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lt m8005 1 8005f for more information www.linear.com/ltm8005 typical application features description 38v in boost module regulator for led drive with 10a switch the lt m ? 8005 is a 38v in , 38v out boost module (power micromodule) led driver designed to regulate current or voltage and is ideal for driving leds. the fixed frequency and current mode architecture result in stable operation over a wide range of supply and output voltages. spread spectrum frequency modulation (ssfm) can be activated for improved electromagnetic compatibility (emc) perfor - mance. the ground-referred voltage fb pin serves as the input for several led protection features, and also allows the converter to operate as a constant voltage source. the pwm input provides led dimming ratios of up to 3000: 1, and the ctrl inputs provide additional analog dimming capability. the low profile package enables utilization of unused space on the bottom of pc boards. the ltm8005 is pack - aged in thermally enhanced, compact over-molded ball grid array (bga) package suitable for automated assem - bly by standard surface mount equipment. the ltm8005 is rohs compliant. 350ma at 30.5v to 35.5v led string from 6v to 27v v in (boost) with spread spectrum applications n wide input voltage range: 5v to 38v n supports boost or sepic power topologies n adjustable led current up to 1.6a n 40v 10a internal power switch n wide temperature range: ?40c to 150c n input and output current reporting n internal switch for pwm and output disconnect n internal spread spectrum frequency modulation n 3000:1 true color pwm? dimming n open led protection with openled flag n short-circuit protection and shortled flag n soft-start with programmable fault restart timer n 9mm 11.25mm 2.22mm bga n high power led, high voltage led n accurate current-limited voltage regulators all registered trademarks and trademarks are the property of their respective owners. ltm8005 8005 ta01a en/uvlo ovlo pwm v ref ctrl1 ctrl2 v out isn led aux fb ismon ramp ss vc rt gnd openled shortled ivinp v in ivinn sw da led string c out 2 4.7f 50v l 8.2h l: coilcraft xal7030-822me c in , c out : murata grm31cr71h475ka12 pin not used in this circuit: ivincomp 100k 93.1k 1m 19.1k 4.7k 23.2k f = 350khz 10nf 6.8nf 0.1f 0.1f c in 2 4.7f 50v 12.4k 374k v in 6v to 27v 18.7k
lt m8005 2 8005f for more information www.linear.com/ltm8005 pin configuration absolute maximum ratings v in , en/uvlo, ivinn, ivinp ..................................... 50v isn above led .......................................................... 40v sw, isn, led, v out , vout-da .................................. 40v sw, isn, led, v out , v out ? d a ................. 45v transient ctr l1 , ctr l2 ?????? . .................................. 15v pwm, shortled, openled ................................... 12v fb, ovlo .................................................................... 8v maximum junction temperature (e-grade, i-grade, mp-grade) ....................... ... 125 c maximum junction temperature (h-grade) .......... 150 c storage temperature ............................................. 150 c peak solder reflow body temperature ................. 260 c (note 1) f g h j k e a b c d 2 1 4 3 5 6 7 8 bga package 80-pad (11.25mm 9mm 2.22mm) top view gnd ctrl2 ctrl1 rt ss vc fb gnd bank 5 isn ivinn v in bank 2 sw bank 1 gnd ivinp en/uvlo ivincomp aux ismon bank 6 led bank 4 v out bank 3 da openled shortled ramp pwm v ref ovlo ja = 19.3c/w, jcbottom = 3.0c / w, jctop = 16.3c/w, jb = 7.2c/w, weight = 0.4g values determined per jedec 15-9, 51-12 order information part number terminal finish part marking* package type msl rating temperature range device finish code ltm8005ey#pbf sac305 (rohs) ltm8005 e1 bga 3 ?40c to 125c ltm8005iy#pbf sac305 (rohs) ltm8005 e1 bga 3 ?40c to 125c ltm8005hy#pbf sac305 (rohs) ltm8005 e1 bga 3 ?40c to 150c ltm8005mpy#pbf sac305 (rohs) ltm8005 e1 bga 3 ?55c to 125c consult marketing for parts specified with wider operating temperature ranges. *device temperature grade is identified by a label on the shipping container. pad or ball finish code is per ipc/jedec j-std-609. ? terminal finish part marking: www.linear.com/leadfree ? recommended lga and bga pcb assembly and manufacturing procedures: www.linear.com/umodule/pcbassembly ? lga and bga package and tray drawings: www.linear.com/packaging http://www.linear.com/product/ltm8005#orderinfo
lt m8005 3 8005f for more information www.linear.com/ltm8005 electrical characteristics parameter conditions min typ max units minimum input voltage l 5 v led dc current ctrl1=1.5v ctrl1=0.6v ctrl1=0.2v 1.65 0.8 0.16 a a a sw current limit 10 12 14 a sw r ds(on) 19 m ismon voltage i led =1.5a 0.88 0.96 v quiescent current into v in en/uvlo=0v (disabled), pwm=0v en/uvlo=1.15v, pwm=0v rt =82.5k to gnd, fb=1.5v (not switching) 35 40 3.5 a a ma v ref voltage i ref =?100a l 1.95 2.00 2.08 v v ref line regulation 5v < v in < 48v 0.1 % v ref load regulation ?100a < i ref < 0a 1 % ss current sourcing, ss=0v sinking, i led overcurrent 28 2.8 a a i led overcurrent threshold 2.4 a isn-led r ds(on) 53 m vc output impedance 2000 k vc standby input bias current pwm=0v ?20 20 na vc pin current vc=1.2v, sourcing vc=1.2v, sinking 10 30 a a voltage at fb pin l 1.23 1.25 1.27 v fb amplifier g m 500 s fb pin input bias current current out of pin, fb=v fb 200 na fb openled threshold openled falling 1.176 1.222 v fb overvoltage threshold 1.26 1.34 v fb shortled threshold shortled falling 300 350 mv led current c/10 threshold 0.16 a input current limit threshold ivinp?ivinn 53 67 mv ivincomp voltage ivinp?ivinn=60mv 1.2 v switching frequency rt =82.5k rt =26.1k rt =6.65k 85 240 800 105 300 1000 125 360 1200 khz khz khz switching frequency modulation ramp=2v 70 % ramp input low threshold 1 v ramp input high threshold 2 v ramp pin source current ramp=0.4v 12 a ramp pin sink current ramp=1.6v 12 a ctrl1, ctrl2 pin current ctrl1, ctrl2=1v 200 na pwm input threshold rising 1 v pwm pin bias current 10 a the l denotes the specifications which apply over the specified operating temperature range, otherwise specifications are at t a = 25 c . ctrl1 = ctrl2 = pwm = 5v, unless otherwise noted (note 2).
lt m8005 4 8005f for more information www.linear.com/ltm8005 electrical characteristics parameter conditions min typ max units en/uvlo threshold voltage falling 1.22 v en/uvlo threshold voltage rising 1.24 v en/uvlo pin bias current en/uvlo=1.15v, v in = 12v 19 a openled output low i openled =0.5ma 0.3 v shortled output low i shortled =0.5ma 0.3 v ovlo threshold voltage rising falling 1.21 1.17 1.30 1.26 v v the l denotes the specifications which apply over the specified operating temperature range, otherwise specifications are at t a = 25 c . ctrl1 = ctrl2 = pwm = 5v, unless otherwise noted (note 2). note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: the ltm8005e is guaranteed to meet performance specifications from 0c to 125c internal. specifications over the full ?40c to 125c internal operating temperature range are assured by design, characterization and correlation with statistical process controls. the ltm8005i is guaranteed to meet specifications over the full ?40c to 125c internal operating temperature range. the ltm8005mp is guaranteed to meet specifications over the full ?55c to 125c internal operating temperature range. the ltm8005h is guaranteed to meet specifications over the full ?40c to 150c internal operating temperature range. note that the maximum internal temperature is determined by specific operating conditions in conjunction with board layout, the rated package thermal resistance and other environmental factors. note 3: the ltm8005 contains over-temperature protection that is intended to protect the device during momentary overload conditions. the internal temperature exceeds the maximum operating junction temperature when the over-temperature protection is active. continuous operation above the specified maximum operating junction temperature may impair device reliability.
lt m8005 5 8005f for more information www.linear.com/ltm8005 typical performance characteristics v ref vs load switching frequency vs ss voltage demonstration circuit dc2257a output current ripple 34v at 1.2a led, 12v in dc2257a conducted emi with and without spread spectrum enabled led current vs ctrl1 led current vs ctrl2 led current vs fb (ctrl1=ctrl2=v ref ) t a = 25c, unless otherwise noted. ctrl1 voltage (v) 0 0.25 0.50 0.75 1 1.25 1.50 0 0.4 0.8 1.2 1.6 2.0 led current (a) 8005 g01 ctrl2 voltage (v) 0 0.25 0.50 0.75 1 1.25 1.50 0 0.4 0.8 1.2 1.6 2.0 led current (a) 8005 g02 v fb (v) 0 0.3 0.6 0.9 1.2 1.5 0 0.5 1.0 1.5 2.0 led current (a) 8005 g03 vref vs load current load current (a) 0 45 90 135 180 0 0.5 1.0 1.5 2.0 2.5 v ref (v) 8005 g04 v ss (v) 0 0.3 0.6 0.9 1.2 1.5 r t = 23.2k 0 70 140 210 280 350 frequency (khz) 8005 g05 1s/div current ripple 50ma/div 8005 g06 c ramp = 22nf spread spectrum disabled spread spectrum enabled frequency (mhz) 0.1 1.1 2.1 3.0 4.0 5.0 1 21 41 60 80 100 emissions (dbv) 8005 g07
lt m8005 6 8005f for more information www.linear.com/ltm8005 typical performance characteristics output disconnect response (short circuit) output disconnect response (input > output) dc2257a cispr 22 radiated results without spread spectrum dc2257a cispr 22 radiated results with spread spectrum t a = 25c, unless otherwise noted. 500ns/div v out 10v/div v led 10v/div i led 10a/div 8005 g10 1ms/div v in 10v/div v out 10v/div v led 10v/div 8005 g11 spread spectrum disabled frequency (mhz) 0 250 500 750 1000 0 10 20 30 40 emissions (dbv/m) 8005 g08 spread spectrum enabled frequency (mhz) 0 250 500 750 1000 0 10 20 30 40 emissions (dbv/m) 8005 g09
lt m8005 7 8005f for more information www.linear.com/ltm8005 pin functions gnd (bank 1, pin k1, pin k8): tie these gnd pins to a local ground plane below the ltm8005 and the circuit components. in most applications, the bulk of the heat flow out of the ltm8005 is through these pads, so the printed circuit design has a large impact on the thermal performance of the part. see the pcb layout and thermal considerations sections for more details. return the feed - back divider to this net. sw (bank 2): power switch node. this is the drain of the internal power switching mosfet. for boost, buck-boost mode and buck mode topologies, connect this bank to the inductor and the da bank. for a sepic, connect this bank to an inductor winding and the positive coupling capacitor terminal. da (bank 3): power diode anode. for boost, buck-boost mode and buck mode topologies, connect this bank to the inductor and the sw bank. for a sepic, connect this bank to an inductor winding and the negative coupling capacitor terminal. v out (bank 4): power output pins. apply the output filter capacitor between these pins and the gnd pins. isn (bank 5): output current sense resistor. the ltm8005 incorporates a sense resistor between v out and isn to set the output current regulation point and for output current monitoring. if a larger output current is required, apply an external resistor between v out and isn. keep this pin voltage within 0.3v of v out . led (bank 6): led current output. connect the anode of the led string to this bank. v in (pin f1): input power. the v in pin supplies current to the ltm8005 ? s internal regulators and circuitry, and must be bypassed with a 0.22f (or larger) capacitor placed close to the ltm8005. ivinn (pin f2 ): input sense resistor signal. apply an external sense resistor between ivinp and ivinn to set the maximum input current and for input current moni - toring. if this function is not required, tie both ivinp and ivinn to v in . keep this pin voltage within 0.3v of v in . en/uvlo (pin g1): enable and precision uvlo. an accu - rate 1.22v falling threshold with externally programmable hysteresis detects when power is ok to enable switching. rising hysteresis is generated by the external resistor divider, an internal 499k resistor between en/uvlo and v in and an accurate internal 3a pull-down current. above the threshold, en/uvlo input bias current is sub-a. below the falling threshold, a 3a pull-down current is enabled so the user can optimize the hysteresis with the external resistor selection. an undervoltage condition resets soft-start. the en/uvlo pin may be connected directly to v in , but do not drive this pin directly from another low impedance voltage source. if en/uvlo must be driven from a voltage source, do so with at least a 50 series resistor. ivinp (pin g2 ): input sense resistor signal. apply an external sense resistor between ivinp and ivinn to set the maximum input current and for input current moni - toring. if this function is not required, tie both ivinp and ivinn to v in . keep this pin voltage within 0.3v of v in . ovlo (pin h1 ): input overvoltage lockout pin. an accurate 1.25v rising threshold detects when power is ok to enable switching. if not used, tie this pin to gnd. ivincomp (pin h2 ): input current sense amplifier output pin. the voltage at ivincomp pin is proportional to i in as v ivincomp = i in ? r insns ? 20. a 10nf capacitor to gnd is provided internally at this pin to compensate the input current loop. do not load this pin with a current and do not drive this pin with an external source, although additional capacitance may be added externally. shortled (pin h7 ): an open-collector pull-down on shortled asserts when any of the following conditions happen: 1. fb < 0.3v after ss pin reaches 1.7v at start-up. 2. led overcurrent (i led > 2.4a). to function, the pin requires an external pull-up resistor. shortled status is only updated during pwm high state and latched during pwm low state. shortled remains asserted until the ss pin is discharged below 0.2v. if not used, leave floating or tie to gnd. openled (pin h8 ): fault indicator. an open-collector pull-down on openled asserts if the fb input is above 1.20v (typical), and the led current is less than 0.16a (typical). to function, the pin requires an external pull-up
lt m8005 8 8005f for more information www.linear.com/ltm8005 resistor. openled status is updated only during pwm high state and latched during pwm low state. if not used, leave floating or tie to gnd. ismon (pin j1): led current report pin. the led cur - rent is reported as v ismon = (led current)/1.6. leave the ismon pin unconnected if not used. when pwm is low, ismon is driven to ground. bypass with a 47nf capacitor or higher if needed. do not drive this pin with an external source. aux (pin j2 ): auxiliary pin. this pin is internally con - nected to v out to ease layout. conveniently located next to fb, it is provided to simplify layout of the output voltage feedback network. v ref (pin j6 ): voltage reference output pin. typically 2.015v . this pin drives a resistor divider for the ctrl pins, either for analog dimming or for temperature limit/ compensation of the led load. it can supply up to 100a. do not drive this pin with an external source. pwm (pin j7): pwm input signal pin. a low signal turns off switching, idles the oscillator, disconnects the vc pin from all internal loads, and disconnects the output load from v out . pwm has an internal 500k pull-down resis- tor. if not used, connect to v ref . ramp (pin j8): the ramp pin is used for spread spec- trum frequency modulation. the internal switching fre - quency is spread out to 70% of the original value, where the modulation frequency is set by 12a/(2 ? 1v ? c ramp ). if not used, tie this pin to gnd. fb (pin k2): voltage loop feedback pin. fb is intended for constant-voltage regulation or for led protection/open led detection. the internal transconductance amplifier with output vc regulates fb to 1.25v (nominal) through the dc/dc converter. if the fb input is regulating the loop, and led current is less than 0.15a (typical), the openled pull-down is asserted. this action may signal an open led fault. if fb is driven above 1.3v (by an external power sup - ply spike, for example), the internal n-channel mosfet is turned off and the load is disconnected from v out to protect the leds from an overcurrent event. do not tie this pin to gnd as the shortled will be asserted and the part will be shut down. vc (pin k3 ): transconductance error amplifier output pin. used to stabilize the control loop with an rc network. this pin is high impedance when pwm is low, a feature that stores the demanded current state variable for the next pwm high transition. connect a capacitor between this pin and gnd; a resistor in series with the capacitor is recom - mended for fast transient response. do not leave this pin open, and do not drive this pin with an external source. ss (pin k4): soft-start pin. this pin modulates oscillator frequency and compensation pin voltage (vc). the soft- start interval is set with an external capacitor. the pin has a 28a (typical) pull-up current source to an internal 2.5v rail. this pin can be used as fault timer. provided the ss pin has exceeded 1.7v to complete a blanking period at start-up, the pull-up current source is disabled and a 2.8a pull-down current is enabled when any one of the following fault conditions happen: 1. led overcurrent (i led > 2.4a) 2. output short (fb < 0.3v after start-up) 3. thermal limit the ss pin must be discharged below 0.2v to re-initiate a soft-start cycle. switching is disabled until ss begins to recharge. it is important to select a capacitor large enough that fb can exceed 0.3v under normal load conditions before ss exceeds 1.7v. do not leave this pin open and do not drive this pin with an external source. rt (pin k5 ): switching frequency adjustment pin. set the frequency using a resistor to gnd. do not leave the rt pin open. do not drive this pin with an external source. ctrl1, ctrl2 (pin k6, k7 ): current sense threshold adjustment. ctrl1 and ctrl2 have identical functions. the output current is regulated by ctr l1 or ctr l2 . the pin with the lowest voltage takes precedence. for 0.1v < v ctrlx < 1v the led current is v ctrlx ? 1.5a less an offset. for v ctrlx > 1.2v the current sense threshold is constant at the full-scale value of 1.6a . for 1v< v ctrlx <1.2v , the dependence of the current sense threshold upon v ctrlx transitions from a linear function to a constant value, reaching 98% of full-scale value by v ctrlx = 1.1v . do not leave this pin open. if not used, tie to v ref . connect either ctrl pin to gnd for zero led current. pin functions
lt m8005 9 8005f for more information www.linear.com/ltm8005 block diagram ltm8005 0.068 499k 10nf boost led controller 8005 bd v in en/uvlo v out aux fb isn led ivincomp ismon openled shortled gnd ivinp ivinn sw da ovlo pwm v ref ctrl1 ctrl2 ss ramp rt vc
lt m8005 10 8005f for more information www.linear.com/ltm8005 operation the ltm8005 is a stand-alone non-isolated switching dc/ dc regulator intended for led driver applications. this module power converter provides a regulated current from an input voltage range of 5v to 38v, and up to 38v output. a simplified block diagram is provided in the pre- vious section. the ltm8005 is equipped with a ground referred power switch and a power rectifier. connect external power devices, such as an inductor, to these pins to implement boost, buck-boost mode, buck mode or sepic topologies to drive a string of leds. the ltm8005 features an integrated sense resistor to control the led current. the maximum regulated current is 1.6a , and this can be reduced by applying a voltage less than 1.2v to the ctrl1 or ctrl2 pins. the output current is reported by the voltage on the ismon pin. the ltm8005 also features an integrated pmos discon - nect switch to implement pwm dimming that is controlled by a signal on the pwm pin. the pmos also disconnects the leds during fault conditions. if input current limiting is desired, apply an external sense resistor to the ivinp and ivinn pins. the full input current will flow through this external sense resistor, so choose a resistor with an appropriate power rating. the ltm8005 will start to decrease the power if the voltage between the ivinp and invinn pins exceeds 60mv. a 10nf capacitor is provided internally to compensate the input current regulation loop, but additional capacitance may be added externally to further filter the voltage at the ivincomp pin. the ltm8005 features spread spectrum frequency modulation, which causes the switching frequency to modulate to a frequency that is approximately 70% of the programmed value set by the rt resistor. this modu - lation decreases the energy emitted at a single frequency, reducing the emi amplitude. the modulation behavior is set by a capacitor on the ramp pin to gnd. input voltage turn-on and turn-off thresholds are set by resistor networks at the en/uvlo and ovlo pins. applying a voltage of greater than 1.24v to the en/uvlo pin enables the part. openled and shortled are active low open drain sta - tus bits that indicate an open led or shorted led condi - tion. openled transitions to a logic low when the fb pin rises above 1.2v and the led current decreases below 160ma . shortled transitions to a logic low when the fb pin falls below 300mv or the led current exceeds 2.4a. further details on these and other functions are given in the applications information section. an external soft start capacitor at the ss pin minimizes the current spike that occurs at start up and the ss pin also programs hiccup or latchoff mode fault protection. the ltm8005 is equipped with a thermal shutdown that inhibits power switching at high junction temperatures. the activation threshold of this function is above the abso - lute maximum temperature rating to avoid interfering with normal operation, so prolonged or repetitive operation under a condition in which the thermal shutdown activates may damage or impair the reliability of the device.
lt m8005 11 8005f for more information www.linear.com/ltm8005 programming the turn-on and turn-off thresholds with the en/uvlo pin the falling under-voltage lockout (uvlo) value can be accurately set by the resistor divider, as shown in figure1. a small 3a pull-down current is active when en/uvlo is below the threshold. the purpose of this current is to allow the user to program the rising hysteresis. the fol - lowing equations should be used to determine the values of the resistors: v in(falling) = 1.22 ? r1 ? 499k + r2 r2 v in(rising) = v in(falling) + (3a ? r1 ! ltm8005 8005 f01 v in v in en/uvlo r1 499k r2 figure1. set an accurate uvlo with a resistor divider programming the overvoltage lockout threshold with the ovlo pin the input overvoltage lockout protection feature can be implemented by a resistor from the v in to ovlo pins as shown in figure2. the following equations should be used to determine the values of the resistors: v in,ovlo = 1.25 ? r3 + r4 r4 ltm8005 ovlo v in r3 r4 8005 f02 figure2. set an overvoltage lockout threshold with a resistive divider applications information led current adjustment the maximum output led current is internally set to 1.6a , typical. if both ctrl pins are tied to a voltage higher than 1.2v, maximum current is available. if a voltage less than 1.2v is applied to either ctrl1 or ctrl2 , the led current will decrease. the two ctrl pins have identical func - tions. whichever is the lowest takes precedence. either ctrl pin can also be used to dim the led current to zero, although relative accuracy decreases with the decreasing applied voltage sense threshold. the ctrl pins should not be left open (tie to v ref if not used). either ctrl pin can also be used in conjunction with a thermistor to provide overtemperature protection for the led load, or with a resistor divider to v in to reduce output power and switching current when v in is low. internal power switch voltage stress the ltm8005 is equipped with an integrated ground referred n-channel power mosfet whose drain is con - nected to the sw bank. the absolute maximum rating of the sw bank is 40v continuous, 45v transient. when using the ltm8005 in a boost power topology, the voltage stress on the sw bank is nominally a diode drop above v out . in the sepic or buck-boost topologies, however, the voltage stress on the sw bank is substantially higher than v out , nominally v in + v out . do not exceed the absolute maximum voltage of the sw bank under any operating condition. programming output voltage (constant-voltage regulation) and output voltage open led and shorted led thresholds the ltm8005 has a voltage feedback pin fb that can be used to program a constant-voltage output. in addition, fb programming determines the output voltage that will cause openled and shortled to assert. for a boost
lt m8005 12 8005f for more information www.linear.com/ltm8005 applications information led driver, the output voltage can be programmed by selecting the values of r5 and r6 (see figure3) according to the following equation: v out = 1.25 ? r5 + r6 r6 ltm8005 fb v out r5 r6 8005 f03 figure3. set the openled and shortled voltage thresholds with two resistors for a led driver in buck-boost mode or buck mode con- figuration, the fb voltage is typically level shifted to a signal with respect to gnd as illustrated in figure4. the output can be expressed as: v out = 1.25 ? r7 r8 + v be(q1) ltm8005 fb r7 q1 r sense r8 8005 f04 led array v out + ? figure4. level shifting the fb voltage is commonly used in buck-boost mode or buck mode configurations if the open led clamp voltage is programmed correctly using the resistor divider, then the fb pin should never exceed 1.2v when leds are connected. to detect both open-circuit and short-circuit conditions at the output, the ltm8005 monitors both output voltage and current. when fb exceeds 1.2v , openled is asserted if the out- put current is less than about 160ma. openled is de- asserted when the output current increases above about 0.45a or fb drops below 1.19v (typical). the shortled pin is asserted if the output current is about 2.4a or the fb pin falls below 300mv (typical) after initial start-up and ss reaches about 1.7v. the ratio between the fb openled threshold of 1.2v and the shortled threshold of 0.3v can limit the range of v out . the range of v out using the maximum shortled threshold of 0.35v is about 3.5:1. the range of v out can be made wider using the circuits shown in figure5 and figure6. for a v out range that is greater than 8:1, consult factory applications. ltm8005 fb v out v ref r10 r12 r11 8005 f05 figure5. feedback resistor connection for wide range output in boost and sepic applications v ref r15 ltm8005 fb r13 q1 r sense r14 8005 f06 led array v out + ? figure6. feedback resistor connection for wide range output in buck-boost mode or buck mode applications the equations to widen the range of v out are derived using a shortled threshold of 0.35v , an openled threshold of 1.2v and a reference voltage v ref of 2v. the resistor values for r11 and r12 in figure5 can be calculated as shown below. see the example that follows for a suggested r10 value. r11 = 1.7 ? r10 1.65 ? v outmax ( ) ? 0.8 ? v outmin ( ) ? 1.7 r12 = 1.7 ? r10 0.35 ? v outmax ( ) ? 1.2 ? v outmin ( )
lt m8005 13 8005f for more information www.linear.com/ltm8005 applications information example: calculate the resistor values required to increase the v out range of a boost led driver to 7.5:1 and have openled occur when v out is 38v: step 1: choose r10 = 374k step 2: v outmin = 38/7.5 = 5.1 step 3: r11 = 1.7 ? 374k ? 1.65 ? 38 ( ) ? 0.8 ? 5.1 ( ) ? 1.7 = 11.2k ? use r11 = 11.3k. r12 = 1.7 ? 374k ? 0.35 ? 38 ( ) ? 1.2 ? 5.1 ( ) = 88.6k ? use r12 = 88.7k. the resistor values for r14 and r15 in figure6 can be calculated as shown below. see the example that follows for a suggested r13 value. r14 = 1.7 ? r13 1.65 ? v outmax ( ) ? 0.8 ? v outmin ( ) ? 0.85 ? v be(q1) ( ) r15 = 1.7 ? r13 0.35 ? v outmax ( ) ? 1.2 ? v outmin ( ) ? 0.85 ? v be(q1) ( ) = 1.7 ? 187k ? 1.65 ? 17 ( ) ? 0.8 ? 3.4 ( ) ? 0.85 ? 0.7 ( ) = 12.9k ? use r14 = 12.7k r15 = 1.7 ? 187k ? 0.35 ? 17 ( ) ? 1.2 ? 3.4 ( ) ? 0.85 ? 0.7 ( ) = 249k ? use r15 = 249k led overcurrent protection feature the ltm8005 has an overload protection feature inde - pendent of the output led current regulation. this feature prevents the development of excessive switching currents and protects the power components. the overload protec - tion threshold (2.4a typical) is designed to be 50% higher than the default led current sense threshold. once the led overcurrent is detected, the internal power switch is turned off to stop switching, the pwm mosfet is turned off to disconnect the led array from the power path, and fault protection is initiated via the ss pin. an anti-parallel schottky or ultrafast diode d2 should be connected as shown in figure7 to protect the led node from swinging well below ground when being shorted to ground through a long cable. the internal protection loop takes a finite amount of time to respond to the overload, so the diode is recommended if the system must survive an overload on the led string. ltm8005 led gnd d2 8005 f07 led string parasitic inductance of long cable figure7. connect an anti-parallel diode d2 from led to gnd to protect the ltm8005 from negative voltage swings when the connecting to a led string through a long cable
lt m8005 14 8005f for more information www.linear.com/ltm8005 applications information pwm dimming control for brightness there are two methods to control the led current for dimming using the ltm8005 . one method uses the ctrl pins to adjust the current regulated in the leds. a sec- ond method uses the pwm pin to modulate the led cur - rent between zero and full current to achieve a precisely programmed average current, without the possibility of color shift that occurs at low current in leds. to make pwm dimming more accurate, the switch demand cur - rent is stored on the vc node during the quiescent phase when pwm is low. this feature minimizes recovery time when the pwm signal goes high. to further improve the recovery time, a disconnect mosfet switch has been implemented to open the led current path to prevent the output capacitor from discharging during the pwm signal low phase. the minimum pwm on or off time depends on the choice of operating frequency set by the rt input. for best current accuracy, the minimum recommended pwm high time should be at least three switching cycles (3s for f sw = 1mhz). a low duty cycle pwm signal can cause excessive start-up times if it is allowed to interrupt the soft-start sequence. therefore, once start-up is initiated by a pwm signal, the ltm8005 will ignore a logical disable by the external pwm input signal. the device will continue to soft-start with switching and tg enabled until either the voltage at ss reaches about 1v or the output current reaches one-fourth of the full-scale current. at this point the device will begin following the dimming control as designated by pwm. if at any time an output overcurrent is detected, the internal mosfets will be disabled even as ss continues to charge. programming the switching frequency the rt frequency adjust pin allows the user to program the switching frequency from 100khz to 1mhz to opti - mize efficiency/performance or external component size. higher frequency operation yields smaller component size but increases switching losses and gate driving cur - rent, and may not allow sufficiently high or low duty cycle operation. lower frequency operation gives better perfor - mance at the cost of larger external component size. for an appropriate rt resistor value see table 1. an external resistor from the rt pin to gnd is required ? do not leave this pin open. table1. typical switching frequency vs r t value (1% resistor) f osc (khz) r t (k) 1000 6.65 900 7.50 800 8.87 700 10.2 600 12.4 500 15.4 400 19.6 300 26.1 200 39.2 100 82.5 spread spectrum frequency modulation switching regulators can be particularly troublesome for applications where electromagnetic interference (emi) is a concern. to improve the emi performance, the ltm8005 includes a spread spectrum frequency fea - ture. if there is a capacitor (c ramp ) at the ramp pin, a triangle wave sweeping between about 1v and 2v is gen- erated. this signal is then fed into the internal oscillator to modulate the switching frequency between about 70% of the base frequency and the base frequency, which is set by the rt resistor. the modulation frequency is set by 12a/(2 ? c ramp ). the results of emi measurements are sensitive to the ramp frequency selected with the capacitor. 1khz is a good starting point to optimize peak measurements, but some fine tuning of this selection may be necessary to get the best overall emi results in a particular system. consult factory applications for more detailed information about emi reduction. the typical performance characteristics section contains plots that show the ltm8005 conducted and radiated emissions with and without spread spectrum enabled.
lt m8005 15 8005f for more information www.linear.com/ltm8005 applications information duty cycle considerations switching duty cycle is a key variable defining converter operation; therefore, its limits must be considered when programming the switching frequency for a particular application. the fixed minimum on-time and minimum off-time and the switching frequency define the minimum and maximum duty cycle of the switch, respectively. when calculating operating limits, use typical room temperature values of 320ns and 290ns for minimum on-time and off-time, respectively. setting input current limit the ltm8005 has a standalone input current sense ampli - fier to limit the input current. the input current i in shown in figure8 is converted to a voltage output at the ivincomp pin. when the ivincomp voltage exceeds 1.2v the inter - nal power switch is turned off, and the converter stops switching. the input current limit is calculated as follows: i in = 60mv r insns the isp/isn regulation loop, which consists of the output capacitance c out and the dynamic resistance of the led load. the minimum c filt value of 10nf is integrated into the ltm8005. loop compensation the lt m8005 uses an internal transconductance error amplifier whose vc output compensates the control loop. the external inductor, output capacitor and the compen - sation resistor and capacitor determine the loop stability. the inductor and output capacitor are chosen based on performance, size and cost. the compensation resistor and capacitor at vc are selected to optimize control loop response and stability. for typical led applications, a 10nf compensation capacitor at vc is adequate, and a series resistor should always be used to increase the slew rate on the vc pin to maintain tighter regulation of led current during fast transients on the input supply to the converter. soft-start capacitor selection for many applications, it is important to minimize the inrush current at start-up. the ltm8005 soft-start cir - cuit significantly reduces the start-up current spike and output voltage overshoot. the soft-start interval is set by the soft-start capacitor (c ss ) selection according to the equation: t ss = c ss ? 2v / 28a a typical value for the soft-start capacitor is 0.1f. the soft-start pin voltage reduces the oscillator frequency and the maximum current in the switch. soft-start also oper - ates as fault protection, which forces the converter into hiccup or latchoff mode. detailed information is provided in the fault protection: hiccup mode and latchoff mode section. fault protection: hiccup mode and latchoff mode if an led overcurrent condition, internal intv cc under - voltage, output short (fb 0.3v), or thermal limit hap - pens, the integrated pmos disconnect switch disconnects the led array from the power path, and the integrated power switching mosfet is turned off. if the soft-start pin is charging and still below 1.7v, then it will continue figure8. apply a current sense resistor between ivinp and ivinn to limit input current filter capacitor c filt shown in figure8 filters the voltage at the ivincomp pin to minimize ripple due to the input current. c filt also compensates the input current regula- tion loop, and is selected based on the loop response in addition to the intended voltage ripple on ivincomp. the ivincomp pin resistance to ground and c filt form a second pole in the input current regulation loop in addi - tion to the dominant pole at vc pin. suggested values for c filt of 10nf to 0.1f will usually provide a second pole in the input current regulation loop that results in stable loop response and is equivalent to the second pole in ltm8005 ivinp ivinn ivincomp 8005 f08 to load r insns i in v in c filt
lt m8005 16 8005f for more information www.linear.com/ltm8005 applications information to do so with a 28a source. once above 1.7v, the pull- up source is disabled and a discharge current of about 2.8a is activated. while the ss pin is discharging, the integrated switching mosfet is turned off. when the ss pin is discharged below about 0.2v , a new cycle is initiated. this is hiccup mode operation. if the fault still exists when ss crosses below about 0.2v, then a full ss charge/discharge cycle has to complete before switching is enabled. if a resistor, typically 402k, is placed between the v ref pin and ss pin to hold ss pin higher than 0.2v during a fault, then the ltm8005 will enter latchoff mode with switching stopped and the load disconnected from v out . to exit latchoff mode, the en/uvlo pin must be toggled low to high. capacitor selection considerations ceramic capacitors are small, robust and have very low esr. however, not all ceramic capacitors are suitable. x5r and x7r types are stable over temperature and applied voltage and give dependable service. other types, includ - ing y5v and z5u have very large temperature and voltage coefficients of capacitance. in an application circuit they may have only a small fraction of their nominal capaci - tance resulting in much higher output voltage ripple than expected. another precaution regarding ceramic capacitors con - cerns the maximum input voltage rating of the ltm8005. a ceramic input capacitor combined with trace or cable inductance forms a high q (under damped) tank circuit. if the ltm8005 circuit is plugged into a live supply, the input voltage can ring to twice its nominal value, possi - bly exceeding the device?s rating. this situation is easily avoided; see the hot-plugging safely section. input capacitor selection the input capacitor supplies the transient input current for the power inductor of the converter and must be placed and sized according to the transient current require - ments. the switching frequency, output current and tol - erable input voltage ripple are key inputs to estimating the capacitor value. an x7r type ceramic capacitor is a good choice because it has the least variation with tem- perature and dc bias. typically, boost and sepic con - verters require a lower value capacitor than a buck mode converter. in the buck mode configuration, the input capacitor has large pulsed currents due to the current returned through the schottky diode when the switch is off. it is important to place the capacitor as close as possible to the schottky diode and to the gnd return of the switch. it is also impor - tant to consider the ripple current rating of the capacitor. for best reliability, this capacitor should have low esr and esl and have an adequate ripple current rating. output capacitor selection the selection of the output capacitor depends on the load and converter configuration, i.e., step-up or step-down and the operating frequency. for led applications, the equivalent resistance of the led is typically low and the output filter capacitor should be sized to attenuate the cur - rent ripple. use of an x5r or x7r type ceramic capacitor is recommended. to achieve the same led ripple current, the required fil - ter capacitor is larger in the boost and buck-boost mode applications than that in the buck mode applications. lower operating frequencies will require proportionately higher capacitor values. the component values shown in the data sheet applications are appropriate to drive the specified led string. the product of the output capacitor and led string impedance decides the second dominant pole in the led current regulation loop. it is prudent to validate the power supply with the actual load (or loads). inductor selection the inductor used with the ltm8005 should have a satu - ration current rating appropriate to the peak inductor cur - rent under all expected operating conditions. choose an inductor value based on operating frequency to provide a peak-to-peak inductor ripple current appropriate to the 12a (typical) switch current limit and duty cycle.
lt m8005 17 8005f for more information www.linear.com/ltm8005 applications information pcb layout most of the headaches associated with pcb layout have been alleviated or even eliminated by the high level of integration of the ltm8005. the ltm8005 is neverthe - less a switching power supply, and care must be taken to minimize emi and ensure proper operation. even with the high level of integration, you may fail to achieve specified operation with a haphazard or poor layout. see figure 9 for the suggested layout of a boost topology application and figure 10 for the suggested layout of a buck-boost mode topology application. ensure that the grounding and heat sinking are acceptable. a few rules to keep in mind are: 1. place the r fb , r t and v c components as close as possible to their respective pins. 2. place the c in capacitors as close as possible to the v in and gnd connection of the ltm8005. 3. place the c out capacitors as close as possible to the v out and gnd connection of the ltm8005. 4. place the c in and c out capacitors such that their ground currents flow directly adjacent to or under - neath the ltm8005. figure9. layout showing suggested external components, gnd plane and thermal vias for a boost application 8005 f09 (optional diode) ctrl2 ctrl1 rt ss vc fb gnd gnd gnd/thermal vias isn v in sw ivinp en/uvlo aux v out c in c out openled shortled ramp pwm v ref ivinn v in ovlo gnd to led string to led string cathode (boost) led
lt m8005 18 8005f for more information www.linear.com/ltm8005 8005 f10 ctrl2 ctrl1 rt ss vc fb gnd gnd gnd gnd/thermal vias isn v in sw aux v out c in c led c out openled shortled ramp pwm v ref ovlo gnd to led string to led string cathode (boost) gnd (optional diode) ivinp en/uvlo ivinn v in led applications information figure10. layout showing suggested external components, gnd plane and thermal vias for a buck-boost mode application 5. connect all of the gnd connections to as large a cop - per pour or plane area as possible on the top layer. avoid breaking the ground connection between the external components and the ltm8005. 6. use vias to connect the gnd copper area to the board? s internal ground planes. liberally distribute these gnd vias to provide both a good ground con - nection and thermal path to the internal planes of the printed circuit board. pay attention to the location and density of the thermal vias in figures 9 and 10. the ltm8005 can benefit from the heat sinking afforded by vias that connect to internal gnd planes at these locations, due to their proximity to internal power handling components. the optimum number of thermal vias depends upon the printed circuit board design. for example, a board might use very small via holes. it should employ more thermal vias than a board that uses larger holes.
lt m8005 19 8005f for more information www.linear.com/ltm8005 applications information hot-plugging safely the small size, robustness and low impedance of ceramic capacitors make them an attractive option for the input bypass capacitor of the ltm8005 . however, these capaci - tors can cause problems if the ltm8005 is plugged into a live supply (see analog devices application note 88 for a complete discussion). the low loss ceramic capaci - tor combined with stray inductance in series with the power source forms an underdamped tank circuit, and the voltage at the v in pin of the ltm8005 can ring to more than twice the nominal input voltage, possibly exceeding the ltm8005?s rating and damaging the part. if the input supply is poorly controlled or the ltm8005 is hot-plugged into an energized supply, the input network should be designed to prevent this overshoot. this can be accomplished by installing a small resistor in series to v in , but the most popular method of controlling input voltage overshoot is to add an electrolytic bulk cap to the v in net. this capacitor?s relatively high equivalent series resistance damps the circuit and eliminates the voltage overshoot. the extra capacitor improves low frequency ripple filtering and can slightly improve the efficiency of the circuit, though it is likely to be the largest component in the circuit. thermal considerations the ltm8005 output current may need to be derated if it is required to operate in a high ambient temperature or deliver a large amount of continuous power. the amount of current derating is dependent upon the input voltage, output power and ambient temperature. it is incumbent upon the user to verify proper operation over the intended system?s line, load and environmental operating conditions. the thermal resistance numbers listed in page 2 of the data sheet are based on modeling the module package mounted on a test board specified per jesd51-9 ( ?test boards for area array surface mount package thermal measurements ? ). the thermal coefficients provided in this page are based on jesd 51-12 (? guidelines for reporting and using electronic package thermal information?). for increased accuracy and fidelity to the actual applica - tion, many designers use fea to predict thermal perfor - mance. to that end, page 2 of the data sheet typically gives four thermal coefficients: ja ? thermal resistance from junction to ambient jcbottom ? thermal resistance from junction to the bot- tom of the product case jctop ? thermal resistance from junction to top of the product case jb ? thermal resistance from junction to the printed cir - cuit board. while the meaning of each of these coefficients may seem to be intuitive, jedec has defined each to avoid confusion and inconsistency. these definitions are given in jesd 51-12, and are quoted or paraphrased below: ja is the natural convection junction-to-ambient air thermal resistance measured in a one cubic foot sealed enclosure. this environment is sometimes referred to as ? still air? although natural convection causes the air to move. this value is determined with the part mounted to a jesd 51-9 defined test board, which does not reflect an actual application or viable operating condition. jcbottom is the thermal resistance between the junction and bottom of the package with all of the component power dissipation flowing through the bottom of the package. in the typical module con - verter, the bulk of the heat flows out the bottom of the package, but there is always heat flow out into the ambient environment. as a result, this thermal resistance value may be useful for comparing pack - ages but the test conditions don? t generally match the user?s application.
lt m8005 20 8005f for more information www.linear.com/ltm8005 applications information junction-to-board resistance junction-to-case (bottom) resistance case(bottom)-to-board resistance junction-to-case (top) resistance case(top)-to-board resistance board-to-ambient resistance junction junction-to-ambient resistance (jesd 51-9 defined board) module converter ambient 8005 f11 figure11. jctop is determined with nearly all of the compo - nent power dissipation flowing through the top of the package. as the electrical connections of the typical module converter are on the bottom of the package, it is rare for an application to operate such that most of the heat flows from the junction to the top of the part. as in the case of jcbottom , this value may be useful for comparing packages but the test conditions don?t generally match the user?s application. jb is the junction-to-board thermal resistance where almost all of the heat flows through the bottom of the module converter and into the board, and is really the sum of the jcbottom and the thermal resistance of the bottom of the part through the solder joints and through a portion of the board. the board tem - perature is measured a specified distance from the package, using a two sided, two layer board. this board is described in jesd 51-9. given these definitions, it should now be apparent that none of these thermal coefficients reflects an actual physical operating condition of a module converter. thus, none of them can be individually used to accurately predict the thermal performance of the product. the only appropriate way to use the coefficients is when running a detailed thermal analysis, such as fea, which considers all of the thermal resistances simultaneously. a graphical representation of these thermal resistances is given in figure11. the blue resistances are contained within the module converter, and the green are outside. the die temperature of the ltm8005 must be lower than the maximum rating of 150c, so care should be taken in the layout of the circuit to ensure good heat sinking of the ltm8005. the bulk of the heat flow out of the ltm8005 is through the bottom of the module converter and the bga pads into the printed circuit board. consequently a poor printed circuit board design can cause excessive heating, resulting in impaired performance or reliability. please refer to the pcb layout section for printed circuit board design suggestions.
lt m8005 21 8005f for more information www.linear.com/ltm8005 typical applications 1.2a at up to 17v led string from 6v to 18v in (buck-boost mode) with spread spectrum ltm8005 8005 ta02 en/uvlo ovlo pwm v ref ctrl1 ctrl2 v out isn led aux fb ismon ramp ss vc rt gnd openled shortled ivinpv in ivinn sw da c out 2 10f 50v l 10h l: coilcraft xal8080-103me c in : murata grm31cr71e106ka12 c out : murata grm32er71h106ka12 pin not used in this circuit: ivincomp 100k 113k 1m 2.4k 23.2k f = 350khz 10nf 6.8nf 0.1f 0.1f c in 2 10f 25v 21.5k 348k led string v in 6v to 18v 73.2k (optional ultra-fast diode if led string is far away) v in 6v in to 31v in to 36v out boost regulator ltm8005 8005 ta03 en/uvlo ovlo pwm v ref ctrl1 ctrl2 ivincomp v out isn led aux fb ismon ramp ss vc rt gnd openled shortled ivinpv in ivinn sw da c out 3 4.7f 50v c out2 56f v out 36v l 4.7h r sense 7m c in , c out1 : murata grm31cr71h475ka12 c out2 : suncon 50hvp56m l: xal8080-472meb r sense : venkel ulcr2512-7m00jt 95.3k 16.9k 1m 10k 31.6k f = 250khz 22nf 0.1f 0.22f c in 3 4.7f 50v 12.4k 348k v in 6v to 31v 38v max. 33v ovlo +
lt m8005 22 8005f for more information www.linear.com/ltm8005 typical applications 6v in to 24v in to 12v out sepic with current limit ltm8005 8005 ta04 en/uvlo ovlo pwm v ref ctrl1 ctrl2 ivincomp v out isn led aux fb ismon ramp ss vc rt gnd openled shortled ivinpv in ivinn sw da c out1 4 22f 16v c out2 150f v out 12v 3.56a current limit 90.9k 21.5k 1m 5.1k 31.6k f = 250khz 10nf 0.1f 0.1f c in 4 4.7f 50v 12.4k 107k r sense1 60m v in 6v to 24v 38v max. 26v ovlo + ? ? l1a 4.4h l1b 4.4h c coup 3 22f 16v r sense2 10m c in : murata grm31cr71h475ka12 c out1 , c coup : murata grm32er61c226ke20l c out2 : suncon 25hvh150m l1: wurth 74485540440 r sense1 : vishay wsl2010r0600fea18 r sense2 : venkel ulcr2512-10m0jt
lt m8005 23 8005f for more information www.linear.com/ltm8005 package description table2. ltm8005 pinout (sorted by pin number) pin name pin name pin name pin name pin name a1 sw b1 sw c1 sw d1 gnd e1 gnd a2 sw b2 sw c2 sw d2 gnd e2 gnd a3 sw b3 sw c3 sw d3 gnd e3 gnd a4 sw b4 sw c4 sw d4 gnd e4 gnd a5 da b5 da c5 da d5 gnd e5 gnd a6 da b6 da c6 da d6 gnd e6 gnd a7 v out b7 v out c7 v out d7 gnd e7 gnd a8 v out b8 v out c8 v out d8 gnd e8 gnd pin name pin name pin name pin name pin name f1 v in g1 en/uvlo h1 ovlo j1 ismon k1 gnd f2 ivinn g2 ivinp h2 ivincomp j2 aux k2 fb f3 gnd g3 gnd h3 gnd j3 gnd k3 vc f4 gnd g4 gnd h4 gnd j4 gnd k4 ss f5 gnd g5 gnd h5 gnd j5 gnd k5 rt f6 isn g6 led h6 gnd j6 v ref k6 ctrl1 f7 isn g7 led h7 shortled j7 pwm k7 ctrl2 f8 isn g8 led h8 openled j8 ramp k8 gnd
lt m8005 24 8005f for more information www.linear.com/ltm8005 package photo
lt m8005 25 8005f for more information www.linear.com/ltm8005 information furnished by analog devices is believed to be accurate and reliable. however, no responsibility is assumed by analog devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. specifications subject to change without notice. no license is granted by implication or otherwise under any patent or patent rights of analog devices. 5. primary datum -z- is seating plane 6. solder ball composition is 96.5% sn/3.0% ag/0.5% cu 7 package row and column labeling may vary among module products. review each package layout carefully ! notes: 1. dimensioning and tolerancing per asme y14.5m-1994 2. all dimensions are in millimeters ball designation per jesd ms-028 and jep95 4 3 details of pin #1 identifier are optional, but must be located within the zone indicated. the pin #1 identifier may be either a mold or marked feature package top view 4 pin ?a1? corner x y aaa z aaa z package bottom view 3 see notes suggested pcb layout top view bga 80 0514 rev ? ltmxxxxxx module tray pin 1 bevel package in tray loading orientation component pin ?a1? detail a pin 1 0.000 0.5 0.5 1.5 1.5 2.5 2.5 3.5 3.5 4.5 3.5 2.5 1.5 0.5 0.5 1.5 2.5 3.5 4.5 0.000 detail a ?b (80 places) f g h j k e a b c d 2 1 4 3 5678 d a detail b package side view z m x yzddd m zeee 0.40 0.025 ? 80x e b e e b a2 f g bga package 80-lead (11.25mm 9mm 2.22mm) (reference ltc dwg # 05-08-1979 rev ?) symbol a a1 a2 b b1 d e e f g h1 h2 aaa bbb ccc ddd eee min 2.07 0.35 1.72 0.45 0.35 0.27 1.45 nom 2.22 0.40 1.82 0.50 0.40 11.25 9.00 1.00 9.00 7.00 0.32 1.50 max 2.37 0.45 1.92 0.55 0.45 0.37 1.55 0.15 0.10 0.20 0.30 0.15 notes dimensions total number of balls: 80 detail b substrate a1 b1 ccc z mold cap // bbb z z h2 h1 7 see notes
please refer to http://www.linear.com/product/ltm8005#packaging for the most recent package drawings.
lt m8005 26 8005f for more information www.linear.com/ltm8005 lt 0218 ? printed in usa www.linear.com/ltm8005 analog devices, inc. 2018 related parts typical application part number description comments lt3795 110v, led driver controller ic 4.5v < v in < 100v. external power switch, diode, current sense resister ltm8040 step-down module led driver 4v < v in <36v, i led < 1a ltm8042/ ltm8042-1 boost module driver with lower led current and built-in inductor 3v < v in <30v (40v transient). i led < 1a(ltm8042), i led < 350ma (ltm8042-1) LTM8006 boost led driver with 75v internal power switch 4.5v < v in < 38v, i led < 1.6a ltm8055 36v in , 36v out , buck-boost module regulator 5v < v in < 36v, 1.2v < v out < 36v, i out < 8.5a ltm8056 58v in , 48v out , buck-boost module regulator 5v < v in <58v, 1.2v < v out < 48v, i out < 5.4a design resources subject description module design and manufacturing resources design: ? selector guides ? demo boards and gerber files ? free simulation tools manufacturing: ? quick start guide ? pcb design, assembly and manufacturing guidelines ? package and board level reliability module regulator products search 1. sort table of products by parameters and download the result as a spread sheet. 2. search using the quick power search parametric table. techclip videos quick videos detailing how to bench test electrical and thermal performance of module products. digital power system management analog devices?s family of digital power supply management ics are highly integrated solutions that offer essential functions, including power supply monitoring, supervision, margining and sequencing, and feature eeprom for storing user configurations and fault logging. ltm8005 8005 ta05 en/uvlo ovlo pwm v ref ctrl1 ctrl2 v out isn led aux fb ismon ramp ss vc rt gnd openled shortled ivinp v in ivinn sw da led string c out 3 4.7f 50v l 10h l: coilcraft xal8080-103me c in , c out : murata grm31cr71h475ka12 pin not used in this circuit: ivincomp pwm (optional clamping diode if led string is far away) 100k 93.1k 1m 19.1k 1.5k 23.2k f = 350khz 22nf 0.1f 0.1f c in 2 4.7f 50v 12.4k 374k v in 6v to 27v 73.2k 1.2a at 35v led string from 6v to 27v in (boost) with pwm dimming

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