feature

Boundary Mode PFC Controller Low Input Current THD Time PWM Control No Current Detection Cycle-by-Cycle Current Limit Leading Edge Blanking Instead of RC Filtering Low Startup Current: 10kV Typical Low Operating Current: Typical 4.5mA Feedback MOT) output over voltage clamp protection clamp gate output voltage: 16.5V

application

General LED Lighting Industrial, Commercial and Residential Facilities Outdoor Lighting: Street, Road, Parking Lot, Architectural and Decorative LED Lighting

illustrate

FL6961 is a general-purpose lighting power controller. Apply coefficient correction for low to high power lumens requiring power. It is a boundary-mode converter designed for flyback or boost. The FL6961 provides a controlled on-time to adjust. Output DC voltage to achieve natural power factor. Correction (pfc). An external maximum on-time switch is programmable to ensure the AC Bronos. A novel multi-vector error amplifier provides fast transient response and accurate output voltage clamping. Built-in circuitry disables the controller. If the output feedback loop is open. The startup current is less than 20 microamps, and the working current is less than 6 mA. Supply voltages up to 25V maximize application flexibility.

Functional Description: Error Amplifier Inverting Input of Error Amplifier Reference Error Amplifier Output Reference Inc. Non-inverting input is internally connected to a fixed 2.5V±2% voltage. The wrong output amplifier is used to determine the on-time of the PWM. output and regulate the output voltage. Achieving low input current THD, the change in on-time should be very small over one input AC cycle. Built-in multiple vector error amplifiers for fast transients. responsive and accurate output voltage clamping. Connecting a capacitor (eg 1µf) to comp and gnd is recommended. The error amplifier converts the voltage to a 125 μmho current. Start-up Current Typical start-up current is less than 20µA. Start-up current allows the use of high-resistance, low-wattage start-up resistors. For example, a 1MΩ/0.25W start-up resistor and 10µF/25V (VCC hold) capacitor is recommended to use an AC to DC power adapter with a wide input range of 85-265 volts AC. Working current The working current is usually 4.5mA. Low operating current improves efficiency and reduces voltage-controlled capacitor requirements. Maximum on-time operation Given a fixed inductor value and maximum output power, on-time vs. line voltage is 2 2 RMS O on VLPT (1) If the line voltage is too low or the inductance value is too high, t is too long. To avoid ultra-low operating frequency and reach the maximum value of power failure protection t is programmable with a resistor, ri, connecting mot and gnd. The 24kΩ resistor RI generates a maximum on-time range of 10 to 50 μs corresponding to a maximum time of 25 μs. The peak current-limit switch current is sensed by a resistor. Signal input to CS pin and comparator. A high voltage on the CS pin terminates the immediate switching cycle and switches cycle-by-cycle up to the current limit. The design threshold protection point is 0.82V. Leading Edge Blanking (LEB) A power-on spike occurs on the CS pin when the power is turned on. The MOSFET is turned on. The current limit comparator is disabled for approximately 400 ns at the start of each switching pulse to avoid premature termination. This is in the blank period. Traditional rc filtering is not necessary, so current limit propagation delay protection can be minimized. Under-voltage lockout (UVLO) turn-on and turn-off threshold voltages are fixed internally at 12V and 9.5V, respectively. This hysteretic behavior guarantees a one-time activation of the start-up resistor and hold-up capacitor.

Ultra-low start-up current of 20µA, 1MΩ is sufficient for start-up at low input line voltage, 85 VRMS. The power dissipation on rin is less than 0.1w, even in high voltage line (Vac=265Vrms) condition. The output driver has low on-resistance and high current drive capability, and the output driver can drive external capacitive loads greater than 3000pf. Cross conduction reduces heat dissipation, avoids current flow, and improves efficiency and reliability. This output driver is internally clamped to a 16.5V Zener diode. Zero Current Detection (ZCD) implements zero current detection of an inductor using its auxiliary winding. When the stored energy inductor fully discharges the output, the voltage turns on the ZCD off and enables a new switching cycle after the ZCD triggers. The power mosfet always turns on with zero inductor current and the losses and noise can be minimized. The converter operates in boundary mode and the peak inductor current is always exactly twice the average current. Force of Nature utilizes low bandwidth, just-in-time modulation for factor correction. The inherent maximum shutdown time is established to ensure proper startup operation. This zcd pin can be used as a sync input. Noise Immunity Noise on current induced or control signals can cause significant pulse width jitter, especially in boundary modes. Slope compensation and built-in noise cancellation can alleviate this problem. Because the FL6961 has a ground pin, the output has a high sink current that cannot be pulled back alone. Good HF or RF layout practices should be followed. Avoiding long PCB traces and component leads, positioning compensation and filtering components close to the fl6961, and increasing the power mosfet gate resistance can all improve performance.