mic5253 micrel mic5253 100ma low noise cap teeny? ldo general descriptionthe mic5253 is an efficient, cmos voltage regulator opti- mized for ultra-low-noise applications. it offers 1.5% initial accuracy, extremely low dropout voltage (165mv at 100ma), and low ground current (typically 95 a at full load). the mic5253 provides a very low noise output, ideal for rfapplications where a clean voltage source is required. a noise bypass pin is also available for further reduction of output noise. designed specifically for handheld and battery-powered de- vices, the mic5253 provides a ttl-logic-compatible enable pin. when disabled, power consumption drops nearly to zero. the mic5253 also works with low-esr ceramic capacitors, reducing the amount of board space necessary for power applications, critical in handheld wireless devices. available in the teeny? sc-70-5 package, the mic5253 offers a wide range of output voltages. key features include current limit, thermal shutdown, faster transient response, and an active clamp to speed up device turn-off. typical application c out = 1.0 f c in = 1.0 f ceramic ceramic 152 3 4 c byp = 0.01 f enable shutdown en v out mic5253-x.xbc5 en (pin 3) may be connected directly to in (pin 1). v in ultra-low-noise regulator application features? input voltage range: 2.7v to 5.5v ? teeny? sc-70-5 package ? ultra-low output noise: 30 v(rms) ? 100ma continuous output current, 150ma peak current ? stability with ceramic output capacitors ? ultralow dropout: 165mv @ 100ma ? high output accuracy: 1.5% initial accuracy3.0% over temperature ? low ground current: 95 a ? ttl-logic-controlled enable input ? zero off-mode current ? thermal shutdown and current limit protection applications? cellular phones and pagers ? cellular accessories ? battery-powered equipment ? laptop, notebook, and palmtop computers ? consumer/personal electronics micrel, inc. ? 2180 fortune drive ? san jose, ca 95131 ? usa ? tel + 1 (408) 944-0800 ? fax + 1 (408) 474-1000 ? http://www.micrel.com m9999- 112305 november 200 5 1 downloaded from: http:///
mic5253 micrel m9999- 112305 2 pin configuration 2 gnd sc-70-5 (c5) pin description pin number pin name pin function 1 in supply input. 2 gnd ground. 3 en enable/shutdown (input): cmos compatible input. logic high = enable; logic low = shutdown. do not leave open. 4 byp reference bypass: connect external 0.01 f c byp 1.0 f capacitor to gnd to reduce output noise. may be left open. 5 out regulator output. ordering information november 200 5 standard marking pb-free marking** mic5253-1.5bc5 715 mic5253-1.5yc5 715 1.5v ?40c to +125c sc-70-5 mic5253-1.8bc5 718 mic5253-1.8yc5 718 1.8v ?40c to +125c sc-70-5 mic5253-1.85bc5 71j mic5253-1.85yc5 71j 1.85v ?40c to +125c sc-70-5 mic5253-2.5bc5 725 mic5253-2.5yc5 725 2.5v ?40c to +125c sc-70-5 mic5253-2.6bc5 726 mic5253-2.6yc5 726 2.6v ?40c to +125c sc-70-5 mic5253-2.7bc5 727 mic5253-2.7yc5 727 2.7v ?40c to +125c sc-70-5 mic5253-2.8bc5 728 mic5253-2.8yc5 728 2.8v ?40c to +125c sc-70-5 mic5253-2.9bc5 729 mic5253-2.9yc5 729 2.9v ?40c to +125c sc-70-5 mic5253-3.0bc5 730 mic5253-3.0yc5 730 3.0v ?40c to +125c sc-70-5 mic5253-3.1bc5 731 mic5253-3.1yc5 731 3.1v ?40c to +125c sc-70-5 mic5253-3.2bc5 732 mic5253-3.2yc5 732 3.2v ?40c to +125c sc-70-5 mic5253-3.3bc5 733 mic5253-3.3yc5 733 3.3v ?40c to +125c sc-70-5 * other voltage options available. contact micrel marketing for details.** under bar symbol ( _ ) may not be to scale. part number voltage* junction temp. range package in out byp en 7xx 1 3 4 5 2 downloaded from: http:///
mic5253 micrel electrical characteristics (5) v in = v out + 1v, v en = v in; i out = 100 a; t j = 25 c, bold values indicate C40 c t j +125 c; unless otherwise noted. symbol parameter conditions min typical max units v o output voltage accuracy i out = 100 a C 1.5 1.5 % C 33 % ? v lnr line regulation v in = v out + 1v to 6v 0.035 0.05 %/v ? v ldr load regulation i out = 0.1ma to 100ma, note 6 1.5 2.5 % v in C v out dropout voltage (7) i out = 50ma 80 150 mv i out = 100ma 165 300 mv i q quiescent current v en 0.4v (shutdown) 0.2 1 a i gnd ground pin current (8) i out = 0ma 75 100 a i out = 100ma 90 150 a psrr ripple rejection f = 100hz, c out = 1.0 f, c byp = 0.1 f6 6d b f = 1khz, v in = v out +1, c byp = 0.1 f7 0d b f = 10khz, v in = v out +1, c byp = 0.1 f6 5d b t on turn-on time 30 150 s i lim current limit v out = 0v 150 250 450 ma e n output voltage noise c out = 1.0 f, c byp = 0.01 f, 30 v(rms) f = 10hz to 100khz enable input v il enable input logic-low voltage v in = 2.7v to 5.5v, regulator shutdown 0.4 v v ih enable input logic-high voltage v in = 2.7v to 5.5v, regulator enabled 1.6 v i en enable input current v il 0.4v, regulator shutdown 0.01 a v ih 1.6v, regulator enabled 0.01 a thermal protection thermal shutdown temperature 150 c thermal shutdown hysteresis 10 c notes: 1. exceeding the absolute maximum ratings may damage the device. 2. the device is not guaranteed to function outside its operating ratings. 3. the maximum allowable power dissipation of any t a (ambient temperature) is p d(max) = (t j(max) Ct a )/ ja . exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. the ja of the mic5253-x.xbc5 (all versions) is 400 c/w on a pc board (see thermal considerations section for further details). 4. devices are esd sensitive. handling precautions recommended. 5. specification for packaged product only. 6. regulation is measured at constant junction temperature using low duty cycle pulse testing. parts are tested for load regulation in the load range from 0.1ma to 100ma. changes in output voltage due to heating effects are covered by the thermal regulation specification. 7. dropout voltage is defined as the input to output differential at which the output voltage drops 2% below its nominal value measured at 1v differential. for outputs below 2.7v, dropout voltage is the input-to-output voltage differential with the minimum input voltage 2.7v. minimum input operating voltage is 2.7v. 8. ground pin current is the regulator quiescent current. the total current drawn from the supply is the sum of the load current plus the ground pin current. absolute maximum ratings (1) supply input voltage (v in ) .................................. 0v to +7v enable input voltage (v en ) ................................. 0v to +7v power dissipation (p d ) ........................ internally limited (3) junction temperature (t j ) ....................... C40 c to +125 c storage temperature ............................... C65 c to +150 c lead temperature (soldering, 5 sec.) ....................... 260 c esd rating (4) ................................................................................ 2kv operating ratings (2) input voltage (v in ) ...................................... +2.7v to +5.5v enable input voltage (v en ) .................................. 0v to v in junction temperature (t j ) ....................... C40 c to +125 c thermal resistance sc-70-5 ( ja ) .................................................... 400 c/w m9999- 112305 november 200 5 3 downloaded from: http:///
mic5253 micrel typical characteristics 0 10 20 30 40 50 60 70 80 psrr (db) frequency (hz) 100 a 1ma 10ma 100ma power supply rejection ratio v out = 1.8v v in = 2.8v 100 1k 10k 100k 1m c out = 1 f c byp = 0.1 f 0 10 20 30 40 50 60 70 80 psrr (db) frequency (hz) 100 a 1ma 10ma 100ma power supply rejection ratio v out = 1.8v v in = 2.8v c out = 1 f c byp = 0.01 f 100 1k 10k 100k 1m 81 82 83 84 85 86 87 88 0 25 50 75 100 125 150 ground current ( a) output current (ma) ground pin current v in = v out + 1v v out =1.8v 70 72 74 76 78 80 82 84 -40 -20 0 20 40 60 80 100 120 ground current ( a) temperature ( c) ground pin current i load = 100 a 0 10 20 30 40 50 60 70 80 012345 ground current ( a) input voltage (v) ground pin current i load = 100 a 0 10 20 30 40 50 60 70 80 90 012345 ground current ( a) input voltage (v) ground pin current i load = 100ma 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 output voltage (mv) input voltage (v) dropout characteristics i load = 100 a i load = 100ma v out = 1.85v 0 50 100 150 200 250 -40 -20 0 20 40 60 80 100 120 dropout voltage (mv) temperature ( c) dropout volta ge v in = 3.6v v out = 2.6v i load = 100ma 0 50 100 150 200 250 300 350 0 25 50 75 100 125 150 dropout voltage (mv) output current (ma) dropout volta ge 125 c 25 c C 40 c v in = 3.6v v out = 2.6v 150 170 190 210 230 250 270 290 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 short circuit current (ma) input voltage (v) short circuit current 2.5 2.55 2.6 2.65 2.7 -40 -20 0 20 40 60 80 100 120 output voltage (v) temperature ( c) output voltage vs. temperature i load = 100 a v out = 2.6v v in = 3.6v 70 72 74 76 78 80 82 84 86 88 90 -40 -20 0 20 40 60 80 100 120 ground current ( a) temperature (c) ground pin current i load = 100ma m9999- 112305 4 november 200 5 downloaded from: http:///
mic5253 micrel c in = 1 f ceramic c out = 1 f ceramic c byp = 0.01 f i out = 100 a line transient response time (500 s/div) output voltage (50mv/div) input voltage (1v/div) 4v 5v c in = 1 f ceramic c out = 1 f ceramic c byp = 0.01 f v in = 4v 100 a 100ma load transient response time (5 s/div) output current (50ma/div) output voltage (20mv/div) c in = 1 f ceramic c out = 1 f ceramic c byp = 0.01 f v in = 4v shutdown delay time (500 s/div) output voltage (500mv/div) enable voltage (1v/div) c in = 1 f ceramic c out = 1 f ceramic c byp = 0.01 f i out = 100 a enable pin delay time (5 s/div) output voltage (500mv/div) enable voltage (1v/div) functional characteristics m9999- 112305 november 200 5 5 downloaded from: http:///
mic5253 micrel block diagram reference voltage startup/ shutdown control en quickstart/ noise cancellation under- voltage lockout thermal sensor in fault error amplifier current amplifier gnd bypout active shutdown m9999- 112305 6 november 200 5 downloaded from: http:///
mic5253 micrel applications informationenable/shutdown the mic5253 comes with an active-high enable pin that allows the regulator to be disabled. forcing the enable pin low disables the regulator and sends it into a zero off-mode- current state. in this state, current consumed by the regulatorgoes nearly to zero. forcing the enable pin high enables the output voltage. this part is cmos and the enable pin cannot be left floating; a floating enable pin may cause an indetermi- nate state on the output. input capacitor the mic5253 is a high performance, high bandwidth device. therefore, it requires a well-bypassed input supply for opti- mal performance. a 1 f capacitor is required from the input to ground to provide stability. low-esr ceramic capacitorsprovide optimal performance at a minimum of space. addi- tional high-frequency capacitors, such as small valued npo dielectric type capacitors, help filter out high frequency noise and are good practice in any rf based circuit. output capacitor the mic5253 requires an output capacitor for stability. the design requires 1 f or greater on the output to maintain stability. the design is optimized for use with low-esrceramic chip capacitors. high esr capacitors may cause high frequency oscillation. the maximum recommended esr is 300m . the output capacitor can be increased, but performance has been optimized for a 1 f ceramic output capacitor and does not improve significantly with largercapacitance. x7r/x5r dielectric-type ceramic capacitors are recom- mended because of their temperature performance. x7r- type capacitors change capacitance by 15% over their oper- ating temperature range and are the most stable type of ceramic capacitors. z5u and y5v dielectric capacitors change value by as much as 50% and 60%, respectively, over their operating temperature ranges. to use a ceramic chip capaci- tor with y5v dielectric, the value must be much higher than an x7r ceramic capacitor to ensure the same minimum capaci- tance over the equivalent operating temperature range. bypass capacitor a capacitor can be placed from the noise bypass pin to ground to reduce output voltage noise. the capacitor by- passes the internal reference. a 0.01 f capacitor is recom- mended for applications that require low-noise outputs. thebypass capacitor can be increased, further reducing noise and improving psrr. turn-on time increases slightly with respect to bypass capacitance. a unique quick-start circuit allows the mic5253 to drive a large capacitor on the bypass pin without significantly slowing turn-on time. refer to the typical characteristics section for performance with differ- ent bypass capacitors.active shutdown the mic5253 also features an active shutdown clamp, which is an n-channel mosfet that turns on when the device is disabled. this allows the output capacitor and load to dis- charge, de-energizing the load. no-load stabilitythe mic5253 will remain stable and in regulation with no load unlike many other voltage regulators. this is especially important in cmos ram keep-alive applications. thermal considerations the mic5253 is designed to provide 100ma of continuous current in a very small package. maximum ambient operating temperature can be calculated based on the output current and the voltage drop across the part. given that the input voltage is 5.0v, the output voltage is 2.9v, and the output current = 100ma. the actual power dissipation of the regulator circuit can be determined using the equation: p d = (v in C v out ) i out + v in i gnd because this device is cmos and the ground current istypically <100 a over the load range, the power dissipation contributed by the ground current is < 1% and can be ignoredfor this calculation. p d = (5.0v C 2.9v) 100ma p d = 0.21w to determine the maximum ambient operating temperatureof the package, use the junction-to-ambient thermal resis- tance of the device and the following basic equation: p (max) t (max) t d ja ja = ? ?? ? ?? ? t j (max) = 125 c, the max. junction temperture of the die ja thermal resistance = 400 c/w table 1 shows junction-to-ambient thermal resistance for themic5253 in the sc-70 package. package ? ? ja recommended ? ? ja 1" sq. ? ? jc minimum footprint copper clad sc-70-5 (c5) 400 c/w 325 c 250 c/w table 1. thermal resistance substituting p d for p d (max) and solving for the ambient operating temperature will give the maximum operating con-ditions for the regulator circuit. the junction-to-ambient ther- mal resistance for the minimum footprint is 400 c/w, from table 1. the maximum power dissipation must not be ex-ceeded for proper operation. for example, when operating the mic5253-2.9bc5 at an input voltage of 5.0v and 100ma load with a minimum footprint layout, the maximum ambient operating tempera- ture t a can be determined as follows: 0.21w 125 c t c/w tc a a = ? = 400 41 m9999- 112305 november 200 5 7 downloaded from: http:///
mic5253 micrel therefore, a 2.9v application at 100ma of output current canaccept an ambient operating temperature of 41 c in a sc-70 package. for a full discussion of heat sinking and thermaleffects on voltage regulators, refer to the regulator thermals section of micrel s designing with low-dropout voltage regu- lators handbook. this information can be found on micrel's website at:http://www.micrel.com/_pdf/other/ldobk_ds.pdf m9999- 112305 8 november 200 5 downloaded from: http:///
mic5253 micrel package information 0.30 (0.012)0.10 (0.004) 2.20 (0.087)1.80 (0.071) 2.40 (0.094)1.80 (0.071) 1.35 (0.053)1.15 (0.045) 0.65 (0.0256) bsc 1.00 (0.039)0.80 (0.032) 0.10 (0.004)0.00 (0.000) dimensions: mm (inch) 0.30 (0.012)0.15 (0.006) 0.18 (0.007)0.10 (0.004) 1.10 (0.043)0.80 (0.032) 5-pin sc-70-5 (c5) micrel, inc. 1849 fortune drive san jose, ca 95131 usa tel + 1 (408) 944-0800 fax + 1 (408) 474-1000 web http://www.micrel.com the information furnished by micrel in this data sheet is believed to be accurate and reliable. however, no responsibility is assumed by micrel for its use. micrel reserves the right to change circuitry and specifications at any time without notification to the customer. micrel products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. a purchaser s use or sale of micrel products for use in life support appliances, devices or systems is at purchasers own risk and purchaser agrees to fully indemnify micrel for any damages resulting from such use or sale. ? 2004 micrel, incorporated. m9999- 112305 november 200 5 9 downloaded from: http:///
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