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L4981：L4981A: Fixed Frequency Average Current Mode; L4981B: Line Modulated Frequency Average Current Mode

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.

Key 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

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