• DCM+QR Combined Operating Mode
• Programmable Gate Driver Current
• Switching Frequency Range: 25kHz–500kHz
• Automatic Valley Lockout from 1 to 6 cycles
• Accurate Output OCP
• Adaptive OCP (Limited Power Source)
• Low Frequency Burst Operation (1kHz)
• Switching Frequency Modulation to Reduce EMI Noise
• Internal Soft-Start  Integrated 700V HV Startup
• Brown-In/Brown-Out Protections
• X Capacitor Discharge Protection (Optional)
• Programmable Output OVP and UVP
• Current Sense Resistor Short Protection
• Internal and External OTP
• Compact Package: SSOP9

The SQ33020 is a high frequency quasi-resonant (QR) flyback controller designed for power delivery (PD) adaptors and quick battery chargers. It can deliver 240W output power with 25kHz–500kHz switching frequency. The SQ33020 operates using peak current control. It provides a QR mode in which the MOSFET can be turned on at a valley point to reduce switching loss, especially under high input voltages.

In conventional QR flyback solutions, the valley number always varies between 1 and 2 or between 3 and 5, which increases VO ripple and creates audible noise. The SQ33020 uses a proprietary circuit to lock the valley number between 1 and 6, which provides more stability than conventional QR solutions.

If load decreases, the SQ33020 will enter discontinuous conduction mode (DCM) to reduce the switching frequency for higher efficiency. Under very light loads, the SQ33020 enters burst mode to reduce power loss.

The SQ33020 provides multiple mechanisms to ensure reliable operation: HV startup, X capacitor discharge, brown-out protection, output and VCC overvoltage protection (OVP), output undervoltage protection (UVP), internal and external overtemperature protection (OTP), and open-loop protection (OLP).

For higher efficiency, use the SQ33239 as a secondary side synchronous rectifier controller in conjunction with the SQ33020 to achieve zero voltage switching (ZVS).

The SQ33020 is available in an SSOP9 package.