TDK-Lambda AC-DC Power Supplies

Open frame power supplies are bare PCB assemblies without an enclosure, offering the most compact size and lowest cost. They are ideal for integration into equipment with existing enclosures or where space is critical. Enclosed power supplies feature a metal or plastic case that provides protection against accidental contact, dust, and EMI. They are suitable for standalone applications or installations where the power supply is externally accessible. TDK-Lambda offers both types with identical electrical specifications, allowing you to choose based on your mechanical and safety requirements.

Select open frame for internal integration with space constraints, or enclosed for standalone or safety-critical applications.

To determine the required power rating, first calculate the total power consumption of your load by summing the power requirements of all components. Add a safety margin of 20-30% to account for inrush currents, peak loads, and component tolerances. Consider the operating environment - if the power supply will operate at high ambient temperatures, derating may be required. TDK-Lambda provides derating curves in their datasheets showing maximum output power versus ambient temperature. For example, a system requiring 200W continuous power with occasional 250W peaks should use at least a 300W rated power supply.

Calculate your load power requirements with 20-30% margin, then verify derating requirements for your operating temperature.

Power factor correction (PFC) is a feature that ensures the AC input current waveform closely follows the voltage waveform, minimizing harmonic distortion and maximizing real power transfer. Active PFC circuits achieve power factors of 0.95 or higher, compared to 0.6-0.7 for non-PFC supplies. Benefits include: Compliance with international harmonic regulations (IEC 61000-3-2)

Reduced input current for the same output power

Lower distribution losses

Ability to use smaller input fuses and circuit breakers. TDK-Lambda power supplies 75W and above typically include active PFC as standard.

For applications requiring compliance with harmonic regulations or operating from limited AC capacity, select TDK-Lambda models with active PFC.

Many TDK-Lambda AC-DC power supplies support parallel operation for increased power capacity or redundancy. There are two types of parallel operation: Passive parallel where units share current based on internal droop characteristics, suitable for N+1 redundancy

Active current sharing using external control signals for precise load balancing. Not all models support parallel operation - check the datasheet for 'Parallel Operation' or 'Current Sharing' specifications. When paralleling power supplies, ensure all units are from the same model series and have matched output voltage settings. External diodes may be required for true redundancy applications.

For parallel operation requirements, select TDK-Lambda models specifically designed for current sharing and follow the application notes for proper configuration.

TDK-Lambda AC-DC power supplies include comprehensive protection features to ensure safe operation and protect your equipment: Overvoltage protection (OVP) shuts down the output if voltage exceeds safe limits

Overcurrent protection (OCP) limits output current during overload conditions

Overtemperature protection (OTP) reduces output or shuts down if internal temperature is excessive

Short circuit protection safely handles output shorts without damage

Input undervoltage lockout prevents operation during brownout conditions. Many models also include remote on/off control, power good signals, and remote sense for voltage regulation at the load.

Review the protection features in the datasheet to ensure they meet your application safety requirements.