N1308 1308 NCP1308 SOP-8

N1308 1308 NCP1308 SOP-8

NCP1308 Controller, Free Running Quasi-Resonant Current Mode 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 s 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 operation (e.g. battery chargers). Thanks to its high-voltage technology, the IC is directly connected to the high-voltage DC rail. As a result, the short-circuit trip point is not dependent upon any VCC auxiliary level. The transformer core reset detection is done through an auxiliary winding which, brought via a dedicated pin. If an OVP is detected on the VCC pin, the IC permanently latches off. Finally, the continuous feedback signal monitoring implemented with an Overcurrent fault Protection circuitry (OCP) makes the final design rugged and reliable.

Features •Free-Running Borderline/Critical Mode Quasi-Resonant Operation •Current-Mode with Adjustable Skip Cycle Capability •Dynamic Self-Supply Type of VCC •Auto-Recovery Overcurrent Protection •Improved UVLO for VCC below 10 V •Latching Overvoltage Protection on VCC •500 mA Peak Current Source/Sink Capability •Internal 1.0 ms Soft-Start •Internal 10 s Minimum TOFF •Adjustable Skip Level •Internal Temperature Shutdown •Internal Leading Edge Blanking •Direct Optocoupler Connection •SPICE Models Available for TRANsient Analysis •This is a Pb-Free Device Typical Applications •AC-DC Adapters for Notebooks, etc. •Offline Battery Chargers •Consumer Electronics (DVD Players, Set-Top Boxes, TVs, etc.) •Auxiliary Power Supplies (USB, Appliances, TVs, etc.)