onsemi ECH8660-TL-H: Key Features and Application Design Considerations
The onsemi ECH8660-TL-H is a highly integrated power IC designed to serve as the core of offline switch-mode power supplies (SMPS). It combines an 800 V avalanche-rugged power MOSFET with a low-power PWM controller in a single package, significantly simplifying the design of high-voltage converters. This device is particularly tailored for high-performance, high-reliability applications requiring robust operation and high efficiency.
Key Features
A primary advantage of the ECH8660-TL-H is its monolithic integration, which reduces external component count, minimizes board space, and enhances overall system reliability. The integrated 800 V MOSFET is engineered with avalanche ruggedness, ensuring it can withstand high-voltage transients commonly encountered in AC/DC line voltages, thereby improving system durability.
The IC incorporates a current-mode PWM controller that provides excellent line and load regulation. This control scheme simplifies feedback loop compensation and offers inherent cycle-by-cycle current limiting, which is crucial for protecting the power supply under overload or short-circuit conditions. Furthermore, the device features a built-in fixed-frequency oscillator with jittering to minimize electromagnetic interference (EMI), easing compliance with stringent regulatory standards.
Additional features include comprehensive protection functions such as over-voltage protection (OVP), over-load protection (OLP), and an internal thermal shutdown mechanism. These safeguards ensure the system operates within its safe operating area (SOA), dramatically enhancing the long-term robustness of the end application. The device also supports low standby power operation, making it suitable for applications needing to meet modern energy efficiency standards.
Application Design Considerations
When designing with the ECH8660-TL-H, several critical factors must be addressed to optimize performance.
1. Transformer Design: The transformer is a pivotal component. Accurate calculation of the primary inductance, turns ratio, and saturation current is essential for achieving the desired output power and efficiency. Proper gaping of the transformer core is necessary to store the right amount of energy and prevent saturation, especially under low-line input voltage conditions.
2. Feedback Loop Stability: Although the current-mode control simplifies compensation, the feedback network must be carefully designed. Selecting the correct optocoupler and compensating the network around the TL431 reference ensures stable operation across all line and load conditions, preventing oscillations and ensuring fast transient response.
3. Thermal Management: Despite high integration, effective heat dissipation is critical for maximizing power delivery and reliability. Ensuring adequate copper area on the PCB for the DIP-7 package and providing sufficient ventilation prevents the internal thermal shutdown from activating during normal operation.
4. EMI Mitigation: While the IC's frequency jitter helps, good layout practices are paramount. This includes keeping the high-current, high-voltage switching loops as small as possible, using proper grounding techniques, and strategically placing filter components to suppress conducted and radiated emissions.
This IC is ideally suited for a wide range of applications, including auxiliary power supplies (AUX) for industrial systems, home appliances, consumer electronics, and LED lighting drivers.
The onsemi ECH8660-TL-H stands out as a robust, highly integrated solution for offline power supplies. Its combination of an 800 V rugged MOSFET, comprehensive protection features, and a low-power controller makes it an excellent choice for designers seeking to create compact, reliable, and efficient power conversion systems with a reduced component count.
Keywords: Integrated Power IC, 800 V MOSFET, Current-Mode PWM, Offline SMPS, Avalanche Ruggedness
