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smartswitch ? aat4625 usb single-channel power switch 4625.2006.04.1.2 1 general description the aat4625 smartswitch is part of analogictech's application specific power mosfet? (aspm?) product family. it is a 1.0a current limited p-chan- nel mosfet power switch designed for high-side load-switching applications. this switch operates with inputs ranging from 2.7v to 5.5v, making it ideal for both 3v and 5v systems. an integrated current-limiting circuit protects the input supply against large changes in load current which may cause the supply to fall out of regulation. the aat4625 is also protected from thermal overload which limits power dissipation and junction temper- atures. the current limit threshold is factory pro- grammed at 1.5a, with a maximum of 2.0a. the quiescent supply current is typically a low 16a. in shutdown mode, the supply current decreases to less than 1a. the aat4625 is available in pb-free, 8-pin sop, tssop, or msop packages, and is specified over the -40c to +85c temperature range. the aat4600 series is a family of adjustable and fixed smartswitch products with a range of current handling capabilities. single versions with adjustable current limit (aat4601) or fixed current limit (aat4625) as well as dual versions with fixed current limit (aat4626) are available. features ? compliant with usb 1.1 and 2.0 specifications ? 2.7v to 5.5v input voltage range ? 1.0a minimum continuous current ? 2.0a maximum current limit ? 60m typical r ds(on) ? low quiescent current: ? typically 16a ? 1a maximum with switch off ? thermal shutdown ? slew rate limited turn on ? fault flag with 10ms blanking ? under-voltage lockout (uvlo) ? temperature range: -40c to +85c ? ul approved?file no. e217765 ? 8-pin sop, tssop, or msop package applications ? general purpose power switching ? hot swap supplies ? notebook computers ? usb ports and peripherals ul recognized component typical application 120 f gnd gnd output out out in en (en) en (en) 0.1 f v cc 5.0v 100k flg 7 2 1 3 8 6 aat4625
pin descriptions pin configuration sop-8 tssop-8 msop-8 (top view) pin # symbol function 1 en (en) enable input: logic-compatible enable input. high input > 2.1v typical. low input < 1.9v typical. active high or active low option available; see ordering information for details. 2 flg fault flag output: active-low, open-drain output. indicates over-current, uvlo, and thermal shutdown. 3 gnd ground. 4,5 nc not internally connected. 6,8 out switch output: these pins are the p-channel mosfet drain connection. 7 in supply input: this pin is the p-channel mosfet source connection. also supplies the ic's internal circuitry. aat4625 usb single-channel power switch 2 4625.2006.04.1.2 1 2 in out out nc en (en) flg gnd nc 1 2 3 4 8 7 6 5
absolute maximum ratings 1 t a = 25c, unless otherwise noted. thermal information 2 symbol description value units sop-8 120 ja maximum thermal resistance tssop-8 150 c/w msop-8 150 sop-8 1.0 w p d maximum power dissipation tssop-8 833 mw msop-8 833 symbol description value units v in in to gnd -0.3 to 6 v v flg flg to gnd -0.3 to 6 v i flg flg current 50 ma v out out to gnd -0.3 to v in + 0.3 v i out output current (internally limited) 2.0 a v en en to gnd -0.3 to 6 v t s storage temperature 150 c t lead maximum soldering temperature (at leads) 300 c aat4625 usb single-channel power switch 4625.2006.04.1.2 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 an fr4 printed circuit board.
electrical characteristics v in = 5v, t a = -40c to +85c, unless otherwise noted. typical values are t a = 25c; bold values designate full temperature range. symbol description conditions min typ max units v in operation voltage 2.7 5.5 v i q quiescent current v in = 5v, en = active 16 30 a i q(off) off supply current v in = 5.5v, en (en) = inactive 1 a v en-thrsh enable input threshold low-to-high transition 2.4 v high-to-low transition 0.8 i en enable input current v en = 0v to 5.5v 0.01 1 a c en enable input capacitance 1 pf r ds(on) on-resistance v in = 5v, t a = 25c 60 100 m v in = 3.0v, t a = 25c 70 115 t on output turn-on delay v in = 5v, r l = 10 0.25 ms t on-rise output turn-on rise time v in = 5v, r l = 10 0.2 ms t off output turn-off delay v in = 5v, r l = 10 5 20 s t off-fall output turn-off fall time v in = 5v, r l = 10 20 s i sd(off) output leakage current en = inactive, v in = 5.5v, v out = 0v 0.03 15 a i limit current limit threshold ramped load applied to enable 1.0 1.5 2.0 a output, v out < 4.0v otmp over-temperature shutdown t j increasing 125 c t j decreasing 115 r flg error flag output resistance v in = 5v, i l = 1ma 30 i sink error flag off current v flg = 5.5v 0.05 1 a v uvlo under-voltage lockout v in = increasing, 1% hysteresis 2.0 2.3 2.7 v t blank fault blanking 10 ms aat4625 usb single-channel power switch 4 4625.2006.04.1.2
typical characteristics v in = 5v, t a = 25c, unless otherwise noted. aat4625 usb single-channel power switch 4625.2006.04.1.2 5 turn on/off response with 10 off-switch current vs. temperature 0.0000 0.0001 0.0010 0.0100 0.1000 1.0000 -40 -20 0 20 40 60 80 100 120 temperature ( off-supply current vs. temperature 0.0010 0.0100 0.1000 1.0000 -40 -20 0 20 40 60 80 100 120 temperature ( current limit 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 012345 output voltage (v) output current (a) quiescent current 0 2 4 6 8 10 12 14 16 18 20 0123456 input voltage (v) input current ( quiescent current vs. temperature 0 5 10 15 20 25 30 -40 -20 0 20 40 60 80 100 120 temp quiescent current (
typical characteristics v in = 5v, t a = 25c, unless otherwise noted. aat4625 usb single-channel power switch 6 4625.2006.04.1.2 r ds(on) vs. temperature 40.0 45.0 50.0 55.0 60.0 65.0 70.0 75.0 80.0 -40 -20 0 20 40 60 80 100 120 temperature ( v cc = 3v v cc = 5v 0 2 4 6 8 -1012345 time ( -3 0 3 6 9 input voltage output current output voltage short-circuit through 0.6 short-circuit through 0.3 0 2 4 6 8 -1012345 tim input and output voltage (v) output current (a) e( -4 0 4 8 12 inpu t voltage out put current out put voltage thermal shutdown response time (50ms/div) en 5v/div fault 5v/div v out 1v/div i in 500ma/div start into 1
aat4625 usb single-channel power switch 4625.2006.04.1.2 7 functional description the aat4625 is an integrated mosfet load switch with a fixed current limit, over-temperature protection, level shifted input, and a fault flag. the current limit control is combined with an over- temperature thermal limit circuit to provide a com- prehensive system to protect the load switch under short-circuit or other adverse operating conditions. the aat4625 is ideally suited for con- trol and protection of peripheral ports such as usb, rs232, and parallel ports. the current limit and over-temperature circuits will act independently. the device current limit is acti- vated when the output load current exceeds a pre- set internal threshold level. the minimum current limit threshold characteristic is specified by i lim(min) . if the load switch ambient temperature becomes excessive or if a short-circuit condition persists, the die temperature will rise, causing the over-temper- ature protection circuit to activate. if the current limit or over-temperature protection circuits are active for more than two milliseconds, the system will be informed via the fault flag. a 10ms fault blanking delay allows the aat4625 to be turned on into large capacitive loads without activating the fault flag. the open drain fault output can be connected directly to system con- trollers driven by voltage levels less than the in pin voltage without additional level shifting circuitry. the load switch is turned on and off by applying a logic level signal to the en pin. the aat4625 enable function is available in both active high and active low logic level versions. the aat4625 typi- cally consumes 16a when operating; when off, the device draws less than 1a. in the off state, current is prevented from flowing between the input and out- put. the en function has logic level thresholds that allow the aat4625 to be ttl compatible and may also be controlled by 2.5v to 5.0v cmos circuits. the voltage level on either en or fault should not exceed the input supply level present on the in pin. functional block diagram 1.2v reference current limit over-temperature protection under- voltage lockout in en (en) gnd flg out
aat4625 usb single-channel power switch 8 4625.2006.04.1.2 applications information operation in current limit if an excessive load is applied to the output of an aat4625, the load current will be limited by the device?s current limit circuitry. refer to the "current limit" curve in the typical characteristics section of this datasheet. if a short circuit were to occur on the load, there would be a demand for more current than what is allowed by the internal current limiting circuit and the voltage at the device output will drop. this causes the aat4625 to dissipate more power than in normal operation, causing the die temperature to increase. when die temperature exceeds the internal over-temperature threshold, the aat4625 will shut down. after shutting down, the aat4625 cools to a level below the over-tem- perature threshold, at which point it will start up again. the aat4625 will continue to cycle off and on until one of the following events occurs: the load current is reduced to a level below the aat4625's current limit setting; the input power is removed; or the output is turned off by a logic high level applied to the en pin. thermal considerations since the aat4625 has internal current limit and over-temperature protection, junction temperature is rarely a concern. if an application requires a large load current in a high-temperature operating environment, there is the possibility that the over- temperature protection circuit (rather than the cur- rent limit circuit) will regulate the current available to the load. in these applications, the maximum current available without risk of activation of the over-temperature circuit can be calculated. the maximum internal temperature while current limit is not active can be calculated using equation 1: eq. 1: in equation 1, i max is the maximum current required by the load. r ds(on)(max) is the maximum rated r ds(on) of the aat4625 at high temperature. r ja is the thermal resistance between the device die and the board onto which it is mounted. t a(max) is the maximum ambient temperature for the print- ed circuit board assembly under the aat4625 when the load switch is not dissipating power. equation 1 can be transformed to provide i max ; refer to equation 2. eq. 2: t sd(min) is the minimum temperature required to activate the device over-temperature protection. the typical thermal limit temperature specification is 125c for the aat4625; for calculations, 115c is a safe minimum value to use. for example, a portable device is specified to oper- ate in a 50c environment. the printed circuit board assembly will operate at temperatures as high as 85c. this portable device has a sealed case and the area of the printed board assembly is relatively small, causing r ja to be approximately 120c/w. using equation 2, if this system requires less than 1.4a, the thermal limit will not activate during normal operation. input capacitor the input capacitor serves two purposes. first, it protects the source power supply from transient current effects generated by the application load circuit. if a short circuit is suddenly applied to the output of an aat4625, there is a microsecond long period during which a large current can flow before the current limit circuit becomes active. refer to the characteristic curve "short circuit through 0.3 ." a properly sized input capacitor can dra- matically reduce the load switch input transient response effects seen by the power supply and other circuitry upstream from the aat4625. the second purpose of the input capacitor is to pre- vent transient events generated by the load circuit from affecting the operation of the aat4625. for example, if an aat4625 is used in a circuit that oper- ates from a 5v power supply with poor step load response, turning on the load switch could cause the = i max = 1.4a 115 - 85 130 120 = i max t sd(min) - t a(max) r ds(on)(max) r ja t j(max) = i max 2 r ds(on)(max) r ja + t a(max)
input power supply to drop below the aat4625's under-voltage lockout threshold. this drop in voltage would cause the aat4625 to turn off until the input power supply voltage level recovers. since this cycle would be self-perpetuating, the entire circuit could be seen to be unstable. in the very rare case where capacitor cost is prohibitive and the input capacitor is omitted, the output load circuit should be slew rate limited when turned on. output capacitor in order to insure stability while the device current limit is active, a small capacitance of approximately 1f should be used. when the aat4625 is activat- ed using the on function, there are no momentary current transients, as in the case when a short cir- cuit is suddenly applied to a device that is already on. refer to the "turn-on/off response" charac- teristics curve. regardless of output capacitor size, output current is limited to the value allowed by the threshold determined by the internal current limiting circuitry. refer to the internal current limit threshold specifications stated in the electrical characteristics section of this datasheet. this permits very large output capacitors to be used. for example, usb ports are specified to have at least 120f of downstream capacitance from their controlling power switch. an output capacitance as large as 1000f would not disturb the input power supply to an aat4625 used to control a usb port. en input the aat4625 is available in both active high and active low enable versions. for specific part num- bers, refer to the ordering information section of this datasheet. when the aat4625 is in the off state, the output is an open circuit and the device quiescent current consumption is reduced to less than 1a. the en threshold voltage is set to allow the aat4625 to be controlled by 5v ttl levels, as well as cmos-compatible levels ranging from 2.5v to 5v. the en function control voltage level should not exceed the input supply level applied to the in pin. fault flag output the aat4625 features an active low fault flag out- put. the fault flag is provided to alert the system if the over-current or over-temperature circuits become active or if the load switch is not receiv- ing a sufficient voltage level to properly operate. if either the current limit or over-temperature cir- cuits in any combination are constantly active for more than approximately 10ms, the fault pin is pulled to ground internally through an open drain device. the 10ms delay on the fault function is intended to prevent capacitive loads connected to the load switch output from activating the fault flag when the device is turned on. the placement of a pull-up resistor between the fault pin and the in pin is recommended. reasonable values for the pull-up resistor should range from 10k to 100k . since the fault flag is an open drain ter- minal, it may be pulled up to any voltage that is not greater than the level present on the in pin. this is done to allow the aat4625 to signal ancil- lary circuitry that is powered by voltage levels less than the level on the in pin. if a fault flag delay greater than 10ms is required, addition delay may be added by use of an rc filter. an rc filter can be added to the fault flag output, as shown in figure 1. aat4625 usb single-channel power switch 4625.2006.04.1.2 9 figure 1: fault flag delay rc filter. r1 10k 100k c1 0.1 f aat4625 1 2 3 45 6 7 8 en flg gnd nc nc out in out v+ usb controller over-current flag input
aat4625 usb single-channel power switch 10 4625.2006.04.1.2 reverse voltage the aat4625 is designed to control current flowing from in to out. if a voltage is applied to out which is greater than that on in, a large reverse current may flow, potentially damaging the device. under-voltage lockout the aat4625 has been designed with an under-volt- age lockout control circuit. the under-voltage lock- out prevents the output mosfet device from turn- ing on until v in exceeds the typical uvlo threshold of 2.3v. during operation, the device will automati- cally shut down if v in falls below the uvlo threshold and the fault flag will be toggled. hot-plug applications application circuit cards with a high inrush current potential can be limited by use of the aat4625. the aat4625 has both slew rate limited turn-on characteristics and a current limit controlled output which make it ideally suited for power port hot-plug applications. a host power back plane or hot-plug receptacle may be sensitive to short duration, high power surges. the aat4625 will turn on in a linear ramping fashion and regulate the inrush current within the specified current limit for the device. the error flag usually will not be affected during appli- cation turn-on, since the 10ms flag blanking time is intended for these types of events. if an application turn-on current surge exceeds 10ms, an rc delay filter may be added to the flag output to prevent the system from receiving an error during the start-up sequence (see figure 2). figure 2: aat4625 inrush current protected application. pcb layout information in order to obtain maximum performance from the aat4625, very careful consideration must be given to the printed circuit board layout. in most port power switch and port protection applications, high voltage and current transient events will occur. proper pcb layout can help reduce the effects of transient events. pcb trace resistance will affect overall circuit transient response; in addition, small voltage drops will be incurred. 0.1 f aat4625 1 2 3 45 6 7 8 en flg gnd nc nc out in out c bulk (120 f) card application circuit v+ gnd inrush current protected application card cable / connector to hot-plug port v bus gnd hot-plug receptacle
refer to the following guidelines for power port pcb layout: 1. pcb traces should be kept as short and direct as possible to minimize the effects of the pcb on circuit performance. 2. make component solder pads large to mini- mize contact resistance. 3. the aat4625 output bulk capacitor and ferrite beads should be placed as close to the device as possible. pcb traces to the output connec- tor should be kept as short as possible to min- imized trace resistance and the associated voltage drop (i 2 r loss). 4. if ferrite beads are used in the circuit, select fer- rite beads with a minimum series resistance. 5. the use of pcb trace vias should be avoided on all traces that conduct high currents. if vias are necessary, make the vias as large as pos- sible and use multiple vias connected in paral- lel to minimize their effect. aat4625 usb single-channel power switch 4625.2006.04.1.2 11 figure 3: summary of typical circuit voltage drops caused by aat4625 circuit components and pcb trace resistance. evaluation board layout the aat4625 evaluation layout (shown in figures 4, 5, and 6) follows the recommend printed circuit board layout procedures and can be used as an example for good application layouts. note that ferrite beads are not used on this simple device evaluation board. the board layout shown is not to scale. figure 4: evaluation board figure 5: evaluation board figure 6: evaluation board component side layout. solder side layout. top side silk screen layout/ assembly drawing. trace resistance 0.01 (5mv) (5mv) c bulk 0.1 f c bulk 0.1 f cable, connector, and contact resistance 0.03 (15mv) (15mv) v+ gnd input power supply 4.50v to 5.25v p-channel mosfet switch on resistance 0.06 (30mv) aat4625 ferrite bead and pcb trace resistance 0.02 (10mv) (10mv) v bus gnd downstream peripheral port 500ma max. load current total voltage drop = 60mv
aat4625 usb single-channel power switch 12 4625.2006.04.1.2 application circuits figure 7: typical usb host port application. figure 8: self-powered single port usb hub. figure 9: usb bus powered single port usb hub. 120 f 0.01 f 100k 1 f 1 f aat3220-3.3 3.3v usb controller aat4625 ferrite beads data data v bus d+ d- gnd v bus d+ d- gnd usb port usb host vin on/off over-current flag in out gnd gnd en out flg gnd nc nc out in 120 f 0.1 f 100k f 1 f aat3220-3.3 3.3v usb controller aat4625 ferrite beads v cc 5.0v data data v bus d+ d- gnd v bus d+ d- gnd usb port 4.50v to 5.25v upstream v bus 100ma maximum vin on/off over-current flag in out gnd gnd en out flg gnd nc nc out in c in 0.1 f r1 100k on/off error flag usb controller aat4625 v bus = 5.0v in out flg en(en) nc 6,8 4,5 7 2 1 3 c out1 0.1 f c out2 120 f data d+ d- v bus gnd ferrite beads
ordering information package information sop-8 all dimensions in millimeters. package enable marking 1 part number (tape and reel) 2 sop-8 en (active-high) 4625-1 aat4625ias-1-t1 sop-8 en (active-low) 4625 aat4625ias-t1 tssop-8 en (active-high) 4625-1 aat4625ihs-1-t1 tssop-8 en (active-low) 4625 aat4625ihs-t1 msop-8 en (active-high) ddxyy aat4625iks-1-t1 msop-8 en (active-low) dcxyy AAT4625IKS-T1 aat4625 usb single-channel power switch 4625.2006.04.1.2 13 1. xyy = assembly and date code. 2. sample stock is generally held on part numbers listed in bold . 0.175 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.
aat4625 usb single-channel power switch 14 4625.2006.04.1.2 tssop-8 all dimensions in millimeters. detail a 4.40
msop-8 all dimensions in millimeters. aat4625 usb single-channel power switch 4625.2006.04.1.2 15 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 sub- ject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, 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. analogictech and the analogictech logo are trademarks of advanced analogic technologies incorporated. all other brand and produ ct names appearing in this document are regis- tered trademarks or trademarks of their respective holders. pin 1 1.95 bsc 0.254 bsc 0.155

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