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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. MAX34561 12v/5v hot-plug switch 19-5621; rev 0; 11/10 general description the MAX34561 is a dual, self-contained, hot-plug switch intended to be used on +12v and +5v power rails to limit through current and to control the power-up output-volt - age ramp. the device contains two on-board n-channel power mosfets that are actively closed-loop controlled to ensure that an adjustable current limit is not exceed - ed. the maximum allowable current through the device is adjusted by external resistors connected between the load and ilim pins. the device can control the power-up output-voltage ramp. capacitors connected to the vramp pins set the desired voltage-ramp rate. the output voltages are unconditionally clamped to keep input overvoltage stresses from harming the load. the device also contains adjustable power-up timers. capacitors connected to the timer pins determine how long after power-on reset (por) the device should wait before starting to apply power to the loads. the timer pins can be driven with a digital logic output to create a device-enable function. the device contains an on-board temperature sensor with hysteresis. if operating conditions cause the device to exceed an internal thermal limit, the device either unconditionally shuts down and latches off awaiting a por, or waits until the device has cooled by the hyster - esis amount and then restarts. applications raid/hard drives servers/routers pci/pci express m infiniband tm/sm base stations features s completely integrated hot-plug functionality for +12v and +5v power rails s dual version of the ds4560 s on-board power mosfets (68m i and 43m i ) s no high-power r sense resistors needed s adjustable current limits s adjustable output-voltage slew rates s adjustable power-up enable timing s output overvoltage limiting s on-board thermal protection s on-board charge pump s user-selectable latchoff or automatic retry operation ordering information + denotes a lead(pb)-free/rohs compliant package. t = tape and reel. * ep = exposed pad. pci express is a registered trademark of pci-sig corp. infiniband is a trademark and service mark of infiniband trade association. part temp range pin-package MAX34561t+ -40 n c to +85 n c 24 tqfn-ep* MAX34561t+t -40 n c to +85 n c 24 tqfn-ep*
MAX34561 12v/5v hot-plug switch 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. voltage range on v cc5 relative to gnd ............ -0.3v to +6.5v voltage range on v cc12 relative to gnd ........... -0.3v to +18v voltage range on ilim5, vramp5, timer5, ard5 relative to gnd ......... -0.3v to (v cc5 + 0.3v), not to exceed +6.5v voltage range on ilim12, vramp12 relative to gnd ................................ -0.3v to (v cc12 + 0.3v), not to exceed +18v voltage range on timer12, ard12 relative to gnd ....................................... -0.3v to +5v (v reg ) 5v drain current continuous ............................................................................ 2a peak ...................................................................................... 4a 12v drain current continuous ............................................................................ 2a peak ...................................................................................... 4a continuous power dissipation (t a = +70 n c) tqfn (derate 20.8mw/ n c above +70 n c) ............... 1666.7mw operating junction temperature range ......... -40 n c to +135 n c operating temperature range .......................... -40 n c to +85 n c storage temperature range .......................... -55 n c to +135 n c lead temperature (soldering, 10s) ................................ +300 n c soldering temperature (reflow) ...................................... +260 n c recommended operating conditions (t j = -40 n c to +135 n c) electrical characteristics (v cc5 = +5v, v cc12 = +12v, t j = +25 n c, unless otherwise noted.) absolute maximum ratings parameter symbol conditions min typ max units v cc5 voltage v cc5 (notes 1, 2) 4.0 5.0 5.5 v v cc12 voltage v cc12 (notes 1, 2) 9 12 13.2 v r ilim_ value r ilim_ 20 400 i c vramp_ value c vramp_ 0.04 5 f f c timer_ value c timer_ 0.04 5 f f timer_ turn-on voltage v on timer5 2.1 v cc5 + 0.3 v timer12 2.6 5.0 timer_ turn-off voltage v off -0.3 +1.5 v parameter symbol conditions min typ max units v cc5 supply current i cc5 (note 3) 1.5 2 ma v cc12 supply current i cc12 (note 3) 1.5 2.25 ma 5v uvlo: rising v ur5 3.7 3.95 v 5v uvlo: falling v uf5 2.7 3.2 v 5v uvlo: hysteresis v uh5 0.5 v 12v uvlo: rising v ur12 8 8.5 v 12v uvlo: falling v uf12 6.5 7 v 12v uvlo: hysteresis v uh12 1 v 5v on-resistance r on5 43 56 m i 12v on-resistance r on12 68 88 m i 5v internal voltage reference v ref5 1.80 v 12v internal voltage reference v ref12 2.35 v
MAX34561 12v/5v hot-plug switch 3 electrical characteristics (continued) (v cc5 = +5v, v cc12 = +12v, t j = +25 n c, unless otherwise noted.) note 1: all voltages are referenced to ground. currents entering the device are specified positive, and currents exiting the device are negative. note 2: this supply range guarantees that the load_ voltage is not clamped by the overvoltage limit. note 3: supply current specified with no load on the load_ pin. note 4: guaranteed by design; not production tested. note 5: i scl_ is the current limit when conduction begins. note 6: i ovl_ is the current limit after the on-board mosfet is fully on. parameter symbol conditions min typ max units 5v mosfet output capacitance c out (note 4) 400 pf 12v mosfet output capacitance c out (note 4) 400 pf 5v and 12v delay time from enable to beginning of conduction t pond c vramp_ = 1 f f 8 ms 5v and 12v gate-charging time from conduction to 90% of v out t gct c vramp_ = 1 f f, c load_ = 1000 f f 48 64 80 ms shutdown junction temperature t shdn (note 4) 120 135 150 n c thermal hysteresis t hys (note 4) 40 n c timer_ charging current i timer 64 80 96 f a vramp_ charging current i vramp 64 80 96 f a 5v overvoltage clamp v ovc5 5.5 6.0 6.5 v 12v overvoltage clamp v ovc12 13.2 15 16.5 v 5v power-on short-circuit current limit i scl5 r ilim5 = 47 i (note 5) 0.6 1.0 1.5 a 12v power-on short-circuit current limit i scl12 r ilim12 = 47 i (note 5) 0.6 1.0 1.5 a 5v operating overload current limit i ovl5 r ilim5 = 47 i (notes 4, 6) 1.5 2.5 3.7 a 12v operating overload current limit i ovl12 r ilim12 = 47 i (notes 4, 6) 1.00 1.8 2.6 a 5v vramp5 slew rate sr vramp c vramp5 = 1 f f 0.16 0.19 0.23 v/ms 12v vramp12 slew rate sr vramp c vramp12 = 1 f f 0.13 0.15 0.18 v/ms ard5 pullup resistor r pu5 100 k i ard12 pullup resistor r pu12 k i
MAX34561 12v/5v hot-plug switch 4 typical operating characteristics (t a = +25c, unless otherwise noted.) on-resistance vs. temperature MAX34561 toc08 temperature (c) r on (m) 100 120 80 60 40 20 0 -20 10 20 30 40 50 60 70 0 -40 12v operation 5v operation overvoltage clamp vs. temperature MAX34561 toc07 temperature (c) overvoltage clamp (v) 100 120 80 60 40 20 0 -20 15.0 15.2 15.4 15.6 15.8 16.0 16.2 14.8 -40 12v operation no load 20 load overvoltage clamp vs. temperature MAX34561 toc06 temperature (c) overvoltage clamp (v) 120 100 60 80 0 20 40 -20 6.10 6.15 6.20 6.25 6.30 6.35 6.40 6.45 6.50 6.55 6.05 -40 no load 20 load 5v operation note: 6.5v = v cc absolute maximum value current limit vs. temperature MAX34561 toc05 temperature (c) current limit (a) 100 120 80 60 40 20 0 -20 0.5 1.0 1.5 2.0 2.5 0 -40 12v operation i ovl12 i scl12 current limit vs. temperature MAX34561 toc04 temperature (c) current limit (a) 100 120 80 60 40 20 0 -20 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 -40 5v operation i ovl5 i scl5 12v current limit vs. ilim resistance MAX34561 toc03 r ilim ( ) 12v current limit (a) 100 50 0.5 1.0 1.5 2.0 2.5 0 0 150 i ovl12 i scl12 5v current limit vs. ilim resistance MAX34561 toc02 r ilim ( ) 5v current limit (a) 50 100 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 0 0 150 i ovl5 i scl5 supply current vs. temperature MAX34561 toc01 temperature (c) i cc (ma) 120 100 60 80 0 20 40 -20 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 0 -40 12v operation 5v operation
MAX34561 12v/5v hot-plug switch 5 typical operating characteristics (continued) (t a = +25c, unless otherwise noted.) thermal shutdown with autoretry enabled v cc = 12v, 2 resistive load MAX34561 toc16 500ms/div v cc12 load12 5v/div load current 500ma/div thermal shutdown with autoretry enabled v cc = 5v, 2 resistive load MAX34561 toc15 1s/div v cc5 load5 2v/div load current 500ma/div turn-on waveforms v cc = 12v, 3300f capacitive load MAX34561 toc14 10ms/div v cc12 load12 load current 500ma/div 5v/div turn-on waveforms v cc = 5v, 3300f capacitive load MAX34561 toc13 5ms/div v cc5 load5 load current 500ma/div 2v/div turn-on waveforms v cc = 12v, 20 resistive load MAX34561 toc12 5ms/div v cc12 load12 load current 500ma/div 5v/div turn-on waveforms v cc = 5v, 20 resistive load MAX34561 toc11 5ms/div 2v/div v cc5 load5 load current 500ma/div typical MAX34561 turn-on waveforms v cc = 12v, 20 resistive load MAX34561 toc10 5ms/div 2v/div v cc12 load12 vramp12 timer12 typical MAX34561 turn-on waveforms v cc = 5v, 20 resistive load MAX34561 toc09 2ms/div 1v/div v cc5 load5 vramp5 timer5
MAX34561 12v/5v hot-plug switch 6 pin configuration pin description 23 24 22 21 8 7 9 v cc5 load5 load5 load5 10 v cc5 v cc12 load12 load12 v cc12 load12 1 2 ard5 4 5 6 17 18 16 14 13 vramp5 timer5 + gnd dnc ilim5 load5 MAX34561 v cc5 v cc12 3 15 ard12 20 11 ilim12 vramp12 19 12 load12 timer12 thin qfn (4mm 4mm) top view ep pin name function 1, 2, 3 v cc5 5v supply input. power-supply input and n-channel power mosfet drain connection. if the 5v side is not used, connect this pin to gnd. 4C7 load5 5v load output. n-channel power mosfet source connection. 8 ilim5 5v supply current-limit adjust. a resistor from this pin to load5 determines the current limit for the 5v pass connection. for better accuracy, dedicate one load pin to connect to ilim through r ilim . see the applications information section for more information. 9 dnc do not connect. do not connect any signal to this pin. 10 gnd ground connection 11 ilim12 12v supply current-limit adjust. a resistor from this pin to load12 determines the current limit for the 12v pass connection. for better accuracy, dedicate one load pin to connect to ilim through r ilim . see the applications information section for more information. 12C15 load12 12v load output. n-channel power mosfet source connection. 16, 17, 18 v cc12 12v supply input. power-supply input and n-channel power mosfet drain connection. if the 12v side is not used, connect this pin to gnd. 19 timer12 12v enable delay control. a capacitor connected to this pin determines the enable delay accord - ing to the equation: enable delay = c timer12 x (v ref12 /i timer ). 20 vramp12 12v voltage ramp control. a capacitor connected to this pin determines the voltage ramp of the load12 output during turn-on according to the equation: dv load12 = 2 x (i vramp /c vramp12 ). 21 ard12 12v autoretry disable. connect this pin to gnd to disable automatic retry functionality; the device latches off during an overtemperature fault. leave this pin open to enable automatic retry function. this pin contains a pullup (r pu12 ) to 5v. this pin is only sampled on device power-on. if the 12v side is not used, connect this pin to gnd.
MAX34561 12v/5v hot-plug switch 7 detailed description the MAX34561 has hot-plug controls for both +12v and +5v power rails. the circuitry for the +12v and +5v con - trols are independent of each other and can be treated as two separate hot-plug switches, even though the gnd pin is common between the two switches. the sections that follow are written from the +12v circuit perspective, but also apply for the +5v switch control. the device begins to operate when the supply voltage v cc12 (or v cc5 ) exceeds its undervoltage lockout level, v ur12 (or v ur5 ). at this level, the corresponding enable circuit and timer12 (timer5) become active. once the device has been enabled, a gate voltage is applied to the corresponding power mosfet, allowing current to begin flowing from v cc12 (v cc5 ) to load12 (load5). the speed of the output-voltage ramp is controlled by the capacitance placed at the vramp12 (vramp5) pin. the load current is continuously monitored during the initial conduction (i scl12 or i scl5 ) and after the cor - responding mosfet is fully on (i ovl12 or i ovl5 ). if the current exceeds the current limit that is set by the exter - nal resistance at ilim12 (ilim5), the gate voltage of the corresponding power mosfet is decreased, reducing the output current to the set current limit. current is limited by the device comparing the volt - age difference between load12 (load5) and ilim12 (ilim5) to an internal reference voltage. if the output cur - rent exceeds the limit that is set by the r ilim12 (r ilim5 ) resistor, the gate voltage of the corresponding power mosfet is decreased, which reduces the output current to the load. when the output power is initially ramping up, the current limit is i scl12 (i scl5 ). once the corresponding mosfet is fully on, the current limit is i ovl12 (i ovl5 ). the i scl12 (i scl5 ) current limit protects the source if there is a dead short on initial power-up. the device acts as a fuse and automatically disables the current flowing to the load when the temperature of the power corresponding mosfet has exceeded the shut - down junction temperature, t shdn . enable/timer the voltage level of timer12 (timer5) is compared to an internal source (see the functional diagram ). when the level on the pin exceeds v on , the comparator out - puts a low level. this then turns on the voltage ramp circuit, enabling the devices output. timer12 (timer5) can be configured into one of four different modes of operation as listed in table 1. timer12 (timer5) pin was designed to work with most logic families. timer12 (timer5) has at least 250mv of hysteresis between v on and v off . it is recommended that any logic gate used to drive timer12 (timer5) be tested to ensure proper operation. pin description (continued) table 1. timer_ pin modes pin name function 22 ard5 5v autoretry disable. connect this pin to gnd to disable automatic retry functionality; the device latches off during an overtemperature fault. leave this pin open to enable automatic retry function. this pin contains a pullup (r pu5 ) to v cc5 . this pin is only sampled on device power-on. if the 5v side is not used, connect this pin to gnd. 23 vramp5 5v voltage ramp control. a capacitor connected to this pin determines the voltage ramp of the load5 output during turn-on according to the equation: dv load5 = 2.3332 x (i vramp /c vramp5 ). 24 timer5 5v enable delay control. a capacitor connected to this pin determines the enable delay according to the equation: enable delay = c timer5 x (v ref5 /i timer ). ep exposed pad. connect to ground. the ep must be soldered to ground for proper thermal and elec - trical operation. operation mode timer pin setup automatic enable no connection to timer12 (timer5) delayed automatic enable capacitor c timer_ connected to timer12 (timer5) enable/disable open-collector device enable with delay/disable open-collector device and c timer _
MAX34561 12v/5v hot-plug switch 8 functional diagram 12v thermal limit external disable timer12 c timer12 +5v v reg +5v v reg v ref12 12v autoretry disable 12v uvlo current limit charge pump load +5v v reg overvoltage limit gnd vramp12 c vramp12 r r r ilim12 r on12 load12 v cc12 ard12 ilim12 v cc12 i vramp i timer r pu12 MAX34561 5v thermal limit external disable timer5 c timer5 v cc5 v cc5 v ref5 5v autoretry disable 5v uvlo current limit charge pump load overvoltage limit gnd vramp5 c vramp5 r r r ilim5 r on5 load5 v cc5 ard5 ilim5 v cc5 i vramp i timer r pu5
MAX34561 12v/5v hot-plug switch 9 once the device has been enabled, there is a delay (t pond ) until conduction begins from v cc12 (v cc5 ) to load12 (load5). this delay is the time required for the charge pump to bring the gate voltage of the cor - responding power mosfet above its threshold level. once the gate is above the threshold level, conduction begins and the output voltage begins ramping. automatic-enable mode when v cc12 (v cc5 ) exceeds v ur12 (v ur5 ), the gate holding the timer12 (timer5) node low is released. the internal current source brings the node to a level greater than v on , enabling the device. delayed automatic-enable mode when v cc12 (v cc5 ) exceeds v ur12 (v ur5 ), the gate holding the timer12 (timer5) node low is released. the internal current source (i timer ) then begins charging c timer_ . when c timer_ is charged to a level greater than v ref12 (v ref5 ), the device turns on. the equation for the delay time is: t delay = (c timer12 x v ref12 )/i timer t delay = (c timer5 x v ref5 )/i timer enable/disable mode a logic gate or open-collector device can be connected to timer12 (timer5) to enable or disable the device. when timer12 (timer5) is held low, the device is dis - abled. when an open-collector device is used to drive timer12 (timer5), the device is enabled when the open collector is in its high-impedance state by the internal current source bringing the timer12 (timer5) node high. timer12 (timer5) is also compatible with most logic families if the output high voltage level of the gate exceeds the v on level, and the gate can sink the i timer current. enable with delay/disable mode an open-collector device is connected in parallel with c timer_ . when the pin is held low, the device is dis - abled. when the open-collector driver is high imped - ance, the internal current source begins to charge c timer_ as in the delayed mode. output-voltage ramp the voltage ramp circuit uses an operational ampli - fier to control the gate bias of the corresponding n-channel power mosfet. when the timer/enable circuit is disabled, a fet is used to keep c vramp_ discharged, which forces the output voltage to gnd. once the enable/timer circuit has been enabled, an internal current source, i vramp , begins to charge the external capacitor, c vramp_ , connected to vramp12 (vramp5). the amplifier controls the gate of the corre - sponding power mosfet so that the load12 (load5) output voltage divided by two tracks the rising voltage level of c vramp_ . the output voltage continues to ramp until it reaches either the input v cc12 (v cc5 ) level or the overvoltage clamp limits. the equation for the output-voltage ramp function is: dv load /dt = 2 x (i vramp /c vramp12 ) for +12v circuit dv load /dt = 2.3332 x (i vramp /c vramp5 ) for +5v circuit thermal shutdown the device enters a thermal shutdown state when the temperature of the corresponding power mosfet reaches or exceeds t shdn , approximately +135 n c. when t shdn is exceeded, the thermal-limiting cir - cuitry disables the device using the enable circuitry. depending on the state of ard12 (ard5), the device attempts to autoretry once the device has cooled, or it latches off. autoretry if ard12 (ard5) is unconnected or connected high, the device continually monitors the temperature once it has entered thermal shutdown. if the junction temperature falls below approximately +95 n c (t shdn - t hys ), the corresponding power mosfet is re-enabled. see the thermal shutdown with autoretry enabled typical operat - ing curves for details. latchoff if ard12 (ard5) is pulled low and the device has entered thermal shutdown, it does not attempt to turn back on. the only way to turn the device back on is to cycle the power to the device. when power is reapplied to v cc12 (v cc5 ), the junction temperature needs to be less than t shdn for the device to be enabled. overvoltage limit the overvoltage-limiting clamp monitors the vramp12 (vramp5) level compared to an internal voltage ref - erence. when the voltage on vramp12 (vramp5) exceeds v ovc12 /2 (or v ovc5 /2.3332), the gate volt - age of the corresponding n-channel power mosfet is reduced, limiting the voltage on load12 (load5) to v ovc12 (v ovc5 ) even as v cc12 (v cc5 ) increases. if the device is in overvoltage for an extended period of time, the device could overheat and enter thermal shutdown. this is caused by the power created by the voltage
MAX34561 12v/5v hot-plug switch 10 drop across the corresponding power mosfet and the load current. see the thermal shutdown with autoretry enabled typical operating curves for details. applications information exposed pad the exposed pad is also a heatsink for the device. the exposed pad should be connected to a large trace or plane capable of dissipating heat from the device. decoupling capacitors it is of utmost importance to properly bypass the device's supply pins. a decoupling capacitor absorbs the energy stored in the supply and board parasitic inductance when the fet is turned off, thereby reducing the magni - tude of overshoot at v cc . this can be accomplished by using a high-quality (low esr, low esl) ceramic capaci - tor connected directly between the v cc and gnd pins. any series resistance with this bypass capacitor lowers its effectiveness and is not recommended. a minimum 0.5f ceramic capacitor is required. however, depend - ing on the parasitic inductances present in the end appli - cation, a larger capacitor could be necessary. unused pins if only one side (5v or 12v) of the device is being used, it is required that the unused v cc , ar, ctimer, and vramp pins be connected to gnd. leaving these input pins unconnected can result in interference of the proper operation of the active portion of the device. load and ilim connections small parasitic resistances in the bond wires of the load pins and in the traces connected to the load pins can result in a voltage offset while current is flowing. since the voltage drop across rilim is used to set the i scl and i ovl limits, this induced offset can increase the value of i scl and i ovl from the specified values for any given r ilim . to greatly reduce this offset, it is recommended that one of the load pins have a dedicated connection to ilim though r ilim , and not be used to pass the load current (figure 1). this would leave three load pins to pass i load , which should be sufficient. because there is only a small amount of current passed from this lone load pin to ilim, there is a negligible voltage offset applied to the internal comparator. this method is the best way to attain an accurate current limit for i load . 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. figure 1. load and ilim connections package type package code outline no. land pattern no. 24 tqfn-ep t2444+4 21-0139 90-0022 MAX34561 load load load load ilim r ilim to application
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 11 ? 2010 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. MAX34561 12v/5v hot-plug switch revision history revision number revision date description pages changed 0 11/10 initial release

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