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_______________________________________________________________ maxim integrated products 1 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxims website at www.maxim-ic.com. MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output general description the MAX5977A/max5977b hot-swap controllers provide complete protection for systems with a 1v to 16v single- supply voltage. during the initial insertion, the hot-swap controllers limit the inrush current from damaging the board or from shorting out the backplane. when the input volt - age is above the undervoltage threshold and below the overvoltage threshold, a 5 f a current source powered from the internal 5v charge pump drives the gate of an external n-channel mosfet, providing a slow turn-on response. an internal current-sense amplifier in the ic monitors the current across an external shunt resistor, providing current sensing for wide input-sense voltage range. the devices provide two levels of overcurrent circuit-breaker protections: a fast-trip threshold for a fast turn-off and a lower slow-trip threshold for a delayed turn-off. exceeding either of the overcurrent circuit-breaker thresholds forces the device into fault mode where the external n-channel mosfet is disabled. the max5977 is available in two versions that provide a latched-off (MAX5977A) or autoretry (max5977b) output when the device is in fault mode. a calibration mode allows further calibration of the inte - grated transconductance amplifier for production testing of the final design. the devices are offered in a 20-pin, 4mm x 4mm, tqfn-ep package and are fully specified from -40 n c to +85 n c. features s 1% accurate current-sense amplifier output s hot-swap monitors operation from 1v to 16v s integrated charge pump fully enhances the external n-channel fet (v gate = v in + 5v) s variablespeed/bilevel k fault protection provides electronic circuit-breaker function s output latched off after fault condition (MAX5977A) s autoretry after fault condition (max5977b) s power-good indicator s calibration mode s small, 20-pin, 4mm x 4mm tqfn-ep package applications servers storage systems network switches and routers general hot-swap 19-5553; rev 1; 1/11 ordering information typical operating circuit variablespeed/bilevel is a trademark of maxim integrated products, inc. note: all devices are specified over the -40 n c to +85 n c oper - ating temperature range . +denotes a lead(pb)-free/rohs-compliant package. *ep = exposed pad. evaluation kit available MAX5977A max5977b calsense source csout fault pg cal pwr agnd scomp fcomp in sense gate gnd 2.7v to 16v calibration mode input r cal r scomp r fcomp r sense r gate +3.3v r csout c gate c l to load current-sense amplifier output fault output power-good output v in 1v to 16v part pin-package fault response MAX5977A etp+ 20 tqfn-ep* latched max5977b etp+ 20 tqfn-ep* autoretry
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 2 stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. pwr, sense, in, fcomp, scomp, gate, source, calsense to gnd ................... -0.3v to +28v pg, cal, bias, uv, ov, fault , csout to gnd .. -0.3v to +6v reg to gnd ............................................................ -0.3v to +4v gate to source ................................................... -0.3v to +6v in to fcomp, in to scomp, in to sense, in to calsense .................................................. -0.3v to +1v gnd to agnd ...................................................... -0.3v to +0.3v fault , pg current ........................................... -1ma to +50ma gate, source, gnd current ........................................ 750ma input/output current (all other pins) .................................. 20ma continuous power dissipation (t a = +70 n c) 20-pin tqfn, single-layer board (derate 16.9mw/ n c above +70 n c) .......................... 1355.9mw 20-pin tqfn, multilayer board (derate 25.6mw/ n c above +70 n c) .......................... 2051.3mw junction-to-ambient thermal resistance (note 1) b ja , single-layer board ........................................... +59 n c/w b ja , multilayer board ................................................ +39 n c/w junction-to-case thermal resistance (note 1) b jc , single-layer and multilayer board ...................... +6 n c/w operating temperature range .......................... -40 n c to +85 n c junction temperature ..................................................... +150 n c storage temperature range ............................ -65 n c to +150 n c lead temperature (soldering, 10s) ................................ +300 n c soldering temperature (reflow) ...................................... +260 n c absolute maximum ratings note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four- layer board. for detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial . electrical characteristics (v pwr = v in = 12v, r sense = 4m i , r fcomp = r scomp = 2k i , r gate = 1k i , c gate = 330nf, c reg = 1 f f, unless otherwise noted. typical values at v pwr = v in = 3.3v, t a = +25 n c, unless otherwise noted.) (note 2) parameter symbol conditions min typ max units operating voltage range v pwr 2.7 3.3 16 v undervoltage lockout v uvlo minimum rising voltage on pwr 2.69 v undervoltage-lockout hysteresis v uvlohys 100 mv supply current i pwr 0.734 4 ma internal ldo output voltage v reg 2.7v < v pwr < 16v, 0 to 5ma 2.49 2.6 v current-monitoring function in input range common-mode range 1 16 v scomp input range 1 16 v fcomp input range 1 16 v in input current 135 f a sense input current v in = v sense = 1v to 16v 6 f a circuit-breaker current (slow comparator) i scomp v scomp = 1v to 16v 24.0 25 26.0 f a circuit-breaker current (fast comparator) i fcomp v fcomp = 1v to 16v 48.1 50 51.4 f a slow current-limit threshold error v sense - v scomp = 50mv -2.0 +2.1 mv fast current-limit threshold error v sense - v fcomp = 100mv -2.2 +1.4 mv slow-comparator response time t scd 1mv overdrive 1 ms 50mv overdrive 130 f s fast-comparator response time t fsd 10mv overdrive, from overload condition, v pwr = 12v 200 ns
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 3 electrical characteristics (continued) (v pwr = v in = 12v, r sense = 4m i , r fcomp = r scomp = 2k i , r gate = 1k i , c gate = 330nf, c reg = 1 f f, unless otherwise noted. typical values at v pwr = v in = 3.3v, t a = +25 n c, unless otherwise noted.) (note 2) parameter symbol conditions min typ max units current-sense amplifier input common-mode range v in - v sense 1.5 v input offset error 0.1 mv transconductance gain g m 10mv p (v in - v sense ) p 50mv, -40 n c p t a p +85 n c 2457 2500 2537 f s 10mv p (v in - v sense ) p 50mv, 0 n c p t a p +25 n c 2467 2500 2532 combined gain and offset accuracy set v in - v sense = 50mv, measure i csout , v csout = 25mv (-40 n c p t a p +85 n c) 122.2 125 128 f a set v in - v sense = 50mv, measure i csout , v csout = 25mv (0 n p t a p +25 n c) 123.5 125 126.5 set v in - v sense = 10mv, measure i csout , v csout = 25mv (-40 n c p t a p +85 n c) 22.5 25 27.6 set v in - v sense = 10mv, measure i csout , v csout = 25mv (0 n p t a p +25 n c) 24.7 25 25.3 total full-scale error 2mv < (v in - v sense ) < 10mv (-40 n c p t a p +85 n c), % error = (i csout - (v in - v sense ) x 0.0025)/(10mv x 0.0025) -10 +10 % of 10mv full-scale output 2mv < (v in - v sense ) < 10mv (0 n c p t a p +25 n c), % error = (i csout - (v in - v sense ) x 0.0025)/(10mv x 0.0025) -1.6 +1.6 2mv < (v in - v sense ) < 25mv (-40 n c p t a p +85 n c), % error = (i csout - (v in - v sense ) x 0.0025)/(25mv x 0.0025) -4.1 +4.1 % of 25mv full-scale output 2mv < (v in - v sense ) < 25mv (0 n c p t a p +25 n c), % error = (i csout - (v in - v sense ) x 0.0025)/(25mv x 0.0025) -0.9 +0.9 2mv < (v in - v sense ) < 50mv (-40 n c p t a p +85 n c), % error = (i csout - (v in - v sense ) x 0.0025)/(50mv x 0.0025) -2.3 +2.3 % of 50mv full-scale output 2mv < (v in - v sense ) < 50mv (0 n c p t a p +25 n c), % error = (i csout - (v in - v sense ) x 0.0025)/(50mv x 0.0025) -0.9 +0.9 output common-mode range csout voltage range 0 2.5 v power-good pg delay t dpg 50 ms pg threshold rising v thrpg v in - v source falling 100 mv pg threshold hysteresis 100 mv
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 4 electrical characteristics (continued) (v pwr = v in = 12v, r sense = 4m i , r fcomp = r scomp = 2k i , r gate = 1k i , c gate = 330nf, c reg = 1 f f, unless otherwise noted. typical values at v pwr = v in = 3.3v, t a = +25 n c, unless otherwise noted.) (note 2) note 2: all devices 100% tested at t a = +25c. limits over temperature guaranteed by design. typical operating characteristics (v pwr = v in = 3.3v, t a = +25 n c, r fcomp = r scomp = 2k i , r gate = 1k i , c gate = 330nf, c reg = 1 f f, unless otherwise noted.) i pwr vs. v pwr max5977 toc01 v pwr (v) i pwr (ma) 15 10 5 0.64 0.65 0.66 0.67 0.68 0.69 0.70 0.71 0.72 0.73 0.63 0 20 v in - v sense vs. i csout v in - v sense (mv) i csout (a) 40 30 20 10 25 50 75 100 125 0 0 50 max5977 toc02 v in = v pwr = 12v r csout = 10k i transconductance vs. temperature max5977 toc03 temperature (c) gm (s) 75 50 25 0 -25 2460 2470 2480 2490 2500 2510 2520 2530 2540 2550 2450 -50 100 v in = v pwr = 12v v in - v sense = 10mv and 50mv parameter symbol conditions min typ max units charge pump (gate) charge-pump output voltage v ohgate relative to v source 4.5 5 5.5 v charge-pump output source current i gatepu v gate = v source = 0v 4 5 6 f a v in - v source < 100mv 8 10 12 charge-pump pulldown current i gatepd v gate = 2v, v source = 0 to 16v 500 ma outputs ( fault , pg) output voltage low v olfault / v olpg i sink = 3.2ma 0.4 v output leakage (open drain) i lkfault / i lkpg tested at 0v and 5.2v 1 f a uv/ov comparator inputs uv/ov threshold v uv/ovr uv, ov rising input voltage threshold 580 590 600 mv uv/ov threshold hysteresis v uv/ovhys uv, ov falling input hysteresis 4 % uv/ov input current i lkuv/ i lkov v uv = v ov = 0v and 5.5v -100 +100 na calibration mode cal low-voltage input v ilcal 0.4 v cal high-voltage input v ihcal 1.4 v cal input current i ihcal v cal = 2.5v, the cal input pulls low if left unconnected 20 f a calsense input current 300 f a fault response retry timeout period t retry max5977b 175 ms
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 5 typical operating characteristics (continued) (v pwr = v in = 3.3v, t a = +25 n c, r fcomp = r scomp = 2k i , r gate = 1k i , c gate = 330nf, c reg = 1 f f, unless otherwise noted.) slow-comparator response time (50mv overdrive) max5997 toc08 v in - v sense 50mv /div v gate 5v /div v source 2v /div 0v 0v 0v 100s /div r sense = 4m i current output error (%) -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1.0 -1.0 current output error vs. v in - v sense max5977 toc06 v in - v sense (mv) 10 20 30 40 0 50 v in = v pwr = 12v r csout = 10ki i _comp vs. temperature max5977 toc04 i _comp (a) 5 10 15 20 25 30 35 40 45 50 55 0 temperature (c) 75 50 25 0 -25 -50 100 i fcomp i scomp slow-comparator response time (50mv overdrive) max5977 toc09 v in - v sense 100mv /div v gate 5v /div v source 2v /div 0v 0v 0v 20s /div r sense = 4m i t scd vs. overdrive voltage max5977 toc07 overdrive voltage (mv) tscd (s) 45 40 35 30 25 20 15 10 5 1000 100 0 50 v gate vs. v in max5977 toc05 v in (v) v gate (v) 15 10 5 4.80 4.85 4.90 4.95 5.00 5.05 5.10 5.15 5.20 5.25 4.75 0 20
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 6 typical operating characteristics (continued) (v pwr = v in = 3.3v, t a = +25 n c, r fcomp = r scomp = 2k i , r gate = 1k i , c gate = 330nf, c reg = 1 f f, unless otherwise noted.) i csout small-signal pulse response max5977 toc12 v in - v sense 5mv /div v csout 100mv /div 0v 0v 20s /div r csout = 10k i i csout large-signal pulse response max5977 toc13 v in - v sense 20mv /div v csout 500mv /div 0v 0v 20s /div r csout = 10k i fast-comparator response time (10mv overdrive) max5977 toc10 v in - v sense 100mv /div v gate 5v /div v source 2v /div 0v 0v 0v 2s /div r sense = 4m i t fsd v fcomp fault retry time (max5977b only) max5977 toc11 v in - v sense 50mv /div v gate 5v /div v source 2v /div 0v 0v 0v 40ms /div r sense = 4m i
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 7 pin description pin configuration 19 20 18 17 7 6 8 pwr ov 9 reg gate csout pg source 1 ep* *connect to agnd. 2 i.c. 4 5 15 14 12 11 i.c. bias sense in scomp fcomp MAX5977A max5977b agnd gnd 3 13 cal 16 10 calsense fault thin qfn top view uv pin name function 1 reg regulator output. bypass reg with a 1 f f capacitor. 2 pwr power-supply input. bypass pwr with a 0.1 f f or higher value capacitor. 3 agnd analog ground 4 uv active-high precision turn-on input. uv is used to turn on/off the output and set the input undervoltage lockout threshold. 5 ov active-low precision turn-on input. ov is used to turn on/off the output and set the input overvoltage lockout threshold. 6 fcomp fast circuit-breaker comparator input. connect fcomp to in with a resistor to set the fast-trip circuit- breaker threshold. 7 scomp slow circuit-breaker comparator input. connect scomp to in with a resistor to set the slow-trip circuit-breaker threshold. 8 in hot-swap voltage-monitoring input 9 sense current-sense voltage input. the voltage across an external sense resistor between in and sense is used to measure the channel current. 10 calsense calibration voltage input 11 pg power-good, active-high open-drain output 12 csout transconductance current-sense amplifier output. the output current of csout is the product of the voltage measured between sense and in and the transconductance gain (2500 f s typ). 13 gnd ground 14 gate gate-driver output. connect gate to the gate of the external n-channel mosfet switch. 15 source mosfet source voltage input. connect source to the source of the external n-channel mosfet. 16 fault active-low, open-drain fault output. when an overcurrent occurs, fault goes low. 17 cal calibration mode select input 18, 19 i.c. internally connected. connect to ground. 20 bias bias input. connect bias to reg. ep exposed pad. connect to agnd.
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 8 functional diagram mux 25a slow cb 50a cs amplifier overdrive delay 5a 10a 10a csout gate source pg fault gnd agnd in sense calsense cal scomp fcomp uv ov pwr reg bias 50ms pg timer s 1 0 MAX5977A max5977b od delay/ cb timer 2mhz oscillator in in - 100mv gate pulldown charge pump fast cb ovp por s r autoretry enable max5977b only 0.6v 0.59v 0.59v ref/ bias ldo uvlo uvp retry timer q
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 9 detailed description the hot-swap controllers provide electronic circuit- breaker protection and precision current sensing for a single-supply voltage from 1v to 16v. programmable undervoltage and overvoltage protection qualifies the supply voltage prior to enhancing the external n-channel mosfet with the internal gate driver. the variablespeed/bilevel fault levels are program - mable with external resistors providing both slow and fast circuit-breaker protection. the transconductance current-sense amplifier provides continuous current monitoring with high accuracy and features a calibration mode for production testing. programmable undervoltage and overvoltage protection the programmable undervoltage and overvoltage pro - tection enables the hot-swap channel when the voltage at uv is above 590mv, and the voltage at ov is below 590mv. after the hot-swap channel is enabled, the hot- swap channel is disabled if the voltage at ov exceeds the 590mv threshold. gate driver an integrated 5v charge pump supplies the gate-driver output of the devices, allowing it to fully enhance the external n-channel mosfet during normal operation. the 5 f a (typ) current source at gate slowly charges the gate-to-source capacitance of the external n-channel mosfet to 5v (typ) relative to the source input. programmable fast-trip and slow-trip overcurrent circuit breaker during normal operation with the channel turned on, two analog comparators are used to detect an overcurrent condition by comparing the voltage across the external sense resistor (r sense ) connected between in and sense to the voltages across the respective external overcurrent circuit-breaker threshold set resistors con - nected from in to fcomp and scomp. precision cur - rent sources at the fcomp and scomp inputs establish these thresholds. if the voltage across the sense resistor is less than the fast-trip and slow-trip overcurrent circuit-breaker thresholds, the gate output remains high. if either of the thresholds is exceeded due to an overcurrent condi - tion, the gate output is pulled down to source by a 500ma current sink, and the fault and pg outputs are asserted low. if the sense voltage rises above the fast circuit-breaker threshold, the devices turn off the external mosfet in 200ns (typ). if the sense voltage rises above the slow circuit-breaker threshold, the internal timer begins counting. if the sense voltage remains above the slow circuit-breaker threshold until the timer expires, the devices turn off the external mosfet. the slow circuit-breaker timer occurs in 1ms (typ) when the slow-current comparator threshold is over - driven by 1mv and 130 f s (typ) when overdriven by 50mv. current-sense amplifier the integrated transconductance current-sense ampli - fier features high accuracy with less than 1% error over its 10mv to 50mv input range, and provides continu - ous current monitoring into the load. the sense voltage of the external sense resistor connected between in and sense is multiplied by the transconductance gain (2500 f s typ) of the amplifier with the resulting current output at csout. calibration mode the devices' calibration mode bypasses the trans - conductance amplifier inputs to measure the voltage between in and calsense when the calibration mode select input cal is high. this enables the user to apply a known calibration voltage across the current-sense amplifier input. this voltage corresponds to a full scale for the actual sense voltage. during the calibration mode, the current-sense amplifier only measures the calibration voltage between in and calsense. the calibration mode is completely asynchronous and does not disrupt the circuit-breaker threshold compari - son. once in calibration mode there is no expiration until the cal input is brought low. this allows the calibration to occur at multiple voltages by applying various calibra - tion voltages during the calibration mode. fault output the fault output goes low when a slow or fast com - parator current-limit fault has occurred. on the MAX5977A, the device is latched in fault mode until it is reset either by initiating a full power-on reset or pulling uv below 590mv. on the max5977b, the device reenables the hot-swap output after the autoretry timer has expired in 175ms and fault is pulled high if the fault condition has been removed and startup conditions are met.
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 10 power-good output the open-drain, active-high output pg indicates the power-good status of the output. once the input voltage satisfies the undervoltage and overvoltage requirements for startup and v in - v source is less than 100mv and the v gate - v source > 4v, the pg timer is started. at the expiration of the 50ms pg timer, pg is asserted high. applications information undervoltage and overvoltage protection the undervoltage and overvoltage protection is pro - grammed with a voltage-divider formed by three resis - tors (r1, r2, and r3) placed in series. the resistor values should be selected such that the series current, i s , is greater than 5 f a. the resistor values are then cal - culated using the following equations with the overvolt - age threshold (v ovr ), undervoltage threshold (v uvr ), and the overvoltage hysteresis (v ovhys ) obtained from the electrical characteristics table: ( ) ( ) ovr s in,ov uvr in,uv ovr ovhys in,uv uvr v r3 i v v r2 1 r3 v v v v r1 1 r2 r3 v ? ? = ? ? = ? ? ? ? ? ? ? ? = ? + ? ? ? ? where v in,uv and v in,ov are the desired undervoltage and overvoltage thresholds for the hot-swap input volt - age in. programmable slow and fast current limit the slow and fast current-limit thresholds are pro - grammed by connecting resistors between the high side of r sense to scomp and fcomp. the current-limit thresholds are set using the following equations: sense, scomp sense scomp i r r 25 a = and: sense, fcomp sense fcomp i r r 50 a = where i sense,_comp is the desired circuit-breaker cur - rent limit for the slow or fast current limit. startup sequence when all conditions for channel turn-on are met, the external n-channel mosfet switch is fully enhanced with a typical gate-to-source voltage of 5v to ensure a low drain-to-source resistance. the charge pump at gate sources 5 f a to control the output voltage turn-on voltage slew rate. an external capacitor must be added from gate to ground to further reduce the voltage slew rate. placing a 1k i resistor in series with this capaci - tance prevents the added capacitance from increasing the gate turn-off time. total inrush current is the load cur - rent summed with the product of the gate voltage slew rate dv/dt and the load capacitance. to determine the output dv/dt during startup, divide the gate pullup current i gatepu by the gate to ground capacitance. the voltage at the source of the external mosfet follows the gate voltage, so the load dv/dt is the same as the gate dv/dt. inrush current is the product of the dv/dt and the load capacitance. the time to start up t su is the hot-swap voltage v in divided by the output dv/dt. be sure to choose an external mosfet that can handle the power dissipated during startup. the inrush cur - rent is roughly constant during startup and the voltage drop across the mosfet (drain to source) decreases linearly as the load capacitance charges. the resulting power dissipation is therefore roughly equivalent to a single pulse of magnitude (v in x inrush current)/2 and duration t su . refer to the thermal resistance charts in the mosfet data sheet to determine the junction tem - perature rise during startup, and ensure that this does not exceed the maximum junction temperature for worst- case ambient conditions. transconductance current-sense amplifier the current-sense resistor, r sense , must be connected between in and sense to sense the average current into the load. the voltage drop across r sense should be less than or equal to the slow current-limit threshold; therefore, r sense should be selected based on the fol - lowing equation: sense sense,fs scomp r i v where i sense , fs is the full-scale current into the load and v scomp is the slow current-limit threshold. a kelvin sense connection should be used to connect r sense to in and sense.
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 11 an output resistor, r csout , must be connected between the transconductance current-sense amplifier output csout and agnd. the transconductance g m , of the amplifier is typically 2500 f s: csout m sense, fs r g v 2.5v n-channel mosfet selection select the external n-channel mosfet according to the applications current level. the mosfets on-resistance (r ds(on) ) should be chosen low enough to have a mini - mum voltage drop at full load to limit the mosfet power dissipation. high r ds(on) causes output ripple if there is a pulsating load. determine the device power rating to accommodate a short-circuit condition on the board at startup and when the device is in automatic-retry mode (see the mosfet thermal considerations section). the MAX5977As fault latch allows the use of mosfets with lower power ratings. a mosfet typically withstands single-shot pulses with higher dissipation than the speci - fied package rating. mosfet thermal considerations during normal operation, the external mosfets dis - sipate little power. the mosfet r ds(on) is low when the mosfet is fully enhanced. the power dissipated in normal operation is p d = i load 2 x r ds(on). the most power dissipation occurs during the turn-on and turn-off transients when the mosfets are in their linear regions. take into consideration the worst-case scenario of a continuous short-circuit fault; consider these two cases: 1) the single turn-on with the device latched after a fault (MAX5977A). 2) the continuous automatic retry after a fault (max5977b). mosfet manufacturers typically include the package thermal resistance from junction to ambient (r b ja ) and thermal resistance from junction to case (r b jc ), which determine the startup time and the retry duty cycle (d = t su /(t su + t retry )). calculate the required transient thermal resistance with the following equation: jmax a ja(max) in inrush t t z v i layout considerations to take full advantage of the switch response time to an output fault condition, it is important to keep all traces as short as possible and to maximize the high-current trace dimensions to reduce the effect of undesirable parasitic resistance and inductance. place the devices close to the cards connector, and a 0.01 f f capacitor to gnd should be placed as close as possible to v in . use a ground plane to minimize impedance and inductance. minimize the current-sense resistor trace length and ensure accurate current sensing with kelvin connec - tions. when the output is short circuited, the voltage drop across the external mosfet becomes large. hence, the power dissipation across the switch increases, as does the die temperature. an efficient way to achieve good power dissipation on a surface-mount package is to lay out two copper pads directly under the mosfet pack - age on both sides of the board. connect the two pads to the ground plane through vias, and use enlarged copper mounting pads on the top side of the board. related parts part description max5970 0 to 16v, dual hot-swap controller with a 10-bit current and voltage monitor and four led drivers max5978 0 to 16v, single hot-swap controller with a 10-bit current and voltage monitor plus four led drivers
MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output 12 typical application circuit chip information process: bicmos package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. package type package code outline no. land pattern no. 20 tqfn-ep t2044+3 21-0139 90-0037 MAX5977A max5977b uv source csout fault pg cal ov calsense pwr bias reg agnd scomp fcomp 125a precision current source max6033aaut25 in sense gate gnd 2.7v to 16v *optional r scomp r fcomp r sense r gate +3.3v r csout max1393 adc c gate c l to load i/o i/o i/o p v in 1v to 16v 49.9i r2 r3 r1 outf 0.1f 5.1ki 4.99ki 10ki 10ki 1f 1f 0.1f outs gnd in
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit 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 13 ? 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. MAX5977A/max5977b 1v to 16v, single-channel, hot-swap controllers with precision current-sensing output revision history revision number revision date description pages changed 0 9/10 initial release 1 1/11 changed current-sense amplifier specifications in electrical characteristics table 3

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