13w Integrated Cfl Using Ir53h420

 
This application note is intended to be used as a development tool to speed up customers’ time to
market.   
 Features
• Drive 13W Compact Lamp
• 110 or 220 Vac Input
• High-Frequency Operation (34kHz)
• Soft Start with Cathode Preheating
(45kHz)
• Lamp Removal Protection
• Burst Mode with Auto Restart
IR53H420 Integrated Half-Bridge
This application note is intended to be used
as a development tool to speed up cus-
tomers’ time to market.  
 The circuit is centered around the IR53H420 Ballast Driver Hybrid which contains the IR2153 Ballast
Driver IC and two 500 volt size 2 HEXFET’s in a half bridge configuration. With a 120 volt AC line
input (AC1-N), the voltage is rectified and doubled to provide a bus voltage of approximately 300
volts. With a 220 volt AC line input (AC1-AC2), the voltage is rectified but not doubled and again
provides a bus voltage of approximately 300 volts.The start up resistor R2 is sized such that it can
supply enough current to start the Oscillator in the IR53H420 but not enough to cause the shunt
clamp to regulate and maintain constant oscillation. With this constraint the power dissipation in
resistor R2 is low enough so that a 1/4 watt unit will suffice. A Charge Pump circuit, consisting of
capacitor C10 and Diodes D5 and D6, is used so that when the IR53H420 begins to oscillate, the
charge pump circuit supplies the current to increase the voltage on Vcc to cause the shunt clamp to
regulate. If the lamp is removed from the circuit there is no longer a path for the charge pump
capacitor C10. This causes the voltage at Vcc of the IR53H420 to begin falling. When the voltage at
Vcc of the IR53H420 falls below the negative undervoltage lockout threshold the Oscillator stops
switching. At this point the voltage will begin to rise again and when the voltage reaches the positive
undervoltage lockout threshold the IC again begins to oscillate. If there is no lamp installed in the
circuit there will be no path for the Charge Pump circuit to supply current and the voltage at Vcc will
again fall below the negative undervoltage lockout threshold. The circuit will continue this sequence
indefinitely until the power is removed or a lamp is reinserted into the circuit. If a lamp is reinserted
into the circuit, the lamp will light.
  

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13w Integrated Cfl Using Ir53h420 application circuits
13w Integrated Cfl Using Ir53h420 application circuits



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