The SG6515DZ is a quasi-resonant (QR) current-mode PWM controller from Fairchild Semiconductor (now ON Semiconductor). It is designed for high-performance offline flyback converters. This controller optimizes performance and minimizes power consumption in adapter applications.

Applications

• AC/DC adapters for laptops and notebooks
• Power supplies for LCD TVs and monitors
• Offline power supplies for set-top boxes
• Auxiliary power supplies
• Battery chargers

Features

• Quasi-Resonant (QR) operation for high efficiency and low EMI
• Valley switching operation
• Low startup current
• Built-in soft-start function
• Frequency hopping to reduce EMI
• Over-voltage protection (OVP)
• Over-temperature protection (OTP)
• Overload protection (OLP)
• Short-circuit protection (SCP)
• Adjustable switching frequency
• Leading-edge blanking

Benefits

• High efficiency reduces power loss and heat dissipation
• Low EMI simplifies system design and reduces compliance costs
• Comprehensive protection features enhance system reliability
• Reduced component count lowers BOM cost
• Improved light-load efficiency

Additional Details

The SG6515DZ utilizes valley switching operation to minimize switching losses and improve efficiency. The QR operation also contributes to reduced EMI emissions, simplifying compliance with regulatory standards. The built-in soft-start function minimizes stress on power components during startup. The frequency hopping feature further reduces EMI by spreading the energy over a wider frequency range. The comprehensive protection features, including OVP, OTP, OLP, and SCP, ensure robust system protection. The adjustable switching frequency allows for optimization of the power supply design. The device has a low startup current, which improves efficiency. The SG6515DZ offers excellent performance and reliability in a compact package. It is commonly used in applications where high efficiency, low EMI, and robust protection are critical requirements. Designers should carefully consider thermal management to ensure reliable operation. Detailed application notes and design guides are available from ON Semiconductor.