DESCRIPTION
The SG6961 is an 8-pin boundary mode PFC controller IC intended for controlling PFC pre-regulators. The SG6961 provides a controlled on-time to regulate the output DC voltage and achieve natural power factor correction. The maximum on-time of the external switch is programmable to ensure safe operation during AC brownouts. An innovative multi-vector error amplifier is built in to provide rapid transient response and precise output voltage clamping. A built-in circuit disables the controller if the output feedback loop is opened. The start-up current is lower than 20µA and the operating current is under 4.5mA. The supply voltage can be up to 20V, maximizing application flexibility.

FEATURES
■ Boundary Mode PFC Controller
■ Low Input Current THD
■ Controlled On-Time PWM
■ Zero-Current Detection
■ Cycle-by-Cycle Current Limiting
■ Leading-Edge Blanking Instead of RC Filtering
■ Low Start-up Current (10µA Typical)
■ Low Operating Current (4.5mA Typical)
■ Feedback Open-Loop Protection
■ Programmable Maximum On-Time (MOT)
■ Output Over-Voltage Clamping Protection
■ Clamped Gate Output Voltage 16.5V

APPLICATIONS
■ Electric Lamp Ballasts
■ AC-DC Switching Mode Power Converter
■ Open-Frame Power Supplies and Power Adapters
■ Flyback Power Converters with ZCS/ZVS