1 for more information www.linear.com/LT8610AX typical application features description 42v , 3.5a synchronous step-down regulator with operation to 175c the lt ? 8610ax is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator rated to 175c junction temperature. the LT8610AX is 100% tested a 175c . top and bottom power switches are included with all necessary circuitry to minimize the need for external components. low ripple burst mode operation enables high efficiency across a wide range of output currents while keeping the output ripple low. a sync pin allows synchronization to an external clock. internal compensation with peak current mode topology allows the use of small inductors and results in fast transient response and good loop stability. the en/uv pin has an accurate 1v threshold and can be used to program v in undervoltage lockout or to shut down the LT8610AX. a capacitor on the tr/ss pin programs the output voltage ramp rate during startup while the pg flag signals when v out is within 9% of the programmed output voltage as well as fault conditions. the lt8610 ax is available in small 16- lead msop package with exposed pad for low thermal resistance. applications n 100% tested at 175c n 2% reference accuracy over C 40 c to 175 c range n wide input voltage range : 3.7v to 42v n ultralow quiescent current burst mode ? operation n high efficiency synchronous operation n 91% eff. at 0.5a, at 175c, 3.3v out from 12v in n 92% eff. at 0.5a, at 175c, 5v out from 12v in n adjustable and synchronizable frequency: 200khz to 2.2mhz n no thermal shutdown n internal compensation n output soft-start and tracking n power good flag n small thermally-enhanced 16-lead msop package n oil and gas exploration l , lt, ltc, ltm, linear technology, the linear logo and burst mode are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. 3.3v step-down converter efficiency at 175c lt8610 ax 8610axf 41.2k 10pf 49.9k v out 3.3v 3.5a v in sw fb gnd 47f en/uv LT8610AX v in 3.7v to 42v f sw = 700khz pg sync tr/ss intv cc rt 60.4k bst bias 1210 x7r 2 8610ax ta01a t a = 175c 12v in load current (ma) 1 4.7f 10 100 1k 10k 0 10 20 30 40 50 1f 60 70 80 90 100 efficiency (%) ef?ciency at 175c 8610ax ta01b 100nf 4.7h 0.1f 100k
2 for more information www.linear.com/LT8610AX pin configuration absolute maximum ratings v in , en/uv, pg .......................................................... 42v bias .......................................................................... 30v fb, tr/ss voltage . ..................................................... 4v sync voltage . ............................................................ 6v operating junction temperature range (note 2) lt8610 ax .............................................. C 40 to 175 c storage temperature range ...................... C 65 to 150 c (note 1) 1 2 3 4 5 6 7 8 sync tr/ss rt en/uv v in v in nc gnd 16 15 14 13 12 11 10 9 fb pg bias intv cc bst sw sw sw top view 17 gnd mse package 16-lead plastic msop ja = 40c /w, jc(pad) = 10c/w exposed pad (pin 17) is gnd, must be soldered to pcb order information electrical characteristics 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: devices are 100% tested at 175c to the limits shown. for normal operating temperature range specifications, please see the lt8610a/ lt8610ab data sheet. the lt8610 ax performance is based on the lt8610ab. the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t a = 25c. lead free finish tape and reel part marking package description temperature range LT8610AXmse#pbf LT8610AXmse#trpbf 8610ax 16-lead plastic msop C40c to 175c consult ltc marketing for parts specified with wider operating temperature ranges. for more information on lead free part marking, go to: http: //www.linear.com/leadfree/ for more information on tape and reel specifications, go to: http: //www.linear.com/tapeandreel/. some packages are available in 500 unit reels through designated sales channels with #trmpbf suffix. parameter conditions min typ max units minimum input voltage l 3.2 3.7 v v in current in regulation v out = 0.97v, v in = 6v, output load = 100a v out = 0.97v, v in = 6v, output load = 1ma l l 26 230 100 400 a a feedback reference voltage v in = 12v l 0.966 0.950 0.972 0.970 0.978 0.990 v v oscillator frequency r t = 60.4k l 665 700 735 khz pg upper threshold offset from v fb v fb falling l 6 9 12 % pg lower threshold offset from v fb v fb rising l C12 C9 C6 % note 3. the LT8610AX is guaranteed over the full C40c to 175c operating junction temperature range. high junction temperatures degrade operating lifetimes. operating lifetime is derated at junction temperatures greater than 125 c. the LT8610AX has no thermal shutdown. (http: //www.linear.com/product/LT8610AX#orderinfo) lt8610 ax 8610axf
3 for more information www.linear.com/LT8610AX typical performance characteristics reference voltage reference voltage at 175c efficiency at 175c, v out = 3.3v efficiency at 175c, v out = 3.3v efficiency at 175c, v out = 5v efficiency at 175c, v out = 5v no load input current at 175c en cycling at 175c power up at 175c f sw = 700khz f sw = 700khz f sw = 700khz f sw = 700khz lt8610 ax 8610axf 175 load current (ma) 0.01 0.1 1 10 100 1k 10k 0 10 200 20 30 40 50 60 70 80 90 100 efficiency (%) 920 ef?ciency at 175c, v out = 5v 8610ax g05 t a = 175c 12v in 24v in 36v in load current (ma) 100 200 300 930 400 500 600 700 800 900 1000 60 65 70 940 75 80 85 90 95 100 efficiency (%) out 8610ax g06 t a = 175c 950 t a = 175c front page app 3.3v out in regulation input voltage (v) 5 10 15 20 25 30 960 35 40 0 20 40 60 80 100 120 140 970 160 180 200 input current (ua) 8610ax g07 t a = 175c 10ms/div v out 2v/div ss 980 2v/div pg 2v/div en 5v/div 8610ax g08 t a = 175c 10ms/div v out 2v/div 990 ss 2v/div pg 2v/div v in 10v/div 8610ax g09 load = 0.5a 1000 reference voltage (mv) reference voltage 8610ax g01 n = 347 = 968.5 = 3.33 reference voltage (mv) 950 955 temperature (c) 960 965 970 975 980 985 990 0 15 30 25 45 number of parts reference voltage at 175c 8610ax g02 t a = 175c 12v in 24v in 36v in load current (ma) 0.01 50 0.1 1 10 100 1k 10k 0 10 20 30 75 40 50 60 70 80 90 100 efficiency (%) ef?ciency at 175c, v out = 3.3v 8610ax g03 100 12v in 24v in 36v in load current (ma) 100 200 300 400 500 600 125 700 800 900 1000 60 65 70 75 80 85 150 90 95 100 efficiency (%) out 8610ax g04 t a = 175c 12v in 24v in 36v in
4 for more information www.linear.com/LT8610AX pin functions sync (pin 1) : external clock synchronization input. ground this pin for low ripple burst mode operation at low output loads. tie to a clock source for synchronization to an external frequency. apply a dc voltage of 3v or higher or tie to intv cc for pulse-skipping mode. when in pulse- skipping mode, the i q will increase to several hundred a. do not float this pin. tr/ss (pin 2): output tracking and soft-start pin. this pin allows user control of output voltage ramp rate during start-up. a tr/ss voltage below 0.97v forces the lt8610 ax to regulate the fb pin to equal the tr/ss pin voltage. when tr/ss is above 0.97v, the tracking function is disabled and the internal reference resumes control of the error amplifier. an internal 2.2a pull-up current from intv cc on this pin allows a capacitor to program output voltage slew rate. this pin is pulled to ground with an internal 230 mosfet during shutdown and fault conditions ; use a series resistor if driving from a low impedance output. this pin may be left floating if the tracking function is not needed. rt (pin 3) : a resistor is tied between rt and ground to set the switching frequency. en/uv (pin 4): the LT8610AX is shut down when this pin is low and active when this pin is high. the hysteretic threshold voltage is 1.00v going up and 0.96v going down. tie to v in if the shutdown feature is not used. an external resistor divider from v in can be used to program a v in threshold below which the lt8610 ax will shut down. v in (pins 5, 6): the v in pins supply current to the lt8610 ax internal circuitry and to the internal topside power switch. these pins must be tied together and be locally bypassed. be sure to place the positive terminal of the input capaci - tor as close as possible to the v in pins, and the negative capacitor terminal as close as possible to the gnd pins. nc (pin 7) : no connect. this pin is not connected to internal circuitry. sw (pins 9, 10, 11) : the sw pins are the outputs of the internal power switches. tie these pins together and con - nect them to the inductor and boost capacitor. this node should be kept small on the pcb for good performance. bst (pin 12): this pin is used to provide a drive voltage, higher than the input voltage, to the topside power switch. place a 0.1f boost capacitor as close as possible to the ic. intv cc (pin 13): internal 3.4v regulator bypass pin. the internal power drivers and control circuits are pow - ered from this voltage. intv cc maximum output cur - rent is 20ma . do not load the intv cc pin with external circuitry. intv cc current will be supplied from bias if v bias > 3.1v , otherwise current will be drawn from v in . voltage on intv cc will vary between 2.8v and 3.4v when v bias is between 3.0v and 3.6v . decouple this pin to power ground with at least a 1f low esr ceramic capacitor placed close to the ic. bias (pin 14) : the internal regulator will draw current from bias instead of v in when bias is tied to a voltage higher than 3.1v. for output voltages of 3.3v and above this pin should be tied to v out . if this pin is tied to a supply other than v out use a 1f local bypass capacitor on this pin. pg (pin 15): the pg pin is the open-drain output of an internal comparator. pg remains low until the fb pin is within 9% of the final regulation voltage, and there are no fault conditions. pg is valid when v in is above 3.4v, regardless of en/uv pin state. fb (pin 16): the LT8610AX regulates the fb pin to 0.970v. connect the feedback resistor divider tap to this pin. also, connect a phase lead capacitor between fb and v out . typically, this capacitor is 4.7pf to 10pf. gnd (pin 8, exposed pad pin 17): ground. these pins are the return path of the internal bottom-side switch and must be tied together. place the negative terminal of the input capacitor as close to the gnd pin and exposed pad as possible. the exposed pad must be soldered to the pcb in order to lower the thermal resistance. lt8610 ax 8610axf
5 for more information www.linear.com/LT8610AX information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa - tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. applications information for application information, block diagram, and typical performance curves from C40c to 150c range, please see the lt8610a/lt8610ab series data sheet. the lt8610 ax will perform similarly to the lt8610ab. the LT8610AX has no thermal shutdown. package description please refer to http: //www.linear.com/product/LT8610AX#packaging for the most recent package drawings. msop (mse16) 0213 rev f 0.53 0.152 (.021 .006) seating plane 0.18 (.007) 1.10 (.043) max 0.17 ? 0.27 (.007 ? .011) typ 0.86 (.034) ref 0.50 (.0197) bsc 16 16151413121110 1 2 3 4 5 6 7 8 9 9 1 8 note: 1. dimensions in millimeter/(inch) 2. drawing not to scale 3. dimension does not include mold flash, protrusions or gate burrs. mold flash, protrusions or gate burrs shall not exceed 0.152mm (.006") per side 4. dimension does not include interlead flash or protrusions. interlead flash or protrusions shall not exceed 0.152mm (.006") per side 5. lead coplanarity (bottom of leads after forming) shall be 0.102mm (.004") max 6. exposed pad dimension does include mold flash. mold flash on e-pad shall not exceed 0.254mm (.010") per side. 0.254 (.010) 0 ? 6 typ detail ?a? detail ?a? gauge plane 5.10 (.201) min 3.20 ? 3.45 (.126 ? .136) 0.889 0.127 (.035 .005) recommended solder pad layout 0.305 0.038 (.0120 .0015) typ 0.50 (.0197) bsc bottom view of exposed pad option 2.845 0.102 (.112 .004) 2.845 0.102 (.112 .004) 4.039 0.102 (.159 .004) (note 3) 1.651 0.102 (.065 .004) 1.651 0.102 (.065 .004) 0.1016 0.0508 (.004 .002) 3.00 0.102 (.118 .004) (note 4) 0.280 0.076 (.011 .003) ref 4.90 0.152 (.193 .006) detail ?b? detail ?b? corner tail is part of the leadframe feature. for reference only no measurement purpose 0.12 ref 0.35 ref mse package 16-lead plastic msop, exposed die pad (reference ltc dwg # 05-08-1667 rev f) lt8610 ax 8610axf
6 for more information www.linear.com/LT8610AX ? linear technology corporation 2016 lt 0416 ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/LT8610AX related parts part number description comments package lt1007x low noise 200c op amp low noise, high speed precision operational amplifier 8-lead to-5 metal can lt580x 200c, 2.5v voltage reference ultra low drift, curvature corrected reference 3-lead to-52 metal can lt581x 200c, 10v voltage reference ultra low drift, curvature corrected reference 3-lead to-39 metal can lt582x 200c, 5v voltage reference ultra low drift, curvature corrected reference 3-lead to-39 metal can lt8610 ax 8610axf
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