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technical data 1 2011 , february ver. 0 3 small outline package sop 8 high - power led driver features ? 2 constant - current output channels ? constant output current invariant to load voltage change ? maximum output constant current per channel: 360 ma ? thermal protection and flag ? output current adjusted through an externa l resi s- tor ? schmitt trigger input ? 5v supply voltage ? package type: pb - free package with thermal pad ordering information device operating temper a- ture range package shipping IK2802Dt = - 40 ... + 85 ? sop - 8 tape& reel current accuracy conditions between channels between ics <3% <6% i out = 40ma ~ 360 ma @ v ds = 0.6v product description ik2802 is an instant on/off led driver for high power led applications and exploits to enhance its output characteristics. ik2802 provides users with 2 - channel constant current ports. users may adjust the output current up to 360 ma through an external resistor, rext, which gives users flexibility in controlling the light intensity of led s. also, users can precisely adjust led brightness from 0% to 100% via output control with pulse width modulation. alternatively, ik2802 provides one - step current adjustment to make 25% of the output current via enabling the quarter pin (qt) as low. ad ditionally, to ensure the system reliability, ik2802 is built with thermal protection (tp) function and thermal pad. the tp function protects ic from over temperature (165c). also, the thermal pad enhances the power dissipation. as a result, a large amoun t of current can be sunk safely in one package. applications ? high - flux led lighting ? automotive interior lighting ik2802
ik2802 2 2011, february ver. 03 typical application circuit figure 1 functional diagram
ik2802 3 2011, february ver. 03 pin configuration pin description pin no. pin name function 1 gnd ground terminal for control logic and current sink 2 r - ext terminal used to connect an external resistor (r ext ) for setting up output current for all output channels 3 qt set all the output current to 25% of the pre - set current when qt is low . default value is high. 4,5 out0~out1 constant current output terminals 6 err open drain thermal error flag, when junction temperature is over 165 oc, err is going to low. 7 oe output enable terminal when oe is active (low), the output pi ns are enabled; when oe is inactive (high), all output pins are turned off (blanked). 8 vdd 5v supply voltage terminal - thermal pad power dissipation terminals connected to gnd* *to eliminate the noise influence, the thermal pad is suggested to be co nnected to gnd on pcb. in addition, desired thermal conductivity will be improved, if a heat - conducting copper foil on pcb is soldered with thermal pad.
ik2802 4 2011, february ver. 03 maximum ratings characteristic symbol rating unit supply voltage v dd 0~7.0 v input voltage v in - 0 .4~v dd + 0.4 v output current i out 3 6 0* ma sustaining voltage v ds - 0.5~+ 27 v gnd terminal current i gnd 720 ma power dissipation* (on pcb, ta=25 oc) sop8 p d 0.8 w thermal resistance** (by s imulation) r th(j - a ) 33.39 oc/w empirical thermal resistance* (on pcb, ta=25 oc) 125 operating junction temperature t j,max 125 oc operating temperature t opr - 40~+85 oc storage temperature t stg - 55~+150 oc *users must notice that the power dissipation (almost equaling to i out x v ds ) should be within the safe operation area shown in figure 7. ** provided by factory. ** * stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are s tress ratings only and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. exposure to absolute - maximum - rated conditions for extended periods may affect device reliability.
ik2802 5 2011, february ver. 03 electrical characteristics characteristics symbol condition min. typ. max. unit supply voltage v dd - 4.5 5.0 5.5 v sustaining voltage at out pin v ds out0~out1 - - 27 .0 v output current i out dc test circuit 40 - 360.0 ma input voltage for oe, qt h level v ih ta= - 40~85 oc 1.6 - v dd v l level v il ta= - 40~85 oc gnd - 0.6 v output leakage current i oh v oh = 27 v - - 0.5 ua err output voltage v ol i ol =+1.0ma - - 0.5 v err turn on impedance r ds,(on),err refer to the test circuit for el ectrical characteristics 3 00 6 00 8 00 ohm output current 1 i out1 v ds =0. 8 v r ex t = 1. 8 kohm - 340 - ma current skew 1 di out/iout i ol = 340 ma v ds =0. 8v r ex t = 1. 8 kohm - 1 3 % output current 2 i out2 v ds =0. 6 v r ex t = 2 . 4 kohm - 240 - ma current skew 2 di out/iout i ol = 240 ma v ds =0. 6 v r ex t = 2 . 4 kohm - 1 3 % regulation of output current vs. sustaining voltage %/dv ds v ds within 1.0v and 3.0v - 0.1 - %/v regulation of output current vs. supply voltage %/dv dd v dd within 4.5v and 5.5v - 1 - %/v pull - up resistor r n(up ) oe , qt 300 600 800 kohm thermal shutdown temperature t xi shutdown t emp . increasing - 165 - oc t xd reset t emp . decreasing - 1 5 5 - oc supply current off i dd (off) 1 r ext =open,out0~out 1 =off - 4 9 ma i dd (off) 2 r ext = 2 . 4 kohm, out0~out1=off - 6 1 0 i dd (off) 3 r ext =1. 8 kohm, out0~out1=off - 7 1 2 on i dd (on) 1 r ext = 2 . 4 kohm, out0~out1=on - 5 1 0 i dd (on) 2 r ext =1. 8 kohm, out0~out1=o n - 6 1 0 test circuit for electrical characteristics
ik2802 6 2011, february ver. 03 figure 2 switching characteristics characteristics symbol condition m in. t yp. max. unit propagation delay time( l to h ) oe - outn t plh v dd =5.0v v ds =1.0v v ih =v dd v il =gnd r ext =1 63 0o hm ( i outn =360ma) v l =4.0v r l =8.5ohm c l =10pf 0.3 0.5 1 us propagation delay time( l to h ) oe - outn t phl 0.3 0.5 1 us pulse width oe t w(oe) 1 - - us output rise time of out (turn off) t or 0.3 0.5 1 us output rise time of out (tur n on) t of 0.3 0.5 1 us test circuit for switching characteristics figure 3
ik2802 7 2011, february ver. 03 application circuits (a) ik2802 application circuit, where v led and v dd share a single voltage source. (b) ik2802 application circuit with dimming control by pw m signal, where v led and v dd use voltage sources separately. figure 4
ik2802 8 2011, february ver. 03 constant current in led lighting applications, ik2802 provides nearly no variation in current from channel to channel and from ic to ic. this can be achieved by: 1) the maxim um current variation between channels is less than 3%, and that between ics is less than 6%. 2) in addition, the current characteristic of output stage is flat and users can refer to the figure as shown below. the output current can be kept constant reg ardless of the variations of led forward voltages (v f ). this guarantee s led to be performed on the same brightness as users specification. figure 5 iout versus vds 0 40 80 120 160 200 240 280 320 360 400 0 1 2 3 4 vds (v) iout (ma) 16,1k 4,9k 2,9k 2,1k 1,6k
ik2802 9 2011, february ver. 03 setting output current the output current of each channel (i out ) is set by an externa l resistor, r ext . the relationship between i out and r ext is shown in the following f igure 6 and table 1 . figure 6 iout(ma) rext(kohm) 360 1.6 0 2 80 2. 07 20 0 2 . 89 12 0 4 . 8 8 40 1 6 . 14 table 1 iout versusu rext 0 40 80 120 160 200 240 280 320 360 400 0 2,5 5 7,5 10 12,5 15 17,5 rext (kohm) iout (ma)
ik2802 10 2011, february ver. 03 package power dissipation (pd) the maximum power dissipation, p d (max) = (t j,max C t a ) / r th(j - a) , decreases as the ambient temperature increases. figure 7 the maximum allowable package power dissipation is determined as p d (max) = (t j,max C t a ) / r th(j - a) . when 2 output channels are turned on simultaneously, the actual package power dissipation is p d (act) = (i dd x v dd ) + (i out x duty x v ds x 2). therefore, to keep p d (act) p d (max), the allowable maximum output current as a function of duty cycle is: i out = { [ (tj C ta) / r th(j - a) ] C (i dd x v dd ) } / v ds / duty / 2, where tj = 125c; duty= t on / t; t on : the time of leds turning on; t: signal period *note: the empirical thermal resistor r th(j - a) =125 c/w is based o n the following structure.
ik2802 11 2011, february ver. 03
ik2802 12 2011, february ver. 03 tp function (thermal protection) therma l protection turns off the output current when the junction temper ature rises to approximately 165 c, a l- lowing the device to cool and the thermal error flag, goes low simultaneously. w hen the junction tem per a- ture cools to approximately 155c, the output c urrent is turned on again. depending on power dissi pation, the r- mal resistance, and ambient tempe rature, the thermal protection circuit may cycle on and off. this limits the di s- sipation of the driver , protecting it from damage due to overheating. load supply voltage (vled) ik2802 is designed to operate with adequate v ds to achieve constant current. v ds together with i out should not exceed the package power dissipation limit, p d(max) . as in figure 8, v ds = v led C v f , and v led is the load supply voltage. p d(act) will be greater than p d(max) , if v ds drops too much voltage on the driver. in this case, it is recommended to use the lowest possible supply voltage or to set an external volta ge reducer, v drop . a voltage reducer lets v ds = (v led C v f ) C v drop . resistors can be used in the applications as shown in figure 8. figure 8
ik2802 13 2011, february ver. 03 package dimensions sop 8 note: the unit for the outline drawing is mm.

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