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R15AAC/AAU (vs15)
2) Inverter Circuit
This unit operates on an output voltage of 21.5V from power source.
2.1
VDD: R105 get a +5VDC for I101 power supply.
2.2
Control IC: I101 (OZ9930)
2.2.1 Enable : When pin 1 of I101 is over 0.55V, I101 works. If it is under 0.55V, I101 turns off.
2.2.2 OSC: When I101 enabled, C104/C105 (pin 2 of I101) determine the operating frequency.
2.2.3 SST: C106 (pin 1 of I101) provides soft start function.
2.2.4 Ignition: IC provides higher operating frequency internally for more striking voltage until regulation of feedback of
lamp current. And provide 2 sec striking time.
2.2.5 Dimming control: The divided voltage of R106/R103/R104 control the duty pulse of burst-mode to drive and
perform a wide dimming control for the CCFL. The burst-mode frequency is determined by operating freq/233.
2.2.6 Regulation: Pin 8 of I101 provide regulation of the CCFL current from feedback. The non-inverting reference is at
1.25V nominal.
2.2.7 Protection: Open-lamp protection in the ignition period is provided through pin 7 of I101.
Removal of the CCFL during normal operation will trigger IC to turns on and shuts off the inverter. This is latch
function.
2.2.8 Output drivers: The configuration prevents any shoot-through issue associated with bridge-type power
conversion applications. Adjusting the overlap conduction between Q104, the CCFL current regulation is achieved.
2.3
Half-bridge swit ching/Transformer: Q104, C122, C123 compose half-bridge swit ching to convert DC into AC for
driver the CCFL.
2.4
Detection: C132, C112, C114, C126, R116, R115, C115 detect the output voltage and ensure a rated voltage by pin7
of I101 ensure not a open-lamp.
2.5
Feedback: D116, D117, R111, R112, C109 sense the lamp current for negative feedback and regulation.
Inverter Board Block Diagram
VCC
VDD
Enable
OSC
SST
Output driver
Protection
Ignition
Regulation
Control IC : OZ9930
ON / OFF
Halfl-bridge switching
Transformer
Lamp
Feed back
Detection
VDD
Dimming Control
Brightness
Control
