general description the ds4560 is a self-contained hot-plug switch intend-ed to be used on +12v power buses to limit through current and to control the power-up output-voltage ramp. the device contains an on-board 25m n-chan- nel power mosfet that is actively closed-loop con-trolled to ensure that an adjustable current limit is not exceeded. the maximum allowable current through the device is determined by an external resistor connected to the ilim pin. the ds4560 also contains the ability to control the power-up output-voltage ramp. a capacitor connected to the vramp pin sets the desired voltage ramp rate. the output voltage is unconditionally clamped to keep input overvoltage stresses from harming the load. the ds4560 also contains an adjustable power-up timer. a capacitor connected to the timer pin determines how long after power-on reset the ds4560 should wait before starting to apply power to the load. the timer pin can also be driven with a digital logic output to cre- ate a device-enable function. the ds4560 contains an on-board temperature sensor with hysteresis. if operating conditions cause the device to exceed an internal thermal limit, the ds4560 either unconditionally shuts down and latches off await- ing a power-on reset (DS4560S-LO), or it waits until the device has cooled by the hysteresis amount and then restarts (ds4560s-ar). applications features ? on-board 25m power mosfet ? adjustable short-circuit current and overloadcurrent limit ? adjustable output-voltage slew rate ? adjustable power-up timer with external enablecapability ? output overvoltage limiting ? on-board thermal protection ? on-board charge pump ? latchoff and autoretry versions available ? 9.0v to 13.2v supply operation ? 8-pin so (150 mils) pb-free package ? ul certification record e211395 ds4560 12v hot-plug switch ________________________________________________________________ maxim integrated products 1 so (150 mils) top view 2 7 load vramp 18 v cc gnd load timer 3 6 load ilim 45 ds4560 + pin configuration ordering information 19-4619; rev 2; 5/09 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. + denotes a lead(pb)-free/rohs-compliant package. t = tape and reel. part thermal shutdown pin-package DS4560S-LO+ latchoff 8 so DS4560S-LO+t latchoff 8 so ds4560s-ar+ autoretry 8 so ds4560s-ar+t autoretry 8 so pin description pin name function 1 gnd ground. this is also a heat sink for the device. 2 vramp output-voltage ramp adjustment 3 timer power-up timer/enable 4 ilim current-limit adjustment 5, 6, 7 load output load connection (mosfet source) 8 v cc input supply voltage (mosfet drain) pci express is a registered trademark of pci-sig corp. infiniband is a trademark and service mark of the infiniband trade association. raid/hard drivesservers/routers pci/pci express infiniband sm base stations downloaded from: http:///
ds4560 12v hot-plug switch 2 _______________________________________________________________________________________ absolute maximum ratingsrecommended operating conditions (t j = -40? to +135?.) stresses beyond those listed under ?bsolute 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 cc and load relative to gnd continuous .........................................................-0.3v to +18v 1ms maximum ....................................................-0.3v to +22v voltage range on ilim and vramp relative to gnd.....................................-0.3v to (v cc + 0.3v), but not to exceed +18v voltage range on timer relative to gnd ...........-0.3v to +5.0v drain current continuous ...........................................................................4a peak ...................................................................................15a operating junction temperature range ...........-40 c to +135 c storage temperature range .............................-55 c to +135 c soldering temperature...........................refer to the ipc/jedec j-std-020 specification. parameter smbol conditions min tp max units supply voltage v cc (notes 1, 2) 9.0 13.2 v r ilim value r ilim 20 400 c vramp value c vramp 0.04 5.00 f c timer value c timer 0.04 5.00 f timer turn-on voltage v on 2.6 5 v timer turn-off voltage v off -0.3 +2.0 v electrical characteristics(v cc = +12v, t j = +25?, unless otherwise noted.) parameter smbol conditions min tp max units supply current i cc (note 3) 1.1 2.00 ma uvlo rising v uvlor 7.5 8.0 8.5 v uvlo falling v uvlof 6.5 7.0 7.5 v uvlo hysteresis v uvloh 1 v on-resistance r on 25 32 m mosfet output capacitance c out 500 pf load voltage during off state v loff (note 4) 200 mv delay time from enable to beginning of conduction t pond c vramp = 1f 5 ms gate-charging time from conduction to 90% of v out t gct c vramp = 1f, c load = 1000f 48 66 80 ms shutdown junction temperature t shdn (note 5) 120 135 150 c thermal hysteresis t hys (note 5) 40 c timer charging current i timer 70 80 92 a overvoltage clamp v ovc 13.5 15.0 16.5 v downloaded from: http:///
ds4560 12v hot-plug switch _______________________________________________________________________________________ 3 note 1: all voltages are referenced to ground. currents entering the ic are specified positive and currents exiting the ic 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: v loff voltage specified with a 2.5ma load applied to load. note 5: not production tested. guaranteed by design. note 6: i scl is the current limit when the output voltage is initially ramping up. note 7: i ovl is the current limit after the output voltage ramping is complete. electrical characteristics (continued)(v cc = +12v, t j = +25?, unless otherwise noted.) parameter smbol conditions min tp max units short-circuit limit i scl r ilim = 56 (note 6) 2.0 2.5 3.0 a overload limit i ovl r ilim = 56 (note 7) 3.5 4.4 5.9 a load voltage slew rate sr load c vramp = 1f 0.13 0.15 0.18 v/ms vramp charging current i vramp 70 80 92 a current limit vs. r ilim ds4560 toc01 r ilim ( ) current limit (a) 100 1 10 0.1 1000 10 i ovl i scl current limit vs. temperature ds4560 toc02 temperature ( c) current limit (a) 120 100 80 60 40 20 -20 0 1 2 3 4 5 6 70 -40 140 i ovl i scl overvoltage clamp vs. temperature ds4560 toc03 temperature ( c) overvoltage clamp (v) 120 100 80 60 40 20 -20 0 15.2 15.4 15.6 15.8 16.0 16.2 16.415.0 -40 140 no load 10 load on-resistance vs. temperature ds4560 toc04 temperature ( c) r on (m ) 120 100 80 60 40 20 0 -20 25 30 35 40 4520 -40 140 supply current vs. temperature ds4560 toc05 temperature ( c) i cc (ma) 120 100 -20 0 20 60 40 80 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00 0 -40 140 typical ds4560 turn-on waveforms v cc = 18v, 10 resistive load ds4560 toc06 v cc 5v/div 0v timer load vramp 2ms/div typical operating characteristics (v cc = 12v, t a = +25?, r ilim = 56 , v cc = 12v, c timer = 0.1?, c vramp = 0.1?, unless otherwise noted.) downloaded from: http:///
ds4560 12v hot-plug switch 4 _______________________________________________________________________________________ typical operating characteristics (continued) (v cc = 12v, t a = +25?, r ilim = 56 , v cc = 12v, c timer = 0.1?, c vramp = 0.1?, unless otherwise noted.) turn-on waveforms 10 resistive load ds4560 toc07 v cc load load current 2v/div 0v 0ma 500ma/div 5ms/div turn-on waveforms 3300 f capacitive load ds4560 toc08 v cc load load current 2v/div 0v 0ma 500ma/div 5ms/div turn-on waveforms v cc = 18v, 10 resistive load ds4560 toc09 v cc load load current 5v/div 0v 0ma 500ma/div 5ms thermal shutdown with autoretry ds4560s-ar+, v cc = 18v, 10 resistive load ds4560 toc10 v cc load load current 5v/div 0v 500ma/div 0ma 500ms/div downloaded from: http:///
ds4560 thermal limit external disable timer c timer +5v 2.5v uvlo current limit charge pump load +5v vreg overvoltage limit gnd rr r ilim loadilim +12v v cc vramp v cc 80 a 80 a c vramp block diagram/typical application circuit ds4560 12v hot-plug switch _______________________________________________________________________________________ 5 detailed description the ds4560 begins to operate when v cc exceeds the undervoltage lockout level, v uvlor . at this level, the enable circuit and timer pin become active. once thedevice has been enabled, a gate voltage is applied to the power mosfet, allowing current to begin flowing from v cc to load. the speed of the output-voltage ramp is controlled by the capacitance placed at thevramp pin. the load current is continuously monitored during the initial voltage ramping (i scl ) and during nor- mal operation (i ovl ). if the current exceeds the current limit that is set by the external resistance at ilim, thegate voltage of the power mosfet is decreased, reducing the output current to the set current limit. current is limited by the ds4560 comparing the voltagedifference between the load and ilim pins to an inter- nal reference voltage. if the output current exceeds the limit that is set by the r ilim resistor, the gate voltage of the power mosfet is decreased, which reduces theoutput current to the load. when the output power is initially ramping up, the current limit is i scl . once the voltage ramping is complete, the current limit is i ovl . the lower i scl current limit protects the source if there is a dead short on initial power-up.the ds4560 acts as a fuse and automatically disables the current flowing to the load when the temperature of the power mosfet has exceeded the shutdown junc- tion temperature, t shdn . downloaded from: http:///
ds4560 12v hot-plug switch 6 _______________________________________________________________________________________ enable/timer the voltage level of the timer pin is compared to aninternal source (see the block diagram) . when the level on the pin exceeds v on , the comparator outputs a low level. this then turns on the voltage ramp circuit,enabling the device? output. this timer pin can be configured into one of four different modes of operation listed in table 1. the timer pin was designed to work with most logic families. the timer pin will have at least 250mv of hysteresis between v on and v off . it is recommended that any logic gate used to drive thetimer pin be tested to ensure proper operation. once the device has been enabled, there is a delay (t pond ) until conduction begins from v cc to load. this delay is the time required for the charge pump tobring the gate voltage of the 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 cc exceeds v uvlor , the gate holding the timer node low is released. the internal currentsource brings the node to a level greater than v on , enabling the device. delayed automatic enable mode when v cc exceeds v uvlor , the gate holding the timer node low is released. the internal currentsource (i timer ) then begins charging c timer . when c timer is charged to a level greater than v on , the device turns on. the equation for the delay time is: t delay = (c timer x v on )/i timer enable/disable mode a logic gate or open-collector device can be connect-ed to the timer pin to enable or disable the device. when the timer pin is held low, the device is disabled. when an open-collector device is used to drive the timer pin, the ds4560 is enabled when the open col- lector is in its high-impedance state by the internal cur- rent source bringing the timer node high. the timer pin is also compatible with most logic families if the out- put 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 withc timer . when the pin is held low, the ds4560 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 amplifierto control the gate bias of the 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 cir-cuit has been enabled, an internal current source, i vramp , begins to charge the external capacitor, c vramp , connected to the vramp pin. the amplifier controls the gate of the power mosfet so that theload 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 cc level or the overvoltage clamp limits. the equation for the output-voltage ramp function is: dv load /dt = 2 x (i vramp /c vramp ) thermal shutdown the ds4560 enters a thermal shutdown state when thetemperature of the power mosfet reaches or exceeds t shdn , approximately +135?. when t shdn is exceed- ed, the thermal-limiting circuitry disables the ds4560using the enable circuitry. the ds4560 is offered in two different versions: an autoretry version and a latchoff version. autoretry version (ds4560s-ar) the autoretry verson continually monitors the tempera-ture once it has entered thermal shutdown. if the junc- tion temperature falls below approximately +95? (t shdn - t hys ), the power mosfet is re-enabled. see the thermal shutdown with autoretry graph for details. table 1. timer pin modes mode of operation timer pin setup automatic enable no connection to timer pin. delayed automatic enable capacitor c timer connected to timer. enable/disable open-collector device. enable with delay/disable open-collector device and c timer . downloaded from: http:///
ds4560 12v hot-plug switch _______________________________________________________________________________________ 7 latchoff version (DS4560S-LO) once the latchoff version has entered thermal shut-down, it does not attempt to turn back on. the only way to turn this device back on is to cycle the power to the device. when power is reapplied to v cc , the junction temperature needs to be less than t shdn for the device to be enabled. overvoltage limit the overvoltage-limiting clamp monitors the vramplevel compared to an internal voltage reference. when the voltage on vramp exceeds v ovc /2, the gate volt- age of the n-channel power mosfet is reduced, limit-ing the voltage on load to v ovc even as v cc increases. if the device is in overvoltage for an extend-ed period of time, the device may overheat and enter thermal shutdown. this is caused by the power created by the voltage drop across the power mosfet and the load current. see the thermal shutdown with autoretry graph for details. applications information the gnd pin of the ds4560 is also a heat sink for thedevice. this pin should be connected to a large trace or plane capable of dissipating heat from the device. package type package code document no. 8 so 21-0041 package information for the latest package outline information and land patterns, goto www.maxim-ic.com/packages . downloaded from: http:///
ds4560 12v hot-plug switch 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. 8 _____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2009 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 6/08 initial release. 1 9/08 in the recommended operating conditions , changed the timer turn-on voltage (v on ) maximum specification from v cc + 0.3v to 5v. 2 2 5/09 added the ul certification number to the featres section. 1 downloaded from: http:///
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