LX1554屬于集成電路（IC）的ACDC轉換器離線開關。由美高森美半導體公司制造生產(chǎn)的LX1554AC 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。

DESCRIPTION

The LX155X family of ultra-low start-up current (250μA max.), current mode control ICs offer new levels of energy efficiency for offline converter applications. They are ideally optimized for personal computer and CRT power supplies although they can be used in any number of off-line applications where energy efficiency is critical. Coupled with the fact that the LX155X series requires a minimal set of external components, the series offers an excellent value for cost conscious consumer applications.

Optimizing energy efficiency, the LX155X series demonstrates a significant power reduction as compared with other similar off-line controllers. Table 1 compares the SG384X, UC384XA and the LX155X start-up resistor power dissipation. The LX155X offers an overall 4X reduction in power dissipation. Additionally, the precise oscillator discharge current gives the power supply designer considerable flexibility in optimizing system duty cycle consistency.

KEY FEATURES

■ ULTRA-LOW START-UP CURRENT (150μA typ.)

■ TRIMMED OSCILLATOR DISCHARGE CURRENT (±2 typ.)

■ INITIAL OSCILLATOR FREQUENCY BETTER THAN ±4

■ OUTPUT PULLDOWN DURING UVLO

■ PRECISION 2.5V REFERENCE (±2 max.)

□ CURRENT SENSE DELAY TO OUTPUT (150ns typ.)

□ AUTOMATIC FEED FORWARD COMPENSATION

□ PULSE-BY-PULSE CURRENT LIMITING

□ ENHANCED LOAD RESPONSE CHARACTERISTICS

□ UNDER-VOLTAGE LOCKOUT WITH HYSTERESIS

□ DOUBLE PULSE SUPPRESSION

□ HIGH CURRENT TOTEM POLE OUTPUT (±1Amp peak)

□ 500kHz OPERATION

APPLICATIONS

■ ECONOMY OFF-LINE FLYBACK OR FORWARD CONVERTERS

■ DC-DC BUCK OR BOOST CONVERTERS

■ LOW COST DC MOTOR CONTROL