描述 Description

The NCP1240 is a new fixed?frequency current?mode controller featuring Dynamic Self?Supply. This function greatly simplifies the design of the auxiliary supply and the VCC capacitor by activating the internal startup current source to supply the controller during start-up, transients, latch, stand-by etc. This device contains a special HV detector which detects the application unplug from the ac input line and triggers the X2 discharge current. This HV structure allows the brown-out detection as well. It features a timer-based fault detection that ensures the detection of overload and an adjustable compensation to help keep the maximum power independent of the input voltage. Due to frequency foldback, the controller exhibits excellent efficiency in light load condition while still achieving very low standby power consumption. Internal frequency jittering, ramp compensation, and a versatile latch input make this controller an excellent candidate for the robust power supply designs. A dedicated Off mode allows to reach the extremely low no load input power consumption via “sleeping” whole device and thus minimize the power consumption of the control circuitry. The NCP1240 differentiates itself from the rest of the fixed frequency flyback controllers with active X2 discharge and HV start up by implementing a Dual-Level Overcurrent protection. For some applications (e.g. limited power supplies), it is necessary that the controller maintains regulation while it has detected a first level of overload. This is to authorize a transient peak power higher than the maximum continuous output power.
This product is IEC60950 compliant. Please see the test report and certification in the Conformance report section below.

特性 Features

? Frequency foldback and skip mode
? Optimized efficiency across the entire load range
? Timer-based overload protection with latched (A version) or auto-recovery (B version) operation
? Protection against overcurrent and short circuit
? High-voltage startup with dynamic self supply
? Simplifies the design of the auxiliary supply
? Integrated brown-out detection
? Protects against any drops in line voltage
? Frequency Modulation
? Softened EMI signature
? Adjustable overpower protection
? Automatically adjusts the current limit depending on the line input voltage (high line or low line)
? Timer based Dual-Level Overcurrent protection
? This is to authorize a transient peak power higher than the maximum continuous output power.

應(yīng)用 Application

? AC-DC Adapters
? Notebook Computers

簡(jiǎn)介

NCP1240屬于集成電路（IC）的ACDC轉(zhuǎn)換器離線開關(guān)。由制造生產(chǎn)的NCP1240AC DC 轉(zhuǎn)換器，離線開關(guān)該系列是元器件級(jí)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(shè)備。集成和未集成系統(tǒng)主要開關(guān)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(lái)實(shí)現(xiàn)此用途，但也有許多專門用于此用途的庫(kù)存產(chǎn)品，請(qǐng)參見(jiàn)“開關(guān)轉(zhuǎn)換器，SMPS 變壓器”標(biāo)題。