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lp2985 micropower sot, 150 ma low-noise ultra low-dropout regulator designed for use with very low esr output capacitors general description the lp2985 is a 150 ma, fixed-output voltage regulator de- signed to provide ultra low-dropout and low noise in battery powered applications. using an optimized vip ? (vertically integrated pnp) pro- cess, the lp2985 delivers unequalled performance in all specifications critical to battery-powered designs: dropout voltage: typically 300 mv @ 150 ma load, and 7mv @ 1 ma load. ground pin current: typically 850 a @ 150 ma load, and 75 a @ 1 ma load. enhanced stability: the lp2985 is stable with output ca- pacitor esr as low as 5 m w , which allows the use of ceramic capacitors on the output. sleep mode: less than 1 a quiescent current when on/off pin is pulled low. smallest possible size: sot-23 package uses absolute minimum board space. precision output: 1 % tolerance output voltages available (a grade). low noise: by adding a 10 nf bypass capacitor, output noise can be reduced to 30 v (typical). multiple voltage options, from 2.5v to 5.0v, are available as standard products. consult factory for custom voltages. features n ultra low dropout voltage n guaranteed 150 ma output current n smallest possible size (sot-23, micro smd package) n requires minimum external components n stable with low-esr output capacitor n < 1 a quiescent current when shut down n low ground pin current at all loads n output voltage accuracy 1 % (a grade) n high peak current capability n wide supply voltage range (16v max) n low z out : 0.3 w typical (10 hz to 1 mhz) n overtemperature/overcurrent protection n ?40c to +125c junction temperature range n custom voltages available applications n cellular phone n palmtop/laptop computer n personal digital assistant (pda) n camcorder, personal stereo, camera block diagram vip ? is a trademark of national semiconductor corporation. ds100140-1 october 1999 lp2985 micropower sot, 150 ma low-noise ultra low-dropout regulator ? 1999 national semiconductor corporation ds100140 www.national.com
basic application circuit connection diagrams ordering information table 1. package marking and ordering information output voltage (v) grade order information package marking supplied as: 5-lead small outline package (m5) 2.5 a lp2985aim5x-2.5 laua 3000 units on tape and reel ds100140-2 *on/off input must be actively terminated. tie to v in if this function is not to be used. **minimum capacitance is shown to ensure stability (may be increased without limit). ceramic capacitor required for output (see application hints) . ***reduces output noise (may be omitted if application is not noise critical). use ceramic or film type with very low leakage current (see application hints). 5-lead small outline package (m5) ds100140-3 top view see ns package number ma05b for ordering information see table 1 micro smd, 5 bump package (bpa05) ds100140-44 bottom view see ns package number bpa05 lp2985 www.national.com 2
ordering information (continued) table 1. package marking and ordering information (continued) output voltage (v) grade order information package marking supplied as: 5-lead small outline package (m5) 2.5 a lp2985aim5-2.5 laua 1000 units on tape and reel 2.5 std lp2985im5x-2.5 laub 3000 units on tape and reel 2.5 std lp2985im5-2.5 laub 1000 units on tape and reel 2.8 a lp2985aim5x-2.8 l0ka 3000 units on tape and reel 2.8 a lp2985aim5-2.8 l0ka 1000 units on tape and reel 2.8 std lp2985im5x-2.8 l0kb 3000 units on tape and reel 2.8 std lp2985im5-2.8 l0kb 1000 units on tape and reel 3.0 a lp2985aim5x-3.0 l0oa 3000 units on tape and reel 3.0 a lp2985aim5-3.0 l0oa 1000 units on tape and reel 3.0 std lp2985im5x-3.0 l0ob 3000 units on tape and reel 3.0 std lp2985im5-3.0 l0ob 1000 units on tape and reel 3.1 a lp2985aim5x-3.1 l0pa 3000 units on tape and reel 3.1 a lp2985aim5-3.1 l0pa 1000 units on tape and reel 3.1 std lp2985im5x-3.1 l0pb 3000 units on tape and reel 3.1 std lp2985im5-3.1 l0pb 1000 units on tape and reel 3.2 a lp2985aim5x-3.2 l0qa 3000 units on tape and reel 3.2 a lp2985aim5-3.2 l0qa 1000 units on tape and reel 3.2 std lp2985im5x-3.2 l0qb 3000 units on tape and reel 3.2 std lp2985im5-3.2 l0qb 1000 units on tape and reel 3.3 a lp2985aim5x-3.3 l0ra 3000 units on tape and reel 3.3 a lp2985aim5-3.3 l0ra 1000 units on tape and reel 3.3 std lp2985im5x-3.3 l0rb 3000 units on tape and reel 3.3 std lp2985im5-3.3 l0rb 1000 units on tape and reel 3.5 a lp2985aim5x-3.5 laia 3000 units on tape and reel 3.5 a lp2985aim5-3.5 laia 1000 units on tape and reel 3.5 std lp2985im5x-3.5 laib 3000 units on tape and reel 3.5 std lp2985im5-3.5 laib 1000 units on tape and reel 3.6 a lp2985aim5x-3.6 l0sa 3000 units on tape and reel 3.6 a lp2985aim5-3.6 l0sa 1000 units on tape and reel 3.6 std lp2985im5x-3.6 l0sb 3000 units on tape and reel 3.6 std lp2985im5-3.6 l0sb 1000 units on tape and reel 4.0 a lp2985aim5x-4.0 l0ta 3000 units on tape and reel 4.0 a lp2985aim5-4.0 l0ta 1000 units on tape and reel 4.0 std lp2985im5x-4.0 l0tb 3000 units on tape and reel 4.0 std lp2985im5-4.0 l0tb 1000 units on tape and reel 5.0 a lp2985aim5x-5.0 l0ua 3000 units on tape and reel 5.0 a lp2985aim5-5.0 l0ua 1000 units on tape and reel 5.0 std lp2985im5x-5.0 l0ub 3000 units on tape and reel 5.0 std lp2985im5-5.0 l0ub 1000 units on tape and reel micro smd, 5 bump package (bpa05) 2.5 a lp2985aibp-2.5 1000 units on tape and reel 2.5 a lp2985aibpx-2.5 3000 units on tape and reel 2.5 std lp2985ibp-2.5 1000 units on tape and reel 2.5 std lp2985ibpx-2.5 3000 units on tape and reel 2.8 a lp2985aibp-2.8 1000 units on tape and reel 2.8 a lp2985aibpx-2.8 3000 units on tape and reel lp2985 www.national.com 3
ordering information (continued) table 1. package marking and ordering information (continued) output voltage (v) grade order information package marking supplied as: micro smd, 5 bump package (bpa05) 2.8 std lp2985ibp-2.8 1000 units on tape and reel 2.8 std lp2985ibpx-2.8 3000 units on tape and reel 3.3 a lp2985aibp-3.3 1000 units on tape and reel 3.3 a lp2985aibpx-3.3 3000 units on tape and reel 3.3 std lp2985ibpx-3.3 1000 units on tape and reel 3.3 std lp2985ibpx-3.3 3000 units on tape and reel lp2985 www.national.com 4
absolute maximum ratings (note 1) if military/aerospace specified devices are required, please contact the national semiconductor sales office/ distributors for availability and specifications. storage temperature range ?65c to +150c operating junction temperature range ?40c to +125c lead temp. (soldering, 5 sec.) 260c esd rating (note 2) 2 kv power dissipation (note 3) internally limited input supply voltage (survival) ?0.3v to +16v input supply voltage (operating) 2.5v to +16v shutdown input voltage (survival) ?0.3v to +16v output voltage (survival, (note 4)) ?0.3v to +9v i out (survival) short circuit protected input-output voltage (survival, ?0.3v to +16v (note 5)) electrical characteristics limits in standard typeface are for t j = 25c. and limits in boldface type apply over the full operating temperature range. un- less otherwise specified: v in =v o (nom) + 1v, i l = 1 ma, c in = 1 f, c out = 4.7 f, v on/off = 2v. symbol parameter conditions typ lp2985ai-x.x lp2985i-x.x units (note 6) (note 6) min max min max d v o output voltage tolerance i l = 1 ma ?1.0 1.0 ?1.5 1.5 % v nom 1ma i l 50 ma ?1.5 1.5 ?2.5 2.5 ?2.5 2.5 ?3.5 3.5 1ma i l 150 ma ?2.5 2.5 ?3.0 3.0 ?3.5 3.5 ?4.0 4.0 output voltage v o (nom)+1v v in 16v 0.007 0.014 0.014 % /v line regulation 0.032 0.032 v in v o dropout voltage (note 7) i l =0 1 3 3 mv 55 i l = 1 ma 7 10 10 15 15 i l =10ma 40 60 60 90 90 i l = 50 ma 120 150 150 225 225 i l = 150 ma 280 350 350 575 575 i gnd ground pin current i l = 0 65 95 95 a 125 125 i l = 1 ma 75 110 110 170 170 i l = 10 ma 120 220 220 400 400 i l = 50 ma 350 600 600 1000 1000 i l = 150 ma 850 1500 1500 2500 2500 v on/off < 0.3v 0.01 0.8 0.8 v on/off < 0.15v 0.05 2 2 v on/off on/off input voltage (note 8) high = o/p on 1.4 1.6 1.6 v low = o/p off 0.55 0.15 0.15 i on/off on/off input current v on/off = 0 0.01 ?2 ?2 a v on/off =5v 5 15 15 e n output noise bw = 300 hz to 50 khz, voltage (rms) c out =10f 30 v c bypass =10nf lp2985 www.national.com 5
electrical characteristics (continued) limits in standard typeface are for t j = 25c. and limits in boldface type apply over the full operating temperature range. un- less otherwise specified: v in =v o (nom) + 1v, i l = 1 ma, c in = 1 f, c out = 4.7 f, v on/off = 2v. symbol parameter conditions typ lp2985ai-x.x lp2985i-x.x units (note 6) (note 6) min max min max ripple rejection f = 1 khz, c bypass =10nf 45 db c out =10f i o (sc) short circuit current r l = 0 (steady state) 400 ma (note 9) i o (pk) peak output current v out 3 v o (nom) ?5 % 350 ma note 1: aabsolute maximum ratingso indicate limits beyond which damage to the component may occur. electrical specifications do not apply when operating th e device outside of its rated operating conditions. note 2: the esd rating of pins 3 and 4 is 1 kv. note 3: the maximum allowable power dissipation is a function of the maximum junction temperature, t j (max), the junction-to-ambient thermal resistance, q j-a , and the ambient temperature, t a . the maximum allowable power dissipation at any ambient temperture is calculated using: where the value of q j-a for the sot-23 package is 220c/w in a typical pc board mounting and the micro smd package is 320c/w. exceeding the maximum al- lowable dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. note 4: if used in a dual-supply system where the regulator load is returned to a negative supply, the lp2985 output must be diode-clamped to ground. note 5: the output pnp structure contains a diode between the v in to v out terminals that is normally reverse-biased. reversing the polarity from v in to v out will turn on this diode. note 6: limits are 100 % production tested at 25c. limits over the operating temperature range are guaranteed through correlation using statistical quality control (sqc) methods. the limits are used to calculate national's average outgoing quality level (aoql). note 7: dropout voltage is defined as the input to output differential at which the output voltage drops 100 mv below the value measured with a 1v differential. note 8: the on/off input must be properly driven to prevent possible misoperation. for details, refer to application hints. note 9: the lp2985 has foldback current limiting which allows a high peak current when v out > 0.5v, and then reduces the maximum output current as v out is forced to ground (see typical performance characteristics curves). lp2985 www.national.com 6
typical performance characteristics unless otherwise specified: c in = 1f, c out = 4.7f, v in = v out (nom) +1, t a = 25c, on/off pin is tied to v in . v out vs temperature ds100140-8 short-circuit current ds100140-9 short-circuit current ds100140-10 short circuit current vs output voltage ds100140-11 ripple rejection ds100140-13 ripple rejection ds100140-14 ripple rejection ds100140-15 ripple rejection ds100140-16 ripple rejection ds100140-17 ripple rejection ds100140-18 ripple rejection ds100140-19 ripple rejection ds100140-23 lp2985 www.national.com 7
typical performance characteristics unless otherwise specified: c in = 1f, c out = 4.7f, v in = v out (nom) +1, t a = 25c, on/off pin is tied to v in . (continued) ripple rejection ds100140-22 output impedance vs frequency ds100140-20 output impedance vs frequency ds100140-21 output noise density ds100140-24 output noise density ds100140-25 ground pin vs load current ds100140-26 dropout voltage vs temperature ds100140-27 dropout voltage vs load current ds100140-28 input current vs pin ds100140-29 gnd pin current vs temperature ds100140-30 instantaneous short circuit current ds100140-31 load transient response ds100140-32 lp2985 www.national.com 8
typical performance characteristics unless otherwise specified: c in = 1f, c out = 4.7f, v in = v out (nom) +1, t a = 25c, on/off pin is tied to v in . (continued) load transient response ds100140-33 load transient response ds100140-34 line transient response ds100140-35 line transient response ds100140-36 line transient response ds100140-37 line transient response ds100140-38 turn-on time ds100140-39 turn-on time ds100140-40 turn-on time ds100140-41 turn-on time ds100140-42 lp2985 www.national.com 9
application hints external capacitors like any low-dropout regulator, the lp2985 requires external capacitors for regulator stability. these capacitors must be correctly selected for good performance. input capacitor an input capacitor whose capacitance is 3 1 f is required between the lp2985 input and ground (the amount of ca- pacitance may be increased without limit). this capacitor must be located a distance of not more than 1 cm from the input pin and returned to a clean analog ground. any good quality ceramic, tantalum, or film capacitor may be used at the input. important: tantalum capacitors can suffer catastrophic fail- ure due to surge current when connected to a low-impedance source of power (like a battery or very large capacitor). if a tantalum capacitor is used at the input, it must be guaranteed by the manufacturer to have a surge current rating sufficient for the application. there are no requirements for esr on the input capacitor, but tolerance and temperature coefficient must be consid- ered when selecting the capacitor to ensure the capacitance will be 3 1 f over the entire operating temperature range. output capacitor: the lp2985 is designed specifically to work with ceramic output capacitors, utilizing circuitry which allows the regula- tor to be stable across the entire range of output current with an output capacitor whose esr is as low as 5 m w .itmay also be possible to use tantalum or film capacitors at the output, but these are not as attractive for reasons of size and cost (see next section capacitor characteristics). the output capacitor must meet the requirement for mini- mum amount of capacitance and also have an esr (equiva- lent series resistance) value which is within the stable range. curves are provided which show the stable esr range as a function of load current (see esr graph below). important: the output capacitor must maintain its esr within the stable region over the full operating temperature range of the application to assure stability. the lp2985 requires a minimum of 2.2 f on the output (output capacitor size can be increased without limit). it is important to remember that capacitor tolerance and variation with temperature must be taken into consideration when selecting an output capacitor so that the minimum re- quired amount of output capacitance is provided over the full operating temperature range. it should be noted that ceramic capacitors can exhibit large changes in capacitance with temperature (see next section, capacitor characteristics ). the output capacitor must be located not more than 1 cm from the output pin and returned to a clean analog ground. noise bypass capacitor: connecting a 10 nf capacitor to the bypass pin significantly reduces noise on the regulator output. it should be noted that the capacitor is connected directly to a high-impedance cir- cuit in the bandgap reference. because this circuit has only a few microamperes flowing in it, any significant loading on this node will cause a change in the regulated output voltage. for this reason, dc leakage current through the noise bypass capacitor must never ex- ceed 100 na, and should be kept as low as possible for best output voltage accuracy. the types of capacitors best suited for the noise bypass ca- pacitor are ceramic and film. high-quality ceramic capacitors with either npo or cog dielectric typically have very low leakage. 10 nf polypropolene and polycarbonate film ca- pacitors are available in small surface-mount packages and typically have extremely low leakage current. capacitor characteristics the lp2985 was designed to work with ceramic capacitors on the output to take advantage of the benefits they offer: for capacitance values in the 2.2 f to 4.7 f range, ceramics are the least expensive and also have the lowest esr val- ues (which makes them best for eliminating high-frequency noise). the esr of a typical 2.2 f ceramic capacitor is in the range of 10 m w to 20 m w , which easily meets the esr limits required for stability by the lp2985. one disadvantage of ceramic capacitors is that their capaci- tance can vary with temperature. most large value ceramic capacitors ( 3 2.2 f) are manufactured with the z5u or y5v temperature characteristic, which results in the capacitance dropping by more than 50 % as the temperature goes from 25c to 85c. this could cause problems if a 2.2 f capacitor were used on the output since it will drop down to approximately 1 f at high ambient temperatures (which could cause the lm2985 to oscillate). if z5u or y5v capacitors are used on the output, a minimum capacitance value of 4.7 f must be observed. a better choice for temperature coefficient in ceramic capaci- tors is x7r, which holds the capacitance within 15 % . un- fortunately, the larger values of capacitance are not offered by all manufacturers in the x7r dielectric. tantalum: tantalum capacitors are less desirable than ceramics for use as output capacitors because they are more expensive when comparing equivalent capacitance and voltage ratings in the 1 f to 4.7 f range. another important consideration is that tantalum capacitors have higher esr values than equivalent size ceramics. this means that while it may be possible to find a tantalum ca- pacitor with an esr value within the stable range, it would have to be larger in capacitance (which means bigger and more costly) than a ceramic capacitor with the same esr value. it should also be noted that the esr of a typical tantalum will increase about 2:1 as the temperature goes from 25c down to ?40c, so some guard band must be allowed. ds100140-7 lp2985 www.national.com 10
application hints (continued) on/off input operation the lp2985 is shut off by driving the on/off input low, and turned on by pulling it high. if this feature is not to be used, the on/off input should be tied to v in to keep the regulator output on at all times. to assure proper operation, the signal source used to drive the on/off input must be able to swing above and below the specified turn-on/turn-off voltage thresholds listed in the electrical characteristics section under v on/off . to prevent mis-operation, the turn-on (and turn-off) voltage signals ap- plied to the on/off input must have a slew rate which is 3 40 mv/s. caution: the regulator output voltage can not be guaranteed if a slow-moving ac (or dc) signal is applied that is in the range between the specified turn-on and turn-off voltages listed under the electrical specification v on/off (see electri- cal characteristics). reverse input-output voltage the pnp power transistor used as the pass element in the lp2985 has an inherent diode connected between the regu- lator output and input. during normal operation (where the input voltage is higher than the output) this diode is reverse-biased. however, if the output is pulled above the input, this diode will turn on and current will flow into the regulator output. in such cases, a parasitic scr can latch which will allow a high current to flow into v in (and out the ground pin), which can damage the part. in any application where the output may be pulled above the input, an external schottky diode must be connected from v in to v out (cathode on v in , anode on v out ), to limit the re- verse voltage across the lp2985 to 0.3v (see absolute maximum ratings). micro smd mounting the micro smd package requires specific mounting tech- niques which are detailed in national semiconductor appli- cation note # 1112. referring to the section surface mount technology (smt) assembly considerations , it should be noted that the pad style which must be used with the 5-pin package is the nsmd (non-solder mask defined) type. for best results during assembly, alignment ordinals on the pc board may be used to facilitate placement of the micro smd device. micro smd light sensitivity exposing the micro smd device to direct sunlight will cause misoperation of the device. light sources such as halogen lamps can also affect electrical performance if brought near to the device. the wavelenghts which have the most detrimental effect are reds and infra-reds, which means that the fluorescent light- ing used inside most buildings has very little effect on perfor- mance. a micro smd test board was brought to within 1 cm of a fluorescent desk lamp and the effect on the regulated output voltage was negligible, showing a deviation of less than 0.1 % from nominal. lp2985 www.national.com 11
physical dimensions inches (millimeters) unless otherwise noted 5-lead small outline package (m5) ns package number ma05b for order numbers, refer to table 1 in the aordering informationo section of this document. lp2985 www.national.com 12
physical dimensions inches (millimeters) unless otherwise noted (continued) notes: unless otherwise specified 1. epoxy coating 2. 63sn/37pb eutectic bump 3. recommend non-solder mask defined landing pad. 4. pin 1 is established by lower left corner with respect to text orientation. remaining pins are numbered counter clockwise. 5. xxx in drawing number represents package size variation where x1 is package width, x2 is pack- age length and x3 is package height. 6.no jedec registration as of aug.1999. micro smd, 5 bump, package (bpa05) ns package number bpa05a for order numbers, refer to table 1 in the aordering informationo section of this document. the dimensions for x1, x2 and x3 are as given: x1 = 0.930 +/? 0.030mm x2 = 1.107 +/? 0.030mm x3 = 0.850 +/? 0.050mm lp2985 www.national.com 13
notes life support policy national's products are not authorized for use as critical components in life support devices or systems without the express written approval of the president and general counsel of national semiconductor corporation. as used herein: 1. life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. 2. a critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. national semiconductor corporation americas tel: 1-800-272-9959 fax: 1-800-737-7018 email: support@nsc.com national semiconductor europe fax: +49 (0) 1 80-530 85 86 email: europe.support@nsc.com deutsch tel: +49 (0) 1 80-530 85 85 english tel: +49 (0) 1 80-532 78 32 fran?ais tel: +49 (0) 1 80-532 93 58 italiano tel: +49 (0) 1 80-534 16 80 national semiconductor asia pacific customer response group tel: 65-2544466 fax: 65-2504466 email: sea.support@nsc.com national semiconductor japan ltd. tel: 81-3-5639-7560 fax: 81-3-5639-7507 www.national.com lp2985 micropower sot, 150 ma low-noise ultra low-dropout regulator national does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and national reserves the righ t at any time without notice to change said circuitry and specifications.

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