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general description the aat4280a smartswitch is a member of analogictech's application specific power mos- fet? (aspm?) product family. the aat4280a is a p-channel mosfet power switch designed for high-side load switching applications. the device has a typical r ds(on) of 80m ? , allowing increased load switch power handling capacity. the device is available in three different versions with flexible turn-on and turn-off characteristics ? from very fast to slew rate limited. the standard aat4280a (-1) version has a slew rate limited turn-on load switch and is functionally compatible with the aat4250 device, while offering superior r ds(on) characteristics. the aat4280a (-2) version fea- tures fast load switch turn-on capabilities, typically less than 500ns turn-on and 3s turn-off times. the aat4280a (-3) variation offers a shutdown load discharge circuit to rapidly turn off a load cir- cuit when the switch is disabled. all aat4280a load switch versions operate with an input voltage ranging from 1.5v to 5.5v, making them ideal for both 3v and 5v systems. input logic levels are ttl and 2.5v to 5v cmos compatible. the qui- escent supply current is very low, typically 25na. the aat4280a is available in a pb-free, 8-pin sc70jw package and is specified over the -40c to +85c temperature range. features ? 1.5v to 5.5v input voltage range ? very low r ds(on) , typically 80m ? (5v) ? slew rate limited turn-on time options ? 1ms ? 0.5s ? 100s ? fast shutdown load discharge option ? low quiescent current ? 25na (typ) ? ttl/cmos input logic level ? temperature range: -40oc to +85c ? 4kv esd rating ? 8-pin sc70jw package applications ? cellular telephones ? digital still cameras ? hot swap supplies ? notebook computers ? personal communication devices ? personal digital assistants (pdas) aat4280a slew rate controlled load switch typical application aat4280a c out 0.1 f c in 1 f out in gnd v out gnd gnd v in on/off gnd in on 4280a.2005.11.1.3 1 smartswitch ?
aat4280a slew rate controlled load switch 2 4280a.2005.11.1.3 pin descriptions pin configuration sc70jw-8 (top view) selector guide slew rate active part number (typ) pull down enable aat4280a-1 1ms active high aat4280a-2 0.5s active high aat4280a-3 100s active high out on/off gnd in in in in in 1 2 3 45 6 7 8 pin # symbol function 1, 5, 6, 7, 8 in this pin is the input to the p-channel mosfet source. bypass to ground through a 1.0f capacitor. 2 out this pin is the p-channel mosfet drain connection. bypass to ground through a 0.1f capacitor. 3 on/off enable input. 4 gnd ground connection.
aat4280a slew rate controlled load switch 4280a.2005.11.1.3 3 absolute maximum ratings 1 t a = 25c, unless otherwise noted. thermal characteristics 3 symbol description value units ja thermal resistance 140 c/w p d power dissipation 714 mw symbol description value units v in in to gnd -0.3 to 6 v v on on/off to gnd -0.3 to 6 v v out out to gnd -0.3 to v in + 0.3 v i max maximum continuous switch current 2.3 a i dm maximum pulsed current in 2.5v 6 a in < 2.5v 3 a t j operating junction temperature range -40 to 150 c t s storage temperature range -65 to 150 c t lead maximum soldering temperature (at leads) 300 c v esd esd rating 2 - hbm 4000 v 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. human body model is a 100pf capacitor discharged through a 1.5k ? resistor into each pin. 3. mounted on an aat4280a demo board in still 25oc air.
aat4280a slew rate controlled load switch 4 4280a.2005.11.1.3 electrical characteristics unless otherwise noted, v in = 5v, t a = -40c to +85c; typical values are t a = 25c. symbol description conditions min typ max units aat4280a all versions v in operation voltage 1.5 5.5 v i q quiescent current on/off = active 1 a i q (off) off supply current on/off = inactive, out = open 1 a i sd (off) off switch current on/off = inactive, v out = 0 1 a v in = 5v, t a = 25c 80 120 v in = 4.2v, t a = 25c 85 130 r ds(on) on resistance v in = 3v, t a = 25c 100 150 m ? v in = 1.8v, t a = 25c 160 250 v in = 1.5v, t a = 25c 200 300 tc rds on resistance temperature coefficient 2800 ppm/c v il on/off input logic low voltage v in = 1.8v to 5.5v 1 0.4 v v in = 2.7v to 4.2v 2 v ih on/off input logic high voltage v in = 4.2v to 5.5v 2.4 v v in = 1.5v to 2.7v 1.4 i sink on/off input leakage v on/off = 5.5v 1 a aat4280a-1 t d(on) output turn-on delay v in = 5v, r load = 10 ? , t a = 25c 20 40 s t on output turn-on rise time v in = 5v, r load = 10 ? , t a = 25c 1000 1500 s t d(off) output turn-off delay time v in = 5v, r load = 10 ? , t a = 25c 4 10 s aat4280a-2 t d(on) output turn-on delay v in = 5v, r load = 10 ? , t a = 25c 0.5 2 s t on output turn-on rise time v in = 5v, r load = 10 ? , t a = 25c 0.5 1 s t d(off) output turn-off delay time v in = 5v, r load = 10 ? , t a = 25c 4 10 s aat4280a-3 t d(on) output turn-on delay v in = 5v, r load = 10 ? , t a = 25c 20 40 s t on output turn-on rise time v in = 5v, r load = 10 ? , t a = 25c 100 150 s t d(off) output turn-off delay time v in = 5v, r load = 10 ? , t a = 25c 4 10 s r pd output pull-down resistance during off on/off = inactive, t a = 25c 150 250 ? 1. for v in outside this range, consult typical on/off threshold curve.
aat4280a slew rate controlled load switch 4280a.2005.11.1.3 5 typical characteristics unless otherwise noted, v in = 5v, t a = 25c. off-switch current vs. temperature 0.001 0.010 0.100 1.000 -40 -20 0 20 40 60 80 100 temperature ( c) off-switch current ( a) on/off threshold vs. input voltage input voltage (v) on/off threshold (v) 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 1.4 1.9 2.4 2.9 3.4 3.9 4.4 4 5.4 v ih v il r ds(on) vs. temperature 40 50 60 70 80 90 100 110 120 -40 -20 0 20 40 60 80 100 temperature ( c) r ds(on) (m ? ) v in = 5v v in = 3v r ds(on) vs. input voltage input voltage (v) r ds(on) (m ? ) 70 90 110 130 150 170 190 210 230 250 270 1.5 1.8 2.0 2.3 2.5 2.8 3.8 4.8 3.0 3.3 4.3 5.3 3.5 4.0 4.5 5.0 5.5 2a 1a 500ma 100ma quiescent current vs. temperature temperature ( c) quiescent current (na) 0 10 20 30 40 50 -40 -20 0 20 40 60 80 100
aat4280a slew rate controlled load switch 6 4280a.2005.11.1.3 typical characteristics?aat4280a-1 unless otherwise noted, v in = 5v, t a = 25c. aat4280a-1 turn-off (v in = 5v; r l = 10 ? ) time (10 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-1 turn-off (v in = 3v; r l = 6 ? ) time (10 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-1 turn-on (v in = 5v; r l = 10 ? ) time (500 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-1 turn-on (v in = 3v; r l = 6 ? ) time (500 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div)
aat4280a slew rate controlled load switch 4280a.2005.11.1.3 7 typical characteristics?aat4280a-2 unless otherwise noted, v in = 5v, t a = 25c. aat4280a-2 turn-off (v in = 5v; r l = 10 ? ) time (5 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-2 turn-off (v in = 3v; r l = 6 ? ) time (5 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-2 turn-on (v in = 5v; r l = 10 ? ) time (5 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-2 turn-on (v in = 3v; r in = 6 ? ) time (5 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div)
aat4280a slew rate controlled load switch 8 4280a.2005.11.1.3 typical characteristics?aat4280a-3 unless otherwise noted, v in = 5v, t a = 25c. aat4280a-3 turn-off (v in = 5v; r l = 10 ? ) time (5 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-3 turn-off (v in = 3v; r l = 6 ? ) time (5 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-3 turn-on (v in = 5v; r l = 10 ? ) time (50 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div) aat4280a-3 turn-on (v in = 3v; r l = 6 ? ) time (50 s/div) on/off (5v/div) v out (2v/div) i in (200ma/div)
aat4280a slew rate controlled load switch 4280a.2005.11.1.3 9 functional description the aat4280a is a family of flexible p-channel mosfet power switches designed for high-side load switching applications. there are three ver- sions of the aat4280a with different turn-on and turn-off characteristics to choose from, depending upon the specific requirements of an application. the first version, the aat4280a-1, has a moderate turn-on slew rate feature, which reduces inrush current when the mosfet is turned on. this func- tion allows the load switch to be implemented with either a small input capacitor or no input capacitor at all. during turn-on slewing, the current ramps linearly until it reaches the level required for the output load condition. the proprietary turn-on cur- rent control method works by careful control and monitoring of the mosfet gate voltage. when the device is switched on, the gate voltage is quickly increased to the threshold level of the mosfet. once at this level, the current begins to slew as the gate voltage is slowly increased until the mosfet becomes fully enhanced. once it has reached this point, the gate is quickly increased to the full input voltage and r ds(on) is minimized. the second version, the aat4280a-2, is a very fast switch intended for high-speed switching applica- tions. this version has no turn-on slew rate control and no special output discharge features. the final switch version, the aat4280a-3, has the addition of a minimized slew rate limited turn-on function and a shutdown output discharge circuit to rapidly turn off a load when the load switch is dis- abled through the on/off pin. all versions of the aat4280a operate with input voltages ranging from 1.5v to 5.5v. all versions of this device have extremely low operating current, making them ideal for battery-powered applica- tions. the on/off control pin is ttl compatible and will also function with 2.5v to 5v logic systems, making the aat4280a an ideal level-shifting load switch. functional block diagram level shift in on/off out gnd turn-on slew rate control * *aat4280a-3 only
aat4280a slew rate controlled load switch 10 4280a.2005.11.1.3 applications information input capacitor a 1f or larger capacitor is typically recommended for c in in most applications. a c in capacitor is not required for basic operation; however, c in is useful in preventing load transients from affecting upstream circuits. c in should be located as close to the device v in pin as practically possible. 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 higher current operation, ceramic capacitors are recommended for c in due to their inherent capabil- ity over tantalum capacitors to withstand input cur- rent surges from low impedance sources, such as batteries in portable devices. output capacitor for proper slew operation, a 0.1f capacitor or greater between v out and gnd is recommended. the output capacitor has no specific capacitor type or esr requirement. if desired, c out may be increased without limit to accommodate any load transient condition without adversely affecting the device turn-on slew rate time. enable function the aat4280a features an enable / disable func- tion. this pin (on/off) is compatible with both ttl or cmos logic. reverse output-to-input voltage conditions and protection under normal operating conditions, a parasitic diode exists between the output and input of the load switch. 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 and possibly damage the load switch. in applications where there is a possibility of v out exceeding v in for brief periods of time during normal operation, the use of a larger value c in capacitor 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 from 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. thermal considerations and high output current applications the aat4280a is designed to deliver a continuous output load current. the limiting characteristic for maximum safe operating output load current is package power dissipation. in order to obtain high operating currents, careful device layout and circuit operating conditions need to be taken into account. the following discussions will assume the load switch is mounted on a printed circuit board utiliz- ing the minimum recommended footprint, as stated in the layout considerations section of this datasheet. at any given ambient temperature (t a ), the maxi- mum package power dissipation can be deter- mined by the following equation: constants for the aat4280a are maximum junction temperature, t j(max) = 125c, and package thermal resistance, ja = 120c/w. worst case conditions are calculated at the maximum operating tempera- ture where t a = 85c. typical conditions are cal- culated under normal ambient conditions where t a = 25c. at t a = 85c, p d(max) = 333mw. at t a = 25c, p d(max) = 833mw. the maximum continuous output current for the aat4280a is a function of the package power dis- p d(max) [t j(max) - t a ] ja =
aat4280a slew rate controlled load switch 4280a.2005.11.1.3 11 sipation and the r ds of the mosfet at t j(max) . the maximum r ds of the mosfet at t j(max) is cal- culated by increasing the maximum room tempera- ture r ds by the r ds temperature coefficient. the temperature coefficient (t c ) is 2800ppm/c. therefore, max r ds 125c = r ds 25c (1 + t c ? t) max r ds 125c = 120m ? (1 + 0.0028 (125c - 25c)) = 154m ? for maximum current, refer to the following equation: for example, if v in = 5v, r ds(max) = 154m ? and t a = 25c, i out(max) = 2.3a. if the output load current were to exceed 2.3a or if the ambient temperature were to increase, the internal die temperature would increase and the device would be damaged. higher peak currents can be obtained with the aat4280a. to accomplish this, the device thermal resistance must be reduced by increasing the heat sink area or by operating the load switch in a duty- cycle manner. high peak output current applications some applications require the load switch to oper- ate at a continuous nominal current level with short duration, high-current peaks. the duty cycle for both output current levels must be taken into account. to do so, first calculate the power dissi- pation at the nominal continuous current level, and then add in the additional power dissipation due to the short duration, high-current peak scaled by the duty factor. for example, a 4v system using an aat4280a operates at a continuous 100ma load current level and has short 2a current peaks, as in a gsm appli- cation. the current peak occurs for 576s out of a 4.61ms period. first, the current duty cycle is calculated: % peak duty cycle: x/100 = 576s/4.61ms % peak duty cycle = 12.5% the load current is 100ma for 87.5% of the 4.61ms period and 2a for 12.5% of the period. since the electrical characteristics do not report r ds(max) for 4v operation, it must be calculated approximately by consulting the chart of r ds(on) vs. v in . the r ds reported for 5v can be scaled by the ratio seen in the chart to derive the r ds for a 4v v in : 120m ? 87m ? /80m ? = 130m ? . de-rated for temperature: 130m ? x (1 + 0.0028 (125c -25c)) = 166m ? . the power dissipation for a 100ma load is calculat- ed as follows: p d(max) = i out 2 r ds p d(100ma) = (100ma) 2 166m ? p d(100ma) = 1.66mw p d(87.5%d/c) = %dc p d(100ma) p d(87.5%d/c) = 0.875 1.66mw p d(87.5%d/c) = 1.45mw the power dissipation for 100ma load at 87.5% duty cycle is 1.45mw. now the power dissipation for the remaining 12.5% of the duty cycle at 2a is calculated: p d(max) = i out 2 r ds p d(2a) = (2a) 2 166m ? p d(2a) = 664mw p d(12.5%d/c) = %dc p d(2a) p d(12.5%d/c) = 0.125 664mw p d(12.5%d/c) = 83mw the power dissipation for 2a load at 12.5% duty cycle is 83mw. finally, the two power figures are summed to determine the total true power dissipa- tion under the varied load: p d(total) = p d(100ma) + p d(2a) p d(total) = 1.45mw + 83mw p d(total) = 84.5mw the maximum power dissipation for the aat4280a operating at an ambient temperature of 85c is 333mw. the device in this example will have a total power dissipation of 84.5mw. this is well within the thermal limits for safe operation of the device; in fact, at 85c, the aat4280a will handle a 2a pulse for up to 50% duty cycle. at lower ambi- ent temperatures, the duty cycle can be further increased. i out(max) p d(max) r ds <
aat4280a slew rate controlled load switch 12 4280a.2005.11.1.3 figure 1: evaluation board figure 2: evaluation board figure 3: evaluation board top side silk screen layout / component side layout. solder side layout. assembly drawing. printed circuit board layout recommendations for proper thermal management and to take advan- tage of the low r ds(on) of the aat4280a, a few cir- cuit board layout rules should be followed: v in and v out should be routed using wider than normal traces, and gnd should be connected to a ground plane. to maximize package thermal dispation and power handling capacity of the aat4280a sc70jw-8 package, the ground plane area con- nected to the ground pins should be made as large as possible. for best performance, c in and c out should be placed close to the package pins. evaluation board layout the aat4280a evaluation layout follows the print- ed circuit board layout recommendations and can be used for good applications layout. refer to figures 1 through 3. note: board layout shown is not to scale.
aat4280a slew rate controlled load switch 4280a.2005.11.1.3 13 ordering information package information sc70jw-8 all dimensions in millimeters. 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 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. device option package marking 1 part number (tape and reel) 2 aat4280a-1 sc70jw-8 ndxyy aat4280aijs-1-t1 aat4280a-2 sc70jw-8 nexyy aat4280aijs-2-t1 aat4280a-3 sc70jw-8 nfxyy AAT4280AIJS-3-T1 1. xyy = assembly and date code. 2. sample stock is generally held for part numbers listed in bold .
aat4280a slew rate controlled load switch 14 4280a.2005.11.1.3 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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