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general description the max4914b/max4915a/b/max4917a/b family of switch- es feature internal current limiting to prevent damage to host devices due to faulty load conditions. these analog switches have a low 0.2 on-resistance and operate from a 2.3v to 5.5v input voltage range. they are available with guaran- teed 100ma, 200ma, and 300ma current limits, making them ideal for sdio and other load switching applications. when the switch is on and a load is connected to the port, a guaranteed blanking time of 14ms ensures that the transient voltages settle down. if after this blanking time the load current is greater than the current limit, the max4914b/max4915b/max4917b latchoff versions enter a latchoff state where the switch is turned off and flag is issued to the microprocessor. the switch can be turned on again by cycling the power or the on pin. the max4915a/max4917a have an autoretry feature where the switch turns off after the blanking time and then continuously checks to see if the overload condi- tion is present. the switch turns on and remains on after the overload condition disappears and flag deasserts. the max4914b is available in the tiny 6-pin ?fn (2mm x 2mm) package, while the max4915a/b and max4917a/b are available in both 6-pin ?fn (2mm x 2mm) and space-saving 5-pin sot23 pack- ages. these devices operate over the -40? to +85? extended temperature range. applications features ? guaranteed current limit: 100ma, 200ma, 300ma ? thermal-shutdown protection ? reverse current protection ? 0.2 on-resistance ? 14ms guaranteed blanking time ? flag function ? 80? supply current ? 8? latchoff current (max4914b/max4915b/max4917b) ? autoretry (max4915a/max4917a) ? 0.01? shutdown current ? 2.3v to 5.5v supply range ? undervoltage lockout ? fast current-limit response time (5?) ? low (0.1? typ) reverse shutdown current ? tiny 6-pin ?fn (2mm x 2mm) and 5-pin sot23 packages max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current ________________________________________________________________ maxim integrated products 1 19-0544; rev 2; 6/08 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information/selector guide part pin-package top mark current limit (ma) retry/latch-off max4914b elt+t 6 ?fn abf 100 latchoff max4915a elt+t 6 ?fn abl 200 autoretry max4915aeuk+t* 5 sot23 aeyn 200 autoretry max4915b elt+t 6 ?fn abg 200 latchoff max4915beuk+t* 5 sot23 aeyk 200 latchoff max4917a elt+t 6 ?fn abn 300 autoretry max4917aeuk+t* 5 sot23 aeyp 300 autoretry max4917b elt+t 6 ?fn abi 300 latchoff MAX4917BEUK+t* 5 sot23 aeym 300 latchoff note: all devices are specified over the -40? to +85? operating temperature range. * future product?ontact factory for availability. + denotes a lead-free/rohs-compliant package. t = tape-and-reel package. pdas and palmtop devices cell phones gps systems handheld devices sdio usb ports notebook computers pin configurations and typical operating circuit appear at end of data sheet.
max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v in = +2.3v to +5.5v, t a = -40? to +85?, unless otherwise noted. typical values are at v in = +3.3v, t a = +25?.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. in, on, flag , out to gnd .....................................-0.3v to +6v out short circuit to gnd .................................internally limited continuous power dissipation (t a = +70?) 5-pin sot23 (derate 7.1mw/? above +70?)............571mw 6-pin ?fn (derate 4.5mw/? above +70?) ................358mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? parameter symbol conditions min typ max units operating voltage v in 2.3 5.5 v v in = +2.3v to +5.0v 80 120 quiescent current i q v on = v in , i out = 0, switch on v in = +5.0v to +5.5v 160 ? latchoff current (note 2) i latch v on = v in , after an over cur r ent faul t m ax 4914b/ m ax 4915b/m ax 4917b ( l atchoff ver si ons) 817a forward shutdown current i shdn v on = 0, v out = 0, v in = +5.5v 0.01 1a reverse shutdown current i shdn v on = 0, v out = +5.5v, v in = +2.3v 0.01 1a max4914b, v out = gnd 100 150 max4915_, v out = gnd 200 300 forward current limit i fwd max4917_, v out = gnd 300 450 ma max4914b, v out - v in 0.5v 150 max4915_, v out - v in 0.5v 300 reverse current limit i rev max4917_, v out - v in 0.5v 450 ma on input leakage v on = v in or gnd -1 +1 a undervoltage lockout uvlo rising edge 1.75 2.25 v undervoltage-lockout hysteresis 100 mv t a = +25?, i out = 95ma 0.2 0.4 on-resistance r on t a = - 40 c to + 85c , i ou t = 95m a0.5 max4914b/max4915b/max4917b 2.0 on input logic-high voltage v ih max4915a/max4917a 1.4 v max4914b/max4915b/max4917b 0.8 on input logic-low voltage v il max4915a/max4917a 0.4 v flag output logic-low voltage i s in k = 1m a0.4v flag output-high leakage current v on = v in = v flag = +5.5v 1 ? thermal shutdown +150 ? thermal-shutdown hysteresis 15 ? dynamic characteristics turn-on time v on from low to high; i out = 10ma, c l = 0.1? (note 3) 100 ?
max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current _______________________________________________________________________________________ 3 typical operating characteristics (v in = 3.3v, t a = +25?, unless otherwise noted.) note 1: all parts are 100% tested at +25?. limits across the full temperature range are guaranteed by design and correlation. note 2: latchoff current does not include the current flowing into flag . note 3: the on-time is defined as the time taken for the current through the switch to go from 0ma to 10ma. the off-time is defined as the time taken for the current through the switch to go from 10ma to 0ma. note 4: retry time is typically 15 times the blanking time. electrical characteristics (continued) (v in = +2.3v to +5.5v, t a = -40? to +85?, unless otherwise noted. typical values are at v in = +3.3v, t a = +25?.) (note 1) parameter symbol conditions min typ max units turn-off time v on from high to low; i out = 10ma, c l = 0.1? (note 3) 40 ns blanking time t blank overcurrent fault (figures 2, 3) 14 60 ms short-circuit current-limit response time v on = v in = +3.3v, short circuit applied to out 5s retry time (note 4) t retry max4915a/max4917a (autoretry versions) (figure 2) (note 4) 210 900 ms quiescent current vs. supply voltage max4914a/b toc01 supply voltage (v) quiescent current ( a) 5.5 5.0 4.0 4.5 3.0 3.5 2.5 10 20 30 40 50 60 70 80 90 100 0 2.0 v on = v in quiescent current vs. temperature max4914a/b toc02 temperature ( c) quiescent current ( a) 60 35 10 -15 20 40 60 80 100 120 0 -40 85 v on = v in v in = 5v v in = 3.3v latchoff current vs. temperature max4914a/b toc03 temperature ( c) latchoff current ( a) 60 35 10 -15 2 4 6 8 10 12 0 -40 85 v on = v in v in = 5v v in = 3.3v 1000 100 0.01 -40 85 forward shutdown current vs. temperature 0.1 1 10 max4914a/b toc04 temperature ( c) forward shutdown current (na) 60 35 10 -15 v cc = 5v v cc = 3.3v 1 -40 85 0.1 0.01 reverse shutdown current vs. temperature max4914a/b toc05 temperature ( c) reverse shutdown current (na) 60 35 10 -15 v in = 3.3v v in = 5v on = gnd, v out = 5.5v latchoff leakage current vs. temperature max4914a/b toc06 temperature ( c) latchoff leakage current (na) 60 35 10 -15 0.001 0.01 0.1 1 10 100 0.0001 -40 85 v in = 5v v in = 3.3v
max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current 4 _______________________________________________________________________________________ typical operating characteristics (continued) (v in = 3.3v, t a = +25?, unless otherwise noted.) normalized on-resistance vs. temperature max4914a/b toc07 temperature ( c) normalized r on 60 35 10 -15 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 -40 85 v cc = 5v output current vs. output voltage max4914a/b toc08 v in - v out (v) output current (ma) 3.0 2.7 2.1 2.4 0.6 0.9 1.2 1.5 1.8 0.3 50 100 150 200 250 300 350 400 450 500 0 03.3 max4915_ switch turn-on/off times vs. temperature max4914a/b toc09 temperature ( c) switch turn-on/off times ( s) 60 35 10 -15 0.01 0.1 1 10 100 -40 85 i load = 10ma on off flag-blanking timeout vs. temperature max4914a/b toc10 temperature ( c) flag-blanking timeout (ms) 60 35 10 -15 25 30 35 40 45 50 20 -40 85 current-limit response (v on rising) max4914a/b toc11 20 s/div v in 2v/div v on 2v/div i out 100ma/div c in = 0.1 f c out = 0.1 f 0v 0v 0ma current-limit response (v in and v on rising together) max4914a/b toc12 20 s/div v in = v on 1v/div i out 100ma/div c in = 0.1 f c out = 0.1 f 0v 0ma current-limit response (out shorted to gnd) max4914a/b toc13 40 s/div v in 2v/div v out 2v/div i out 5a/div c in = 1 f c out = 0.1 f 0v 0v 0a turn-on response max4914a/b toc14 20 s/div v on 1v/div i out 50ma/div 0v 0ma c in = 0.1 f c out = 0.1 f
max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current _______________________________________________________________________________________ 5 pin description typical operating characteristics (continued) (v in = 3.3v, t a = +25?, unless otherwise noted.) pin max4915a/b/ max4917a/b (sot23) max4914a/b/ max4915a/b/ max4917a/b (?fn) name function 12in input. bypass with a 0.1? ceramic capacitor to ground as close to the device as possible. 2 5 gnd ground 3 6 on active-high, switch-on input. a logic-high turns the switch on. 44 flag fault output. this open-drain output goes low when the device stays in forward or reverse current limit for more than the blanking time period. flag is high impedance when a fault is not present or when on is low. 5 3 out switch output. bypass with a 0.1? ceramic capacitor to ground as close to the device as possible. 1 n.c. no connection. not internally connected. turn-off response max4914a/b toc15 200ns/div v on 1v/div i out 10ma/div c in = 0.1 f c out = 0.1 f 0v 0ma flag-blanking response max4914a/b toc16 10ms/div v flag 2v/div i out 200ma/div v in 2v/div v on 2v/div c in = 0.1 f c out = 0.1 f 0v 0v 0v 0ma
max4914b/max4915a/b/max4917a/b detailed description the max4914b/max4915a/b/max4917a/b are for- ward/reverse current-limited switches that operate from a +2.3v to +5.5v input voltage range and guarantee a 100ma, 200ma, and 300ma minimum current-limit threshold for different options. the voltage drop across an internal sense resistor is compared to two reference voltages to indicate a forward or reverse current-limit fault. when the load current exceeds the preset current limit for greater than the fault-blanking time, the switch opens and flag asserts. the max4915a/max4917a have an autoretry function that turns on the switch again after an internal retry time expires. if the faulty load condition is still present after the blanking time, the switch turns off again and the cycle is repeated. if the faulty load condition is not pre- sent, the switch remains on. during this retry time, flag remains low until the fault is removed. the max4914b/max4915b/max4917b do not have the autoretry option, and the switch remains in latchoff mode until the on pin or the input power is cycled from high to low and then high again. the undervoltage-lockout (uvlo) circuit prevents erro- neous switch operation when the input voltage goes too low. reverse current protection all devices limit the reverse current (v out to v in ) from exceeding the maximum i rev value. the switch is shut off and flag is asserted if the reverse current-limit condition persists for more than the blanking time. this feature pre- vents excessive reverse currents from flowing through the device to the source. when the device is in shutdown (v on < v il ), the current from out to in does not exceed 1? (max). switch-on/off control toggle on high to enable the current-limited switches. the switches are continuously on only if v in exceeds the uvlo threshold (typically 2v) and there is no fault. when a forward/reverse current fault is present or the die exceeds the thermal-shutdown temperature of +150?, out is internally disconnected from in and the supply current decreases to 8? (latchoff). the switch is now operating in one of its off states. the switch-off state also occurs when driving on low, thus reducing the supply current (shutdown) to 0.01? (typ). table 1 illustrates the on/off state. flag indicator all devices feature a lat ched fault output, flag . whenever a fault is activated, it latches the flag out- put low and also turns the switch off. flag is an open- 100ma/200ma/300ma current-limit switches with low shutdown reverse current 6 _______________________________________________________________________________________ n blanking time circuitry reverse current detector forward current detector n +2.0v flag out in on gnd logic auto- retry max4914b max4915a/b max4917a/b undervoltage lockout figure 1. functional diagram
drain output transistor and requires an external pullup resistor from flag to in. during shutdown (v on < v il ), the pulldown on the flag output is released in order to limit power dissipation. flag goes low when any of the following conditions occur: the die temperature exceeds the thermal-shutdown temperature limit of +150?. the device is in current limit for more than the fault- blanking period. ? in is below the uvlo threshold. for the max4915a/max4917a (autoretry versions), flag stays low until the overcurrent condition is removed (see figure 2). autoretry (max4915a/max4917a) when the forward or reverse current-limit threshold is exceeded, t blank timer begins counting (figure 2). the timer resets if the overcurrent condition disappears before t blank has elapsed. a retry time delay, t retry , is started immediately after t blank has elapsed, and during that time, the switch is latched off. at the end of t retry , the switch is turned on again. if the fault still exists, the cycle is repeated. if the fault has been removed, the switch stays on. the autoretry feature saves system power in the case of an overcurrent or short-circuit condition. during t blank , when the switch is on, the supply current is at the current limit. during t retry , when the switch is off, the current through the switch is zero. instead of observing the full load current, the switch sees the equivalent load current times duty cycle or i supply = i load ? t blank / (t blank + t retry ). with a typical t blank = 37ms and typical t retry = 555ms, the duty cycle is 6%, which results in a 94% power savings over the switch being on the entire time. the duty cycle is consistent across the process and devices. max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current _______________________________________________________________________________________ 7 on fault switch on/off supply current mode low x off shutdown high undervoltage lockout off shutdown high thermal off immediately (t blank period does not apply) latchoff off after t blank period has elapsed latchoff high current limit on during t blank period, off during t retry period for the max4915a/max4917a (autoretry versions); cycle repeats until fault is removed see the autoretry (max4915a/max4917a) section table 1. max4914b/max4915a/b/max4917a/b switch truth table switch status t blank off on t retry current limit short condition removed t blank t blank flag status figure 2. max4915a/max4917a autoretry fault-blanking diagram
max4914b/max4915a/b/max4917a/b latchoff (max4914b/max4915b/max4917b) when the forward or reverse current-limit threshold is exceeded, the t blank timer begins counting. the timer resets if the overcurrent condition disappears before t blank has elapsed. the switch is shut off if the over- current condition continues up to the end of the blank- ing time. reset the switch by either toggling on (figure 3a) or cycling the input voltage below uvlo, typically 2v (figure 3b). fault blanking all devices feature 14ms (min) fault blanking. fault blanking allows current-limit faults, including momentary short-circuit faults that occur when hot-swapping a capacitive load, and also ensures that no fault is issued during power-up. when a load transient causes the device to enter current limit, an internal counter starts. if the load-transient fault persists beyond the fault-blank- ing timeout, flag asserts low. load-transient faults less than t blank do not cause a flag output assertion. only current-limit faults are blanked. a thermal fault and input voltage drops below the uvlo threshold cause flag to assert immediately and not wait for the blanking time. thermal shutdown the max4914b/max4915a/b/max4917a/b have a ther- mal-shutdown feature to protect the devices from over- heating. the switch turns off and flag goes low immediately (no fault blanking) when the junction temper- ature exceeds +150?. the switch turns back on when the device temperature drops approximately by 15?. applications information input capacitor to limit the input-voltage drop during momentary output short-circuit conditions, connect a capacitor from in to gnd. a 0.1? ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce the voltage drop at the input and are recom- mended for lower voltage applications. output capacitance connect a 0.1? capacitor from out to gnd. this capacitor helps prevent inductive parasitics from pulling out negative during turn-off, thus preventing the devices from tripping erroneously. if the load capacitance is too large, the current may not have enough time to charge the capacitance and the device assumes that there is a faulty load condition. the maxi- mum capacitive load value that can be driven from out is obtained by the following formula: layout and thermal dissipation to optimize the switch response time to output short- circuit conditions, it is very important to keep all traces as short as possible to reduce the effect of undesirable parasitic inductance. place input and output capacitors as close as possible to the device (no more than 5mm). in and out pins must be connected with short traces to the power bus. during normal operation, the power dissipation is small and the package temperature change is minimal. if the output is continuously shorted to ground at the maximum c it v max fwd min blank min in < __ 100ma/200ma/300ma current-limit switches with low shutdown reverse current 8 _______________________________________________________________________________________ load current switch status on pin voltage t blank t blank off on uvlo load current switch status in pin voltage off on t blank t blank flag pin status flag pin status figure 3a figure 3b figure 3. max4914b/max4915b/max4917b latchoff fault blanking
max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current _______________________________________________________________________________________ 9 supply voltage, the operation of the switches with the autoretry option does not cause problems because the total power dissipated during the short is scaled by the duty cycle: where v in = 5.5v, i out = 450ma, t blank = 14ms, and t retry = 210ms. attention must be given to the max4914b/max4915b/ max4917b (latchoff versions), where the latchoff condi- tion must be manually reset by toggling on from high to low. if the latchoff time duration is not sufficiently high, it is possible for the device to reach the thermal- shutdown threshold and never be able to turn the device on until it cools down. p vi t tt mw max in max out max blank retry blank = + = __ 155 chip information process: bicmos 2.3v to 5.5v in out flag gnd on p to sdio port max4914b max4915a/b max4917a/b typical operating circuit gnd flag 15 out in max4915a/b max4917a/b sot23 top view 2 34 on in 1 on gnd n.c. max4914b max4915a/b max4917a/b dfn (2mm x 2mm) 2 3 6 5 4 out + flag + pin configurations
max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current 10 ______________________________________________________________________________________ package type package code document no. 6 ?fn l622-1 21-0164 5 sot23 u5-2 21-0057 package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages .
max4914b/max4915a/b/max4917a/b 100ma/200ma/300ma current-limit switches with low shutdown reverse current maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 11 2008 maxim integrated products is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 5/06 initial release 1 12/06 removed future product notes. added new v ih and v il ec table specs for the max4915 2 6/08 changed v ih and v il ec table specs for the max4917a 2

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