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aat3238 300ma micropower? high performance ldo linear regulator 3238.2006.11.1.6 1 general description the aat3238 micropower low dropout (ldo) linear regulator is ideally suited for portable applications where very fast transient response, extended battery life, and small size are critical. the aat3238 has been specifically designed for high-speed turn-on and turn-off performance, fast transient response, good power supply ripple rejection (psrr), and is reasonably low noise, making it ideal for powering sensitive circuits with fast switching requirements. other features include low quiescent current, typical- ly 70a, and low dropout voltage, typically less than 400mv at the maximum output current level of 300ma. the device is output short-circuit protected and has a thermal shutdown circuit for additional pro- tection under extreme operating conditions. the aat3238 also features a low-power shutdown mode for extended battery life. a reference bypass pin has been provided to improve psrr perform- ance and output noise by connecting a small exter- nal capacitor from the aat3238's reference output to ground. the aat3238 is available in a pb-free, space-saving 6-pin sot23 or 8-pin sc70jw package in factory- programmed voltages. features ? low dropout: 400mv at 300ma ? guaranteed 300ma output ? high accuracy: 1.5% ? 70a quiescent current ? fast line and load transient response ? high-speed device turn-on and shutdown ? high power supply ripple rejection ? low self noise ? short-circuit protection ? over-temperature protection ? uses low equivalent series resistance (esr) ceramic capacitors ? noise reduction bypass capacitor ? shutdown mode for longer battery life ? low temperature coefficient ? factory-programmed output voltages ? sot23 6-pin or sc70jw 8-pin package applications ? cellular phones ? digital cameras ? notebook computers ? personal portable electronics ? portable communication devices typical application powerlinear ? aat3238 en in out byp gnd on/off 1 f 10nf 2.2 f v in gnd gnd v out
aat3238 300ma micropower? high performance ldo linear regulator 2 3238.2006.11.1.6 pin descriptions pin configuration sot23-6 sc70jw-8 (top view) (top view) pin # symbol function sot23-6 sc70jw-8 1 5, 6 in input voltage pin; should be decoupled with 1f or greater capacitor. 2, 5 8 gnd ground connection pin. 3 7 en enable pin; this pin should not be left floating. when pulled low, the pmos pass transistor turns off and all internal circuitry enters low-power mode, consuming less than 1a. 4 1 byp bypass capacitor connection; to improve ac ripple rejection, connect a 10nf capacitor to gnd. this will also provide a soft- start function. 6 2, 3, 4 out output pin; should be decoupled with 2.2f ceramic capacitor. out out out gnd en in in byp 1 2 3 45 6 7 8 gnd out gnd byp en in 1 2 3 4 5 6
absolute maximum ratings 1 t a = 25c, unless otherwise noted. recommended operating conditions thermal information 3 symbol description rating units ja maximum thermal resistance 150 c/w p d maximum power dissipation 667 mw symbol description rating units v in input voltage (v out + v do ) to 5.5 v t ambient temperature range 2 -40 to +85 c symbol description value units v in input voltage 6 v v enin(max) maximum en to input voltage 0.3 v i out dc output current p d /(v in - v o )ma t j operating junction temperature range -40 to 150 c aat3238 300ma micropower? high performance ldo linear regulator 3238.2006.11.1.6 3 1. stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation at c ondi- tions other than the operating conditions specified is not implied. only one absolute maximum rating should be applied at any one time. 2. mounted on a demo board. 3. to calculate minimum input voltage, use the following equation: v in(min) = v out(max) + v do(max) as long as v in 2.5v.
electrical characteristics 1 v in = v out(nom) + 1v for v out options greater than 1.5v. v in = 2.5v for v out 1.5v. i out = 1ma, c out = 2.2f, c in = 1f, t a = -40c to +85c, unless otherwise noted. typical values are t a = 25c. symbol description conditions min typ max units v out output voltage tolerance i out = 1ma to 300ma t a = 25c -1.5 1.5 % t a = -40 to 85c -2.5 2.5 i out output current v out > 1.2v 300 ma v do dropout voltage 2, 3 i out = 300ma 400 600 mv i sc short-circuit current v out < 0.4v 600 ma i q ground current v in = 5v, no load, en = v in 70 125 a i sd shutdown current v in = 5v, en = 0v 1 a v out / line regulation v in = v out + 1 to 5.0v 0.09 %/v v out * v in v out (line) dynamic line regulation v in = v out + 1v to v out + 2v, 2.5 mv i out = 300ma, t r /t f = 2s v out (load) dynamic load regulation i out = 1ma to 300ma, t r < 5s 60 mv t endly enable delay time byp = open 15 s v en(l) enable threshold low 0.6 v v en(h) enable threshold high 1.5 v i en leakage current on enable pin v en = 5v 1 a 1khz 67 psrr power supply rejection ratio i out = 10ma, c byp = 10nf 10khz 47 db 1mhz 45 t sd over-temperature shutdown 145 c threshold t hys over-temperature shutdown 12 c hysteresis e n output noise 50 vrms tc output voltage temperature 22 ppm/c coefficient aat3238 300ma micropower? high performance ldo linear regulator 4 3238.2006.11.1.6 1. the aat3238 is guaranteed to meet performance specifications over the -40c to +85c operating temperature range and is assu red by design, characterization, and correlation with statistical process controls. 2. v do is defined as v in - v out when v out is 98% of nominal. 3. for v out < 2.1v, v do = 2.5v - v out .
aat3238 300ma micropower? high performance ldo linear regulator 3238.2006.11.1.6 5 typical characteristics unless otherwise noted, v in = 5v, t a = 25c. output voltage vs. temperature 1.196 1.197 1.198 1.199 1.200 1.201 1.202 1.203 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 10 0 temperature ( quiescent current vs. temperature 0 10 20 30 40 50 60 70 80 90 100 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 temperature ( ground current vs. input voltage 0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00 2 2.5 3 3.5 4.5 45 input voltage (v) ground current ( i out = 0ma i out = 10ma i out = 50ma i out = 150ma i out = 300ma dropout voltage vs. output current 0 50 100 150 200 250 300 350 400 450 500 0 50 100 150 200 250 300 output current (ma) dropout voltage (mv) 85 c 25 c -40 c dropout characteristics 2.00 2.20 2.40 2.60 2.80 3.00 3.20 2.70 2.80 2.90 3.00 3.10 3.20 3.30 i out = 300ma i out = 150ma i out = 100ma i out = 50ma i out = 10ma i out = 0ma input voltage (v) output voltage (v) dropout voltage vs. temperature 0 60 120 180 240 300 360 420 480 540 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120 temperature ( i l = 300ma i l = 150ma i l = 100ma i l = 50ma
typical characteristics unless otherwise noted, v in = 5v, t a = 25c. aat3238 300ma micropower? high performance ldo linear regulator 6 3238.2006.11.1.6 load transient response 300ma 2.10 2.20 2.30 2.40 2.50 2.60 2.70 2.80 2.90 3.00 time (10s/div) -100 0 100 200 300 400 500 600 700 800 v out i out output voltage (v) output current (ma) load transient response 2.60 2.65 2.70 2.75 2.80 2.85 2.90 time (100s/div) output voltage (v) -100 0 100 200 300 400 500 output current (ma) v out i out line transient response 2.98 2.99 3.00 3.01 3.02 3.03 3.04 time (100s/div) input voltage (v) 0 1 2 3 4 5 6 output voltage (v) v in v out turn-on time from enable (v in present) (c byp = 10nf) time (5s/div) v in = 4v v out = 1v/div v en = 5v/div turn-off response time (c byp = 10nf) time (50s/div) v en (5v/div) v out (1v/div) initial power-up response time (c byp = 10nf) time (400s/div) v en (5v/div) v out (1v/div)
aat3238 300ma micropower? high performance ldo linear regulator 3238.2006.11.1.6 7 typical characteristics unless otherwise noted, v in = 5v, t a = 25c. v ih and v il vs. v in 1.050 1.075 1.100 1.125 1.150 1.175 1.200 1.225 1.250 2.5 3.0 3.5 4.0 4.5 5.0 5.5 v in (v) v ih v il over-current protection -200 0 200 400 600 800 1000 1200 time (20ms/div) output current (ma) aat3238 self noise (c out = 10 0.001 0.01 0.1 1 10 0.01 0.1 1 10 100 1000 10000 frequency (khz) noise amplitude ( band power: 300hz to 50khz = 44.6 vrms/rthz 100hz to 100khz = 56.3 vrms/rthz
aat3238 300ma micropower? high performance ldo linear regulator 8 3238.2006.11.1.6 functional description the aat3238 is intended for ldo regulator applica- tions where output current load requirements range from no load to 300ma. the advanced circuit design of the aat3238 has been specifically optimized for very fast start-up and shutdown timing. this proprietary cmos ldo has also been tailored for superior transient response characteristics. these traits are particularly important for applications that require fast power supply timing, such as gsm cellular telephone handsets. the high-speed turn-on capability of the aat3238 is enabled through the implementation of a fast start control circuit, which accelerates the power-up behav- ior of fundamental control and feedback circuits with- in the ldo regulator. fast turn-off response time is achieved by an active output pull-down circuit, which is enabled when the ldo regulator is placed in the shutdown mode. this active fast shutdown circuit has no adverse effect on normal device operation. the aat3238 has very fast transient response char- acteristics, which is an important feature for applica- tions where fast line and load transient response is required. this rapid transient response behavior is accomplished through the implementation of an active error amplifier feedback control. this propri- etary circuit design is unique to this micropower ldo regulator. the ldo regulator output has been specifically opti- mized to function with low-cost, low-esr ceramic capacitors. however, the design will allow for opera- tion over a wide range of capacitor types. a bypass pin has been provided to allow the addition of an optional voltage reference bypass capacitor to reduce output self noise and increase power supply ripple rejection. device self noise and psrr will be improved by the addition of a small ceramic capacitor in this pin. however, increased values of c bypass may slow down the ldo regulator turn-on time. this ldo regulator has complete short-circuit and thermal protection. the integral combination of these two internal protection circuits gives the aat3238 a comprehensive safety system to guard against extreme adverse operating conditions. device power dissipation is limited to the package type and thermal dissipation properties. refer to the thermal considerations section of this datasheet for details on device operation at maximum output current loads. functional block diagram error amplifier over-current protection over- temperature protection voltage reference + - in en byp out gnd active feedback control fast start control
applications information to assure the maximum possible performance is obtained from the aat3238, please refer to the fol- lowing application recommendations. input capacitor typically, a 1f or larger capacitor is recommend- ed for c in in most applications. a c in capacitor is not required for basic ldo regulator operation. however, if the aat3238 is physically located more than three centimeters from an input power source, a c in capacitor will be needed for stable operation. c in should be located as closely to the device v in pin as practically possible. c in values greater than 1f will offer superior input line transient response and will assist in maximizing the highest possible power supply ripple rejection. ceramic, tantalum, or aluminum electrolytic capac- itors may be selected for c in . there is no specific capacitor esr requirement for c in . however, for 300ma ldo regulator output operation, ceramic capacitors are recommended for c in due to their inherent capability over tantalum capacitors to with- stand input current surges from low impedance sources such as batteries in portable devices. output capacitor for proper load voltage regulation and operational stability, a capacitor is required between pins v out and gnd. the c out capacitor connection to the ldo regulator ground pin should be made as direct as practically possible for maximum device performance. the aat3238 has been specifically designed to func- tion with very low esr ceramic capacitors. for best performance, ceramic capacitors are recommended. typical output capacitor values for maximum out- put current conditions range from 1f to 10f. applications utilizing the exceptionally low output noise and optimum power supply ripple rejection characteristics of the aat3238 should use 2.2f or greater for c out . if desired, c out may be increased without limit. in low output current applications where output load is less than 10ma, the minimum value for c out can be as low as 0.47f. bypass capacitor and low noise applications a bypass capacitor pin is provided to enhance the low noise characteristics of the aat3238 ldo reg- ulator. the bypass capacitor is not necessary for operation of the aat3238. however, for best device performance, a small ceramic capacitor should be placed between the bypass pin (byp) and the device ground pin (gnd). the value of c byp may range from 470pf to 10nf. for lowest noise and best possible power supply ripple rejec- tion performance, a 10nf capacitor should be used. to practically realize the highest power sup- ply ripple rejection and lowest output noise per- formance, it is critical that the capacitor connection between the byp pin and gnd pin be direct and pcb traces should be as short as possible. refer to the pcb layout recommendations section of this document for examples. there is a relationship between the bypass capac- itor value and the ldo regulator turn-on and turn- off time. in applications where fast device turn-on and turn-off time are desired, the value of c byp should be reduced. in applications where low noise performance and/ or ripple rejection are less of a concern, the bypass capacitor may be omitted. the fastest device turn- on time will be realized when no bypass capacitor is used. dc leakage on this pin can affect the ldo regula- tor output noise and voltage regulation perform- ance. for this reason, the use of a low leakage, high quality ceramic (npo or c0g type) or film capacitor is highly recommended. capacitor characteristics ceramic composition capacitors are highly recom- mended over all other types of capacitors for use with the aat3238. ceramic capacitors offer many advantages over their tantalum and aluminum elec- trolytic counterparts. a ceramic capacitor typically aat3238 300ma micropower? high performance ldo linear regulator 3238.2006.11.1.6 9
aat3238 300ma micropower? high performance ldo linear regulator 10 3238.2006.11.1.6 has very low esr, is lower cost, has a smaller pcb footprint, and is non-polarized. line and load tran- sient response of the ldo regulator is improved by using low-esr ceramic capacitors. since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage. equivalent series resistance: esr is a very important characteristic to consider when selecting a capacitor. esr is the internal series resistance associated with a capacitor that includes lead resistance, internal connections, size and area, material composition, and ambient temperature. typically, capacitor esr is measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. ceramic capacitor materials: ceramic capaci- tors less than 0.1f are typically made from npo or c0g materials. npo and c0g materials gener- ally have tight tolerance and are very stable over temperature. larger capacitor values are usually composed of x7r, x5r, z5u, or y5v dielectric materials. these two material types are not recom- mended for use with ldo regulators since the capacitor tolerance can vary more than 50% over the operating temperature range of the device. a 2.2f y5v capacitor could be reduced to 1f over temperature; this could cause problems for circuit operation. x7r and x5r dielectrics are much more desirable. the temperature tolerance of x7r dielectric is better than 15%. capacitor area is another contributor to esr. capacitors that are physically large in size will have a lower esr when compared to a smaller sized capacitor of an equivalent material and capaci- tance value. these larger devices can improve cir- cuit transient response when compared to an equal value capacitor in a smaller package size. consult capacitor vendor datasheets carefully when selecting capacitors for ldo regulators. enable function the aat3238 features an ldo regulator enable/ disable function. this pin (en) is active high and is compatible with cmos logic. to assure the ldo regulator will switch on, the en turn-on control level must be greater than 1.5v. the ldo regulator will go into the disable shutdown mode when the volt- age on the en pin falls below 0.6v. if the enable function is not needed in a specific application, it may be tied to v in to keep the ldo regulator in a continuously on state. when the ldo regulator is in shutdown mode, an internal 1.5k resistor is connected between v out and gnd. this is intended to discharge c out when the ldo regulator is disabled. the internal 1.5k has no adverse effect on device turn-on time. short-circuit protection the aat3238 contains an internal short-circuit pro- tection circuit that will trigger when the output load current exceeds the internal threshold limit. under short-circuit conditions, the output of the ldo reg- ulator will be current limited until the short-circuit condition is removed from the output or the ldo regulator package power dissipation exceeds the device thermal limit. thermal protection the aat3238 has an internal thermal protection cir- cuit which will turn on when the device die temper- ature exceeds 145c. the internal thermal protec- tion circuit will actively turn off the ldo regulator output pass device to prevent the possibility of over- temperature damage. the ldo regulator output will remain in a shutdown state until the internal die temperature falls back below the 145c trip point. the combination and interaction between the short- circuit and thermal protection systems allow the ldo regulator to withstand indefinite short-circuit conditions without sustaining permanent damage.
aat3238 300ma micropower? high performance ldo linear regulator 3238.2006.11.1.6 11 no-load stability the aat3238 is designed to maintain output volt- age regulation and stability under operational no- load conditions. this is an important characteristic for applications where the output current may drop to zero. reverse output-to-input voltage conditions and protection under normal operating conditions, a parasitic diode exists between the output and input of the ldo regulator. the input voltage should always remain greater than the output load voltage, main- taining a reverse bias on the internal parasitic diode. conditions where v out might exceed v in should be avoided since this would forward bias the internal parasitic diode and allow excessive current flow into the v out pin, possibly damaging the ldo regulator. in applications where there is a possibility of v out exceeding v in for brief amounts of time during nor- mal operation, the use of a larger value c in capaci- tor is highly recommended. a larger value of c in with respect to c out will effect a slower c in decay rate during shutdown, thus preventing v out from exceeding v in . in applications where there is a greater danger of v out exceeding v in for extended periods of time, it is recommended to place a schottky diode across v in to v out (connecting the cathode to v in and anode to v out ). the schottky diode forward voltage should be less than 0.45v.
aat3238 300ma micropower? high performance ldo linear regulator 12 3238.2006.11.1.6 ordering information output voltage package marking 1 part number (tape and reel) 2 1.2v sot23-6 kixyy aat3238igu-1.2-t1 1.5v sot23-6 jgxyy aat3238igu-1.5-t1 1.6v sot23-6 jsxyy aat3238igu-1.6-t1 1.8v sot23-6 jrxyy aat3238igu-1.8-t1 1.85v sot23-6 jfxyy aat3238igu-1.85-t1 2.0v sot23-6 aat3238igu-2.0-t1 2.3v sot23-6 aat3238igu-2.3-t1 2.5v sot23-6 kuxyy aat3238igu-2.5-t1 2.7v sot23-6 aat3238igu-2.7-t1 2.8v sot23-6 aat3238igu-2.8-t1 2.85 sot23-6 qgxyy aat3238igu-2.85-t1 3.0v sot23-6 aat3238igu-3.0-t1 3.3v sot23-6 aat3238igu-3.3-t1 3.5v sot23-6 aat3238igu-3.5-t1 1.2v sc70jw-8 aat3238ijs-1.2-t1 1.45v sc70jw-8 aat3238ijs-1.45-t1 1.5v sc70jw-8 jgxyy aat3238ijs-1.5-t1 1.8v sc70jw-8 aat3238ijs-1.8-t1 2.0v sc70jw-8 aat3238ijs-2.0-t1 2.3v sc70jw-8 aat3238ijs-2.3-t1 2.5v sc70jw-8 aat3238ijs-2.5-t1 2.7v sc70jw-8 aat3238ijs-2.7-t1 2.8v sc70jw-8 fcxyy aat3238ijs-2.8-t1 2.85 sc70jw-8 aat3238ijs-2.85-t1 3.0v sc70jw-8 voxyy aat3238ijs-3.0-t1 3.3v sc70jw-8 aat3238ijs-3.3-t1 3.5v sc70jw-8 aat3238ijs-3.5-t1 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . all analogictech products are offered in pb-free packaging. the term ?pb-free? means semiconductor products that are in compliance with current rohs standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. for more information, please visit our website at http://www.analogictech.com/pbfree.
package information sot23-6 sc70jw-8 all dimensions in millimeters. aat3238 300ma micropower? high performance ldo linear regulator 3238.2006.11.1.6 13 0.225 1.90 bsc 0.95 bsc 0.45
aat3238 300ma micropower? high performance ldo linear regulator 14 3238.2006.11.1.6 advanced analogic technologies, inc. 830 e. arques avenue, sunnyvale, ca 94085 phone (408) 737-4600 fax (408) 737-4611 ? advanced analogic technologies, inc. analogictech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an analogictech pr oduct. no circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. analogictech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information b eing relied on is current and complete. all products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warran ty, patent infringement, and limitation of liability. analogictech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with anal ogictech?s standard warranty. testing and other quality con- trol techniques are utilized to the extent analogictech deems necessary to support this warranty. specific testing of all param eters of each device is not necessarily performed.

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