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general description the max5913a/max5914a are quadruple hot-swap con- trollers. the max5913a/max5914a independently con- trol four external n-channel switches to hot-swap system loads from a single v cc supply line. the devices allow the safe insertion and removal of power devices from live network ports. the operating supply voltage range is between +35v and +72v. the devices are intended for applications in power-over-media-dependent interface (mdi), but are not limited to such usage. the max5913a/max5914a feature an internal under- voltage lockout (uvlo) function that prevents the fet from turning on, if v cc does not exceed the default value of +32v. the devices also feature a +12v relay driver with 100ma current drive capable of driving low- voltage +3.3v relays. the max5913a features an active-low relay driver that sinks current when the relay output is enabled. the max5914a features an active- high relay driver output that sources 1ma to drive an external fet relay driver when the relay output is enabled. control circuitry ensures the relays and the fets are off until v cc reaches the uvlo threshold. the max5913a/max5914a use an external sense resistor to enable all the internal current-sense functions. the max5913a/max5914a feature a programmable analog current-limit circuit. if the switch remains in current limit for more than a programmable time, the n-channel fet latches off and the supply can be restarted either by autoretry or by an external command after the preset off- time has elapsed. the max5913a/max5914a are available in a 44-pin mqfp package and are specified for the extended -40? to +85? operating temperature range. applications power-over-lan power-over-mdi ip phone switches/routers telecom line cards network switches/routers midspan power-over-mdi features wide operating input voltage range: +35v to +72v ieee ? 802.3af compatible four independent power switch controllers open-circuit detector on-board charge pumps to drive external n-channel fets current sense with external resistor foldback current limiting +32v input undervoltage lockout on-chip +12v, 100ma voltage relay drivers max5913a/max5914a +48v quad hot-swap controllers for power-over-lan ________________________________________________________________ maxim integrated products 1 rtryen statout ocen dgnd v cc csp1 drain1 gate1 out1 csp2 drain2 fault stat1 stat2 stat3 stat4 csp4 drain4 out4 gate4 csp3 drain3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28 27 26 25 24 23 out3 gate3 v rly rlyd3 rlyd4 dgnd rlyd1 rlyd2 agnd out2 gate2 v dd rtim on4 rlyon4 on3 rlyon3 on2 rlyon2 on1 rlyon1 dc mqfp top view + max5913a max5914a pin configuration ordering information 19-3302; rev 1; 1/11 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. part temp range pin-package max5913a emh+ -40 c to +85 c 44 mqfp MAX5913AEMH+t -40 c to +85 c 44 mqfp max5914a emh+ -40 c to +85 c 44 mqfp max5914aemh+t -40 c to +85 c 44 mqfp typical operating circuit appears at end of data sheet. + denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. ieee is a registered service mark of the institute of electrical and electronics engineers, inc.
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = v csp _ = +48v, v agnd = v dgnd = 0v, v dd = +3.3v, v rly = +12v, t a = -40? to +85?, unless otherwise noted. typical val- ues are at v cc = v csp _ = +48v and t a = +25?.) 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. v cc to agnd or dgnd..........................................-0.6v to +76v drain_, out_ to agnd or dgnd .............-0.6v to (v cc +0.3v) csp_ to v cc ..........................................................-0.3v to +0.3v gate_ to out_ .....................................................-0.3v to +13v v rly to dgnd ........................................................-0.3v to +18v rlyd_ to dgnd........................................-0.3v to (v rly + 0.3v) on_, rlyon_, ocen, rtryen, statout, dc to dgnd........................................................-0.3v to +12v fault to dgnd .....................................................-0.3v to +12v stat_, rtim to dgnd ...............................-0.3v to (v dd + 0.3v) v dd to dgnd ...........................................................-0.3v to +7v dgnd to agnd...........................................................-5v to +5v current into rlyd_ .........................................-50ma to +150ma current into any other pin................................................?0ma continuous power dissipation (t a = +70?) 44-pin mqfp (derate 12.7mw/? above +70?)......... 1.013w operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) ................................ +300? parameter symbol conditions min typ max units power supplies analog supply voltage v cc measured with respect to agnd 35 72 v t a = 0? to +85? 2.7 4 analog supply current i s v cc = v csp _ = 72v i s = i cc + i csp t a = -40? to 0? 5 ma digital supply voltage v dd measured with respect to dgnd 2.5 3.3 3.7 v digital supply current i dd all logic outputs high, rtim unconnected 1.1 3 ma analog supply undervoltage lockout v uvlo v cc rising, circuits enabled 29 32 35 v uvlo hysteresis v uvlo , h 3v uvlo deglitch delay t d , uvlo v on = 3.3v, v rlyon = 3.3v (figure 1) 12.8 25.6 38.4 ms relay driver supply v rly measured with respect to dgnd 14 v ground potential difference v gg voltage difference between dgnd and agnd -4 4 v feedback input and current sense out sense bias current i fp v out _ = v cc 2a initial feedback voltage v fb _ s voltage under which the foldback circuit starts reducing the current-limit value (note 1) 18 v current-limit threshold voltage v sc maximum ? v across r sense at v out > v fb _ s 125 142.5 160 mv foldback voltage v flbk maximum ? v across r sense at v out = 0v 42 48 54 mv fast discharge threshold v fc 360 420 480 mv switch-on threshold v swon maximum v cc - v out at which the switch is defined as fully on, v out increasing 1.2 1.5 1.8 v switch-on comparator hysteresis v swon _ h 160 mv mosfet drivers v gate - v cc when switch is fully on 0 c to +85 c 7911 gate overdrive voltage v gs t a = -40 c to 0 c7912 v gate charge current i gate v gate = 0v 7 10 13 a
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan _______________________________________________________________________________________ 3 electrical characteristics (continued) (v cc = v csp _ = +48v, v agnd = v dgnd = 0v, v dd = +3.3v, v rly = +12v, t a = -40? to +85?, unless otherwise noted. typical val- ues are at v cc = v csp _ = +48v and t a = +25?.) note 1: see typical operating characteristics for current-limit foldback, and refer to current sensing and regulation section. note 2: the resistor at rtim can range from 2k ? to 40k ? . note 3: limits are 100% tested at t a = +25? and t a = +85?. limits at -40? are guaranteed by design and characterization, but are not production tested. parameter symbol conditions min typ max units during current regulation 8 a v on = 0v 1 ma gate discharge current i gate , dis (v csp _ - v drain _) > v fc 15 ma source-gate clamp voltage v sgz v out _ = 0v, force 30ma into gate_, measure v gate - v out 14 16.5 18 v open-circuit detector open-circuit current-threshold voltage v oc minimum ? v across r sense to detect an open circuit 1.5 3 4.5 mv delay to open-circuit detect t oc (figure 2) 450 900 1350 ms deglitch delay t lpfd (v csp _ - v drain __ ) < v oc (figure 2) 106 204 302 ms relay drivers maximum low voltage (max5913a) v rlow rlyon = high, i rlyd _ = 100ma 0.5 v relay pullup current (max5914a) i rplup rlyon = high, v rlyd _ = 0v 0.3 0.8 1.3 ma clamp diode voltage v rclamp force 100ma into rlyd, measure v rlyd - v rly 2v relay output leakage rlyon_ = low, v rlyd _ = v rly 1a timing r rtim = 2k ? 4.8 6.4 8.0 r rtim = 40k ? 76 128 180 short-circuit and startup timer (note 2) t o on time for continuous overcurrent conditions r rtim = 3.2 6.4 9.6 ms dc = logic low 1 dc = logic high 2 auto-retry duty cycle dc = unconnected 4 % port turn-on delay t on _ del v on = 3.3v (figure 3) 12.8 25.6 38.4 ms relay turn-off delay t off _ del after rlyon_ goes low (figure 3) 1.6 3.2 4.8 ms digital interface dc pin input-voltage high v ih _ dc 2.5v v dd 3.7v 0.7 x v dd v dc pin input-voltage low v il _ dc 2.5v v dd 3.7v 0.3 x v dd v dc pin input impedance r in _ dc 1k ? logic input high v ih 2.5v v dd 3.7v 0.8 x v dd v logic input low v il 2.5v v dd 3.7v 0.3 x v dd v logic input leakage 1a fault output-voltage low v fl i sink = 4ma 0.4 v fault high input leakage 1a logic output-voltage high v oh stat_ outputs sourcing 0.5ma v dd - 0.4 mv logic output-voltage low v ol stat_ outputs sinking 0.5ma 0.4 v
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 4 _______________________________________________________________________________________ typical operating characteristics (v csp _ = v cc = +48v, v dd = +3.3v, v rly = +12v, v agnd = v dgnd = 0v, rtim = open, t a = +25?, unless otherwise specified.) 2.0 2.4 3.2 2.8 3.6 4.0 33 45 48 39 42 36 54 57 51 60 63 66 69 72 supply current vs. input voltage max5913a/14a toc01 input voltage (v) supply current (ma) t a = +85 c t a = +25 c t a = -40 c 3.8 3.4 3.0 2.6 2.2 3.5 3.4 3.3 3.2 3.1 3.0 2.9 2.8 2.7 2.6 2.5 -40 10 -15 35 60 85 supply current vs. temperature max5913a/14a toc02 temperature ( c) supply current (ma) v cc = +36v v cc = +48v v cc = +57v v cc = +72v 27 28 30 29 31 32 -40 10 -15 35 60 85 undervoltage lockout vs. temperature max5913a/14a toc03 temperature ( c) uvlo (v) v cc rising v cc falling 9.50 9.25 9.00 8.75 8.50 33 36 39 54 57 60 42 45 48 51 63 69 66 72 gate overdrive voltage vs. input voltage max5913a/14a toc04 input voltage (v) gate overdrive (v) t a = -40 c t a = +85 c t a = +25 c 8.0 8.5 9.0 9.5 gate overdrive voltage vs. temperature max5913a/14a toc05 temperature ( c) gate overdrive (v) -40 35 60 -15 10 85 v cc = +57v v cc = +72v v cc = +48v v cc = +36v startup waveforms max5913a/14a toc06 0 a b c d 0 0 0 4ms/div a: v on = v rlyon , 5v/div b: v rlyd , 20v/div c: v out , 20v/div d: v gate , 20v/div turn-off waveforms max5913a/14a toc07 0 a b c d 0 0 0 4ms/div a: v on = v rlyon , 5v/div b: v rlyd , 20v/div c: v out , 20v/div d: v gate , 20v/div gate turn-off waveform max5913a/14a toc08 0 a b 0 c 0 d 0 10ms/div a: v rlyd , 20v/div b: v rlyon , 5v/div c: v on , 5v/div d: v gate , 20v/div uvlo turn-on delay max5913a/14a toc09 0 a b 0 c 0 d 0 4ms/div rlyon = v dd a: v on , 5v/div b: v cc , 10v/div c: v out , 50v/div d: v gate , 50v/div
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan _______________________________________________________________________________________ 5 turn-on into capacitive load (c l = 0.47 f) max5913a/14a toc10 0 a b 0 c 0 d 0 400 s/div rlyon = v dd a: v on , 5v/div b: v gate , 20v/div c: v out , 20v/div d: i out , 100ma/div turn-on into capacitive load (c l = 47 f) max5913a/14a toc11 0 a b 0 c 0 d 0 1ms/ div rlyon = v dd , r rtim = 2k ? a: v on , 5v/div b: v gate , 20v/div c: v out , 20v/div d: i out , 200ma/div turn-on into capacitive load (c l = 470 f) max5913a/14a toc12 0 a b 0 c 0 d 0 10ms/div rlyon = v dd , r rtim = 40k ? a: v on , 5v/ div b: v gate , 20v/ div c: v out , 20v/ div d: i out , 200ma/ div current-limit foldback (v cc = +36v) max5913a/14a toc13 0 a b 0 c 0 10ms/div rlyon = v dd , r l = 100 ? , r rtim = 40k ? , c load = 470 f a: v on , 5v/div b: v out , 10v/div c: i out , 200ma/div current-limit foldback (v cc = +48v) max5913a/14a toc14 0 a b 0 c 0 10ms/div rlyon = v dd , r l = 139 ? , r rtim = 40k ? , c load = 470 f a: v on , 5v/div b: v out , 10v/div c: i out , 200ma/div current-limit foldback (v cc = +57v) max5913a/14a toc15 0 a b 0 c 0 10ms/div rlyon = v dd , r l = 162 ? , r rtim = 40k ? , c load = 470 f a: v on , 5v/div b: v out , 10v/div c: i out , 200ma/div typical operating characteristics (continued) (v csp _ = v cc = +48v, v dd = +3.3v, v rly = +12v, v agnd = v dgnd = 0v, rtim = open, t a = +25?, unless otherwise specified.)
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 6 _______________________________________________________________________________________ typical operating characteristics (continued) (v csp _ = v cc = +48v, v dd = +3.3v, v rly = +12v, v agnd = v dgnd = 0v, rtim = open, t a = +25?, unless otherwise specified.) current-limit foldback (v cc = +72v) max5913a/14a toc16 0 a b 0 c 0 10ms/div rlyon = v dd , r l = 200 ?, r rtim = 40k ? a: v on , 5v/div b: v out , 10v/div c: i out , 200ma/div current-limit foldback (v cc = +57v) max5913a/14a toc17 0 0 a b c 0 10ms/div rlyon = v dd , r l = open, r rtim = 40k ? , c load = 470 f a: v on , 5v/div b: v out , 10v/div c. i out , 200ma/div overcurrent delay (expanded time scale) max5913a/14a toc20 0 a b 0 1ms/div rtryen = v dd , rlyon = on = v dd , dc = don't care, r rtim = 2k ? , r l = 100 ? a: v gate , 20v/div b: i out , 200ma/div overcurrent delay max5913a/14a toc19 0 a b 0 20ms/div rtryen = v dd , rlyon = on = v dd , dc = 4%, r rtim = 2k ? , r l = 100 ? a: v gate , 20v/div b: i out , 200ma/div current-limit foldback (v cc = +72v) max5913a/14a toc18 0 a c 0 20ms/div rlyon = v dd , r l = open, r rtim = 40k ? , c load = 470 f a: v on , 5v/div b: v out , 20v/div c: i out , 200ma/div b 0 short-circuit response (v cc = +48v) max5913a/14a toc21 0 a b 0 1ms/div on = rlyon = v dd , r l = 1 ? , r rtim = 2k ? a: i out , 200ma/div b: v gate , 20v/div
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan _______________________________________________________________________________________ 7 typical operating characteristics (continued) (v csp _ = v cc = +48v, v dd = +3.3v, v rly = +12v, v agnd = v dgnd = 0v, rtim = open, t a = +25?, unless otherwise specified.) short-circuit response (v cc = +48v expanded time scale) max5913a/14a toc22 0 a b 0 40 s/div on = rlyon = v dd , r l = 1 ? , r rtim = 2k ? a: i out , 200ma/div b: v gate , 20v/div peak short-circuit response (v cc = +48v expanded time scale) max5913a/14a toc23 0 a b 0 1 s/div on = rlyon = v dd , r l = 1 ? , r rtim = 2k ? a: i out , 5a/div b: v gate , 20v/div short-circuit response (v cc = +57v) max5913a/14a toc24 0 a b 0 1ms/div on = rlyon = v dd a: i out , 200ma/div b: v gate , 20v/div peak short-circuit response time (v cc = +57v, expanded time scale) max5913a/14a toc26 0 a b 0 1 s/div on = rlyon = v dd , r l = 1 ? , r rtim = 2k ? a: i out , 5a/div b: v gate , 20v/div short-circuit response (v cc = +72v) max5913a/14a toc27 a b 0 0 1ms/div on = rlyon = v dd a: i out , 200ma/div b: v gate , 50v/div short-circuit response (v cc = +57v, expanded time scale) max5913a/14a toc25 0 a b 0 40 s/div on = rlyon = v dd , r l = 1 ? , r rtim = 2k ? a: i out , 200ma/div b: v gate , 20v/div
t o vs r rtim max5913a/14a toc33 r rtim (k ? ) t o (ms) 35 30 25 20 15 10 5 20 40 60 80 100 120 0 040 t a = -40 c, +25 c, +85 c max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 8 _______________________________________________________________________________________ typical operating characteristics (continued) (v csp _ = v cc = +48v, v dd = +3.3v, v rly = +12v, v agnd = v dgnd = 0v, rtim = open, t a = +25?, unless otherwise specified.) short-circuit response (v cc = +72v, expanded time scale) max5913a/14a toc28 a b 0 0 40 s/div on = rlyon = v dd , r l = 1 ? , r rtim = 2k ? a: i out , 200ma/div b: v gate , 50v/div peak short-circuit response time (v cc = +72v, expanded time scale) max5913a/14a toc29 a b 0 0 1 s/div on = rlyon = v dd , r l = 1 ? , r rtim = 2k ? a: i out , 5a/div b: v gate , 50v/div open-circuit threshold vs. input voltage max5913a/14a toc30 input voltage (v) threshold voltage (mv) 69 66 60 63 42 45 48 51 54 57 36 39 2.2 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 4.0 2.0 33 72 t a = +25 c t a = +85 c t a = -40 c 4.0 3.5 3.0 2.5 2.0 -40 10 -15 35 60 85 open-circuit threshold vs. temperature max5913a/14a toc31 temperature ( c) threshold voltage (mv) v cc = +36v, +48v, +57v, and +72v open-circuit glitch delay max5913a/14a toc32 a b 0 0 40ms/div on = rlyon = v dd , statout = low a: i out , 20ma/div b: v stat , 5v/div c: v gate , 20v/div 0 c
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan _______________________________________________________________________________________ 9 typical operating characteristics (continued) (v csp _ = v cc = +48v, v dd = +3.3v, v rly = +12v, v agnd = v dgnd = 0v, rtim = open, t a = +25?, unless otherwise specified.) t o vs. input voltage max5913a/14a toc34 v dd (v) t o (ms) 3.6 3.3 3.0 2.7 2.4 2.1 0 25 50 75 100 125 1.8 r rtim = 40k ? r rtim = open r rtim = 2k ? retry duty cycle vs. dc max5913a/14a toc35 0 a b 0 c 0 100ms/div v gate = 20v/div, r rtim = 2k ? a: v gate , 20v/div, dc = unconnected (4%) b: v gate , 20v/div, dc = v dd (2%) c: v gate , 20v/div, dc = gnd (1%) channel-to-channel crosstalk max5913a/14a toc36 20 s/div v test 5v/div v out 10mv/div see figure 4 for test circuit pin description pin name function 1 fault active-low fault output. fault is an open-drain output that goes low when a fault is detected on any of the four channels. fault is low when an oc (open circuit) is detected, or when the max5913a/max5914a is in auto-retry caused by an overcurrent condition. when rtryen is low, and the channel switch is latched off due to an overcurrent condition, fault remains low until on_ is driven low. 2, 3, 4, 5 stat1, stat2, stat3, stat4 status outputs. stat_ are push-pull outputs. depending on the statout pin status, stat_ flags either the power-ok_ or port-oc_ status. power-ok_ high indicates: a) on_ input is high. b) the switch port is fully on and startup is completed (v csp _ - v out _) < v swon . c) input voltage is above v uvlo . d) switch is not in current limit. power-ok_ low indicates a fault with any of the above conditions. port-oc_ output high indicates that the switch is latched off because the switch current is less than the open- current threshold, port-oc is low otherwise. 6, 10, 24, 28 csp4, csp3, csp2, csp1 c ur r ent- s ense p osi ti ve inp ut. c onnect to v cc and p l ace a cur r ent- sense r esi stor fr om c s p _ to d rain _. u se a kel vi n sense tr ace fr om a cur r ent- sense r esi stor to c s p _ ( see fi g ur e 7) . 7, 11, 23, 27 drain4, drain3, drain2, drain1 mosfet drain current-sense negative input. connect to drain of power mosfet and connect a current-sense resistor from csp_ to drain_. use kelvin sense trace from current-sense resistor to drain_ (see figure 7).
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 10 ______________________________________________________________________________________ pin description (continued) pin name function 8, 12, 21, 25 out4, out3, out2, out1 mosfet source output voltage sense. connect to a power mosfet source through a 100 ? series resistor. 9, 13, 22, 26 gate4, gate3, gate2, gate1 mosfet gate driver output. the max5913a/max5914a regulate the gate-drive voltage to (v cc + 9v) to fully turn on the power n-channel mosfet. gate_ sources 10? during startup to slowly turn on the mosfet switch. gate_ sinks 1ma to turn off the mosfet switch. 14 v rly relay supply-voltage input. referenced to dgnd. 15, 16, 18, 19 rlyd3, rlyd4, rlyd1, rlyd2 relay-drive output. for the max5913a, rlyd_ sinks 100ma when the relay driver is enabled. for the max5914a, rlyd_ sources 1ma when the relay driver is enabled. 17, 30 dgnd digital ground. all logic voltages are referred to dgnd. the voltage difference between dgnd and agnd can be up to 4v. 20 agnd analog ground. all analog voltages are referred to agnd. 29 v cc analog power supply. connect v cc to +35v to +72v power supply. uvlo circuitry turns off the mosfet switch and relay for v cc < v uvlo . bypass v cc to agnd with a 1? capacitor. 31 ocen open-circuit detector enable input. drive ocen high to enable open-circuit detector, or drive low to disable. when enabled, the open-circuit detector waits for a 900ms delay after power-ok conditions are met before enabling the open-circuit detector function. 32 statout status output multiplexer (mux) control input. controls the signal mux into the stat_ outputs. drive statout high to route power-ok_ status to stat_ outputs, or drive statout low to route port-oc_ status to stat_ outputs. 33 rtryen auto-retry enable input. drive rtryen high to enable auto-retry. drive rtryen low to enable switch latch-off mode. when switch is latched off, a high-to-low transition on the on_ control input clears the latch. 34 dc duty-cycle programming input. dc sets the minimum off-time after an overcurrent condition latches off the switch. when rtryen is high, dc sets the auto-retry duty cycle. drive dc low for 1% duty cycle, drive dc high for 2%, or leave dc unconnected for 4% duty cycle. 35, 37, 39, 41 rlyon1, rlyon2, rlyon3, rlyon4 relay-driver control input. drive rlyon_ high to enable rlyd_, drive rlyon_ low to turn off the mosfet switch for the channel and disable rlyd_. 36, 38, 40, 42 on1, on2, on3, on4 mosfet switch control input. drive on_ high to enable gate_ to turn on the mosfet switch. rlyon_ must be high to enable the switch. drive on_ low to disable the switch. pulling on_ low also resets the latch when rtryen is low or if the switch is latched off due to open-circuit detection. 43 rtim timing oscillator frequency set input. connect a 2k ? to 40k ? resistor from rtim to dgnd to set the maximum continuous overcurrent time, t o . leave rtim unconnected to set default 6.4ms t o . 44 v dd digital power supply. bypass v dd to dgnd with a 1? capacitor.
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan ______________________________________________________________________________________ 11 detailed description the max5913a/max5914a quadruple hot-swap con- trollers provide power-over-mdi, also known as power- over-lan systems (figure 5). the max5913a/ max5914a enable control of four external n-channel mosfet switches from a single v cc ranging from +35v to +72v, with timing control and current-limiting functions built in. the max5913a/max5914a features include undervolt- age lockout (uvlo), 100ma relay drivers, dual-level cur- rent sense, foldback current limit, programmable overcurrent time and auto-retry periods, internal charge pumps to drive external mosfet and soft-start, port sta- tus output indicating power-ok (pok) or open-circuit conditions (figure 6). switch and relay control inputs the max5913a/max5914a on_ inputs turn on the corre- sponding mosfet switch. driving on_ high turns on the switch if the corresponding rlyon is driven high, and v cc > v uvlo for more than 25.6ms. driving rlyon_ high immediately turns on the corresponding relay, and activates the 25.6ms delay after which the corresponding on_ input is active. driving rlyon_ low immediately turns off the switch and activates a 3.2ms delay, after which the relay is turned off. these internal delays safely allow driving on_ and rlyon_ simultaneously. the relay is turned on while the switch is off so that there is no volt- age across the relay contacts. the relay is turned off while the switch is off so that there is no current flowing when the relay contacts are opened (see figure 3). input voltage and uvlo the max5913a/max5914a operate from a +35v to +72v supply voltage. v cc powers the max5913a/max5914a analog circuitry and is monitored continuously during startup and normal operation. the max5913a/max5914a keep all mosfet switches and relay drivers securely off before v cc rises above v uvlo . the max5913a/ max5914a turn off all mosfet switches and relay drivers after v cc falls below v uvlo - v uvlo,h . startup when the turn-on condition is met (see the input voltage and uvlo and switch and relay control inputs sections), the max5913a/max5914a slowly turn on the external mosfet switch by charging its gate using a constant current source, i gate (10? typ). the gate voltage slope is determined by the total gate capaci- tance c gate connected to this node. since the output voltage follows the gate voltage, thus the output rises with a slope determined by: if a capacitor load is connected to the output, the total current through the fet is: where c l is the load capacitance and i l is the current required by any load connected to the output during the startup phase. if the current through the fet reaches the programmed current-limit value: the internal current-limit circuitry activates and regu- lates this fet current to be a value, i lim , that depends on v out (i flbk ) (figure 8). see the current sensing and regulation section. in this case, the maximum rate of change of the output is determined by: the formula shows the necessity for i lim to be larger than i l in order to allow the output voltage to rise. the foldback function is active as long as the circuit is in overcurrent condition. should the overcurrent condition persist for a period longer than the maximum time t o , the switch is latched off and gate_ is discharged to ground with a 1ma pulldown current. if auto-retry is enabled, the switch turns on again after a waiting period, t off , which is determined by the pro- grammed duty cycle. after the startup, the internal charge pumps provide (v cc + 9v) typical gate overdrive to fully turn on the switch. when the switch is fully on (voltage drop across the switch is 1.5v), and the switch is not in current limit, the pok signal is asserted. current sensing and regulation the max5913a/max5914a control port current with using two voltage comparators (dual-level detection) that sense the voltage drop across an external current- sense resistor. connect csp_ to v cc and connect a current-sense resistor between csp_ and drain_. kelvin sensing should be used as shown in figure 7. ? ? v t ii c out lim l l = ? i v r max sc sense = ii c c i gate l gate l =+ ? ? v t i c out gate gate =
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 12 ______________________________________________________________________________________ the first comparator compares the sensed voltage against the v sc threshold (typically 142.5mv). choose a sense resistor as follows: r sense = v sc / i max where i max is the maximum current allowed through the switch. when i max is reached, foldback current-limit circuitry regulates the current limit as a function of v out (figure 8). as v out approaches zero, the maximum voltage drop across the sense resistor is lowered to a minimum value of 48mv (typ). this foldback feature helps reduce the power dissipation in the external power fet during output overload and output short-circuit conditions. if a load with very low activation voltage is permanently connected to the output, make the minimum limit current sufficiently larger than the load current. if the load current indeed exceeds the foldback-limit value, the max5913a/ max5914a are not able to power up the switch. test circuits and timing diagrams v uvlo v cc v gate t d, uvlo +1v v ih v il +1v rlyon rlyd (max5913a) t on_del t off_del v rly v gate +42v 3.3v dgnd rlyon1 on1 on2 rlyon2 csp2 csp1 drain2 out2 270 f 270 f 270 f 470 f 270 f 0.33 ? 200 ? 100 ? 100 ? 0.33 ? gate2 drain1 out1 gate1 v out v cc v test max5913a/max5914a (v cc - v out ) 1.5v (power-ok is good) v cc t oc v gate t lpfd +1v oc detector enabled (internal signal) figure 1. uvlo deglitch delay figure 3. port turn-on delay, relay turn-off delay figure 4. channel-to-channel crosstalk test circuit figure 2. open-circuit detector deglitch delay
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan ______________________________________________________________________________________ 13 a second comparator with a detection threshold of 3v sc activates a fast 15ma pulldown of the gate. the purpose of this comparator is to rapidly discharge the gate when a momentary current peak overstresses the external fet, helping the regulation to act more rapidly. the sense resistor is also used to detect an open-circuit or low-current condition with a typical threshold of 3mv. open-circuit detection the max5913a/max5914a detect when a port has low current or is open circuit, and turn off the switch to that port. after the switch is turned on and the pok condi- tions are met, the open-circuit detector is enabled after a 900ms delay. the open-circuit voltage threshold is set at 3mv across the current-sense resistor. drive ocen high to enable open-circuit detectors for all four ports. drive ocen low to disable the detectors. each port has an open-circuit flag that can be read from stat_ out- puts when the statout is low. stat_ output high indi- cates that the switch is latched off due to an open-circuit condition on that port. to reset the latch pull on_ low and then high to restart (table 1). output voltage sense and power-ok the max5913a/max5914a sense the output voltage of the port at the source of the external mosfet switch. n v rly v cc v rly v dd rtim +12v +3.3v digital interface outputs digital interface inputs dgnd agnd rlyd1 rlyd4 csp1 drain1 out1 csp4 drain4 gate4 out4 gate1 fault stat1 stat2 stat3 stat4 v cc port 1 on1 on2 on3 on4 rlyon1 rlyon2 rlyon3 rlyon4 ocen rtryen statout dc v cc = +35v to +72v max5913a n v rly port 4 figure 5. typical application circuit
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 14 ______________________________________________________________________________________ internally the circuit compares the output voltage with v cc to determine when the fet is completely on. a pok condition is met when: (v cc - v out ) 1.5v the internal circuit monitors v out to determine the value of the foldback current when the circuit goes into current-limit conditions. the value of the current limit decreases as the output voltage decreases in order to limit the power dissipation of the fet. the nonlinear relationship between v out and i lim is depicted in figure 8. the foldback circuit is active whenever the max5913a/ max5914a are in current-limit mode after an overcur- rent condition has been detected. connect a catch diode to analog ground and a 100 ? resistor in series with out_ to limit the current during negative inductive kicks that can bring out_ below the ground potential (figure 5). relay drivers the max5913a/max5914a include on-chip relay drivers, ryld_, capable of sinking 100ma. when rlyon_ goes high, the max5913a/max5914a immediately enable the relay driver, and the corresponding on_ switch control input is delayed 25.6ms to allow the relay to close under a zero-voltage condition. when rlyon_ goes low, the max5913a/max5914a immediately turn off the corre- sponding switch, and then turn off the relay driver after a 3.2ms delay, ensuring the relay contacts open under a zero-current condition. the polarity of the max5913a foldback nl control from logic controller drain r sense gate to logic controller csp 10 a 8 a 1ma out ocen on agnd dgnd rlyon rlyd v rly v cc charge pump pok comparator delay dual level detection 1ma v dd 1.236v uvlo rtim dc rtryen open-circuit detector dc counter reset logic relay control timing oscillator logic controller csp -1.5v 3mv 142.5mv 420mv v dd dgnd max5913a max5914a figure 6. functional diagram
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan ______________________________________________________________________________________ 15 rlyd_ is opposite to that of the max5914a. for the max5913a, upon the assertion of the rlyon_ input, rlyd_ sinks 100ma to dgnd. for the max5914a, when rlyon_ is high, an internal 1ma current source pulls up rlyd_ to v dd . a 100ma catch diode is internally con- nected between ryld_ and v rly to protect the max5913a/max5914a from inductive kicks from the relay coil. v rly must be connected to the high-side relay supply voltage. programmable timing, rtim an external resistor from rtim to dgnd sets the fre- quency of the internal oscillator upon which t o and the auto-retry times are based. use 2k ? to 40k ? resistors for r rtim . t o = (r rtim / 2k ? ) (6.4ms) if rtim is unconnected, an internal resistor sets t o to a nominal 6.4ms. auto-retry and programmable duty cycle the max5913a/max5914a feature auto-retry with adjustable duty cycle. driving rtryen high enables the auto-retry function. when the switch encounters an over- current for a period greater than t o , the switch is turned off, and remains off for a t off programmed by dc, a three-level input. after the t off period, the switch is automatically turned on again. when the port encoun- ters a continuous overload or short-circuit condition, the switch turns on and off repeatedly with the on duty cycle of 1%, 2%, or 4% depending on the dc input state (table 2). when rtryen is low, the auto-retry is dis- abled, and a fault condition at the switch turns the switch off and the switch remains latched off. driving the corresponding on control input low resets the latch. pulling on high to turn on the switch. however, the max5913a/max5914a always wait a minimum time, t off , before restarting the switch. logic interface and status outputs the max5913a/max5914a logic interface controls the device functionality. all the basic control functions for the four switches are separated. on_ enables individual on/off control of each mosfet (the corresponding relay must be on to turn on the switch). rlyon_ enables indi- vidual on/off control of each relay. stat_ indicates pok or port-oc (open circuit) status of each switch. the other logic pins are common to all four switches. a sin- gle fault output goes low when any of the four chan- nels is latched off. driving ocen high enables the open-circuit detectors. driving rtryen high enables the auto-retry function, rtryen low enables the switch latch-off function. dc, a three-level logic input, pro- grams the duty cycle. the statout input selects the signal multiplexed at stat_ outputs (table 1.). driving statout high routes pok status to the stat_ outputs. driving statout low routes port-oc status to the stat_ outputs. fault management uvlo and power-ok the max5913a/max5914a monitor the v cc input voltage and each switch? current and voltage to determine pok, overcurrent, or port-oc status. when v cc falls below the uvlo threshold, fault goes low and all four switches and relays are turned off. when the volage across the switch is less than 1.5v, the switch is fully on, and if the switch is not in current limit or open circuit, pok status is good (high). open-circuit faults with the open-circuit detector enabled, when any switch current falls below the open-circuit detector threshold current, the open-circuit detector turns off the switch after a 25.6ms delay, fault goes low, and the port-oc flag is set for that switch. to clear the switch latched-off condition, fault and port-oc flags drive the corresponding on input low. port_ condition ocen statout stat_ enabled. switch fully on and not in current limit. x h h (power-ok_ is good) enabled. switch in current limit, or v ds > 1.5v. x h l (power-ok_ is not good) enabled. switch current is less than oc threshold, port is latched off. hl h (port-oc_ , port current is low or zero) enabled. switch fully on and output current is greater than oc threshold. hl l (port-oc_ , port current is good) disabled. l l l table 1. status output
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 16 ______________________________________________________________________________________ overcurrent faults when an on-switch current exceeds the current-limit threshold, foldback circuitry activates and regulates the switch current. when the current limit lasts for longer than t o , the switch latches off. the pok status flag is set low, and the fault flag is set. if auto-retry is enabled, the switch remains off for a period t off . if auto-retry is disabled, the switch remains latched off, and fault is low. reset the latch and fault by driving correspond- ing on_ low. applications information considerations for circuit design include output capaci- tor requirements, current-limit requirements, setting the maximum on-time in current limit, and choosing a suit- able mosfet and on-time duty cycle in auto-retry. output capacitor requirements the load capacitor requirements should be determined first, as this affects the required startup. current-limit requirements (choosing r sense ) the current limit should be set to at least 20% higher than the expected full load current. if current limit is also used to control startup current, then set this limit high enough so that the output voltage can rise and settle before t o elapses (see the setting t o (choosing r rtim ) section). setting t o (choosing r rtim ) choose the t o time by connecting a 2k ? to 40k ? resistor from rtim to dgnd. the minimum 6.4ms t o is set with r rtim = 2k ? . the maximum 128ms t o is set with r rtim = 40k ? set according to the following equation: t o = (r rtim / 2k ? ) (6.4ms) t o should be chosen appropriately, depending on the startup condition. there are two cases: 1) for startup without current limit, when: the startup current does not reach the maximum current-limit threshold and t o will not activate during startup condition. in this case, set t o to a small value, but large enough to allow the switch to remain on during large output load-current transients. the smaller the t o , the faster the max5913a/max5914a turn off the external fet in case of output overload or short-circuit condition. 2) for startup with current limit, when: which is expected when: is large, t o must be set to be long enough to allow the output voltage to rise and settle before t o elapses. in this case, t o must satisfy the following equation: where v cc is the input voltage and given that i l < i lim . choosing power mosfet the fet must withstand a short-circuit condition where its power dissipation is p diss = v cc i lim . the fet must have sufficient thermal capacitance to prevent thermal heating damage during the t o time. choose duty cycle (setting dc) the duty cycle can be adjusted to allow time for heat to dissipate between t o cycles, allowing use of smaller mosfets with lower thermal capacitance. for smaller duty cycle, a smaller fet is sufficient. see table 2 for setting the duty cycle. the auto-retry off-time should not be too long to keep the system wait time during retry period to a reasonable value. for example, when t o is set to 128ms and duty cycle is set to 1%, the retry time is 99 128ms = 12.7s. application circuits in a typical lan system there are two ways to deliver power over the lan cable. power can be supplied to the unused cable pairs, or power can be supplied over the signal pairs (figures 9 and 10). tc ii c vv ii ol max l l cc max l = ? + ? ? 18 2 3 18 c c l gate ii c c i v r gate l gate l sc sense =+ ? ? ? ? ? ? ii c c i v r gate l gate l sc sense =+<
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan ______________________________________________________________________________________ 17 sense resistor csp_ drain_ high-current path max5913a max5914a figure 7. recommended layout for kelvin-sensing current through sense resistor i lim i max /3 0v 18v v out i max = v sc r sense ? figure 8. foldback current-limit response dc t off duty cycle 0 99 ? t o 1% 1 49 ? t o 2% open 24 ? t o 4% table 2. duty programming cycle
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 18 ______________________________________________________________________________________ n pd cat 5 rj45 powered device (ip phone, etc.) data rj45 +48v power over signal pairs lan switch +48v +48v out max5913a max5914a figure 9. power sent over signal pairs n pd cat 5 cat 5 rj45 powered device (ip phone, etc.) rj45 rj45 rj45 +48v power over spare pairs midspan hub +48v +48v out max5913a max5914a figure 10. power sent over spare pairs
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan ______________________________________________________________________________________ 19 n v rly v cc v rly v dd rtim +12v +3.3v digital interface outputs digital interface inputs dgnd agnd rlyd1 rlyd4 csp1 drain1 out1 csp4 drain4 gate4 out4 gate1 fault stat1 stat2 stat3 stat4 v cc port 1 on1 on2 on3 on4 rlyon1 rlyon2 rlyon3 rlyon4 ocen rtryen statout dc v cc = +35v to +72v max5913a n v rly port 4 typical operating 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 draw- ings may show a different suffix character, but the drawing per- tains to the package regardless of rohs status. package type package code outline no. land pattern no. 44 mqfp m44+3 21-0826 90-0169
max5913a/max5914a +48v quad hot-swap controllers for power-over-lan 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. 20 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 5/04 initial release 1 1/11 released the max5914a. updated the ordering information , electrical characteristics , typical operating characteristics , pin description , and the programming timing, rtim section 1?, 15

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