NCP1308

NCP1308 PWM Current-Mode Controller for Free-Running Quasi-Resonant Operation The NCP1308 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. An internal 10 ms timer prevents the free-run frequency to exceed a high frequency (therefore below the 150 kHz CISPR-22 EMI starting limit), while the skip adjustment capability lets the user select the frequency at which the burst foldback takes place. The Dynamic Self-Supply (DSS) drastically simplifies the transformer design in avoiding the use of an auxiliary winding to supply the NCP1308. This feature is particularly useful in applications where the output voltage varies during ...