FAN6747WALMY: Green-Mode PWM Controller for Flyback Converter, 65KHz, 2 level OCP

The highly integrated FAN6747W PWM controller provides several features to enhance the performance of flyback converters. To minimize standby power consumption, a proprietary Green-Mode function provides off-time modulation to decrease the switching frequency with load condition.

Under zero-load condition, the power supply enters Burst Mode and burst frequency can be low to reduce power. Green Mode enables the power supply to meet international power conservation requirements.

The FAN6747W is specially designed for SMPS with peak-current output. It incorporates a cycle-by-cycle current limiting and two-level Over-Current-Protection (OCP) that can handle peak load with a debounce time. Once the current is over the threshold level, it triggers the first counter 15ms and checks if VDD is below 10V; if it is, the PWM latches off for SCP. If VDD is higher than 10V; it keeps counting to 215ms, then the PWM latches off for OCP.

FAN6747WA also integrates a frequency-hopping function that helps reduce EMI emission of a power supply with minimum line filters. The built-in synchronized slope compensation helps achieve stable peak-current control. To keep constant output power limit over the universal AC input range, the current limit is adjusted according to AC line voltage detected by the HV pin. The gate output is clamped at 14V to protect the external MOSFET from over-voltage damage.

Other protection functions include AC-line brownout protection with hysteresis and VDD over-voltage protection. For over-temperature protection, an external NTC thermistor is applied to sense the ambient temperature. When OCP, OVP, SCP, or OTP is activated, an internal circuit latches off the controller. The latch is reset when VDD drops to VDD-LH.