The energy efficiency of refrigerators has improved over the decades. If you replace an aging beer refrigerator in your garage with the latest model, you can save as much on your electricity bill as one free beer a day! However, the recent trend towards increased functionality and connection features has created new challenges for design engineers to design refrigerator power supplies that provide high output current while maintaining high efficiency during full load and light load periods.
The DER-868 is a good reference design for this application scenario. Designed using Powigan-based InnoSwitch3-EP flyback switch IC, the 60W refrigerator power supply can provide 5A output current with constant power efficiency for refrigerators equipped with DC motors, ice makers and LED touch screens. In a conventional flyback power supply, efficiency decreases significantly under light load.
This is a problem for any refrigerator, which spends most of its time on light load. The InnoSwitch3-EP device maintains high efficiency over the entire load range. For example, the DER-868 has an efficiency of 93% at full load at 115VAC input and 90.41% at 10% load. In contrast, the CoC v5 Tier 2 standard only requires an efficiency of 79% for a 60W power supply at 10% load. DER-868 demonstrates how the InnoSwitch3-EP design easily meets global efficiency requirements.
Smaller power supplies with fewer components are easier to produce, and the fewer components, the lower the repair rate. The DER-868 requires only 45 components and the InnoSwitch3-EP IC's 750V PowiGaN switch achieves lower on-off and on-off losses, eliminates the need for metal fins and reduces the associated effects of vibration. Powigan-based devices are also extremely reliable and durable, protecting the system from voltage spikes even during longer-lasting input surges and quickly recovering after the surge is over.
