View LT3070_8977452.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

1 typical application features description 800ma single resistor rugged linear regulator the lt ? 3088 is an 800ma low dropout linear regulator designed for rugged industrial applications . a key feature of the ic is the extended safe operating area (soa). the lt3088 can be paralleled for higher output current or heat spreading. the device withstands reverse input and reverse output-to-input voltages without reverse current flow. the lt3088s precision 50a reference current source allows a single resistor to program output voltage to any level between zero and 34.5v. the current reference architecture makes load regulation independent of output voltage. the lt3088 is stable with or without input and output capacitors. internal protection circuitry includes reverse-battery and reverse-current protection, current limiting and thermal limiting. the lt3088 is offered in the 3- lead sot-223, 3-lead dd-pak, and an 8-lead 3mm 3mm dfn package. wide safe operating area supply applications n extended safe operating area n maximum output current: 800ma n stable with or without input/output capacitors n wide input voltage range: 1.2v to 36v n single resistor sets output voltage n output adjustable to 0v n 50 a set pin current: 1% initial accuracy n output voltage noise: 27v rms n parallel multiple devices for higher current, heat spreading and lower noise n pin compatible upgrade to lt1117 n reverse-battery and reverse-current protection n <1 mv typical load regulation independent of v out n <0.001%/ v typical line regulation n 3-lead sot-223, 3-lead dd-pak, 8-lead 3mm 3mm dfn packages n all surface mount power supply n rugged industrial power supply n post regulator for switching supplies n low output voltage supply n intrinsic safety applications l, lt , lt c , lt m , linear technology and the linear logo are registered trademarks of linear technology corporation . all other trademarks are the property of their respective owners . set pin current 3088 ta01a in 10f* *optional out + ? lt3088 i out 1.5v 800ma v in 750* set 30.1k 50a temperature (c) ? 75 ? 50 49.0 set pin current (a) 49.2 49.6 49.8 50.0 51.0 50.4 0 50 75 3088 g01 49.4 50.6 50.8 50.2 ? 25 25 100 125 175150 i load = 2ma lt3088 3088fb for more information www.linear.com/lt3088
2 absolute maximum ratings in pin to out pin differential voltage ..................... 40v set pin current ( note 6 ) ..................................... 25ma set pin voltage ( relative to out , note 6 ) .............. 10v output short-circuit duration .......................... indefinite operating junction temperature range ( note 2 ) e- , i-grades ....................................... C 40 c to 125 c h-grade ............................................. C 40 c to 150 c mp-grade .......................................... C 55 c to 150 c (note 1) all voltages relative to v out pin configuration order information lead free finish tape and reel part marking * package description temperature range lt3088edd#pbf lt3088edd#trpbf lgsz 8-lead (3mm 3mm) plastic dfn C40c to 125c lt3088idd#pbf lt3088idd#trpbf lgsz 8-lead (3mm 3mm) plastic dfn C40c to 125c lt3088hdd#pbf lt3088hdd#trpbf lgsz 8-lead (3mm 3mm) plastic dfn C40c to 150c lt3088est#pbf lt3088est#trpbf 3088 3- lead plastic sot-223 C40c to 125c lt3088ist#pbf lt3088ist#trpbf 3088 3- lead plastic sot-223 C40c to 125c lt3088hst#pbf lt3088hst#trpbf 3088 3- lead plastic sot-223 C40c to 150c lt3088mpst #pbf lt3088mpst#trpbf 3088 3- lead plastic sot-223 C55c to 150c lt3088em#pbf lt3088em#trpbf lt3088m 3-lead plastic dd-pak C40c to 125c lt3088im#pbf lt3088im#trpbf lt3088m 3-lead plastic dd-pak C40c to 125c lt3088hm#pbf lt3088hm#trpbf lt3088m 3-lead plastic dd-pak C40c to 150c lt3088mpm#pbf lt3088mpm#trpbf lt3088m 3-lead plastic dd-pak C55c to 150c consult ltc marketing for parts specified with wider operating temperature ranges . * the temperature grade is identified by a label on the shipping container . 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. storage temperature range .................. C 65 c to 150 c lead temperature ( soldering , 10 sec ) m , st packages only ........................................ 300 c top view 9 out dd package 8-lead (3mm 3mm) plastic dfn 5 6 7 8 4 3 2 1out out out set in in nc nc t jmax = 150c, ja = 28c/w, jc = 5.3c/w exposed pad (pin 9) is out, must be soldered to pcb 3 2 1 front view tab is out in out set st package 3-lead plastic sot-223 t jmax = 150c, ja = 25c/w, jc = 15c/w m package 3-lead plastic dd-pak front view tab is out in out set 3 2 1 t jmax = 150c, ja = 14c/w, jc = 3c/w lt3088 3088fb for more information www.linear.com/lt3088
3 the l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at t j = 25c. (note 2) electrical characteristics parameter conditions min typ max units set pin current i set v in = 2v, i load = 2ma 2v v in 36v, 2ma i load 800ma l 49.5 49 50 50 50.5 51 a a offset voltage v os (v out C v set ) v in = 2v, i load = 2ma v in = 2v, i load = 2ma l C1.5 C3.5 0 0 1.5 3.5 mv mv i set load regulation ?i load = 2ma to 800ma C0.1 na v os load regulation ? i load = 2ma to 800ma (note 7) dd package l C0.5 C3 mv m, st packages l C1.5 C4 mv line regulation ? i set ?v os ?v in = 2v to 36v, i load = 2ma ?v in = 2v to 36v, i load = 2ma 1.5 0.001 na/v mv/v minimum load current (note 3) 2v v in 36v l 0.4 2 ma dropout voltage (note 4) i load = 100ma i load = 800ma l 1.21 1.35 1.6 v v current limit v in = 5v, v set = 0v, v out = C0.1v l 0.8 1.2 a reference current rms output noise (note 5) 10hz f 100khz 5.7 na rms error amplifier rms output noise (note 5) i load = 800ma, 10hz f 100khz, c out ?=?0f, c set ?=?0.1f 27 v rms ripple rejection v ripple = 0.5v p-p , i load = 0.1a, c set = 0.1f, c out =10f, v in = v out(nominal) + 3v f = 120hz f = 10khz f = 1mhz 75 90 75 20 db db db thermal regulation, i set 10ms pulse 0.003 %/w 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: unless otherwise specified, all voltages are with respect to v out . the lt3088 is tested and specified under pulse load conditions such that t j t a . the lt3088e is tested at t a = 25 c and performance is guaranteed from 0c to 125c. performance of the lt3088e over the full C40c and 125c operating temperature range is assured by design, characterization, and correlation with statistical process controls. the lt3088i is guaranteed over the full C40c to 125c operating junction temperature range. the lt3088mp is 100% tested and guaranteed over the C55c to 150c operating junction temperature range. the lt3088h is tested at 150c operating junction temperature. high junction temperatures degrade operating lifetimes. operating lifetime is degraded at junction temperatures greater than 125c. note 3: minimum load current is equivalent to the quiescent current of the part. since all quiescent and drive current is delivered to the output of the part, the minimum load current is the minimum current required to maintain regulation. note 4: for the lt3088, dropout is specified as the minimum input-to- output voltage differential required supplying a given output current. note 5: adding a small capacitor across the reference current resistor lowers output noise. adding this capacitor bypasses the resistor shot noise and reference current noise ; output noise is then equal to error amplifier noise (see applications information section). note 6: diodes with series 400 resistors clamp the set pin to the out pin. these diodes and resistors only carry current under transient overloads. during normal operation, keep the out-to-set differential voltage below 2v. note 7: load regulation is kelvin sensed at the package. note 8: this ic includes overtemperature protection that protects the device during momentary overload conditions . junction temperature exceeds the maximum operating junction temperature when overtemperature protection is active. continuous operation above the specified maximum operating junction temperature may impair device reliability. lt3088 3088fb for more information www.linear.com/lt3088
4 typical performance characteristics offset voltage offset voltage (v out C v set ) offset voltage (v out C v set ) load regulation minimum load current dropout voltage set pin current set pin current t j = 25 c unless otherwise specified. offset voltage (v out C v set ) temperature (c) ? 75 ? 50 49.0 set pin current (a) 49.2 49.6 49.8 50.0 51.0 50.4 0 50 75 3088 g01 49.4 50.6 50.8 50.2 ? 25 25 100 125 175150 i load = 2ma set pin current distribution (a) 49 n = 2994 49.5 50 3088 g02 50.5 51 v os distribution (mv) ?2 n = 2994 ?1 0 3088 g04 1 2 input-to-output differential (v) 0 ?1.0 offset voltage (mv) ?0.6 ?0.2 0.2 6 12 18 24 3088 g05 30 0.6 1.0 ?0.8 ?0.4 0.0 0.4 0.8 36 i load = 2ma load current (a) 0 offset voltage (mv) ?0.6 3088 g06 ?0.8 0.2 0.5 0.1 0.3 0.70.6 0.4 ?0.2 0.2 ?0.4 0.0 0.8 t j = 25c t j = 125c temperature (c) ? 75 ? 50 ?1.0 offset voltage load regulation (mv) set pin current load regulation (na) ?0.9 ?0.7 ?0.5 ?0.3 0 50 100 175150 3088 g07 ?0.1 0.0 ?10 ?9 ?7 ?5 ?3 ?1 ?0.8 ?0.6 ?0.4 ?0.2 ?8 ?6 ?4 ?2 0 ? 25 25 75 125 ?i load = 2ma to 0.8a temperature (c) ? 75 ? 50 0 minimum load current (a) 100 200 300 800 500 0 50 75 3088 g08 600 700 400 ? 25 25 100 125 175150 v in ? v out = 36v v in ? v out = 2v load current (a) 0 1.0 dropout voltage (v) 1.1 1.2 1.3 1.4 1.6 1.5 0.1 0.3 0.2 0.4 0.5 0.6 3088 g09 0.7 0.8 t j = ?50c t j = 25c t j = 125c temperature (c) ? 75 ? 50 ?1.0 offset voltage (mv) ?0.8 ?0.4 ?0.2 0.0 1.0 0.4 0 50 75 3088 g03 ?0.6 0.6 0.8 0.2 ? 25 25 100 125 175150 i load = 2ma lt3088 3088fb for more information www.linear.com/lt3088
5 dropout voltage current limit current limit temperature (c) ? 75 ? 50 1.0 dropout voltage (v) 0 50 75 3088 g10 ? 25 25 100 125 175150 1.1 1.2 1.3 1.4 1.6 1.5 i load = 800ma i load = 2ma temperature (c) ? 75 ? 50 0.0 current limit (a) 0 50 75 3088 g11 ? 25 25 100 125 175150 0.2 0.6 1.2 2.0 1.6 0.4 0.8 1.0 1.4 1.8 v in = 7v v out = 0v input-to-output differential voltage (v) 0 0.0 current limit (a) 0.4 0.8 1.2 6 12 18 24 3082 g12 30 1.6 0.2 0.6 1.0 1.4 36 typical performance characteristics t j = 25 c unless otherwise specified. linear regulator load transient response linear regulator load transient response time (s) 0 output voltage deviation (mv) load current (ma) ?50 0 50 160 180 8088 g13 ?100 100 ?100 40 80 120 20 200 60 100 140 0 150 100 v in = 3v v out = 1v c set = 0.1f c out = 2.2f ?i load =5ma to 100ma time (s) 0 output voltage deviation (mv) load current (a) ?100 0 100 160 180 3088 g14 ?200 1.0 0.0 40 80 120 20 200 60 100 140 0.5 300 200 v in = 3v v out = 1v c set = 0.1f c out = 2.2f ?i load = 100ma to 800ma linear regulator load transient response time (s) 0 output voltage deviation (mv) load current (ma) ?50 0 50 40 45 3088 g15 ?100 100 ?100 10 20 30 5 50 15 25 35 0 150 100 v in = 3v v out = 1v c set = 30pf c out = 0 ?i load = 5ma to 100ma t r = t f = 1s linear regulator load transient response linear regulator line transient response time (s) 0 output voltage deviation (v) load current (a) ?0.3 0.0 0.3 40 45 3088 g16 0.8 0.4 ?0.4 10 20 30 5 50 15 25 35 0.0 0.6 v in = 3v v out = 1v c set = 30pf c out = 0 ?i load = 100ma to 800ma t r = t f = 1s time (s) 0 output voltage deviation (mv) input voltage (v) 40 3 4 40 45 3088 g17 20 0 ?40 10 20 30 5 50 15 25 35 ?20 6 5 r set = 20k r load = 1.25 c out = 2.2f c set = 0.1f current source line transient response time (s) 0 output current (ma) input voltage (v) 120 3 4 80 90 3088 g18 110 100 80 20 40 60 10 100 30 50 70 90 6 5 r set = 6.04k r out = 3.01 c out = 0 c set = 30pf 100ma current source configuration lt3088 3088fb for more information www.linear.com/lt3088
6 current source line transient response linear regulator turn-on response time (s) 0 output current (ma) input voltage (v) 600 3 4 80 90 3088 g19 550 500 400 20 40 60 10 100 30 50 70 450 6 5 r set = 6.04k r out = 0.6 c out = 0 c set = 30pf 500ma current source configuration time (s) 0 output voltage (v) input voltage (v) 0 1 2 80 90 3080 g20 1.0 0.5 ?0.5 20 40 60 10 100 30 50 70 0.0 4 3 r set = 20k r load = 1.25 c out = 2.2f ceramic c set = 0 typical performance characteristics t j = 25 c unless otherwise specified. ripple rejection ripple rejection output impedance residual output voltage with less than minimum load current source turn-on response current source turn-on response time (s) 0 output current (ma) input voltage (v) 80 100 120 80 90 3088 g22 60 40 0 20 40 60 10 100 30 50 140 20 0 1 3 2 r set = 6.04k r out = 3.01 c out = 0 c set = 30pf 100ma current source configuration time (s) 0 output current (ma) input voltage (v) 400 500 600 80 90 300 200 0 20 40 60 10 100 30 50 70 100 0 1 3 2 3088 g23 r set = 6.04k r out = 0.6 c out = 0 c set = 30pf 500ma current source configuration r test () 0 output voltage (mv) 400 500 2000 3088 g24 300 200 0 500 1000 1500 100 600 v in = 36v v in = 5v v out set pin = 0v r test v in frequency (hz) 10 100 40 ripple rejection (db) 50 60 70 80 1k 10k 100k 1m 10m 3088 g25 30 20 10 0 90 100 i load = 100ma i load = 500ma i load = 800ma c out = 2.2f ceramic c set = 0.1f v in = v out(nominal) + 2v frequency (hz) 10 100 40 ripple rejection (db) 50 60 70 80 1k 10k 100k 1m 10m 3088 g26 30 20 10 0 90 100 v in = v out + 5v v in = v out + 2v v in = v out + 1.5v c out = 2.2f ceramic c set = 0.1f i load = 100ma frequency (hz) 10 1 output impedance () 10 100 1k 10k 100k 1m 10m 100 1k 10k 100k 1m 10m 3088 g27 i source = 10ma i source = 100ma i source = 500ma current source configuration linear regulator turn-on response time (ms) 0 output voltage (v) input voltage (v) 0 1 2 16 18 3088 g21 1.0 0.5 ?0.5 4 8 12 2 20 6 10 14 0.0 4 3 r set = 20k r load = 1.25 c out = 2.2f ceramic c set = 0.1f lt3088 3088fb for more information www.linear.com/lt3088
7 ripple rejection (120hz) temperature (c) ? 75 ? 50 70 ripple rejection (db) 72 76 78 80 90 84 0 50 75 3088 g28 74 86 88 82 ? 25 25 100 125 175150 v in = v out(nominal) + 2v ripple = 500mv p-p f = 120hz i load = 0.1a c out = 2.2f c set = 0.1f typical performance characteristics t j = 25 c unless otherwise specified. ripple rejection (10khz) temperature (c) ? 75 ? 50 50 ripple rejection (db) 52 56 60 62 70 66 0 50 75 3088 g29 54 68 64 ? 25 25 100 125 175150 v in = v out(nominal) + 2v ripple = 500mv p-p f = 10khz i load = 0.1a c out = 2.2f c set = 0.1f ripple rejection (1mhz) noise spectral density ripple rejection 10hz to 100khz output voltage noise temperature (c) ?75 ?50 ripple rejection (db) 42 46 175 150 3088 g30 34 30 0 50 100 ?25 25 75 125 50 38 40 36 44 32 48 v in = v out(nominal) + 2v ripple = 200mv p-p f = 1mhz i load = 0.1a c out = 2.2f c set = 0.1f frequency (hz) 10 10 error amplifier noise spectral density (nv/hz) reference current noise spectral density (pa/hz) 100 1000 1 10 100 1k 100 10k 100k 3988 g32 time 1ms/div v out 50v/div 3088 g33 noise independent of output voltage c set = 0.1f c out = 4.7f i load = 800ma lt3088 3088fb for more information www.linear.com/lt3088 3 3.5 4 4.5 5 20 25 30 35 40 i load = 800ma c out = 2.2f 45 50 55 60 ripple rejection (db) ripple rejection 3088 g31 10khz 100khz 1mhz in?to?out differential (v) 1.5 2 2.5
8 block diagram pin functions in: input. this pin supplies power to regulate internal circuitry and supply output load current . for the device to operate properly and regulate, the voltage on this pin must be between the dropout voltage and 36v above the out pin ( depending on output load current, see dropout voltage specifications ). out: output. this is the power output of the device . the lt3088 requires a 2ma minimum load current for proper output regulation. set : set. this pin is the error amplifier s noninverting input and also sets the operating bias point of the circuit . a fixed 50a current source flows out of this pin . a single external resistor programs vout . output voltage range is 0v to 34.5v. exposed pad / tab : output. the exposed pad of the dd package and the tab of the m and st packages are tied internally to out . as such, tie them directly to out at the pcb. the amount of copper area and planes connected to out determine the effective thermal resistance of the packages. nc: ( dd package only) no connection. no connect pins have no connection to internal circuitry and may be tied to in, out, gnd or floated. ? + 50a in set out 3088 bd lt3088 3088fb for more information www.linear.com/lt3088
9 applications information introduction the lt3088 regulator is easy to use and has all the pro - tection features expected in high performance regulators . included are short-circuit protection , reverse-input protec - tion and safe operating area protection , as well as thermal shutdown with hysteresis. safe operating area (soa) for the lt3088 is extended, allowing for use in harsh indus - trial and automotive environments where sudden spikes in input voltage lead to high power dissipation. the lt3088 fits well in applications needing multiple rails . this new architecture adjusts down to zero with a single resistor, handling modern low voltage digital ics as well as allowing easy parallel operation and thermal manage - ment without heat sinks. adjusting to zero output allows shutting off the powered circuitry . a precision 0 tc 50 a reference current source connects to the noninverting input of a power operational amplifier. the power operational amplifier provides a low impedance buffered output to the voltage on the noninverting input . a single resistor from the noninverting input to ground sets the output voltage . if this resistor is set to 0, zero output voltage results . therefore, any output voltage can be obtained between zero and the maximum defined by the input power supply is obtainable. the benefit of using a true internal current source as the reference, as opposed to a bootstrapped reference in older regulators, is not so obvious in this architecture . a true reference current source allows the regulator to have gain and frequency response independent of the impedance on the positive input. on older adjustable regulators, such as the lt1086 loop gain changes with output voltage and bandwidth changes if the adjustment pin is bypassed to ground. for the lt3088, the loop gain is unchanged with output voltage changes or bypassing . output regulation is not a fixed percentage of output voltage , but is a fixed fraction of millivolts . use of a true current source allows all of the gain in the buffer amplifier to provide regulation , and none of that gain is needed to amplify up the reference to a higher output voltage. programming linear regulator output voltage the lt3088 generates a 50a reference current that flows out of the set pin. connecting a resistor from set to ground generates a voltage that becomes the reference point for the error amplifier (see figure 1). the reference voltage equals 50a multiplied by the value of the set pin resistor (ohms law). any voltage can be generated and there is no minimum output voltage for the regulator . figure 1. basic adjustable regulator 3088 f01 in set out + ? lt3088 50a r load c set r set c in v out = 50a ? r set c out table 1 lists many common output voltages and the clos - est standard 1 % resistor values used to generate that output voltage. regulation of the output voltage requires a minimum load current of 2ma. for true zero voltage output operation , return this 2ma load current to a negative output voltage . table 1 . 1% resistors for common output voltages v out (v) r set (k) 1 20 1.2 24.3 1.5 30.1 1.8 35.7 2.5 49.9 3.3 66.5 5 100 lt3088 3088fb for more information www.linear.com/lt3088
10 applications information with the 50 a current source used to generate the reference voltage, leakage paths to or from the set pin can create errors in the reference and output voltages . high quality insulation should be used (e.g., teflon, kel-f); cleaning of all insulating surfaces to remove fluxes and other residues is required . surface coating may be necessary to provide a moisture barrier in high humidity environments. minimize board leakage by encircling the set pin and circuitry with a guard ring operated at a potential close to itself. tie the guard ring to the out pin . guarding both sides of the circuit board is required . bulk leakage reduction depends on the guard ring width . 50na of leakage into or out of the set pin and its associated circuitry creates a 0.1% reference voltage error . leakages of this magnitude , coupled with other sources of leakage , can cause signifi - cant offset voltage and reference drift , especially over the possible operating temperature range. figure 2 depicts an example guard ring layout. if guard ring techniques are used , this bootstraps any stray capacitance at the set pin . since the set pin is a high impedance node , unwanted signals may couple into the set pin and cause erratic behavior. this will be most noticeable when operating with minimum output capacitors at full load current . the easiest way to remedy this is to bypass the set pin with a small amount of capacitance from set to ground, 10pf to 20pf is sufficient. using the lt3088 as a replacement for the lt1117 the lt3088 can be used as an upgrade or replacement for the lt1117 regulator. the lt3088 offers superior performance over the lt1117, including extended input voltage range, lower output voltage capability , extended safe operating area , and protection features such as reverse voltage / current protection . figure ? 3 shows how the lt1117 is used as a basic adjustable regulator . two methods are shown in figures 4 and 5 to change from the lt1117 to the lt3088. the first method (shown in figure ? 4) requires no changes to existing board layouts : replace the lt1117 with the lt3088, change resistor r2 to set the desired output voltage , and do not stuff resistor r1 ( the minimum load requirement of 2ma for the lt3088 must still be met ). the second method is shown in figure ? 5: a 25k resistor is figure 2. guard ring layout example of dd package 3088 f02 out gnd set figure 3. lt1117 basic adjustable regulator figure 4. upgrade to lt1117 requires no layout changes figure 5. resistor in series with set pin matches lt1117 operation 3088 f03 r2 r1 v out v in v ref 1.25v i adj 50a lt1117 in adj out v out = v ref 1 + + i adj r2 r2 ? r1 ( ) + 3088 f04 r2 r1* v out v in i set 50a lt3088 in set out v out = i set ? r2 *do not stuff r1 + 3088 f05 r2 r1 v out v in 1.25v 25k i set 50a lt3088 in set out v out = 1.25v 1 + + i set r2 r2 ? r1 ( ) + lt3088 3088fb for more information www.linear.com/lt3088
11 added in series with the set pin of the lt3088 and uses the same existing resistor divider. this technique can be used to easily satisfy the lt3088s 2ma minimum load current requirement. configuring the lt3088 as a current source setting the lt3088 to operate as a 2-terminal current source is a simple matter . the 50 a reference current from the set pin is used with one resistor to generate a small voltage, usually in the range of 100mv to 1v (200mv is a level that rejects offset voltage , line regulation , and other errors without being excessively large). this voltage is then applied across a second resistor that connects from out to the first resistor. figure? 6 shows connections and formulas to calculate a basic current source configuration . again, the lower current levels used in the lt3088 neces- sitate attention to board leakages as error sources (see the programming linear regulator output voltage section ). selecting r set and r out in current source applications in figure? 6, both resistors r set and r out program the value of the output current . the question now arises : the ratio of these resistors is known , but what value should each resistor be? the first resistor to select is r set . the value selected should generate enough voltage to minimize the error caused by the offset between the set and out pins . a reasonable starting level is ~ 200mv of voltage across r set ( r set equal to 4.02k). resultant errors due to offset voltage are a few percent . the lower the voltage across r set becomes, the higher the error term due to the offset. from this point , selecting r out is easy , as it is a straight- forward calculation from r set . take note , however , resistor errors must be accounted for as well . while larger voltage drops across r set minimize the error due to offset , they also increase the required operating headroom. obtaining the best temperature coefficient does not require the use of expensive resistors with low ppm temperature coefficients . instead , since the output current of the lt3088 is determined by the ratio of r set to r out , those resis - tors should have matching temperature characteristics . less expensive resistors made from the same material provide matching temperature coefficients. see resistor manufacturers data sheets for more details. higher output currents necessitate the use of higher watt - age resistors for r out . there may be a difference between the resistors used for r out and r set . a better method to maintain consistency in resistors is to use multiple resis - tors in parallel to create r out , allowing the same wattage and type of resistor as r set . stability and input capacitance the lt3088 does not require an input capacitor to main - tain stability. input capacitors are recommended in linear regulator configurations to provide a low impedance input source to the lt3088. if using an input capacitor , low esr, ceramic input bypass capacitors are acceptable for applications without long input leads . however, applica- tions connecting a power supply to an lt3088 circuits in and gnd pins with long input wires combined with low esr, ceramic input capacitors are prone to voltage spikes, reliability concerns and application-specific board oscillations. the input wire inductance found in many figure?6. using the lt3088 as a current source in set out + ? lt3088 50a i out v set r set 3088 f06 + ? r out i out 2ma v set = 50a ? r set i out = v set r out = 50a ? r set r out lt3088 3088fb for more information www.linear.com/lt3088
12 battery-powered applications , combined with the low esr ceramic input capacitor, forms a high q lc resonant tank circuit . in some instances this resonant frequency beats against the output current dependent ldo bandwidth and interferes with proper operation . simple circuit modifica - tions/solutions are then required. this behavior is not indicative of lt3088 instability, but is a common ceramic input bypass capacitor application issue. the self-inductance, or isolated inductance, of a wire is directly proportional to its length . wire diameter is not a major factor on its self-inductance . for example, the self- inductance of a 2- awg isolated wire (diameter = 0.26") is about half the self-inductance of a 30- awg wire (diameter = 0.01"). one foot of 30- awg wire has about 465nh of self inductance. one of two ways reduces a wire s self-inductance. one method divides the current flowing towards the lt3088 between two parallel conductors . in this case, the farther apart the wires are from each other , the more the self- inductance is reduced; up to a 50 % reduction when placed a few inches apart. splitting the wires basically connects two equal inductors in parallel , but placing them in close proximity gives the wires mutual inductance adding to the self-inductance. the second and most effective way to reduce overall inductance is to place both forward and return current conductors (the input and gnd wires ) in very close proximity . two 30- awg wires separated by only 0.02", used as forward and return current conduc - tors, reduce the overall self-inductance to approximately one-fifth that of a single isolated wire. if wiring modifications are not permissible for the applica - tions , including series resistance between the power supply and the input of the lt3088 also stabilizes the application . as little as 0.1 to 0.5, often less, is effective in damp- ing the lc resonance. if the added impedance between the power supply and the input is unacceptable , adding esr to the input capacitor also provides the necessary damping of the lc resonance . however, the required esr is generally higher than the series impedance required. stability and frequency compensation for linear regulator configurations the lt3088 does not require an output capacitor for stability. ltc recommends an output capacitor of 10f with an esr of 0.5 or less to provide good transient performance in linear regulator configurations . larger values of output capacitance decrease peak deviations and provide improved transient response for larger load current changes. bypass capacitors , used to decouple individual components powered by the lt3088, increase the effec- tive output capacitor value . for improvement in transient performance , place a capacitor across the voltage setting resistor. capacitors up to 1f can be used . this bypass capacitor reduces system noise as well , but start-up time is proportional to the time constant of the voltage setting resistor (r set in figure 1 ) and set pin bypass capacitor . stability and frequency compensation for current source configurations the lt3088 does not require input or output capacitors for stability in many current-source applications . clean, tight pcb layouts provide a low reactance, well controlled operating environment for the lt3088 without requiring capacitors to frequency compensate the circuit . figure? 6 highlights the simplicity of using the lt3088 as a current source . some current source applications use a capacitor con - nected in parallel with the set pin resistor to lower the current source s noise. this capacitor also provides a soft-start function for the current source . see quieting the noise section for further details . when operating without output capacitors, the high impedance nature of the set pin as the input of the error amplifier allows signal from the output to couple in , showing as high frequency ring- ing during transients. bypassing the set resistor with a capacitor in the range of 20pf to 30pf dampens the ringing . depending on the pole introduced by a capacitor or other complex impedances presented to the lt3088, external lt3088 3088fb for more information www.linear.com/lt3088
13 applications information compensation may be required for stability . techniques are discussed to achieve this in the following paragraphs . linear technology strongly recommends testing stability in situ with final components before beginning production . although the lt3088 s design strives to be stable without capacitors over a wide variety of operating conditions , it is not possible to test for all possible combinations of input and output impedances that the lt3088 will encounter . these impedances may include resistive , capacitive, and inductive components and may be complex distributed networks. in addition, the current source s value will dif - fer between applications and its connection may be gnd referenced , power supply referenced , or floating in a signal line path. linear technology strongly recommends that stability be tested in situ for any lt3088 application. in lt3088 applications with long wires or pcb traces , the inductive reactance may cause instability . in some cases , adding series resistance to the input and output lines (as shown in figure ? 7) may sufficiently dampen these possible high-q lines and provide stability . the user must evaluate the required resistor values against the design s headroom constraints. in general , operation at low output current levels (<20ma) automatically requires higher values of programming resistors and may provide the necessary damping without additional series impedance. if the line impedances in series with the lt3088 are complex enough such that series damping resistors are not sufficient, a frequency compensation network may be necessary . several options may be considered. figure? 8 depicts the simplest frequency compensation networks as a single capacitor across the two terminals of the current source . some applications may use the capacitance to stand off dc voltage but allow the transfer of data down a signal line. for some applications , pure capacitance may be unaccept - able or present a design constraint . one circuit example typifying this is an intrinsically-safe circuit in which an overload or fault condition potentially allows the capaci - tor s stored energy to create a spark or arc. for applica- tions where a single capacitor is unacceptable , figure? 8 alternately shows a series rc network connected across the two terminals of the current source . this network has the added benefit of limiting the discharge current of the in set out + ? lt3088 50a r set r out r series r series long line reactance/inductance 3088 f07 long line reactance/inductance figure ?7. adding series resistance decouples and dampens long line reactances figure?8. compensation from input to output of current source provides stability 3088 f08 in set out + ? lt3088 c comp or r set r out r comp c comp 50a lt3088 3088fb for more information www.linear.com/lt3088
14 applications information capacitor under a fault condition , preventing sparks or arcs . in many instances, a series rc network is the best solution for stabilizing the application circuit . typical resis - tor values will range from 100 to 5k. once again, linear technology strongly recommends testing stability in situ for any lt3088 application across all operating conditions , especially ones that present complex impedance networks at the input and output of the current source . if an application refers the bottom of the lt3088 current source to gnd , it may be necessary to bypass the top of the current source with a capacitor to gnd . in some cases, this capacitor may already exist and no additional capacitance is required. for example , if the lt3088 is used as a variable current source on the output of a power supply, the output bypass capacitance would suffice to provide lt3088 stability. other applications may require the addition of a bypass capacitor . a series rc network may also be used as necessary , and depends on the ap- plication requirements. in some extreme cases , capacitors or series rc networks may be required on both the lt3088 s input and output to stabilize the circuit . figure? 9 depicts a general application using input and output capacitor networks rather than an input-to-output capacitor. as the input of the current source tends to be high impedance , placing a capacitor on the input does not have the same effect as placing a capacitor on the lower impedance output . capacitors in the range of 0.1f to 1f usually provide sufficient bypassing on the input , and the value of input capacitance may be increased without limit. pay careful attention to using low esr input capacitors with long input lines (see the stabil - ity and input capacitance section for more information). using ceramic capacitors give extra consideration to the use of ceramic capacitors . ceramic capacitors are manufactured with a variety of di - electrics, each with different behavior across temperature and applied voltage. the most common dielectrics used are specified with eia temperature characteristic codes of z5u, y5v, x5r and x7r. the z5u and y5v dielectrics are good for providing high capacitances in a small package , but they tend to have strong voltage and temperature coef - ficients as shown in figures 10 and 11 . when used with a 5v regulator, a 16v 10f y5v capacitor can exhibit an effective value as low as 1f to 2f for the dc bias voltage applied and over the operating temperature range . the x5r and x7r dielectrics result in more stable characteristics and are more suitable for use as the output capacitor . the x7r type has better stability across temperature , while the x5r is less expensive and is available in higher values. care still must be exercised when using x5r and x7r capacitors . the x5r and x7r codes only specify operating temperature range and maximum capacitance change over temperature . capacitance change due to dc bias with x5r and x7r capacitors is better than y5v and z5u capacitors, but can still be significant enough to drop capacitor values below appropriate levels . capacitor dc bias characteristics tend to improve as component case size increases , but expected capacitance at operating voltage should be verified. 3088 f09 in set out + ? lt3088 i out r set r out c out or v in c out r out c in r in 50a figure ?9. input and/or output capacitors may be used for compensation lt3088 3088fb for more information www.linear.com/lt3088
15 applications information voltage and temperature coefficients are not the only sources of problems . some ceramic capacitors have a piezoelectric response. a piezoelectric device generates voltage across its terminals due to mechanical stress . in a ceramic capacitor, the stress can be induced by vibrations in the system or thermal transients. paralleling devices higher output current is obtained by paralleling multiple lt3088s together. tie the individual set pins together and tie the individual in pins together . connect the outputs in common using small pieces of pc trace as ballast resistors to promote equal current sharing . pc trace resistance in milliohms/ inch is shown in table 2. ballasting requires only a tiny area on the pcb. table 2 . pc board trace resistance weight (oz) 10mil width 20mil width 1 54.3 27.1 2 27.1 13.6 trace resistance is measured in m /in. the worst-case room temperature offset, only 1.5mv between the set pin and the out pin, allows the use of very small ballast resistors . as shown in figure? 12, each lt3088 has a small 10m ballast resistor , which at full output current gives better than 80 % equalized sharing of the current. the external resistance of 10m (5m for the two devices in parallel) only adds about 8mv of output regulation drop at an output of 1.6a. even with an output voltage as low as 1v, this only adds 0 .8% to the regulation . of course , paralleling more than two lt3088s yields even higher output current . spreading the devices on the pc board also spreads the heat. series input resistors can further spread the heat if the input-to-output difference is high. figure?11. ceramic capacitor dc bias characteristics figure?10. ceramic capacitor temperature characteristics temperature (c) ?50 40 20 0 ?20 ?40 ?60 ?80 ?100 25 75 3088 f10 ?25 0 50 100 125 y5v change in value (%) x5r both capacitors are 16v, 1210 case size, 10f dc bias voltage (v) change in value (%) 3088 f11 20 0 ?20 ?40 ?60 ?80 ?100 0 4 8 10 2 6 12 14 x5r y5v 16 both capacitors are 16v, 1210 case size, 10f set + ? lt3088 50a 10m 10m in v in 4.8v to 36v v out 3.3v 1.6a out 10f 1f 33k 3088 f12 set + ? lt3088 50a in out figure ?12. parallel devices lt3088 3088fb for more information www.linear.com/lt3088
16 applications information quieting the noise the lt3088 offers numerous noise performance advan - tages. every linear regulator has its sources of noise. in general, a linear regulator s critical noise source is the reference. in addition, consider the error amplifier s noise contribution along with the resistor dividers noise gain. many traditional low noise regulators bond out the voltage reference to an external pin (usually through a large value resistor) to allow for bypassing and noise reduction . the lt3088 does not use a traditional voltage reference like other linear regulators . instead, it uses a 50a reference current. the 50a current source generates noise current levels of 18pa/hz (5.7na rms over a 10hz to 100khz bandwidth). the equivalent voltage noise equals the rms noise current multiplied by the resistor value. the set pin resistor generates spot noise equal to 4ktr (k = boltzmann s constant, 1.38 ? 10 C23 j/k, and t is abso- lute temperature ) which is rms summed with the voltage noise. if the application requires lower noise performance , bypass the voltage setting resistor with a capacitor to gnd . note that this noise-reduction capacitor increases start-up time as a factor of the rc time constant. the lt3088 uses a unity-gain follower from the set pin to the out pin . therefore, multiple possibilities exist (besides a set pin resistor ) to set output voltage . for example, using a high accuracy voltage reference from set to gnd removes the errors in output voltage due to reference current tolerance and resistor tolerance . active driving of the set pin is acceptable . the typical noise scenario for a linear regulator is that the output voltage setting resistor divider gains up the reference noise, especially if v out is much greater than v ref . the lt3088s noise advantage is that the unity-gain follower presents no noise gain whatsoever from the set pin to the output. thus, noise figures do not increase accordingly. error amplifier noise is typical 85nv/hz(27v rms over a 10hz to 100khz bandwidth). the error amplifiers noise is rms summed with the other noise terms to give a final noise figure for the regulator. paralleling of regulators adds the benefit that output noise is reduced. for n regulators in parallel , the output noise drops by a factor of n. curves in the typical performance characteristics sec - tion show noise spectral density and peak-to-peak noise characteristics for both the reference current and error amplifier over a 10hz to 100khz bandwidth. load voltage regulation the lt3088 is a floating device . no ground pin exists on the packages. thus, the ic delivers all quiescent current and drive current to the load . therefore, it is not possible to provide true remote load sensing . the connection re- sistance between the regulator and the load determines load regulation performance . the data sheet s load regulation specification is kelvin sensed at the package s pins. negative-side sensing is a true kelvin connection by returning the bottom of the voltage setting resistor to the negative side of the load (see figure?13). connected as shown , system load regulation is the sum of the lt3088s load regulation and the parasitic line resistance multiplied by the output current . to minimize load regulation, keep the positive connection between the regulator and load as short as possible . if possible, use large diameter wire or wide pc board traces. figure?13. connections for best load regulation in set + ? lt3088 50a 3088 f13 out r set r p parasitic resistance r p r p load lt3088 3088fb for more information www.linear.com/lt3088
17 applications information thermal considerations the lt3088 s internal power and thermal limiting circuitry protects itself under overload conditions . for continuous normal load conditions, do not exceed the 125c (e- and i-grades) or 150 c (h- and mp-grades ) maximum junc - tion temperature. carefully consider all sources of thermal resistance from junction-to-ambient . this includes (but is not limited to ) junction-to-case, case-to-heat sink inter - face, heat sink resistance or circuit board-to-ambient as the application dictates . consider all additional , adjacent heat generating sources in proximity on the pcb . surface mount packages provide the necessary heat sinking by using the heat spreading capabilities of the pc board, copper traces and planes . surface mount heat sinks, plated through-holes and solder-filled vias can also spread the heat generated by power devices. junction-to-case thermal resistance is specified from the ic junction to the bottom of the case directly , or the bot - tom of the pin most directly in the heat path . this is the lowest thermal resistance path for heat flow . only proper device mounting ensures the best possible thermal flow from this area of the packages to the heat sinking material. note that the exposed pad of the dfn package and the tab of the dd-pak and sot-223 packages are electrically connected to the output (v out ). tables 3 through 5 list thermal resistance as a function of copper areas on a fixed board size . all measurements were taken in still air on a 4- layer fr-4 board with 1oz solid internal planes and 2oz external trace planes with a total finished board thickness of 1.6mm. table 3 . dd package, 8-lead dfn copper area board area thermal resistance (junction-to-ambient) topside* backside 2500mm 2 2500mm 2 2500mm 2 26c/w 1000mm 2 2500mm 2 2500mm 2 26c/w 225mm 2 2500mm 2 2500mm 2 28c/w 100mm 2 2500mm 2 2500mm 2 31c/w *device is mounted on topside table 4 . st package, 3- lead sot-223 copper area board area thermal resistance (junction-to-ambient) topside* backside 2500mm 2 2500mm 2 2500mm 2 23c/w 1000mm 2 2500mm 2 2500mm 2 23c/w 225mm 2 2500mm 2 2500mm 2 25c/w 100mm 2 2500mm 2 2500mm 2 27c/w *device is mounted on topside table 5 . m package, 3-lead dd-pak copper area board area thermal resistance (junction-to-ambient) topside* backside 2500mm 2 2500mm 2 2500mm 2 13c/w 1000mm 2 2500mm 2 2500mm 2 14c/w 225mm 2 2500mm 2 2500mm 2 16c/w *device is mounted on topside for further information on thermal resistance and using thermal information, refer to jedec standard je sd51, notably jesd51-12. pcb layers , copper weight , board layout and thermal vias affect the resultant thermal resistance . tables 3 through 5 provide thermal resistance numbers for best-case 4-layer boards with 1oz internal and 2oz external copper. modern, multilayer pcbs may not be able to achieve quite the same lt3088 3088fb for more information www.linear.com/lt3088
18 level performance as found in these tables . demo circuit dc2279as board layout using multiple inner v out planes and multiple thermal vias achieves 18 c/ w performance for the dd package. calculating junction temperature example: given an output voltage of 0.9v, an in voltage of 2.5v 5%, output current range from 10ma to 0.5a and a maximum ambient temperature of 50c, what is the maximum junction temperature for the dd-pak on a 2500mm2 board with topside copper of 1000mm 2 ? the power in the circuit equals : p total = (v in C v out )(i out ) the current delivered to the set pin is negligible and can be ignored. v in(max_continuous) = 2.625v (2.5v + 5%) v out = 0.9v, i out = 0.5a, t a = 50c power dissipation under these conditions equals: p total = (v in C v out )(i out ) p total = (2.625v C 0.9v)(0.5a) = 0.87w junction temperature equals : t j = t a + p total ? ja (using tables) t j = 50c + 0.87w ? 14c/w = 62c in this case, the junction temperature is below the maxi - mum rating, ensuring reliable operation. reducing power dissipation in some applications it may be necessary to reduce the power dissipation in the lt3088 package without sacrificing output current capability . two techniques are available . the first technique, illustrated in figure ? 14, employs a resis - tor in series with the regulator s input. the voltage drop across r s decreases the lt3088s in-to-out differential voltage and correspondingly decreases the lt3088 s power dissipation. as an example , assume: v in = 7v, v out = 3.3v and i out(max) = 0.8a. use the formulas from the calculating junction temperature section previously discussed . without series resistor r s , power dissipation in the lt3088 equals: p total = (7v C 3.3v) ? 0.8a = 2.96w if the voltage differential (v diff ) across the lt3088 is chosen as 1.5v, then r s equals: r s = 7v C 3.3v C 1.5v 0.8a = 2.75 ? power dissipation in the lt3088 now equals: p total = 1.5v ? 0.8a = 1.2w the lt3088 s power dissipation is now only 40 % compared to no series resistor . r s dissipates 1 . 75w of power . choose appropriate wattage resistors or use multiple resistors in parallel to handle and dissipate the power properly. applications information figure?14. reducing power dissipation using a series resistor 3088 f14 in v in set out + ? lt3088 50a r set r s v out v in c2 c1 lt3088 3088fb for more information www.linear.com/lt3088
19 the second technique for reducing power dissipation , shown in figure ? 15, uses a resistor in parallel with the lt3088. this resistor provides a parallel path for current flow, reducing the current flowing through the lt3088. this technique works well if input voltage is reasonably constant and output load current changes are small. this technique also increases the maximum available output current at the expense of minimum load requirements. as an example , assume: v in = 5v, v in(max) = 5.5v, v out = 3.3v, v out(min) = 3.2v, i out(max) = 0.8a and i out(min) = 0.3a. also, assuming that r p carries no more than 90 % of i out(min) = 270ma. calculating r p yields: r p = 5.5v C 3.2v 0.27a = 8.52 ? ( 5% standard value = 9.1) the maximum total power dissipation is: ( 5.5v C 3.2v) ? 0.8a = 1.84w however, the lt3088 supplies only: 0.8a C 5.5v C 3.2v 9.1 ? = 0.55a therefore, the lt3088s power dissipation is only: p diss = (5.5v C 3.2v) ? 0.55a = 1.26w r p dissipates 0.58w of power . as with the first technique , choose appropriate wattage resistors to handle and dis - sipate the power properly. with this configuration, the lt3088 supplies only 0.55a. therefore, load current can increase by 0.25a to a total output current of 1.05a while keeping the lt3088 in its normal operating range. high temperature operation care must be taken when designing the lt3088h / lt3088mp applications to operate at high ambient tem - peratures . the lt3088 h / lt3088 mp operates at high temperatures, but erratic operation can occur due to un - foreseen variations in external components . some tantalum capacitors are available for high temperature operation , but esr is often several ohms ; capacitor esr above 0.5 is unsuitable for use with the lt3088h/lt3088mp. multiple ceramic capacitor manufacturers now offer ceramic capaci - tors that are rated to 150 c using an x8r dielectric . check each passive component for absolute value and voltage ratings over the operating temperature range. leakages in capacitors or from solder flux left after insuf - ficient board cleaning adversely affects low current nodes , such as the set pins . consider junction temperature in- crease due to power dissipation in both the junction and nearby components to ensure maximum specifications are not violated for the lt3088h /lt3088 mp or external components. applications information 3088 f15 in set out + ? lt3088 50a r set v out v in c2 c1 r p figure ?15. reducing power dissipation using a parallel resistor lt3088 3088fb for more information www.linear.com/lt3088
20 applications information protection features the lt3088 incorporates several protection features ideal for harsh industrial and automotive environments , among other applications. in addition to normal monolithic regula- tor protection features such as current limiting and thermal limiting, the lt3088 protects itself against reverse-input voltages, reverse-output voltages, and large out-to-set pin voltages. current limit protection and thermal overload protection protect the ic against output current overload conditions . for normal operation, do not exceed the rated absolute maximum junction temperature . the thermal shutdown circuit s temperature threshold is typically 165 c and incorporates about 5c of hysteresis. the lt3088 s in pin withstands 40v voltages with respect to the out and set pins . reverse current flow , if out is greater than in , is less than 1ma ( typically under 100a), protecting the lt3088 and sensitive loads. clamping diodes and 400 limiting resistors protect the lt3088s set pin relative to the out pin voltage . these protection components typically only carry current under transient overload conditions . these devices are sized to handle 10v differential voltages and 25ma crosspin current flow without damage . relative to these applica - tion concerns, note the following two scenarios . the first scenario employs a noise-reducing set pin bypass ca - pacitor while out is instantaneously shorted to gnd . the second scenario follows improper shutdown techniques in which the set pin is reset to gnd quickly while out is held up by a large output capacitance with light load . during normal operation , keep out-to-set differential voltages below 2v. in set r set 30.1k 10m out + ? lt3088 i set 50a v out 3v 1.6a v in in set 10m out + ? lt3088 i set 50a 3088 ta02 8.2* 3.3v out 2.3a *4mv drop ensures lt3088 is off with no load multiple lt3088s can be used in set 20m 5v out + ? lt3088 i set 50a 3088 ta03 6.2k 10f lt1963-3.3 47f 20m typical applications paralleling regulators boosting fixed output regulators lt3088 3088fb for more information www.linear.com/lt3088
21 typical applications reference buffer adding soft-start * lt1019 v out *min load 2ma in set out + ? lt3088 i set 50a 3088 ta04 1f output gnd 47f input v in v out 3.3v 0.8a in set out lt3088 i set 50a 3088 ta05 0.1f 10f in4148 v in 4.8v to 38v 66.5k 10f + ? using a lower value set resistor using an external reference current 20k in set out + ? lt3088 i set 50a 1f 3088 ta07 in set out + ? lt3092 10a 1ma v in v out 0v to 20v 20k 205 1f r set 2k v out = 0.2v + 5ma ? r set in set out + ? lt3088 i set 50a 4.7f 3088 ta06 4.02k 40.2 v in 12v v out 0.2v to 10v 4.7f lt3088 3088fb for more information www.linear.com/lt3088
22 package description please refer to http://www .linear.com/product/lt3088#packaging for the most recent package drawings. 3.00 0.10 (4 sides) note: 1. drawing to be made a jedec package outline m0-229 variation of (weed-1) 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on top and bottom of package 0.40 0.10 bottom view?exposed pad 1.65 0.10 (2 sides) 0.75 0.05 r = 0.125 typ 2.38 0.10 1 4 8 5 pin 1 top mark (note 6) 0.200 ref 0.00 ? 0.05 (dd8) dfn 0509 rev c 0.25 0.05 2.38 0.05 recommended solder pad pitch and dimensions apply solder mask to areas that are not soldered 1.65 0.05 (2 sides) 2.10 0.05 0.50 bsc 0.70 0.05 3.5 0.05 package outline 0.25 0.05 0.50 bsc dd package 8-lead plastic dfn (3mm 3mm) (reference ltc dwg # 05-08-1698 rev c) lt3088 3088fb for more information www.linear.com/lt3088
23 package description please refer to http://www .linear.com/product/lt3088#packaging for the most recent package drawings. .114 ? .124 (2.90 ? 3.15) .248 ? .264 (6.30 ? 6.71) .130 ? .146 (3.30 ? 3.71) .264 ? .287 (6.70 ? 7.30) .0905 (2.30) bsc .033 ? .041 (0.84 ? 1.04) .181 (4.60) bsc .024 ? .033 (0.60 ? 0.84) .071 (1.80) max 10 max .012 (0.31) min .0008 ? .0040 (0.0203 ? 0.1016) 10 ? 16 .010 ? .014 (0.25 ? 0.36) 10 ? 16 recommended solder pad layout st3 (sot-233) 0502 .129 max .059 max .059 max .181 max .039 max .248 bsc .090 bsc st package 3-lead plastic sot-223 (reference ltc dwg # 05-08-1630) lt3088 3088fb for more information www.linear.com/lt3088
24 package description please refer to http://www .linear.com/product/lt3088#packaging for the most recent package drawings. .050 (1.270) .143 +.012 ?.020 ( ) 3.632 +0.305 ?0.508 .100 (2.54) bsc .013 ? .023 (0.330 ? 0.584) .095 ? .115 (2.413 ? 2.921) .004 +.008 ?.004 ( ) 0.102 +0.203 ?0.102 .050 .012 (1.270 0.305) .059 (1.499) .045 ? .055 (1.143 ? 1.397) .165 ? .180 (4.191 ? 4.572) .330 ? .370 (8.382 ? 9.398) .060 (1.524) typ .390 ? .415 (9.906 ? 10.541) 15 .300 (7.620) .075 (1.905) .183 (4.648) .060 (1.524) .060 (1.524) .256 (6.502) bottom view of dd pak hatched area is solder plated copper heat sink m (dd3) 0212 rev f .420 .350 .585 .090 .070 .100 .420 .276 .325 .205 .080 .585 .090 .070 .100 recommended solder pad layout for thicker solder paste applications recommended solder pad layout note: 1. dimensions in inch/(millimeter) 2. drawing not to scale .320 m package 3-lead plastic dd pak (reference ltc dwg # 05-08-1460 rev f) detail a detail a 0 ? 7 typ 0 ? 7 typ lt3088 3088fb for more information www.linear.com/lt3088
25 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 . revision history rev date description page number a 9/15 corrected load regulation conditions corrected graph scales corrected thermal numbers on parallel resistor use 3 5 19 b 10/15 corrected pin numbers on sot-223 package 2 lt3088 3088fb for more information www.linear.com/lt3088
26 ? linear technology corporation 2015 lt 1015 rev b ? printed in usa linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax : (408) 434-0507 www.linear.com/lt3088 related parts typical application high efficiency adjustable supply part number description comments lt1185 3a negative low dropout regulator v in : C4.5v to C35v, 0.8v dropout voltage, dd-pak and to-220 packages lt1764/ lt1764a 3a, fast transient response, low noise ldo 340mv dropout voltage, low noise: 40v rms , v in = 2.7v to 20v, to-220, tssop and dd-pak, lt1764 a version stable also with ceramic capacitors lt1963/ lt1963a 1.5a low noise, fast transient response ldo 340mv dropout voltage, low noise: 40v rms , v in = 2.5v to 20v, lt1963 a version stable with ceramic capacitors, to-220, dd, tssop, sot-223 and so-8 packages lt1965 1.1a, low noise, low dropout linear regulator 290mv dropout voltage, low noise: 40v rms , v in : 1.8v to 20v, v out : 1.2v to 19.5v, stable with ceramic capacitors, to-220, dd-pak, msop and 3mm 3mm dfn packages lt3022 1a, low voltage, vldo linear regulator v in : 0.9v to 10v, dropout voltage: 145mv typical, adjustable output (v ref = v out(min) = 200mv), stable with low esr, ceramic output capacitors, 16-pin dfn ( 5mm 3mm) and 16- lead msop packages LT3070 5a, low noise, programmable v out , 85mv dropout linear regulator with digital margining dropout voltage : 85mv, digitally programmable v out : 0.8v to 1.8v, digital output margining: 1%, 3% or 5%, low output noise: 25v rms (10hz to 100khz), parallelable: use two for a 10a output, stable with low esr ceramic output capacitors ( 15 f minimum), 28-lead 4mm 5mm qfn package lt3071 5a, low noise, programmable v out , 85mv dropout linear regulator with analog margining dropout voltage : 85mv, digitally programmable v out : 0.8v to 1.8v, analog margining: 10%, low output noise: 25v rms (10hz to 100khz), parallelable: use two for a 10a output, i mon output current monitor, stable with low esr ceramic output capacitors (15f minimum) 28-lead 4mm 5mm qfn package lt3080/ lt3080-1 1.1a, parallelable, low noise, low dropout linear regulator 300mv dropout voltage ( 2-supply operation), low noise: 40 v rms , v in : 1 . 2v to 36v, v out : 0v to 35. 7v, current-based reference with 1-resistor v out set; directly parallelable ( no op amp required), stable with ceramic capacitors, to-220, dd-pak, sot-223, ms8e and 3mm 3mm dfn-8 packages; lt3080 -1 version has integrated internal ballast resistor lt3082 200ma, parallelable, single resistor, low dropout linear regulator outputs may be paralleled for higher output, current or heat spreading, wide input voltage range: 1.2v to 40v low value input/output capacitors required: 2.2f, single resistor sets output voltage 8- lead sot-23, 3- lead sot-223 and 8-lead 3mm 3mm dfn packages lt3085 500ma, parallelable, low noise, low dropout linear regulator 275mv dropout voltage ( 2-supply operation), low noise : 40 v rms , v in : 1 . 2v to 36v, v out : 0v to 35. 7v, current-based reference with 1-resistor v out set; directly parallelable (no op amp required), stable with ceramic capacitors, ms8e and 2mm 3mm dfn-6 packages lt3092 200ma 2- terminal programmable current source programmable 2- terminal current source, maximum output current = 200ma, wide input voltage range: 1.2v to 40v, resistor ratio sets output current , initial set pin current accuracy = 1%, current limit and thermal shutdown protection, reverse-voltage protection, reverse-current protection, 8- lead sot-23, 3- lead sot-223 and 8-lead 3mm 3mm dfn packages. lt3083 adjustable 3a single resistor low dropout regulator low noise: 40 v rms , 50 a set pin current, output adjustable to 0v, wide input voltage range : 1 . 2v to 23v (dd-pak and to-220), low dropout operation: 310mv (2 supplies) run/ss 0.47f 47f 1f 1f 1000pf v in 6.3v to 36v 6.8h v in bd lt3680 15k 590k 1k 10k 3088 ta08 2n3904 mtd2955 cmdsh-4e mbra340t3 gnd boost in out v c sw fb 63.4k rt pg sync 15k lt3088 500k 22f 6v v out 0v to 25v, 800ma set 0.1f lt3088 3088fb for more information www.linear.com/lt3088

▲Up To Search▲

Price & Availability of LT3070

	To Download LT3070 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .