The NCP1207ADR2G is a PWM Current-Mode Controller for free running quasi-resonant operation. It combines a true current mode modulator and a demagnetization detector to ensure full borderline/critical conduction mode in any load/line conditions and minimum drain voltage switching (quasi-resonant operation). Due to its inherent skip cycle capability, the controller enters burst mode as soon as the power demand falls below a predetermined level. As this happens at low peak current, no audible noise can be heard. For the controller an internal 8ms timer prevents the free-run frequency to exceed 125kHz. For the controller the internal timer duration is reduced to 4.5ms to allow operation at higher frequencies. The dynamic self-supply (DSS) drastically simplifies the transformer design in avoiding the use of an auxiliary winding to supply the controller. Due to its high-voltage technology, the IC is directly connected to the high-voltage DC rail.
