FL6300A: Quasi-Resonant Current Mode PWM Controller for Lighting

The FL6300A lighting power controller includes a highly integrated PWM controller and provides several features to enhance the performance of flyback converters in medium- to high-power lumens applications.

The FL6300A is applied on quasi-resonant flyback converters, where maximum operating frequency is limited to below 100 kHz. A built-in HV startup circuit can provide more startup current to reduce the startup time of the controller. Once the VDD voltage exceeds the turn-on threshold voltage, the HV startup function is disabled to reduce power consumption. An internal valley voltage detector ensures that the power system operates at quasi-resonant operation over a wide-range of line voltage and load conditions, as well as reducing switching loss to minimize switching voltage on the drain of the power MOSFET.

To minimize standby power consumption and improve light-load efficiency, a proprietary Green-Mode function provides off-time modulation to decrease switching frequency and perform extended valley voltage switching to keep to a minimum switching pulse. The operating frequency is limited by minimum tOFF time, which is 38 µs to 8 µs.

FL6300A also provides many protection functions. Pulse-by-pulse current limiting ensures the fixed-peak current-limit level, even when a short circuit occurs. Once an open-circuit failure occurs in the feedback loop, the internal protection circuit disables PWM output immediately. When VDD drops below the turn-off threshold voltage, the controller disables PWM output. The gate output is clamped at 18 V to protect the power MOSFET from high gate-source voltage conditions. The minimum tOFF time limit prevents the system frequency from being too high. When over-voltage protection (OVP) is triggered by DET or when internal over-temperature protection (OTP) is triggered, the power system enters Latch Mode until AC power is removed.

Features

• High-Voltage Startup
• Quasi-Resonant Operation
• Cycle-by-Cycle Current Limiting
• Peak-Current-Mode Control
• Leading-Edge Blanking (LEB)
• Internal Minimumt t_OFF
• Internal 5ms Soft-Start
• Over-Power Compensation
• GATE Output Maximum Voltage
• Auto-Recovery Over-Current Protection (FB Pin)
• Auto-Recovery Open-Loop Protection (FB Pin)
• Latch Protection VDD Pin and Output Voltage (DET Pin) OVP
• Frequency Operation Below 100 kHz

Application Notes