KA7541DTF

www.fairchildsemi.com KA7541 Simple Ballast Controller Features Descriptions • • • • • • • The KA7541 provides simple and high performance electronic ballast control functions. KA7541 is optimized for electronic ballast requiring a minimum board area, reduced component count and low power dissipation. Internal soft start circuitry eliminates the need for an external soft start PTC resistor. The initial soft start switching frequency and soft start time can be adjusted depending on the types of lamps. Protection circuitry has also been added to prevent burning out of switches in no lamp condition. output gate drive circuit clamps power MOSFET gate voltage irrespective of supply voltage Internal soft start Flexible soft start frequency No lamp protection Trimmed 1.5% internal bandgap reference Under voltage lock out with 1.8V of hysteresis Totem pole output with high state clamp Low start up and operating current 8-DIP 1 8-SOP 1 Rev. 1.0.3 ©2001 Fairchild Semiconductor Corporation KA7541 Internal Block Diagram UVLO 2V Ref − 1 CS 1.8V Internal bias + 0.22µF 2.5µA Vref UVLO Oscilator + + + 3V 8Ict 1V 30kΩ OUT 1 6 OUT 2 5 GND SQ Oscilator 3pF F.D R latch − 3 22kΩ 7 VCC 9.5V IC + 2 180pF RS VCC Ik = IS / 6 Ict Ct 8 − IH VZ + VCC Current mirror + Frequency divider IS Vref 2kΩ 40kΩ Ldet IH = Ik × (Vref − VSS) / Vref IS = Vref / RS − 4 5pF + Shut down signal 2V Absolute Maximum Ratings Parameter Symbol Value Unit VCC 30 V IOH, IOL ±300 mA Iclamp ±10 mA Soft start, and no lamp detection input voltage VIN −0.3 to 6 V Operating temperature range Topr -25 to 125 °C Storage temperature range Tstg −65 to 150 °C Supply voltage Peak drive output current Drive output clamping diodes VO>VCC, or VO