DIT8545 aug. 2002 - 1 - www.interpionsemi.com c eratrans driver for lcd backlight d it8545 is an advanced lcd backlight inverter co n- trol ic based on the piezo - ceramic transformer. the new control scheme employing the variable fr e- quency and duty control achieves the very high eff i- ciency over 90%. in this control scheme, the soft start and zero voltage switching functions are aut o- matically obtained. DIT8545 can realize the ccfl backlight inverter with small size and low cost. - soft start function - programmable operating frequency - analog dimming control function - burst dimming control - on/off cont rol function - open lamp protection - 10ssop package device package operating temp DIT8545 10ssop - 225 - 25 o c ~ +85 o c descriptions block diagram order information features bias generator uvlo bandgap reference 10 9 8 7 6 1 2 3 4 5 error amp latch vcc out gnd on/off prot tonctl eo ei rt ct tonct l rt ct vfvco driver
DIT8545 aug. 2002 - 2 - www.interpionsemi.com c eratrans driver for lcd backlight pin descriptions no symbol i/o description 1 ct i timing capacitor connection 2 rt i timing resistor connection 3 ei i error amplifier input 4 eo o error amplifier output 5 tonctl i switch on time control input 6 prot i open lamp protection input 7 on/off - on/off control input 8 gnd i ground 9 out o output 10 vcc - supply voltage input pin connections out gnd prot ct 1 rt 2 ei 3 eo 4 5 tonctl vcc on/off DIT8545 6 7 8 9 10
DIT8545 aug. 2002 - 3 - www.interpionsemi.com c eratrans driver for lcd backlight characteristics symbol value unit supply voltage vcc 13.5 v power dissipation pd 0.3 w operating temperature topr - 25 ~ +85 o c storage temperature tstg - 55 ~ 150 o c absolute maximum ratings characteristics symbol value unit supply voltage vcc 3~13.5 v oscillator frequency fosc 40~250 khz recommended operating conditions electrical characteristics characteristics symbol conditions min typ max unit [ operating current specifications] on state supply current icc(on) on/off=2v - 3.5 6 ma off state supply current icc(off) on/off=0v - 350 600 ua average operating current iop ct=470pf - 4 7 ma on state start - up current ist(on) vcc= vthh - 0.3v on/off=2v - 250 400 ua off state start - up current ist(off) vcc= vthh - 0.3v on/off=0v - 200 400 ua [ voltage controlled oscillator ] rt voltage vref 1.235 1.260 1.285 v rt voltage line regulation vline vcc=5v - >12v - 20 2 20 mv rt voltage load regulation vload io=100ua~1ma - 20 2 20 mv rt terminal maximum current irtmax rt=0v - 7 16 ma (ta = 25 o c, vcc=5v, rt=13.8 k ct=1.5v, prot=0v unless otherwise specified.)
DIT8545 aug. 2002 - 4 - www.interpionsemi.com c eratrans driver for lcd backlight characteristics symbol conditions min typ max unit operating frequency fosc ct=470pf 120 135 150 khz frequency change with supply voltage dfosc vcc=5v to 12v - 0.3 1.5 %/v minimum duty ratio dmin tonctl = 0v 10 20 30 % maximum duty ratio dmax tonctl = 3v 55 65 75 % tonctl input bias current ib(ton) tonctl = 0v - - 0.1 - 1 ua [ uvlo section ] upper threshold voltage vthh vcc variation 2.6 2.8 2.95 v lower threshold voltage vthl vcc variation 2.4 2.6 2.8 v uvlo hysteresis voltage vhys vcc variation 0.1 0.2 0.4 v [ on/off section ] on/off logic high voltage von/off - 1 1.3 1.8 v on/off input bias current ib(on/off) on/off=2v 5 20 50 ua [ error amplifier section] erramp input bias current ib(ei) - 0.1 - 1 ua inverting reference voltage vfb 1.220 1.260 1.300 v erramp output source cu r- rent isource 3 10 30 ma erramp output sink current isink 5 15 40 ma erramp output high voltage vhigh 3.2 4.2 4.5 v erramp output low voltage vlow - 0.1 0.4 v [ open lamp protection section ] protection input bias cu r- rent iprot prot=1.5v - 1 40 ua protection input voltage vprot - 1 1.35 1.60 v electrical characteristics (ta = 25 o c, vcc=5v, rt=13.8 k ct=1.5v, prot=0v unless otherwise specified.)
DIT8545 aug. 2002 - 5 - www.interpionsemi.com c eratrans driver for lcd backlight characteristics symbol conditions min typ max unit [ output driver section ] output high voltage 1 voh1 vcc = 3v, io = 1ua 2.0 2.4 2.8 v output high voltage 2 voh2 vcc = 5v, io = 1ua 3.5 4.5 5.5 v output high voltage 3 voh3 vcc = 8v, io = 20ma 2.5 3.3 4.2 v output low voltage 1 vol1 vcc = 3v, io = 100ua - 0.1 0.4 v output low voltage 2 vol2 vcc=5v, io = 1ma - 0.2 0.4 v output voltage with uvlo activated vouv vcc=2v 0 0.2 0.4 v output source current io(source) 20 ma output sink current io(sink) 20 ma electrical characteristics (ta = 25 o c, vcc=5v, rt=13.8k, ct=1.5v, prot=0v unless otherwise specified.)
DIT8545 aug. 2002 - 6 - www.interpionsemi.com c eratrans driver for lcd backlight typical application vcc out gnd on/off prot tonctl eo ei rt ct d8545 1 2 3 4 5 10 9 8 7 6 b1 l1 m1 analog dimming on/off & burst dimming vin gnd ct1 ccfl rv1 c1 c2 r1 c3 c4 r4 r2 r3 r5 c5 r6 c6 d1 d2 r7 r8 c7 r9 r10 r11
DIT8545 aug. 2002 - 7 - www.interpionsemi.com c eratrans driver for lcd backlight electrical diagrams 0.0 0.5 1.0 1.5 2.0 0 10 20 30 40 50 60 70 ct=470p rt=13.8kohm duty(%) vtctrl vs duty vtctrl(v) 0.0 0.5 1.0 1.5 2.0 0 20 40 60 80 100 120 140 160 180 200 ct=470p rt=13.8kohm vtctrl vs frequency vtctrl(v) frequency(khz) fig.1 : vtctrl vs. duty fig.2 : vtctrl vs. frequency
DIT8545 aug. 2002 - 8 - www.interpionsemi.com c eratrans driver for lcd backlight package dimension
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