描述 Description

The NCP1239 is a fixed-frequency current-mode controller featuring the 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.
With a supply range up to 35 V, the controller hosts a jittered 65 or 100-kHz switching circuitry operated in peak current mode control. When the power on the secondary side starts to decrease, the controller automatically folds back its switching frequency down to minimum level of 26 kHz. As the power further goes down, the part enters skip cycle while limiting the peak current that insures excellent efficiency in light load condition.
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.

特性 Features

? Fixed-frequency 65-kHz or 100-kHz current-mode control operation
? Fixed-frequency is simple to implement and predictable in term of EMI
? Frequency foldback down to 26 kHz and skip mode
? Maximize performance in light load conditions
? Adjustable Over Power Protection (OPP) circuit
? OPP can be adjusted to the need of specific applications
? High-voltage Current Source with Brown-out (BO) detection
? BO monitor and detect a falling input voltage, needed in some applications
? Internal fixed 8-ms soft-start
? Simplified implementation that does not require programming
? Frequency jittering in normal and frequency foldback modes
? Lowers switching frequency EMI
? 64-ms timer-based short-circuit protection with auto-recovery or latched operation
? Allows for safe operation while tolerant to faults if needed
? Pre-short ready
? Safe operation yet tolerant to faults
? Latched OVP on Vcc (NCP1239 A & B versions)
? Safe operation
? Latched OVP/OTP input for improved robustness
? Safe operation
? +500 mA/ -500 mA peak source/sink drive capability
? Can drive larger FETs
? Internal thermal shutdown
? Safe operation
? Extremely low no-load standby power
? Ideal for environmentally friendly applications
? Pin-to-pin compatible with the existing NCP1236/1247 series
? Enable cost saving compared to other device
? Internal ramp compensation
? 35-V Vcc operation

應(yīng)用 Application

? Ac-dc converters for TVs, set-top boxes and printers
? Offline adapters for notebooks and netbooks

簡(jiǎn)介

NCP1239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NCP1239AC 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“開關(guān)轉(zhuǎn)換器，SMPS 變壓器”標(biāo)題。