel provides EMC application notes and can recommend specific filters for your application. Contact our FAE team for EMC design review.
6. What safety certifications do I need?
Required safety certifications depend on: Application type: Medical, industrial, consumer, etc.; Target markets: US, Europe, Asia, etc.; End product standards: System-level certification requirements. Common certifications: IEC 62368-1: Audio/video and IT equipment (replaces 60950-1 and 60065); IEC 60601-1: Medical electrical equipment; IEC 61010-1: Laboratory and measurement equipment; EN 50155: Railway applications; UL/CSA: North American markets; CCC: China market. Cosel power supplies carry comprehensive certifications. Verify that specific models have required certifications for your application. Contact our certification team for documentation.