TK75020

TK75020 ZVS RESONANT CONTROLLER FEATURES s Optimized for Off-Line and Battery Powered Operation s Internal Zero-Voltage Detector s Soft-Start s Pulse-by-Pulse Current Limit s Overdissipation Protection with Soft-Start s Overvoltage Protection with Soft-Start s Low-Current Standby mode s Programmable On/Off Timing s Enable Control APPLICATIONS s s s s Cold Cathode Fluorescent Lamps Resonant Power Supplies Power Supplies for Notebook Computers Power Supplies for Personal Electronics DESCRIPTION The TK75020 is a low-cost, high-performance Zero-Voltage Switching (ZVS) controller IC. The primary applications are in inverters for Cold Cathode Fluorescent Lamps (CCFL) and in ZVS quasi-resonant or multi-resonant converters. The combination of a unique (patent-pending) control concept and a ZVS resonant inverter generates low-distortion sine wave for the fluorescent lamp, leading to extended lamp life and high luminous efficiency. The IC features all necessary circuits of a controller for such applications, including externally adjustable timing parameters (frequency, Ton(min), Toff(max)), current limit, Soft-Start, enable, error amplifier, and a trimmed reference. The same reference is used for undervoltage protection and other critical internal biases. Supply current in the “off” mode is kept at a minimum level (2 µA typical). Special care has been taken to avoid undesirable turn-on of the external power MOSFET when sufficient supply voltage is not available, or when the device is...