描述 Description

The NCP1338 combines a true current mode modulator and a demagnetization detector which ensures full Borderline/Critical Conduction Mode in any load/line conditions together with minimum drain voltage switching (Quasi-Resonant operation). The transformer core reset detection is done internally, without using any external signal, due to the Soxyless concept. The frequency is internally limited to 130 kHz, preventing the controller from operating above the 150 kHz CISPR-22 EMI starting limit.By monitoring the feedback pin activity, the controller enters skip mode as soon as the power demand falls below a predetermined level. As each restart is softened by an internal Soft-Skip?, and as the frequency cannot go below 25 kHz, no audible noise can be heard.The NCP1338 also features an efficient protective circuitry which, in presence of an overcurrent condition, disables the output pulses and enters a safe burst mode, trying to restart. Once the default has gone, the device auto-recovers. Also included is a bulk voltage monitoring function (known as brown-out protection), an adjustable overpower compensation, and a VCC OVP. The Fault Timer is reset by any of these conditions, to ensure that the controller immediately restarts when the condition disappear. Finally, an internal 4.0 ms Soft-Start eliminates the traditional startup stress. NCP1338 can be used in applications where the VCC supply voltage is delivered by an external dc voltage source.NCP1338 vs NCP1337:When a BO condition is applied, both controllers stop. When the BO condition is removed, NCP1337 doesn't restart if the fault timer has timed out; whereas NCP1338 always restarts (if Vcc is higher than 12 V).

特性 Features

? Overvoltage Protection
? rugged design
? Internal Leading Edge Blanking
? Noise immunity
? Free-Running Borderline/Critical Mode Quasi-Resonant Operation
? Reduces EMI and capacitive losses
? Soft-Skip Mode with Minimum Switching Frequency for Standby
? reduces noise and increases efficiency in stand-by mode
? Current-Mode
? Auto-Recovery Short-Circuit Protection Independent of Auxiliary Voltage
? Brown-Out Protection
? Two Externally Triggerable Fault Comparators (one for a disable function, and the other for a permanent latch)
? Internal 4.0 ms Soft-Start
? 500 mA Peak Current Drive Sink Capability
? 130 kHz Max Frequency
? Internal Temperature Shutdown
? Direct Optocoupler Connection
? Dynamic Self-Supply with Levels of 12 V (On) and 10 V (Off)
? SPICE Models Available for TRANsient and AC Analysis
? Pb-Free Device

應用 Application

? Ac-dc Adapters for Notebooks, etc.
? Offline Battery Chargers
? Auxiliary Power Supplies (USB, Appliances, TVs, etc.)
? Consumer Electronics (DVD Players, Set-Top Boxes, TVs, etc.)

簡介

NCP1338屬于集成電路（IC）的ACDC轉換器離線開關。由制造生產(chǎn)的NCP1338AC DC 轉換器，離線開關該系列是元器件級控制產(chǎn)品，用于構建將交流市電轉換為直流電（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。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“開關轉換器，SMPS 變壓器”標題。