Diodes' AP3301 is a peak-current control quasi-resonant (QR) PWM controller optimized for high performance, low standby power, and cost-effective offline flyback power supplies.

The AP3301 has multiple modes of operation to minimize power losses dependent on loads.

• Fixed frequency CCM PWM: With heavy or increasing output loads, the AP3301 operates in continuous conduction mode (CCM) with a fixed switching frequency of 62 kHz; this optimizes power conversion efficiency.
• QR mode: at medium loads, AP3301 enters valley lock QR mode with frequency fold-back to improve system efficiency and EMI performance. The maximum switching frequency (about 120 kHz) is set to clamp the QR frequency to improve efficiency.
• Burst mode: at no- or light-load, AP3301 enters burst mode to minimize standby power consumption. The minimum switching frequency (about 20 kHz) is set to avoid audible noise.

The AP3301 includes comprehensive protection features such as cycle-by-cycle current limit (OCP), V_CC overvoltage protection (VOVP), internal overtemperature protection (OTP), and overload protection (OLP). AP3301 has additional output overvoltage protection (SOVP) and brownout protection (BNO) to enhance system reliability.

Features

• Multiple modes of operation: 62 kHz CCM PWM mode, QR-mode, and burst mode
  • Optimizes efficiency across all load levels
• Active frequency dithering in 62 kHz CCM PWM and QR modes
  • Reduces EMI emission
• Adjustable OCP line compensation
  • Making OCP balance more flexible
• Output overvoltage protection (SOVP)
  • Precise output OVP protection which improves the OVP performance
• Overcurrent protection, V_CC overvoltage protection, internal overtemperature, and overload protection
  • Increases system reliability and robustness
• AC input brownout protection (BNO)
  • BNO protects the system from damage due to ultra-low line condition

Applications

• Switching AC-DC adapters
• ATX / BTX auxiliary power
• Set-top box (STB) power supplies
• Open-frame switching power supplies