第二代功率因数控制器 SECOND-GENERATION POWER FACTOR CONTROLLER
Key Features: • INTERNAL START-UP CIRCUIT • INTERNAL CURRENT SENSE BLANKING • IMPROVED MICROPOWER START-UP CURRENT 300µA max. • CLAMPED E.A. OUTPUT FOR LOWER TURN-ON OVERSHOOT • MULTIPLIER CLAMP LIMITS MAXIMUM INPUT CURRENT • INTERNAL OVERVOLTAGE PROTECTION REPLACES BUILT-IN C.S. OFFSET • PWM OUTPUT CLAMP LIMITS MOSFET GATE DRIVE VOLTAGE • INCREASED UVLO HYSTERESIS REDUCES START-UP TIMING LX1562 only • LOW OPERATING CURRENT CONSUMPTION • INTERNAL 1.5% REFERENCE • TOTEM POLE OUTPUT STAGE • AUTOMATIC CURRENT LIMITING OF BOOST STAGE • DISCONTINUOUS MODE OF OPERATION WITH NO CURRENT GAPS • NO SLOPE COMPENSATION REQUIRED The LX1562 is a second-generation family of power factor correction controllers using a discontinuous mode of operation. They are optimized for electronic ballast applications. Many improvements have been made over the original SG3561A controller introduced by Silicon General Semiconductor in 1992. New features include the addition of an internal start-up circuit eliminating bulky external components while allowing independent boost converter operation. Addition of internal current sense blanking eliminating the need for an external R/C filter network. Internal clamping of the error amplifier and multiplier outputs improves turn on overshoot characteristics and current limiting. Special circuitry has also been added to prevent no load runaway conditions. And finally, output drive clamps limiting power MOSFET gate drive independent of supply voltage greatly enhance the products practical application. Although the IC design has been optimized for electronic ballast applications, it can also be used for power factor correction in lower power typ < 300W AC-DC converters. One unique feature of the device is encompassed by the addition of internal logic circuitry to detect zero crossing of the inductor current thus maintaining the discontinuous current mode of operation. This feature prevents large current gaps from appearing thereby minimizing distortion and enhancing power factor correction.