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lp2989 micropower/low noise, 500 ma ultra low-dropout regulator for use with ceramic output capacitors general description the lp2989 is a fixed-output 500 ma precision ldo regula- tor designed for use with ceramic output capacitors. output noise can be reduced to 18v (typical) by connecting an external 10 nf capacitor to the bypass pin. using an optimized vip ? (vertically integrated pnp) pro- cess, the lp2989 delivers superior performance: dropout voltage: typically 310 mv @ 500 ma load, and 1 mv @ 100 a load. ground pin current: typically 3 ma @ 500 ma load, and 110 a @ 100 a load. sleep mode: the lp2989 draws less than 0.8 a quiescent current when shutdown pin is pulled low. error flag: the built-in error flag goes low when the output drops approximately 5% below nominal. precision output: guaranteed output voltage accuracy is 0.75% (aao grade) and 1.25% (standard grade) at room tem- perature. features n ultra low dropout voltage n guaranteed 500 ma continuous output current n very low output noise with external capacitor n so-8 surface mount package n < 0.8 a quiescent current when shutdown n low ground pin current at all loads n 0.75% output voltage accuracy (aao grade) n high peak current capability (800 ma typical) n wide supply voltage range (16v max) n overtemperature/overcurrent protection n ?40c to +125c junction temperature range applications n notebook/desktop pc n pda/palmtop computer n wireless communication terminals n smps post-regulator block diagram vip ? is a trademark of national semiconductor corporation. ds101339-1 july 2000 lp2989 micropower/low noise, 500 ma ultra low-dropout regulator for use with ceramic output capacitors ? 2000 national semiconductor corporation ds101339 www.national.com
connection diagram ordering information table 1. package marking and ordering information for so-8 (m) devices output voltage grade order information package marking supplied as: 2.5 a lp2989aimx-2.5 2989aim2.5 2500 units on tape and reel 2.5 a lp2989aim-2.5 2989aim2.5 shipped in anti-static rails 2.5 std lp2989imx-2.5 2989im2.5 2500 units on tape and reel 2.5 std lp2989im-2.5 2989im2.5 shipped in anti-static rails 3.3 a lp2989aimx-3.3 2989aim3.3 2500 units on tape and reel 3.3 a lp2989aim-3.3 2989aim3.3 shipped in anti-static rails 3.3 std lp2989imx-3.3 2989im3.3 2500 units on tape and reel 3.3 std lp2989im-3.3 2989im3.3 shipped in anti-static rails basic application circuit surface mount packages: so-8 package type m: see ns package drawing number m08a ds101339-2 ds101339-3 * capacitance values shown are minimum required to assure stability, but may be increased without limit. larger output capacitor provides improved dy namic re- sponse. ** shutdown must be actively terminated (see app. hints). tie to input (pin4) if not used. lp2989 www.national.com 2
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 temperature (soldering, 5 seconds) 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) 2.1v to +16v sense pin ?0.3v to +6v output voltage (survival) (note 4) ?0.3v to +16v i out (survival) short circuit protected input-output voltage (survival) (note 5) ?0.3v to +16v 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 out = 4.7 f, c in = 1 f, v s/d = 2v. symbol parameter conditions typical lp2989ai-x.x (note 6) lp2989i-x.x (note 6) units min max min max v o output voltage tolerance ?0.75 0.75 ?1.25 1.25 %v nom 1ma < i l < 500 ma v o (nom) + 1v v in 16v ?1.5 1.5 ?2.5 2.5 ?4.0 2.5 ?5.0 3.5 1ma < i l < 500 ma v o (nom) + 1v v in 16v ?25c t j 125c ?3.5 2.5 ?4.5 3.5 output voltage line regulation v o (nom) + 1v v in 16v 0.005 0.014 0.014 %/v 0.032 0.032 load regulation 1 ma < i l < 500 ma 0.4 %v nom v in v o dropout voltage (note 7) i l = 100 a 1 33 mv 44 i l = 200 ma 150 200 200 300 300 i l = 500 ma 310 425 425 650 650 i gnd ground pin current i l = 100 a 110 175 175 a 200 200 i l = 200 ma 1 22 ma 3.5 3.5 i l = 500 ma 3 66 99 v s/d < 0.18v 0.5 2 2 a v s/d < 0.4v 0.05 0.8 0.8 i o (pk) peak output current v out 3 v o (nom) ? 5% 800 600 600 ma i o (max) short circuit current r l = 0 (steady state) (note 9) 1000 e n output noise voltage (rms) bw = 100 hz to 100 khz, c out =10f c bypass = .01 f v out = 2.5v 18 v(rms) ripple rejection f = 1 khz, c out =10f 60 db lp2989 www.national.com 3
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 out = 4.7 f, c in = 1 f, v s/d = 2v. symbol parameter conditions typical lp2989ai-x.x (note 6) lp2989i-x.x (note 6) units min max min max output voltage temperature coefficient (note 8) 20 ppm/c shutdown input v s/d s/d input voltage v h = o/p on 1.4 1.6 1.6 v v l = o/p off i in 2a 0.50 0.18 0.18 i s/d s/d input current v s/d = 0 0.001 ?1 ?1 a v s/d =5v 5 15 15 error comparator i oh output ahigho leakage v oh = 16v 0.001 11 a 22 v ol output alowo voltage v in =v o (nom) ? 0.5v, i o (comp) = 150 a 150 220 220 mv 350 350 v thr (max) upper threshold voltage ?4.8 ?6.0 ?3.5 ?6.0 ?3.5 %v out ?8.3 ?2.5 ?8.3 ?2.5 v thr (min) lower threshold voltage ?6.6 ?8.9 ?4.9 ?8.9 ?4.9 ?13.0 ?3.0 ?13.0 ?3.0 hyst hysteresis 2.0 note 1: absolute maximum ratings indicate limits beyond which damage to the component may occur. electrical specifications do not apply when operating the d e- vice outside of its rated operating conditions. note 2: esd testing was performed using human body model, a 100 pf capacitor discharged through a 1.5 k w resistor. 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 temperature is calculated using: the value of q j?a for the so-8 (m) package is 160c. exceeding the maximum allowable power 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 lp2989 output must be diode-clamped to ground. note 5: the output pnp structure contains a diode between the v in and v out terminals that is normally reverse-biased. forcing the output above the input will turn on this diode and may induce a latch-up mode which can damage the part (see application hints). note 6: limits are 100% production tested at 25c. limits over the operating temperature range are guaranteed through correlation using statistical qualit y 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: temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range. note 9: see typical performance characteristics curves. lp2989 www.national.com 4
typical performance characteristics unless otherwise specified: t a = 25c, c out = 4.7 f, c in = 1 f, s/d is tied to v in ,v in =v o (nom) + 1v, i l = 1 ma, v out = 2.5v. input current vs v in ds101339-5 input current vs v in ds101339-6 i gnd vs shutdown ds101339-7 i gnd vs shutdown ds101339-8 i gnd vs shutdown ds101339-9 i gnd vs shutdown ds101339-10 lp2989 www.national.com 5
typical performance characteristics unless otherwise specified: t a = 25c, c out = 4.7 f, c in = 1 f, s/d is tied to v in ,v in =v o (nom) + 1v, i l = 1 ma, v out = 2.5v. (continued) line transient response ds101339-11 line transient response ds101339-26 line transient response ds101339-15 line transient response ds101339-16 load transient response ds101339-17 load transient response ds101339-18 lp2989 www.national.com 6
typical performance characteristics unless otherwise specified: t a = 25c, c out = 4.7 f, c in = 1 f, s/d is tied to v in ,v in =v o (nom) + 1v, i l = 1 ma, v out = 2.5v. (continued) dropout voltage vs load current ds101339-19 dropout voltage vs temperature ds101339-20 dropout characteristics ds101339-21 ground pin current vs load current ds101339-22 gnd pin current vs temperature and load ds101339-23 v out vs shutdown ds101339-24 lp2989 www.national.com 7
typical performance characteristics unless otherwise specified: t a = 25c, c out = 4.7 f, c in = 1 f, s/d is tied to v in ,v in =v o (nom) + 1v, i l = 1 ma, v out = 2.5v. (continued) input current vs v in ds101339-25 turn-on waveform ds101339-28 turn-on waveform ds101339-29 turn-on waveform ds101339-30 turn-on waveform ds101339-31 short circuit current vs temperature ds101339-32 lp2989 www.national.com 8
typical performance characteristics unless otherwise specified: t a = 25c, c out = 4.7 f, c in = 1 f, s/d is tied to v in ,v in =v o (nom) + 1v, i l = 1 ma, v out = 2.5v. (continued) short circuit current vs v out ds101339-33 short circuit current ds101339-34 short circuit current ds101339-35 output noise density ds101339-36 output noise density ds101339-37 lp2989 www.national.com 9
typical performance characteristics unless otherwise specified: t a = 25c, c out = 4.7 f, c in = 1 f, s/d is tied to v in ,v in =v o (nom) + 1v, i l = 1 ma, v out = 2.5v. (continued) ripple rejection ds101339-39 ripple rejection ds101339-40 ripple rejection ds101339-41 ripple rejection ds101339-42 ripple rejection ds101339-43 ripple rejection ds101339-44 lp2989 www.national.com 10
typical performance characteristics unless otherwise specified: t a = 25c, c out = 4.7 f, c in = 1 f, s/d is tied to v in ,v in =v o (nom) + 1v, i l = 1 ma, v out = 2.5v. (continued) ripple rejection ds101339-45 ripple rejection in dropout ds101339-46 ripple rejection vs load ds101339-47 lp2989 www.national.com 11
application hints external capacitors like any low-dropout regulator, the lp2989 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 lp2989 input and ground (the amount of capacitance may be increased without limit). this capacitor must be located a distance of not more than 0.5 2 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 failure 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 lp2989 is designed specifically to work with ceramic output capacitors, utilizing circuitry which allows the regulator to be stable across the entire range of output current with an output capacitor whose esr is as low as 5 m w . it may also be possible to use tantalum or film capacitors at the output, but these are not as attrac- tive 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 lp2989 requires a minimum of 4.7 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. some ceramic capacitors can exhibit large changes in capacitance with temperature, so x7r or x5r dielectric are strongly recommended. the output capacitor must be located not more than 0.5 2 from the output pin and returned to a clean analog ground. noise bypass capacitor: connecting a 10 nf capaci- tor to the bypass pin significantly reduces noise on the regu- lator output. however, the capacitor is connected directly to a high-impedance circuit 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 ceramic: the lp2989 was designed to work with ceramic capacitors on the output to take advantage of the benefits they offer: for capacitance values in the 4.7 f range, ceram- ics are the least expensive and also have the lowest esr values (which makes them best for eliminating high-frequency noise). the esr of a typical 4.7 f ceramic capacitor is in the range of 10 m w to 15 m w , which easily meets the esr limits required for stability by the lp2989. one disadvantage of ceramic capacitors is that their capaci- tance can vary with temperature. many 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 4.7 f capacitor were used on the output since it will drop down to approximately 2.4 f at high ambient temperatures (which could cause the lp2989 to oscillate). if z5u or y5v capacitors are used on the output, a minimum capacitance value of 10 f must be observed. a better choice for temperature coefficient in ceramic capaci- tors is x7r or x5r, which holds the capacitance within about 15% over the operating temperature range. tantalum: tantalum output capacitors are not recom- mended for use with the lp2989 because: tantalum capacitors are less desirable than ceramics for use as output capacitors because they are typically more expen- sive 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. film: polycarbonate and polypropelene film capacitors have excellent electrical performance: their esr is the low- ds101339-38 stable region for output capacitor esr lp2989 www.national.com 12
application hints (continued) est of the three types listed, their capacitance is very stable with temperature, and dc leakage currrent is extremely low. one disadvantage is that film capacitors are larger in physi- cal size than ceramic or tantalum which makes film a poor choice for either input or output capacitors. however, their low leakage makes them a good choice for the noise bypass capacitor. since the required amount of ca- pacitance is only .01 f, small surface-mount film capacitors are avalable in this size. shutdown input operation the lp2989 is shut off by driving the shutdown input low, and turned on by pulling it high. if this feature is not to be used, the shutdown 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 shutdown 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 applied to the shutdown input must have a slew rate which is 3 40 mv/s. caution: the regulator output voltage can not be guaran- teed if a slow-moving ac (or dc) signal is applied that is in the range between the specified turn-on and turn-off volt- ages listed under the electrical specification v on/off (see electrical characteristics). reverse input-output voltage the pnp power transistor used as the pass element in the lp2989 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 lp2989 to 0.3v (see absolute maximum ratings). lp2989 www.national.com 13
physical dimensions inches (millimeters) unless otherwise noted 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) 180-530 85 86 email: europe.support@nsc.com deutsch tel: +49 (0) 69 9508 6208 english tel: +44 (0) 870 24 0 2171 fran?ais tel: +33 (0) 1 41 91 8790 national semiconductor asia pacific customer response group tel: 65-2544466 fax: 65-2504466 email: ap.support@nsc.com national semiconductor japan ltd. tel: 81-3-5639-7560 fax: 81-3-5639-7507 www.national.com so-8 package type m ns package number m08a lp2989 micropower/low noise, 500 ma ultra low-dropout regulator for use with ceramic output capacitors 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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