Acer AL702 AL702 Monitor Service Guide - Page 9

A L502 10. Inverter Th is u n it o perates on an ou tpu t v oltag e of 15V from po wer sou rce. 10.1 Reg u lato r: Q101 g e t a +5VDC for I102 power su pp ly . 10.2 UVP: Q106 tu rn s off wh en th e Vi n is u n der 14V. Th en pin 3 of I102 i s pu lled low an d in v erte r off immedi ately . Th at is th e u n der v oltag e protection . 10.3 Co n trol IC: I102 (OZ960S) 10.3.1 En a ble : Wh en pin 3 of I102 is ov er 1.5V, I102 works . If it is u n de r 1.5V, I102 tu rn s o ff. 10.3.2 OSC: Wh e n I102 en ab led, R108/C115 (pin 17/pin 18 of I102) dete rmin e th e o perat in g frequ en cy . 10.3.3 SST: C104 (p in 4 of I102) prov ides soft sta rt fu n ct ion . 10.3.4 Ig n it ion : R109 (pin 8 of I102) prov ide s h ig h er operatin g frequ e n cy for more strikin g v ol tag e u n t il reg u l ation of f eedbac k of l amp cu rren t. C103 (pin 1 of I102) d etermi n e th e strikin g ti me. 10.3.5 Dimmin g con trol: Th e di v ided v oltag e o f R106/R105/R104 con trol th e du ty pu lse of b u rst-mode to driv e Q105 an d perform a wide di mmin g c on trol for th e CCFL. T h e bu rs t-mode frequ en cy is d etermin ed by C116. 10.3.6 Reg u lation : Pin 9/p in 10 o f I102 p rov ide reg u lat ion of t h e CCFL cu rren t from f eedback. Th e n on -in v ertin g refere n ce (pin 10 of I102) is at 1.25V n omin al. 10.3.7 Protecti on : Open -lamp p rotection in t h e ig n ition period is prov ided th rou g h both pin 1 an d pin 2 of I102. Remov al of th e CCFL du rin g n orma l operatio n will tri g g er Q104 to tu rn s on an d sh u ts off th e in v erter. Th is is latch f unction. 10.3.8 Ou tpu t driv ers: Th e con fig u ration prev en ts an y sh oot-th rou g h issu e associated with bridg e-ty pe power con v ersion applic ation s. Ad ju stin g th e ov erlap co n du ction be tween I101 P-MOSFET a n d I103 N-M OSFET, I101 N-MOSFET an d I103 P-MOSFET , th e CCFL cu rren t reg u latio n is ach iev ed. 10.4 Fu ll-b ridg e swit ch in g /Tran s forme r: I101/I103 /C123/C125/T101/T102 compose f u ll-b ridg e swit ch in g to con v ert DC in t o AC fo r driv e r th e CCFL. 10.5 Detection : C124/C119/CR102 detec t th e ou tpu t v oltag e an d en su re a rated v o ltag e by pin 2 of I102. Q102/Q103 en su re n ot a open -lamp. 10.6 Feedb ack: CR101/R120/R121/D108 se n se th e l amp cu rren t for n eg ativ e fee dback an d reg u latio n . Th e di v ided v oltag e on R121 will be a t 1.25V. Inverter Board Block Diagram VCC ON / OFF Brightness control Regulator U.V.P. Control IC : OZ960 Enable OSC SST Dimming control Output driver Protection Ignition Regulation Full-bridge switching Transformer Detection Feed back Lamp Page 8 CircuitD escrip tion