描述 Description

The L4981 I.C. provides the necessary features to achieve a very high power factor up to 0.99.

Realized in BCD 60II technology this power factor corrector (PFC) pre-regulator contains all the control functions for designing a high efficiency-mode power supply with sinusoidal line current consumption.

The L4981 can be easily used in systems with mains voltages between 85V to 265V without anyline switch. This new PFC offers the possibility to work at fixed frequency (L4981A) or modulated frequency (L4981B) optimizing the size of the input filter; both the operating frequency modes working with an average current mode PWM controller, maintaining sinusoidal line current without slope compensation.

Besides power MOSFET gate driver, precise voltage reference (externally available), error amplifier, under voltage lockout, current sense and the soft start are included. To limit the number of the external components, the device integrates protections as overvoltage and overcurrent. The overcurrent level can be programmed using simple resistor for L4981A. For a better precision and for L4981B an external divider must be used.

特性 Features

? PRECISE 2% ON CHIP REFERENCE EXTERNALLY AVAILABLE
? OVERVOLTAGE, OVERCURRENT PROTECTION
? SOFT START
? LOW START-UP CURRENT (0.3mA TYP.)
? HIGH CURRENT BIPOLAR AND DMOS TOTEM POLE OUTPUT
? CONTROL BOOST PWM UP TO 0.99P.F.
? UNIVERSAL INPUT MAINS
? LIMIT LINE CURRENT DISTORTION TO < 5%
? AVERAGE CURRENT MODE PWM FOR MINIMUM NOISE SENSITIVITY
? UNDER VOLTAGE LOCKOUT WITH HYSTERESIS AND PROGRAMMABLE TURN ON THRESHOLD
? FEED FORWARD LINE AND LOAD REGULATION

簡介

L4981屬于集成電路（IC）的PFC（功率因數(shù)校正）。由制造生產(chǎn)的L4981PFC（功率因數(shù)校正）功率因數(shù)校正 (PFC) 是用于調(diào)整交流電路中的電壓和電流之間的相位角，使之趨近于零的半導(dǎo)體器件。不同模式包括平均電流、邊界導(dǎo)通、連續(xù)導(dǎo)通、臨界導(dǎo)通、電流控制式頻率折返、不連續(xù)和不連續(xù)導(dǎo)通，開關(guān)頻率從 6 kHz 至 1.7 MHz 可調(diào)。