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smartswitch ? AAT3237 300ma micropower? ldo with powerok preliminary information 3237.2004.01.0.93 1 general description the AAT3237 micropower? low dropout linear regulator is ideally suited for portable applications where low noise, extended battery life and small size are critical. the AAT3237 has been specifi- cally designed for low output noise performance, fast transient response and high power supply rejection ratio (psrr). other features include low quiescent current, typi- cally 70a, and low dropout voltage which is typi- cally less than 400mv at full output current. the device is output short circuit protected and has a thermal shutdown circuit for additional protection under extreme conditions. the AAT3237 also features a low-power shutdown mode for extended battery life. a power-ok open- drain output signals when v out is in regulation. the AAT3237 is available in a space saving 6-pin sot23 or 8-pin sc70jw package in 13 factory pro- grammed voltages of 1.2v, 1.5v, 1.8v, 2.0v, 2.3v, 2.5v, 2.7v, 2.8v, 2.85v, 2.9v, 30.v, 3.3v, or 3.5v. features ? low dropout - 400mv at 300ma ? guaranteed 300ma output ? high accuracy 1.5% ? 70a quiescent current ? high power supply ripple rejection ? powerok (pok) output ? fast line and load transient response ? short circuit protection ? over-temperature protection ? uses low esr ceramic capacitors ? shutdown mode for longer battery life ? low temperature coefficient ? 13 factory programmed output voltages ? sot23 6-pin or sc70jw 8-pin package applications ? cellular phones ? notebook computers ? desktop computers ? portable communication devices ? personal portable electronics ? digital cameras typical application AAT3237 en in out pok gnd on/off 1 f 2.2 f v in gnd gnd v out pok powerlinear ?
AAT3237 300ma micropower? ldo with powerok 2 3237.2004.01.0.93 pin descriptions pin configuration sot23-6 sc70jw-8 (top view) (top view) out out out 1 2 gnd en in in pok 1 2 3 4 8 7 6 5 1 2 3 pok en out gnd 4 6 5 gnd in 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 pok power-ok output. this open-drain output is low when out is out of regulation. connect a pull up resistor from pok to out. 6 2, 3, 4 out output pin - should be decoupled with 2.2f ceramic capacitor.
absolute maximum ratings (t a =25c unless otherwise noted) note: stresses above those listed in absolute maximum ratings may cause permanent damage to the device. functional operation a t con- ditions other than the operating conditions specified is not implied. only one absolute maximum rating should be applied at an y one time. thermal information note 1: mounted on a demo board. recommended operating conditions note 2: 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. symbol description rating units v in input voltage 2 (v out +v do ) to 5.5 v t ambient temperature range -40 to +85 c symbol description rating units ja maximum thermal resistance 1 (sot23-6, sc70jw-8) 150 c/w p d maximum power dissipation 1 (sot23-6, sc70jw-8) 667 mw symbol description value units v in, pok input voltage, pok 6 v i out dc output current p d /(v in -v o )ma t j operating junction temperature range -40 to 150 c t lead maximum soldering temperature (at leads, 10 sec) 300 c AAT3237 300ma micropower? ldo with powerok 3237.2004.01.0.93 3
electrical characteristics (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 = -40 to 85c unless otherwise noted. typical values are t a =25c) note 1: v do is defined as v in - v out when v out is 98% of nominal. note 2: for v out < 2.1v, v do = 2.5v - v out . note 3: c in = 10f 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 1, 2 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 /v out * ? v in line regulation 3 v in = v out + 1 to 5.0v 0.09 %/v ? v out (line) dynamic line regulation v in =v out +1v to v out +2v, i out =300ma, 5 mv t r /t f =2s ? v out (load) dynamic load regulation i out = 1ma to 300ma, t r <5s 60 mv 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 v pok pok trip threshold v out rising, t a =25c 90 94 98 % of v out v pokhys pok hysteresis 1 % of v out v pok(ol) pok output voltage low i sink = 1ma 0.4 v i pok pok output leakage current v pok < 5.5v, v out in regulation 1 a 1 khz 65 psrr power supply rejection ratio i out =10ma 10khz 45 db 1mhz 42 t sd over temp shutdown threshold 145 c t hys over temp shutdown hysteresis 12 c e n output noise noise power bw = 300hz-50khz 250 vrms/rthz tc output voltage temp. coeff. 22 ppm/c AAT3237 300ma micropower? ldo with powerok 4 3237.2004.01.0.93
AAT3237 300ma micropower? ldo with powerok 3237.2004.01.0.93 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 ( c) output voltage (v) 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 ( c) quiescent current ( a) 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 v in (v) i gnd ( a) 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 v in (v) v out (v) i out = 300ma i out = 150ma i out = 100ma i out = 50ma i out = 10ma i out = 0ma 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 tem p erature ( c ) dropout voltage (mv) i l = 300ma i l = 150ma i l = 100ma i l = 50ma
typical characteristics (unless otherwise noted, v in = 5v, t a = 25c) load transient response 300ma 2.10 2.20 2.30 2.40 2.50 2.60 2.70 2.80 2.90 3.00 10 s/div v out (v) -100 0 100 200 300 400 500 600 700 800 i out (ma) v out i out load transient response 2.60 2.65 2.70 2.75 2.80 2.85 2.90 time (100 s/div) v (v) out -100 0 100 200 300 400 500 i out (ma) i out v out pok output response time (200 s/div.) v in (2v/div) v out (2v/div) v pok (1v/div) line transient response 2.85 2.90 2.95 3.00 3.05 3.10 3.15 3.20 3.25 time (100 s/div) v (v) out -2 -1 0 1 2 3 4 5 6 v (v) in v in v out turn off time with pok delay time (200 s/div) v en (2v/div) v pok (2v/div) v out (2v/div) turn on time and pok delay time (10 s/div) v enable (2v/div) v out (500mv/div) v pok (500mv/div) AAT3237 300ma micropower? ldo with powerok 6 3237.2004.01.0.93
typical characteristics (unless otherwise noted, v in = 5v, t a = 25c) v en(h) and v en(l) 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 en (v) v en(h) v en(l) AAT3237 self noise 0.01 0.1 1 10 0.01 0.1 1 10 100 1000 frequency (khz) noise amplitude ( v/rthz) over current protection -200 0 200 400 600 800 1000 1200 time (20 ms/div) i out (ma) AAT3237 300ma micropower? ldo with powerok 3237.2004.01.0.93 7
AAT3237 300ma micropower? ldo with powerok 8 3237.2004.01.0.93 functional description the AAT3237 is intended for ldo regulator appli- cations where output current load requirements range from no load to 300ma. the advanced circuit design of the AAT3237 pro- vides excellent transient response and fast turn-on ability. the ldo regulator output has been specif- ically optimized to function with low cost, low esr ceramic capacitors. however, the design will allow for operation over a wide range of capacitor types. the AAT3237 has an integrated power-ok com- parator which indicates when the output is out of regulation. the device enable circuit is provided to shutdown the ldo regulator for power conservation in portable products. the enable circuit has an additional out- put capacitor discharge circuit to assure sharp appli- cation circuit turn off upon device shutdown. this ldo regulator has complete short circuit and thermal protection. the integral combination of these two internal protection circuits give the AAT3237 a comprehensive safety system during extreme adverse operating conditions. device power dissipation is limited to the package type and thermal dissipation properties. refer to the thermal considerations discussion in the section for details on device operation at maximum output cur- rent loads. functional block diagram over-current protection voltage reference 94% error amplifier over-temperature protection in pok en gnd out
applications information to assure the maximum possible performance is obtained from the AAT3237, 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 AAT3237 is physically located more than 3 centimeters from an input power source, a c in capacitor will be needed for stable operation. c in should be located as close 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 capaci- tors 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 AAT3237 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 output current conditions range from 1f to 10f. applications utilizing the exceptionally low output noise and optimum power supply ripple rejection characteristics of the AAT3237 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 then 10ma, the minimum value for c out can be as low as 0.47f. capacitor characteristics ceramic composition capacitors are highly recom- mended over all other types of capacitors for use with the AAT3237. ceramic capacitors offer many advantages over their tantalum and aluminum elec- trolytic counterparts. a ceramic capacitor typically 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): esr is a very important characteristic to consider when selecting a capacitor. esr is the internal series resistance asso- ciated with a capacitor, which includes lead resist- ance, 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 capacitors less than 0.1f are typically made from npo or cog materials. npo and cog materials are typi- cally tight tolerance very stable over temperature. larger capacitor values are typically composed of x7r, x5r, z5u and y5v dielectric materials. large ceramic capacitors, typically greater then 2.2f are often available in the low cost y5v and z5u dielectrics. these two material types are not rec- ommended 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 which are physically large in size will have a lower esr when compared to a smaller sized capacitor of an equivalent material and capacitance value. these larger devices can improve circuit tran- sient response when compared to an equal value capacitor in a smaller package size. AAT3237 300ma micropower? ldo with powerok 3237.2004.01.0.93 9
AAT3237 300ma micropower? ldo with powerok 10 3237.2004.01.0.93 applications information consult capacitor vendor data sheets carefully when selecting capacitors for ldo regulators. pok output the aat 3237 features an integrated power-ok comparator which can be used as an error flag. the pok open-drain output goes low when out is 6% below its nominal regulation voltage. connect a pull-up resistor from pok to out. enable function the AAT3237 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 2.0 volts. the ldo regulator will go into the disable shutdown mode when the voltage on the en pin falls below 0.6 volts. if the enable function is not needed in a specific applica- tion, it may be tied to v in to keep the ldo regula- tor in a continuously on state. when the ldo regulator is in the 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 AAT3237 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 regu- lator will be current limited until the short circuit condition is removed from the output or ldo regu- lator package power dissipation exceeds the device thermal limit. thermal protection the AAT3237 has an internal thermal protection cir- cuit which will turn on when the device die tempera- ture exceeds 145c. the internal thermal protection circuit will actively turn off the ldo regulator output pass device to prevent the possibility of over temper- ature 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. no-load stability the AAT3237 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 then 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 0.45 volts.
AAT3237 300ma micropower? ldo with powerok 3237.2004.01.0.93 11 ordering information note: sample stock is generally held on all part numbers listed in bold . note 1: xyy = assembly and date code. output voltage package marking 1 part number (tape and reel) 1.2v sot23-6 ejxyy AAT3237igu-1.2-t1 1.5v sot23-6 AAT3237igu-1.5-t1 1.8v sot23-6 AAT3237igu-1.8-t1 2.0v sot23-6 AAT3237igu-2.0-t1 2.3v sot23-6 AAT3237igu-2.3-t1 2.5v sot23-6 AAT3237igu-2.5-t1 2.7v sot23-6 AAT3237igu-2.7-t1 2.8v sot23-6 fbxyy AAT3237igu-2.8-t1 2.85v sot23-6 grxyy AAT3237igu-2.85-t1 2.9v sot23-6 gsxyy AAT3237igu-2.9-t1 3.0v sot23-6 gmxyy AAT3237igu-3.0-t1 3.3v sot23-6 hrxyy AAT3237igu-3.3-t1 3.5v sot23-6 AAT3237igu-3.5-t1 1.2v sc70jw-8 AAT3237ijs-1.2-t1 1.5v sc70jw-8 AAT3237ijs-1.5-t1 1.8v sc70jw-8 AAT3237ijs-1.8-t1 2.0v sc70jw-8 AAT3237ijs-2.0-t1 2.3v sc70jw-8 AAT3237ijs-2.3-t1 2.5v sc70jw-8 AAT3237ijs-2.5-t1 2.7v sc70jw-8 AAT3237ijs-2.7-t1 2.8v sc70jw-8 AAT3237ijs-2.8-t1 2.85v sc70jw-8 AAT3237ijs-2.85-t1 2.9v sc70jw-8 AAT3237ijs-2.9-t1 3.0v sc70jw-8 AAT3237ijs-3.0-t1 3.3v sc70jw-8 AAT3237ijs-3.3-t1 3.5v sc70jw-8 AAT3237ijs-3.5-t1
AAT3237 300ma micropower? ldo with powerok 12 3237.2004.01.0.93 package information sot23-6 1.90 bsc 0.95 bsc 0.45 0.15 0.10 bsc 2.85 0.15 0.075 0.075 0.40 0.10 6 1.575 0.125 1.20 0.25 1.10 0.20 2.80 0.20 4 4 10 5 0.15 0.07 gauge plane 0.60 ref
sc70jw-8 0.225 0.075 0.45 0.10 0.05 0.05 2.10 0.30 2.00 0.20 7 3 4 4 1.75 0.10 0.85 0.15 0.15 0.05 1.10 max 0.100 2.20 0.20 0.048ref 0.50 bsc 0.50 bsc 0.50 bsc AAT3237 300ma micropower? ldo with powerok 3237.2004.01.0.93 13
AAT3237 300ma micropower? ldo with powerok 14 3237.2004.01.0.93 advanced analogic technologies, inc. 830 e. arques avenue, sunnyvale, ca 94085 phone (408) 737-4600 fax (408) 737-4611 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 specifications or to discontinue any product or service wi thout notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being 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 warranty, patent infringement, and limitation of l iability. analogictech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accorda nce with analogictech?s standard warranty. testing and other quality control techniques are utilized to the extent analogictech deems necessary to support this warranty. specific tes ting of all parameters of each device is not necessarily performed.

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