L6565

QUASI-RESONANT SMPS CONTROLLER

■ QUASI-RESONANT (QR) ZERO-VOLTAGESWITCHING (ZVS) TOPOLOGY

■ LINE FEED FORWARD TO DELIVER CONSTANT POWER vs. MAINS CHANGE

■ FREQUENCY FOLDBACK FOR OPTIMUM STANDBY EFFICIENCY

■ PULSE-BY-PULSE & HICCUP-MODE OCP

■ ULTRA-LOW START-UP (< 70µA) AND QUIESCENT CURRENT (< 3.5mA)

■ DISABLE FUNCTION (ON/OFF CONTROL)

■ 1% PRECISION (@ Tj = 25°C) INTERNAL REFERENCE VOLTAGE

■ ±400mA TOTEM POLE GATE DRIVER WITH UVLO PULL-DOWN

■ BLUE ANGEL, ENERGY STAR, ENERGY 2000 COMPLIANT

APPLICATIONS

■ TV/MONITOR SMPS

■ AC-DC ADAPTERS/CHARGERS

■ DIGITAL CONSUMER

■ PRINTERS, FAX MACHINES, PHOTOCOPIERS AND SCANNERS

DESCRIPTION

The L6565 is a current-mode primary controller IC, specifically designed to build offline Quasi-resonant ZVS (Zero Voltage Switching at switch turn-on) flyback converters.

Quasi-resonant operation is achieved by means of a transformer demagnetization sensing input that triggers MOSFET's turn-on.

Converter's power capability variations with the mains voltage are compensated by line voltage feedforward. At light load the device features a special function that automatically lowers the operating frequency still maintaining the operation as close to ZVS as possible. In addition to very low start-up and quiescent currents, this feature helps keep low the consumption from the mains at light load and be Blue Angel and Energy Star compliant.

The IC includes also a disable function, an on-chip filter on current sense, an error amplifier with a precise reference voltage for primary regulation and an effective two-level overcurrent protection.

BLOCK DIAGRAM

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