描述 Description

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 10us timer prevents the free-run frequency to exceed a high frequency (therefore below the 150kHz 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 has been detected on the Vcc pin, the IC permanently latches-off.Finally, the continuous feedback signal monitoring implemented with an over-current fault protection circuitry (OCP) makes the final design rugged and reliable.

特性 Features

FreeRunning Borderline/Critical Mode QuasiResonant Operation
CurrentMode with Adjustable Skip Cycle Capability
Dynamic SelfSupply Type of VCC
AutoRecovery Overcurrent Protection
Improved UVLO for VCC below 10 VDevice Package Shipping
Latching Overvoltage Protection on VCC
500 mA Peak Current Source/Sink Capability
Internal 1.0 ms SoftStart
Internal 10 us Minimum TOFF
Adjustable Skip Level
Internal Temperature Shutdown
Internal Leading Edge Blanking
Direct Optocoupler Connection
SPICE Models Available for TRANsient Analysis
This is a PbFree Device

應用 Application

ACDC Adapters for Notebooks, etc.Offline Battery ChargersConsumer Electronics (DVD Players, SetTop Boxes, TVs, etc.)Auxiliary Power Supplies (USB, Appliances, TVs, etc.)

簡介

NCP1308屬于集成電路（IC）的ACDC轉(zhuǎn)換器離線開關。由制造生產(chǎn)的NCP1308AC DC 轉(zhuǎn)換器，離線開關該系列是元器件級控制產(chǎn)品，用于構(gòu)建將交流市電轉(zhuǎn)換為直流電（通常電壓大幅降低）的設備。集成和未集成系統(tǒng)主要開關元件的器件均包括在內(nèi)。由于高輸入輸出電壓比，以及此類系統(tǒng)中通常需要隔離，這些器件通常與外部變壓器配合使用。盡管通常使用定制變壓器來實現(xiàn)此用途，但也有許多專門用于此用途的庫存產(chǎn)品，請參見“開關轉(zhuǎn)換器，SMPS 變壓器”標題。