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fn6264 rev 4.00 page 1 of 12 august 27, 2013 fn6264 rev 4.00 august 27, 2013 isl97634 white led driver with wide pwm dimming range datasheet the isl97634 represents an efficient and highly integrated pwm boost led driver that is suitable for led backlighting in small size lcd panels. with integrated schottky diode, ovp, and wide range of pwm dimmin g capability, the isl97634 provides a simple, reliable, and flexible solution to the backlight designers. the isl97634 features a wide range of pwm dimming control capability. it allows dimming frequency as low as dc to 32khz beyond audible spectrum. the isl97634 also features a feedback disconnect switch to prevent the output from being modulated by the pwm dimming si gnal that minimizes system disturbance. the isl97634 is available in the 8 ld tdfn (2mmx3mm) package. there are 14v, 18v, and 26v ovp options that are suitable for various nu mber of leds in series. the isl97634 is specified for operation over the -40c to +85c ambient temperature at input voltage from 2.4v to 5.5v. related literature ?see tb470 , ?using the isl97634 white led driver demo board? features ?drives up to 26v output ?integrated over-voltage protec tion (ovp) of 14v, 18v, and 26v for various number of leds in series ? pwm dimming control from dc to 32khz ? output disconnect switch ? integrated schottky diode ? 2.4v to 5.5v input ? 85% efficiency ? 1.4mhz switching frequency allows small lc ? 1a shutdown current ? internally compensated ?8 ld tdfn (2mmx3mm) ? pb-free (rohs compliant) applications ? led backlighting for: - cell phones -smartphones -mp3 -pmp - automotive navigation panel - portable gps figure 1. typical application circuit vin lx fbsw gnd vin pwm/en fb vout nc 10h or 22h
isl97634 fn6264 rev 4.00 page 2 of 12 august 27, 2013 block diagram fet pwm logic controller gm amplifier 95mv gm amp compensation pwm comparator vin pwm/en lx gnd fb rset cout l vin (2.4v to 5.5v) 2 leds to 7 leds cin isl97634 vout bandgap reference generator fbsw pwm/en driver gm amp compensation current sense 1.4mhz oscillator and ramp generator
isl97634 fn6264 rev 4.00 page 3 of 12 august 27, 2013 pin configuration isl97634 (8 ld tdfn) top view 2 3 4 1 7 6 5 8 gnd vin pwm/en nc lx vout fbsw fb thermal pad pin descriptions pin number pin name description 1 gnd ground pin. connect to local ground. 2 vin input supply pin. connect to the input supply voltage, the inductor and the input supply decoupling capacitor. 3 pwm/en pwm or enable pin. connect external pwm signal allows pulse width modulation current operation. enable signal allows peak current operation or disable signal shuts down the device. 4ncno connect 5 fb feedback pin. connect the sense resistor between fb and ground. the cathode of bottom led can also be connected at this pin if the output current is not to be pwmed. 6 fbsw fb disconnect switch. connect to the cathode of the bottom led if the output current to be pwmed. 7 vout output pin. connect to the anode of the top led and the output filter capacitor. 8 lx switching pin. connect to inductor. pad connect to ground plane on the pcb to maximize thermal performance. ordering information part number (notes 1, 2, 3) part marking ovp options (v) temp range (c) package tape and reel (pb-free) pkg. dwg. # isl97634irt14z-t ele 14 -40 to +85 8 ld 2x3 tdfn l8.2x3a ISL97634IRT14Z-TK ele 14 -40 to +85 8 ld 2x3 tdfn l8.2x3a isl97634irt18z-t elf 18 -40 to +85 8 ld 2x3 tdfn l8.2x3a isl97634irt18z-tk elf 18 -40 to +85 8 ld 2x3 tdfn l8.2x3a isl97634irt26z-t elg 26 -40 to +85 8 ld 2x3 tdfn l8.2x3a isl97634irt26z-tk elg 26 -40 to +85 8 ld 2x3 tdfn l8.2x3a notes: 1. please refer to tb347 for details on reel specifications 2. these intersil pb-free plastic packaged products employ spec ial pb-free material sets, molding compounds/die attach materials , and 100% matte tin plate plus anneal (e3 termination finish , which is rohs compliant and compatible wi th both snpb and pb-free soldering opera tions). intersil pb-free products are msl classified at pb-fr ee peak reflow temperatures that meet or exceed the pb-free requirements of ipc/jed ec j std-020. 3. for moisture sensitivity level (msl), please see device information page for isl97634 . for more information on msl please see tech brief tb363 .
isl97634 fn6264 rev 4.00 page 4 of 12 august 27, 2013 absolute maximum ratings (t a = +25c) thermal information input voltage ( v in ) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 6v lx voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 28v fbsw voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 28v all other pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 6v operating conditions temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40c to +85c thermal resistance ? ja (c/w) ? jc (c/w) 8 ld tdfn package (notes 4, 5). . . . . . . . . 77 12 maximum junction temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . .+125c storage temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-65c to +150c pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below http://www.intersil.com/ pbfree/pb-freereflow.asp caution: do not operate at or near the maximum ratings listed for extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty. important note: all parameters having min/max specifications are guaranteed over temperature of -40c to +85c unless otherwise stated. typ values are for information purposes only at tj = tc = ta = +25c. notes: 4. ? ja is measured in free air with the componen t mounted on a high effective thermal conduc tivity test board with ?direct attach? fe atures. see tech brief tb379 . 5. for ? jc , the ?case temp? location is the center of the exposed metal pad on the package underside. electrical specifications v in = v pwm/en = 3v. boldface limits apply over the operating temperature range, -40c to +85c. parameter description condition min (note 6) typ max (note 6) unit v in supply voltage 2.4 5.5 v i in supply current pwm/en = 3v, enabled, not switching 0.8 1.5 ma pwm/en = 0v, disabled 1 a f sw switching frequency 1,300 1,450 1,600 khz dmax maximum switching duty cycle 90 95 % i lim lx current 400 470 ma r sw(lx) lx switch on-resista nce ilx = 100ma 900 m ileak lx switch leakage current vlx = 28v 0.01 1 a vfb feedback voltage 90 95 100 mv ifb fb pin bias current vfb = 95mv 1 a r sw(fbsw) fbsw switch on-resistance 10 v diode schottky diode forward voltage idiode = 100ma, t a = +25c 600 850 mv ovp overvoltage protection isl97634irt14z 14 v isl97634irt18z 18 v isl97634irt26z 26 28 v vil logic low voltage of pwm/en 0.6 v vih logic high voltage of pwm/en 1.5 v pwm_on minimum pwm on-time 1.5 s en_delay en to vout delay 200 s note: 6. parameters with min and/or max limits are 100% tested at +25 c, unless otherwise specified. te mperature limits established by characterization and are not production tested.
isl97634 fn6264 rev 4.00 page 5 of 12 august 27, 2013 typical performance curves figure 2. efficiency vs pwm duty cy cle figure 3. quiescent current vs v in (pwm/en = hi) figure 4. load regulation (v in = 4v) figure 5. line regulation figure 6. dimmng linearity (f b voltage) vs duty cycle figure 7. pwm dimming at 1khz, d = 1% 50 55 60 65 70 75 80 85 90 0 20406080100 efficiency (%) pwm duty cycle (%) 3 leds, 10h 3 leds, 22h 7 leds, 10h 7 leds, 22h 4 leds, 10h v in = 4v rset = 4 ?? f pwm = 1khz iled_peak = 25ma -0.2 0.0 0.2 0.4 0.6 0.8 1.0 0246 i q (ma) 135 v in (v) 19.92 19.96 20.00 20.04 20.08 0 5 10 15 20 25 30 i o (ma) v out (v) 19.62 19.64 19.66 19.68 19.70 19.72 19.74 19.76 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) i o (ma) 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 120 duty cycle (%) 7 leds v in = 4v rset = 4 ? l = 10h fb voltage (mv) 20khz 32khz 1khz iled pwm/en lx v out v in = 4v r 1 = 4 ?? l 1 = 22h
isl97634 fn6264 rev 4.00 page 6 of 12 august 27, 2013 detailed description the isl97634 uses a constant frequency, current mode control scheme to provide excellent line and load regulation. there are three ovp thresholds set at 14v, 18v and 26v respectively. the isl97634 operates from an input voltage of 2.4v to 5.5v and ambient temperature from -40c to +85c. the switching frequency is around 1.45mhz and allows the driver circuit to employ small lc components. the peak forward current of the led is set using the r set resistor. in the steady state mode, the led peak current is given by equation 1: pwm dimming the isl97634?s pwm/en pin can be tied permanently to high for a fixed current operation. on the other hand, the isl97634 can be applied with an extern al pwm signal to pulse width modulated output current. it is well understood that the led brightness is a linear function of the led current. in addition, the average led current corresponds to the duty cycle ?d? of the pwm signal as shown in equation 2: as a result, pwm signal provides a means to dim the led brightness. pwm dimming offers the best leds matching over dc dimming. it is because the led peak current operating point is far away from the knee of the diode i-v curve where part to part variations are high. the pwm dimming test results are shown in figure 7 with tw o pwm frequencies, 1khz and 20khz. the vertical scale parameter fb is proportional to the current and therefore the brightness. for the isl97634, pwm dimming provides linear dimming adjustment with low frequency signal, such as 1khz and below. the applied pwm dimming signal can be up to 32khz; figure 8. pwm dimming at 1khz, d = 1% zoom in figure 9. pwm dimming at 1khz, d = 99% figure 10. pwm dimm ing at 20khz, d = 50% typical performance curves (continued) iled pwm/en lx v out v in = 4v r 1 = 4 ?? l 1 = 22h iled pwm/en lx v out v in = 4v r 1 = 4 ?? l 1 = 22h iled pwm/en lx v out v in = 4v l1 = 22h r 1 = 4 ?? i led v fb r set --------------- = (eq. 1) i led-avg v fb r set --------------- d ? = (eq. 2)
isl97634 fn6264 rev 4.00 page 7 of 12 august 27, 2013 however, the dimming linearity is compromised at low duty cycles as their durations are too short for the isl97634?s control loop to respond properly. this non-ideality behavior does not cause any functional problem. the pwm dimming linear responses in figure 6 are expanded in figure 11. at 1khz pwm dimming, the duty cycle can virtually vary from below 1% to dc. on the other hand, at 20khz pwm dimming, the linearity range is from 5% to dc only. the low level non-linearity effects at high frequency pwm dimming is also reflected in the efficiency measurements in figure 12. feedback disconnect switch the isl97634 functions properly without using the fbsw. however, the output capacitor wi ll discharge during the pwm off time resulting in poor dimming li nearity at low duty cycles. the output discharge effect can be s een in figure 13. moreover, the output is modulated by the pwm signal that may create interference to other systems. . the fbsw should be used for pwm dimming as illustrated in the ?typical application circuit? on page 1. during the pwm off time, the fbsw is opened. the leds are floating and therefore the output capacitor has no path to discharge. the led current responds accurately with the pw m signal (see figure 14). the output switches very quickly to the target current with minimal settling ringing and without being modulated by the pwm signal, and therefore minimizes any system disturbance. overvoltage protection the isl97634 comes with overvoltage protection. the ovp trip points are at 14v, 18v and 26v for isl97634irt14z, isl97634irt18z and isl97634irt26z respectively. the maximum led current and ovp threshold are shown in table 1. when the device reaches the ovp, the lx stops switching, disabling the boost circuit until v out falls about 7% below the ovp threshold. at this point, lx will be allowed to switch again. the ovp event will not cause th e device to shutdown. an output capacitor that is only rated for the required voltage range can therefore be used, which will optimize the component costs in some cases. figure 11. dimming linearity vs duty cycles zoom in 0 1 2 3 4 5 6 7 8 9 10 024681012 duty cycle (%) 7 leds v in = 4v rset = 4 ? l = 10h fb voltage (mv) 20khz 32khz 1khz figure 12. efficiency vs pwm dimming frequencies 50 55 60 65 70 75 80 85 90 0 5 10 15 20 25 30 iled (ma) efficiency (%) v in = 4v rset = 4 ?? l = 22h 3 leds iled pwm/en lx v out v in = 4v r1 = 4 ?? l1 = 22h figure 13. pwm dimming at 1khz without using fbsw figure 14. pwm dimming at 1khz using fbsw iled pwm/en lx v out v in = 4v r1 = 4 ?? l1 = 22h
isl97634 fn6264 rev 4.00 page 8 of 12 august 27, 2013 shutdown when pwm/en is taken low the isl97634 enters into the power-down mode where the supply current is reduced to less than 1a. the device resumes normal when the pwm/en goes high. components selection the input capacitance is typically 0.22f. the output capacitor should be in the range of 0.22f to 1f. x5r or x7r type of ceramic capacitors of the appropriate voltage rating are recommended. when choosing an inductor, make sure the average and peak current ratings are adequate by using equations 3, 4 and 5 (80% efficiency assumed): where: ? ? i l is the peak-to-peak inductor current ripple in amps ? l is the inductance in h ?f osc is the switching frequency, typically 1.45mhz the isl97634 supports a wide range of inductance values (10h to ~82h). for lower inductor values or lighter loads, the boost inductor current may become discontinuous. for high boost inductor values, the boost inductor current will be in continuous mode. in addition to the inductor value and switching frequency, the input voltage, number of leds and the led current also affects whether the converter operates in continuous conduction or discontinuous conduction mode. both operating modes are allowed and normal. the disconti nuous conduction mode yields lower efficiency due to higher peak current. compensation the product of the output capacitor and the load create a pole while the inductor creates a right half plane zero. both of these attributes degrade the phase margin but the isl97634 has internal compensation network th at ensures the device operates reliably under the specified conditions. the internal compensation and the highly integrated functions of the isl97634 make it a design friendly device to be used in high volume, high reliability applications. applications analog dimming analog dimming is usually not recommended because of the brightness non-linearity at low levels dimming. however, some systems are emi or noise sensitiv e that analog dimming may be more suitable than pwm dimmin g under those situations. the isl97632 is part of the same family as the isl97634 and has been designed with a serial interface to give access to 32 separate dimming levels. alternatively analog dimming can be achieved by applying a variable dc voltage (v dim ) at the fb pin (see figure 15) to adjust the led current. as the dc dimming signal voltage increases above vfb, the voltage drop on r 1 and r 2 increases and the voltage drop on rset decreases. thus, the led current decreases as shown in equation 6: if v dim is taken below fb, the inverse will happen and the brightness will increase. the dc dimming signal voltage can be a variable dc voltage from a pot, a dcp (digitally controlled potentiometer), or a dc voltage generated by filtering a high frequency pwm control signal. as brightness is directly proportional to led currents, v dim may be calculated for any desired ?relative brightness? (f) using equation 7: where f = i led (dimmed)/i led (undimmed). these equations are valid for values of r 1 and r 2 such that both r 1 >>rset and r 2 >>rset. the analog dimming circuit can be tailored to a desired relative brightness for different v dim ranges using equation 8. where v dim_max is the maximum v dim voltage and f min is the minimum relative brightness (i.e., the brightness with v dim_max applied). i.e., v dim_max = 5v, f min = 10% (i.e., 0.1), r 2 = 189k i.e., v dim_max = 1v, f min = 10% (i.e., 0.1), r 2 = 35k table 1. part no. ovp max iled isl97634irt14z 14v 70ma isl97634irt18z 18v 50ma isl97634irt26z 26v 30ma i lavg i led v out ? 0.8 v in ? --------------------------------- = (eq. 3) i lpk i lavg 1 2 -- - i l ? ? + = (eq. 4) i l ? v in v out v in C ?? ? lv out f osc ?? -------------------------------------------------- - = (eq. 5) i led v fb r 1 r 2 + ?? v dim r 1 ? C ? r 2 r ? set --------------------------------------------------------------- ---------- - = (eq. 6) figure 15. analog dimming control application circuit isl97634 c1 v in lx pwm fb gnd l1 22h c2 0.22f r set 4.75 ? leds 1f lx v in 3.3v r1 r2 v dim v out 3.3k v dim r 2 r 1 ------ - v fb 1 r 1 r 2 ------ - f C + ?? ?? ?? ?? = (eq. 7) r 2 v dim_max v fb C ?? r 1 ? ?? v fb 1f min C ?? ? ?? --------------------------------------------------------------- ---- = (eq. 8)
isl97634 fn6264 rev 4.00 page 9 of 12 august 27, 2013 efficiency improvement figure 2 shows the efficiency measurements during pwm operation. the choice of the indu ctor has a significant impact on the power efficiency. equation 4 shows the higher the inductance, the lower the peak current, theref ore, the lower the conduction and switching losses. on the other hand, it has also a higher series resistance. nevertheless, the effi ciency improvement effect by lowering the peak current is grea ter than the resistance increases with larger value of inductor. effi ciency can also be improved for systems that have high supply voltages. since the isl97634 can only supply from 2.4v to 5.5v, v in must be separated from the high supply voltage for the boost circuit as shown in figure 16 and the efficiency improvement is shown in figure 17. . operation with vout above 26v for led backlighting applications th at need an output voltage above 26v, the voltage range of the isl97634 is not sufficient. however, the isl97634 can be used as an led controller with an external protection mosfet connected in ca scode fashion to achieve higher output voltage as shown in figure 18. a 60v logic level n-channel mosfet is configured such that it s drain ties between the inductor and the anode of schottky diode, its gate ties to the input, and its source ties to the isl97634 lx no de connecting to the drain of the internal switch. when the internal sw itch turns on, it pulls the source of m1 down to ground and lx conducts as normal. when the internal switch turns off, the source of m1 will be pulled up by the follower action of m1, limiting the maximum voltage on the isl97634 lx pin to below v in , but allowing the output voltage to go much higher than the breakdown limit on the lx pin. the switch current limit and maximum duty cycle will not be changed by this setup, so input voltage will need to be carefully considered to make sure that the required output voltage and current levels are achievable. because the source of m1 is effectively floating when the internal lx switch is off, the drain-to-source capacitance of m1 may be sufficient to capacitively pull the node high enough to break down the gate oxide of m1. to prevent this, v out should be connected to v in , allowing the internal schottky diode to limit the peak voltage. this will also ho ld the vout pin at a known low voltage, preventing the built in ovp function from causing problems. this ovp function is effectively useless in this mode as the real output voltage is outside its intended range. if the user wants to implement their own ovp protecti on (to prevent damage to the output capacitor), they should inse rt a zener diode from vout to the fb pin. in this setup, it would be wise not to use the fbsw to fb switch, as otherwise, the zener diode will have to be a high power one capable of dissipating the entire led load power. then the led stack can then be connected directly to the sense resistor via a 10k ? resistor to fb. a zener can be placed from vout to the fb pin allowing an overvoltage event to pull-up on fb with a low breakdown current (and thus low power zener diode) as a result of the 10k ? resistor. sepic operation for applications where the output voltage is not always above the input voltage, a buck or boost regulation is needed. a sepic (single-ended primary inductance converter) topology, shown in figure 19, can be considered for such an application. a single cell li-ion battery operating a cellular phone backlight or flashlight is one example. the battery voltage is between 2.5v and 4.2v, depending on the state of charge. on the other hand, the output may require only one 3v to 4v medium power led for illumination because the light guar d of the backlight assembly is optimized for cost efficiency trade-off reason. in fact, a sepic configured led driver is flexible enough to allow the output to be well above or below the input voltage, unlike the previous example. another example is when the number of leds and input requirements are differen t from platform to platform, a common circuit and pcb that fit all the platforms in some cases figure 16. separate high input voltage for higher efficiency operation vs = 12v l1 22h 1 2 r1 4 ? c3 0.22f d2 d3 d1 d5 d6 d4 isl97634 fbsw lx vout pwm / en vin fb gnd c1 1f c2 0.1f v in = 2.7v to 5.5v figure 17. efficiency improvement with 9 and 12v inputs v s = 9v v s = 12v 0 5 10 15 20 25 30 iled (ma) efficiency (%) 90 85 80 75 70 v in = 4v 7 leds l1 = 22h r1 = 4 ? f pwm figure 18. high voltage led driver using a cascode vout lx isl97634 pwm/en vin fbsw gnd fb r1 6.3 ? l1 10h or 22h 12 v in = 2.7v to 5.5v c3 4.7f d0 10bq100 m1 fqt13n06l c1 1f sk011c226kar c2 0.1f
fn6264 rev 4.00 page 10 of 12 august 27, 2013 isl97634 intersil products are manufactured, assembled and tested utilizing iso9001 quality systems as noted in the quality certifications found at www.intersil.com/en/suppor t/qualandreliability.html intersil products are sold by description on ly. intersil may modify the circuit design an d/or specifications of products at any time without notice, provided that such modification does not, in intersil's sole judgment, affect the form, fit or function of the product. accordingly, the reader is cautioned to verify that datasheets are current before placing orders. information fu rnished by intersil is believed to be accu rate and reliable. however, no responsib ility is assumed by intersil or its subsidiaries for its use; nor for any infrin gements of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of intersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com for additional products, see www.intersil.com/en/products.html ? copyright intersil americas llc 2006-2013. all rights reserved. all trademarks and registered trademarks are the property of their respective owners. may be beneficial enough that it outweighs the disadvantage of adding additional component cost. l 1 and l 2 can be a coupled inductor in one package. the simplest way to understand sepic topology is to think about it as a boost regulator where the input voltage is level shifted downward at the same magnitude and the lowest reference level starts at -v in rather than 0v. the sepic works as follows; assu me the circuit in figure 19 operates normally when the isl97 634 internal switch opens and it is in the pwm off state. after a short duration where few lc time constants elapsed, the circuit is considered in the steady-state within the pwm off period that l 1 and l 2 are shorted. v b is therefore shorted to the ground and c 3 is charged to v in with v a =v in . when the isl97634 internal switch closes and the circuit is in the pwm on-state, v a is now pulled to ground. since the voltage in c 3 cannot be changed instantaneously, v b is shifted downward and becomes -v in . the next cycle when the isl97634 switch opens, v b boosts up to the targeted output like the standard boost regulator operatio n, except the lowest reference point is at -v in . the output is approximated in equation 9: where d is the on-time of the pwm duty cycle. the convenience of sepic comes wi th some trade-off in addition to the additional l and c costs. the efficiency is usually lowered because of the relatively large effi ciency loss through the schottky diode if the output voltage is low. the l 2 series resistance also contributes additional loss. figure 20 shows the efficiency measurement of a single led a pplication as the input varies between 2.7v and 4.2v. note v b is considered the level-shifte d lx node of a standard boost regulator. the higher the in put voltage, the lower the v b voltage will be during pwm on period. the result is that the efficiency will be lower at higher input voltages because the sepic has to work harder to boost up to the required level. this behavior is the opposite to the standard boost re gulator?s and the comparison is shown in figure 20. pcb layout considerations the layout is very important for the converter to function properly. r set must be located as close as possible to the fb and gnd pins. longer traces to the leds are acceptable. similarly, the supply decoupling cap and the output filter cap should be as close as possible to the vin and vout pins. the heat of the ic is mainly di ssipated through the thermal pad of the package. maximizing the copper area connected to this pad if possible and connect to ground plane on the pcb. connect all vias to the correct voltage potential (p ower plane) indicated in the datasheet. in addition, a solid grou nd plane is always helpful for the emi performance. figure 19. sepic led driver c1 1f l1 22h 1 2 v a v b v in = 2.7v to 5.5v 22h l2 c3 1f c4 0.22f d1 r1 1 ? c2 0.1f vin sdin lx vout fbsw fb gnd isl97634 d0 v out v in d 1d C ?? ------------------ = (eq. 9) 0 5101520 iled (ma) efficiency (%) 76 72 68 64 60 1 led l 1 = l 2 = 22h c 3 = 1f r 1 = 4.7 ? figure 20. efficiency measurem ent of a single led sepic driver v in = 4.2v v in = 2.7v
isl97634 fn6264 rev 4.00 page 11 of 12 august 27, 2013 about intersil intersil corporation is a leader in the design and manufacture of high-performance analog, mixed-signal and power management semiconductors. the company's products addr ess some of the largest markets within th e industrial and infr astructure, personal computing and high-end consumer markets. for more information about intersil, visit our website at www.intersil.com . for the most updated datasheet, application notes, related documentatio n and related parts, please see the respective product information page found at www.intersil.com . you may report errors or suggestions fo r improving this datasheet by visiting www.intersil.com/en/support/ask-an-expert.html . reliability reports are also available from our website at http://www.intersil.com/en/support/q ualandreliability.html#reliability revision history the revision history provided is for informational purposes only and is believed to be accurate, but not warranted. please go t o web to make sure you have the latest revision. date revision change august 27, 2013 fn6264.4 changed the information of "max 7 led in series" to "up to 26v" for more accuracy. page 1: in first paragraph, changed "pwm boost led driver that is suitab le for 1.8" to 3.5" lcds that employ 2 to 7 white leds for backlighting." to " pwm boost led driver that is suit able for led backlighting in small size lcd panels." added ?related literature? in ?features?, changed "ovp (14v, 18v, and 26v for 3, 4 and 7 le ds applications)" to "integrated over-voltage protection (ovp) of 14v, 18v, and 26v for various number of leds in series". changed "drives up to 7 leds in series (3.5v/20ma type)" to "drives up to 26v output" ordering information on page 3 added ovp options column. updated pb-free note to new verbiage based on lead finish. added note to min max column of spec table "parameters wi th min and/or max limits are 100% tested at +25c, unless otherwise specified. temperature limits established by characterization and are not production tested." added "boldface limits apply" verbiage to common conditions of spec table. bolded applicable specs. ?overvoltage protection? on page 7, changed "the maximum numbers of leds.." to "the maximum led current.." page 8, table 1, deleted "max no.of leds" column page 9: changed section title from "8 leds operat ion" to ?operation with vout above 26v? in same section, changed first sentence from "for medium size lcds that need more than 7 low power leds for backlighting, such as a portable media player or automotive navigation panel displays, the voltage range.." to "for led backlighting applications that need an output voltage above 26v, the voltage range.." figure 17, changed inductance value from "2.2h" to "10h or 22h" figure 17, changed figure title from "con ceptual 8 leds high voltage driver" to "h igh voltage led driver using a cascode". added ?revision history? and ?about intersil? on page 11. page 12: updated pod l8.2x3a to most recent rev. upda ted format and added recommended land pattern
isl97634 fn6264 rev 4.00 page 12 of 12 august 27, 2013 package outline drawing l8.2x3a 8 lead thin dual flat no-lead plastic package with e-pad rev 1, 06/09 located within the zone indicated. the pin #1 indentifier may b e unless otherwise specified, tolerance : decimal 0.05 tiebar shown (if present) is a non-functional feature. the configuration of the pin #1 identifier is optional, but mus t be between 0.20mm and 0.32mm from the terminal tip. dimension b applies to the metal lized terminal and is measured dimensions in ( ) for reference only. dimensioning and tolerancing conform to amse y14.5m-1994. 6. either a mold or mark feature. 3. 5. 4. 2. dimensions are in millimeters. 1. notes: bottom view detail "x" side view typical recommended land pattern top view (4x) 0.15 index area pin 1 pin #1 index area c seating plane base plane 0.08 see detail "x" c c 5 6 6 a b 0.75 0.05 0.05 0.20 ref package 2.00 3.00 1.80 +0.1/ -0.15 1.65 + 0.1/ -0.15 0.50 0.25 2.20 1.65 1.80 (8x0.25) 3.00 2.00 (8x0.20) (8x0.40) (8x0.40) (6x0.50) outline

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