January 1999 TOKO, Inc.

Page 1

TK75020

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 Cold Cathode Fluorescent Lamps

s Resonant Power Supplies

s Power Supplies for Notebook Computers

s 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, T

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 held in the off mode.

Even with no V

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.

ORDERING INFORMATION

TAPE/REEL CODE

TL: Tape Left

Tape/Reel Code

TK75020

TK75020

75020

VCC

DRV

GND

OVP

EN

CT

TOFF(MAX)

TON/SS

Vref

CL

ZVD

EAOUT

EAINV

ODP

ZVS RESONANT CONTROLLER