TK75020

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 mA 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 held in the off mode. Even with no Vcc applied, the drive pin of the IC will sink in excess of 20 mA while maintaining the voltage below 1 V to prevent that leakage currents turn on the power MOSFET. An internal zero-voltage detector monitors the voltage across the MOSFET and ensures that the turn-on will only take place under zero-voltage conditions.  A unique overdissipation protection prevents the overheating of the power MOSFET in case the zero-voltage switching is lost.

The TK75020 is available in a 14-lead surface mount package.