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is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 1 ? rev. a, 06/24/2016 ? 10-to-150ma constant-current led driver for automotive jun 2016 general description the is32lt3170 and IS32LT3171 are adjustable linear current devices with excellent temperature stability. a single resistor is all that is required to set the operating current from 10ma to 150ma. the devices can operate from an input voltage from 2.5v to 42v with a minimal voltage headroom of 1v (typical). designed with a low dropout voltage; the device can drive led strings close to the supply voltage without switch capacitors or inductors. the is32lt3170/71 simplifies designs by providing a stable current without the additional requirement of input or output capacitors, inductors, fets or diodes. the complete constant current driver requires only a current set resistor and a small pcb area making designs both efficient and cost effective. the en pin (1) of the is32lt3170 can be tied to vbat or bcm pwm signal for high side dimming. the en pin (1) of the IS32LT3171 can function as the pwm signal input used for low side dimming. as a current sink it is ideal for led lighting applications or current limiter for power supplies. the device is provided in a lead (pb) free, sot23-6 package. features ? low-side current sink - current preset to 10ma - adjustable from 10ma to 150ma with external resistor selection ? wide input voltage range from - 2.5v to 42v (IS32LT3171) - 5v to 42v (is32lt3170) with a low dropout of typical 1v ? up to 10khz pwm input (IS32LT3171 only) ? protection features: - 0.26%/k negative temperature coefficient at high temp for thermal protection ? up to 1w power dissipation in a small sot23-6 package ? rohs compliant (pb-free) package ? automotive aec-q100 qualified applications ? automotive and avionic lighting ? architectural led lighting ? channel letters for advertising, led strips for decorative lighting ? retail lighting in fridge, freezer case and vending machines ? emergency lighting (e.g. steps lighting, exit way sign etc.) typical application circuit figure 1 typical application circuit
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 2 ? rev. a, 06/24/2016 ? pin configuration package pin configuration (top view) sot23-6 pin description no. pin description 1 en enable pin (pwm input IS32LT3171 only). 2,3,5 out current sink. 4 gnd ground. 6 rext optional current adjust.
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 3 ? rev. a, 06/24/2016 ? ordering information automotive range: -40c to +125c order part no. package qty/reel is32lt3170-stla3-tr IS32LT3171-stla3-tr sot-23-6, lead-free 3000 copyright ? ? ? 2016 ? integrated ? silicon ? solution, ? inc. ? all ? rights ? reserved. ? issi ? reserves ? the ? right ? to ? make ? changes ? to ? this ? specification ? and ? its ? products ? at ? any ? time ? without ? notice. ? issi ? assumes ? no ? liability ? arising ? out ? of ? the ? application ? or ? use ? of ? any ? information, ? products ? or ? services ? described ? herein. ? customers ? are ? advised ? to ? obtain ? the ? latest ? version ? of ? this ? device ? specification ? before ? relying ? on ? any ? published ? information ? and ? before ? placing ? orders ? for ? products. ? integrated ? silicon ? solution, ? inc. ? does ? not ? recommend ? the ? use ? of ? any ? of ? its ? products ? in ? life ? support ? applications ? where ? the ? failure ? or ? malfunction ? of ? the ? product ? can ? reasonably ? be ? expected ? to ? cause ? failure ? of ? the ? life ? support ? system ? or ? to ? significantly ? affect ? its ? safety ? or ? effectiveness. ? products ? are ? not ? authorized ? for ? use ? in ? such ? applications ? unless ? integrated ? silicon ? solution, ? inc. ? receives ? written ? assurance ? to ? its ? satisfaction, ? that: ? a.) ? the ? risk ? of ? injury ? or ? damage ? has ? been ? minimized; ? b.) ? the ? user ? assume ? all ? such ? risks; ? and ? c.) ? potential ? liability ? of ? integrated ? silicon ? solution, ? inc ? is ? adequately ? protected ? under ? the ? circumstances ?
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 4 ? rev. a, 06/24/2016 ? absolute maximum ratings (note 1) maximum enable voltage, v en(max) only for is32lt3170-stla3-tr v en(max) only for IS32LT3171-stla3-tr 45v 6v maximum output current, i out(max) 200ma maximum output voltage, v out(max) 45v reverse voltage between all terminals, v r 0.5v junction to ambient, ja 94.8c/w power dissipation, p d(max) (note 2) 1w maximum junction temperature, t jmax 150c storage temperature range, t stg -65c ~ +150c operating temperature range, t a =t j -40c ~ +125c esd (hbm) esd (cdm) 2kv 500v note 1: stresses beyond those listed under ?absolute maximum ratings? may cause permanent damage to the device. these are stress rating s only and functional operation of the device at these or any other condition beyond those indicated in the operational sections of th e specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. note 2: detail information please refer to package thermal de-rating curve on page 14. electrical characteristics ? ? this symbol in the table means these parameters are for is32lt3170-stla3-tr. ? ? this symbol in the table means these parameters are for IS32LT3171-stla3-tr. ? ? ? this symbol in the table means these limits are guaranteed at room temp t a = t j = 25c. ? ? ? this symbol in the table means these limits are guaranteed at full temp range t a = t j = -40c~1 25 c. test condition is t a = t j = -40c~125c, unless otherwise specified. (note 3) symbol parameter condition min. typ. max. unit v bd_out out pin breakdown voltage v en = 0v 42 v i en enable current v en = 24v 0.35 ma v en = 3.3v 0.35 r int internal resistor i rint = 10ma 106 ? i out output current v out = 1.4v, v en = 24v, r ext open ? 9 10 11 ma ? 7.5 10 11.5 v out = 1.4v, v en = 3.3v, r ext open ? 9 10 11 ? 7.5 10 11.5 v out > 2.0v, v en = 24v, r ext = 10 ? ? 105 112 120 ma ? 95 112 120 v out > 2.0v, v en = 3.3v, r ext = 10 ? ? 105 112 120 ? 95 112 120 output current range (note 4, 5) v out > 2.0v, v en = 24v 10 150 ma v out > 2.0v, v en = 3.3v 10 150
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 5 ? rev. a, 06/24/2016 ? dc characteristics with stabilized led load ? ? this symbol in the table means these parameters are for is32lt3170-stla3-tr. ? ? this symbol in the table means these parameters are for IS32LT3171-stla3-tr. test condition is t a = t j = -40c~125c, unless otherwise specified. (note 3) symbol parameter condition min. typ. max. unit v s sufficient supply voltage on en pin 5 42 v 2.5 5.5 v hr lowest sufficient headroom voltage on out pin i out = 100ma 1 1.2 v ? i out /i out (note 4) output current change versus ambient temp change v out > 2.0v, v en = 24v, r ext = 10 ? -0.26 %/k v out > 2.0v, v en = 3.3v, r ext = 10 ? -0.26 output current change versus vout v out > 2.0v, v en = 24v, r ext = 10 ? 1.9 %/v v out > 2.0v, v en = 3.3v, r ext = 10 ? 1.9 note 3: production testing of the device is performed at 25c. functional operation of the device and parameters specified over -40c t o +125c temperature range, are guaranteed by design and characterization. note 4: guaranteed by design. note 5: the maximum output current is dependent on the pcb board design, air flow, ambient temperature and power dissipation in the dev ice. please refer to the package thermal de-rating curve on page 14 for more detail information.
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 6 ? rev. a, 06/24/2016 ? functional block diagram is32lt3170 IS32LT3171
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 7 ? rev. a, 06/24/2016 ? typical performance characteristics is32lt3170 output voltage ( v) output current (ma) 0 5 10 15 20 25 30 0.523.556.589.51112.514 v en = 42v r ext open t a = -40 c t a = 85 c t a = 125 c t a = 25 c figure 2 i out vs. v out output voltage ( v) output current (ma) 0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 0 50 100 150 v en = 42v r ext = 10 ? t a = 125 c t a = 85 c t a = 25 c t a = -40 c figure 4 i out vs. v out output voltage ( v) output current (ma) 0 20 40 60 80 100 120 140 160 180 200 02468101214 v en = 5v f pwm = 100hz@1% duty cycle t a = 25 c r ext = 7.5 ? r ext = 10 ? r ext = 20 ? r ext open figure 6 i out vs. v out output voltage ( v) output current (ma) 0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 0 20 40 60 80 v en = 42v r ext = 20 ? t a = 125 c t a = 85 c t a = 25 c t a = -40 c figure 3 i out vs. v out output voltage ( v) output current (ma) 0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 0 20 40 60 80 100 120 140 160 180 v en = 42v r ext = 7.5 ? t a = 125 c t a = 85 c t a = 25 c t a = -40 c figure 5 i out vs. v out output voltage ( v) output current (ma) 0 20 40 60 80 100 120 140 160 180 200 02468101214 v en = 42v t a = 25 c r ext open r ext = 20 ? r ext = 10 ? r ext = 7.5 ? figure 7 i out vs. v out
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 8 ? rev. a, 06/24/2016 ? v en ( v) output current (ma) 0 4 8 12 16 20 5152535 42 v out = 2v r ext open t a = -40 c t a = 125 c t a = 85 c t a = 25 c figure 8 i out vs. v en v en ( v) output current (ma) 5152535 42 0 30 60 90 120 150 v out = 2v r ext = 10 ? t a = 125 c t a = -40 c t a = 25 c t a = 85 c figure 10 i out vs. v en v en ( v) output current (ma) 42 0 20 40 60 80 100 120 140 160 180 0 5 10 15 20 25 30 35 40 v out = 2v t a = 25 c r ext = 7.5 ? r ext = 10 ? r ext = 20 ? r ext open figure 12 i out vs. v en v en ( v) output current (ma) 5 152535 42 t a = 125 c 0 20 40 60 80 v out = 2v r ext = 20 ? t a = -40 c t a = 25 c t a = 85 c figure 9 i out vs. v en v en ( v) output current (ma) 5152535 42 0 25 50 75 100 125 150 175 200 v out = 2v r ext = 7.5 ? t a = 125 c t a = -40 c t a = 25 c t a = 85 c figure 11 i out vs. v en v en ( v) supply current (a) 42 0 5 10 15 20 25 30 35 40 0 100 200 300 400 500 i out = 0a r ext open t a = 125 c t a = 85 c t a = 25 c t a = -40 c figure 13 i en vs. v en
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 9 ? rev. a, 06/24/2016 ? r ext ( ? ) output current (ma) 0 50 100 150 200 250 110100 v en = 42v v out = 2v figure 14 i out vs. r ext
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 10 ? rev. a, 06/24/2016 ? IS32LT3171 output voltage ( v) output current (ma) 0 5 10 15 20 25 30 0.523.556.589.51112.514 v en = 3.3v r ext open t a = -40 c t a = 125 c t a = 25 c t a = 85 c figure 15 i out vs. v out output voltage ( v) output current (ma) 0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 0 50 100 150 v en = 3.3v r ext = 10 ? t a = 125 c t a = 85 c t a = 25 c t a = -40 c figure 17 i out vs. v out output voltage ( v) output current (ma) 0 20 40 60 80 100 120 140 160 180 200 02468101214 v en = 5v f pwm = 100hz@1% duty cycle t a = 25 c r ext = 7.5 ? r ext = 10 ? r ext = 20 ? r ext open figure 19 i out vs. v out output voltage ( v) output current (ma) 0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 0 20 40 60 80 v en = 3.3v r ext = 20 ? t a = 125 c t a = 85 c t a = -40 c t a = 25 c figure 16 i out vs. v out output voltage ( v) output current (ma) 0.5 2 3.5 5 6.5 8 9.5 11 12.5 14 0 20 40 60 80 100 120 140 160 180 v en = 3.3v r ext = 7.5 ? t a = -40 c t a = 25 c t a = 125 c t a = 85 c figure 18 i out vs. v out output voltage ( v) output current (ma) 0 20 40 60 80 100 120 140 160 180 200 02468101214 v en = 3.3v t a = 25 c r ext = 7.5 ? r ext = 10 ? r ext = 20 ? r ext open figure 20 i out vs. v out
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 11 ? rev. a, 06/24/2016 ? v en ( v) output current (ma) 0 4 8 12 16 20 2.5 3 3.5 4 4.5 5 v out = 2v r ext open t a = -40 c t a = 125 c t a = 85 c t a = 25 c figure 21 i out vs. v en v en ( v) output current (ma) 0 30 60 90 120 150 v out = 2v r ext = 10 ? t a = 125 c t a = -40 c t a = 25 c t a = 85 c 2.5 3 3.5 4 4.5 5 figure 23 i out vs. v en v en ( v) output current (ma) 0 20 40 60 80 100 120 140 160 180 2.5 3 3.5 4 4.5 5 r ext = 7.5 ? r ext = 10 ? r ext = 20 ? r ext open v out = 2v t a = 25 c figure 25 i out vs. v en v en ( v) output current (ma) 0 20 40 60 80 2.5 3 3.5 4 4.5 5 v out = 2v r ext = 20 ? t a = -40 c t a = 125 c t a = 25 c t a = 85 c figure 22 i out vs. v en v en ( v) output current (ma) 0 25 50 75 100 125 150 175 200 v out = 2v r ext = 7.5 ? 2.5 3 3.5 4 4.5 5 t a = 125 c t a = 85 c t a = 25 c t a = -40 c figure 24 i out vs. v en v en ( v) supply current (a) 0 100 200 300 400 500 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 i out = 0a r ext open t a = 125 c t a = 85 c t a = -40 c t a = 25 c figure 26 i en vs. v en
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 12 ? rev. a, 06/24/2016 ? r ext ( ? ) output current (ma) 0 50 100 150 200 250 110100 v en = 3.3v v out = 2v figure 27 i out vs. r ext time (200ns/div) i out 50ma/div v en 2v/div v out = 3v, 3 leds v en = 5v, 100hz, 50% duty cycle r ext = 10 ? t j = 25 c figure 29 v en vs. i out delay and rising edge time (100ns/div) i out 50ma/div v en 2v/div v out = 3v, 3 leds v en = 5v, 100hz, 50% duty cycle r ext = 10 ? t j = -40 c figure 31 v en vs. i out delay and falling edge time (200ns/div) i out 50ma/div v en 2v/div v out = 3v, 3 leds v en = 5v, 100hz, 50% duty cycle r ext = 10 ? t j = -40 c figure 28 v en vs. i out delay and rising edge time (200ns/div) i out 50ma/div v en 2v/div v out = 3v, 3 leds v en = 5v, 100hz, 50% duty cycle r ext = 10 ? t j = 125 c figure 30 v en vs. i out delay and rising edge time (100ns/div) i out 50ma/div v en 2v/div v out = 3v, 3 leds v en = 5v, 100hz, 50% duty cycle r ext = 10 ? t j = 25 c figure 32 v en vs. i out delay and falling edge
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 13 ? rev. a, 06/24/2016 ? time (100ns/div) i out 50ma/div v en 2v/div v out = 3v, 3 leds v en = 5v, 100hz, 50% duty cycle r ext = 10 ? t j = 125 c figure 33 v en vs. i out delay and falling edge
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 14 ? rev. a, 06/24/2016 ? applications information is32lt3170/71 provides an easy constant current source solution for led lighting applications. it uses an external resistor to adjust the led current from 10ma to 150ma. the led current can be determined by the external resistor r ext as equation (1): ma i ma r set ext 10 106 10 ? ? ? ? (1) where i set is in ma. paralleling a low tolerance resistor r ext with the internal resistor r int will improve the overall accuracy of the current sense resistance. the resulting output current will vary slightly lower due to the negative temperature coefficient (ntc) resulting from the self heating of the is32lt3170/71. high input voltage application when driving a long string of leds whose total forward voltage drop exceeds the is32lt3170 v bd_out limit of 42v, it is possible to stack several leds(such as 2 leds) between the en pin and the out pins 2,3, and 5 so the voltage on the en pin is higher than 5v. the remaining string of leds can then be placed between power supply +v s and en pin, (figure 34). the number of leds required to stack at en pin will depend on the led?s forward voltage drop (vf) and the +v s value. is32lt3170 gnd out +v s > 42v en 1 4 2,3,5 6 rext r ext ? figure 34 high input voltage application circuit note: when operating the is32lt3170 at voltages exceeding the device operating limits, care needs to be taken to keep the en pin and out pin voltage below 42v. thermal protection and dissipation the is32lt3170/71 implements thermal foldback protection to reduce the led current when the package?s thermal dissipation is exceeded and prevent ?thermal runaway?. the thermal foldback implements a negative temperature coefficient (ntc) of -0.26%/k. when operating the chip at high ambient temperatures, or when driving maximum load current, care must be taken to avoid exceeding the package power dissipation limits. exceeding the package dissipation will cause the device to enter thermal protection mode. the maximum package power dissipation can be calculated using the following equation (2): ja a max j max d t t p ? ? ? ) ( ) ( (2) where t j(max) is the maximum junction temperature, t a is the ambient temperature, and ja is the junction to ambient thermal resistance; a metric for the relative thermal performance of a package. the recommended maximum operating junction temperature, t j(max) , is 125c and so the maximum ambient temperature is determined by the package parameter; ja . the ja for the is32lt3170/71 sot23-6 package is 94.8c/w. therefore the maximum power dissipation at t a = 25c is: w w c c c p max d 1 / 8 . 94 25 125 ) ( ? ? ? ? ? ? the actual power dissipation p d is: en en out out d i v i v p ? ? ? ? (3) to ensure the performance, the die temperature (t j ) of the is32lt3170/71 should not exceed 125c. the graph below gives details for the package power derating. temperature ( c ) power dissipation (w) 0 0.2 0.4 0.6 0.8 1 1.2 -40 -25 -10 5 20 35 50 65 80 95 110 125 sot23-6 figure 35 p d vs. t a (sot23-6)
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 15 ? rev. a, 06/24/2016 ? the thermal resistance is achieved by mounting the is32lt3170/71 on a standard fr4 double-sided printed circuit board (pcb) with a copper area of a few square inches on each side of the board under the is32lt3170/71. multiple thermal vias, as shown in figure 36, help to conduct the heat from the exposed pad of the is32lt3170/71 to the copper on each side of the board. the thermal resistance can be reduced by using a metal substrate or by adding a heatsink. figure 36 board via layout for thermal dissipation
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 16 ? rev. a, 06/24/2016 ? classification reflow profiles profile feature pb-free assembly preheat & soak temperature min (tsmin) temperature max (tsmax) time (tsmin to tsmax) (ts) 150c 200c 60-120 seconds average ramp-up rate (tsmax to tp) 3c/second max. liquidous temperature (tl) time at liquidous (tl) 217c 60-150 seconds peak package body temperature (tp)* max 260c time (tp)** within 5c of the specified classification temperature (tc) max 30 seconds average ramp-down rate (tp to tsmax) 6c/second max. time 25c to peak temperature 8 minutes max. figure 37 classification profile
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 17 ? rev. a, 06/24/2016 ? package information sot23-6
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 18 ? rev. a, 06/24/2016 ? recommended land pattern note: 1. land pattern complies to ipc-7351. 2. all dimensions in mm. 3. this document (including dimensions, notes & specs) is a recommendation based on typical circuit board manufacturing paramet ers. since land pattern design depends on many factors unknown (eg. user?s board manufacturing specs), user must determine suitability for use.
is32lt3170/71 integrated silicon solution, inc. ? www.issi.com ?? 19 ? rev. a, 06/24/2016 ? revision history revision detail information date 0a initial release 2015.08.04 a update ec table update automotive grade 2016.06.24

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