描述 Description

Features:
? OPTIMIZED FOR OFF-LINE CONTROL
? LOW START-UP CURRENT (<1mA)
? AUTOMATIC FEED FORWARD COMPENSATION
? TRIMMED OSCILLATOR DISCHARGE CURRENT
? PULSE-BY-PULSE CURRENT LIMITING
? ENHANCED LOAD RESPONSE CHARACTERISTICS
? HYSTERESIS (SG1844 only)
? DOUBLE PULSE SUPPRESSION
? HIGH-CURRENT TOTEM-POLE OUTPUT
? INTERNALLY TRIMMED BANDGAP REFERENCE
? 500kHz OPERATION
? UNDERVOLTAGE LOCKOUT SG1844 - 16 volts SG1845 - 8.4 volts
? LOW SHOOT-THROUGH CURRENT <75mA OVER TEMPERATURE The SG1844/45 family of control ICs provides all the necessary features to implement off-line fixed frequency, current-mode switching power supplies with a minimum number of external components. Current-mode architecture demonstrates improved line regulation, improved load regulation, pulse-by-pulse current limiting and inherent protection of the power supply output switch. The bandgap reference is trimmed to ±1% over temperature. Oscillator discharge current is trimmed to less than ±10%. The SG1844/45 has under-voltage lockout, current-limiting circuitry and start-up current of less than 1mA. The totem-pole output is optimized to drive the gate of a power MOSFET. The output is low in the off state to provide direct interface to an N-channel device. Both operate up to a maximum duty cycle range of zero to <50% due to an internal toggle flip-flop which blanks the output off every other clock cycle. The SG1844/45 is specified for operation over the full military ambient temperature range of -55°C to 125°C. The SG2844/45 is specified for the industrial range of -25°C to 85°C, and the SG3844/45 is designed for the commercial range of 0°C to 70°C.

簡介

SG1844Y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SG1844YAC DC 轉(zhuǎn)換器，離線開關(guān)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(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(guān)轉(zhuǎn)換器，SMPS 變壓器”標(biāo)題。