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LTC4223-1/LTC4223-2 1 422312f typical application features applications description dual supply hot swap controller for advanced mezzanine card the ltc ? 4223 positive voltage hot swap tm controller allows a board to be safely inserted and removed from a live amc or microtca backplane. it controls the main 12v supply with an external n-channel mosfet and the 3.3v auxiliary supply with an integrated switch. the 12v output ramp rate is adjustable and includes inrush current limiting. the 12v output is also protected against short circuit faults with a fast acting current limit and a 5% accurate timed circuit breaker. the 3.3v output includes both soft start and overcurrent protection. the LTC4223 features a current monitor output for the 12v supply, and reports fault and power-good status for both supplies. it also detects card presence and allows independent control of the 12v and auxiliary 3.3v sup- ply outputs. the LTC4223-1 features a latch-off circuit breaker, while the LTC4223-2 provides automatic retry after a fault. advanced mezzanine card application allows safe insertion into live amc or microtca backplane controls 12v main and 3.3v auxiliary supplies limits peak fault current in 1s adjustable current limit with circuit breaker integrated 0.3 aux switch high side current sense gate drive for external n-channel mosfet adjustable response time for overcurrent protection adjustable supply voltage power-up rate thermal shutdown protection LTC4223-1: latch off after fault LTC4223-2: automatic retry after fault 16-lead ssop and 5mm 4mm dfn packages advanced mezzanine card, microtca systems workstations and server i/o telecom networks , lt, ltc and ltm are registered trademarks of linear technology corporation. all other trademarks are the property of their respective owners. normal power-up waveform 422312 ta01a 12v sense 12v gate 12v out 12v in v cc auxin auxout en auxon12on auxpgood 12pgood fault 12v 3.3v 6m si7336adp carrier connector moduleconnector timer LTC4223-1/LTC4223-2 gnd 12v7.4a 3.3v 150ma 10 51 330nf 0.1 f 47 15nf ipmc 12imon adc 20m s /div 12pgood 5v/div en 5v/div auxout 5v/div 12v out 5v/div auxpgood 5v/div 422312 ta01b downloaded from: http:///
LTC4223-1/LTC4223-2 2 422312f absolute maximum ratings supply voltages 12v in ..................................................... C0.3v to 20v auxin .................................................... C0.3v to 10v v cc ........................................................... C0.3v to 7v input voltages 12on, auxon, ? e ? n ................................... C0.3v to 7v timer ..........................................C0.3v to v cc + 0.3v 12v sense ............................................... C0.3v to 20v output voltages ? f ? a ? u ? l ? t, ? 1 ? 2 ? p ? g ? o ? o ? d, ? a ? u ? x ? p ? g ? o ? o ? d, 12imon ................................................... C0.3v to 7v (note 1) gn package 16-lead plastic ssop 12 3 4 5 6 7 8 top view 1615 14 13 12 11 10 9 12v sense 12v in 12imon 12on auxin v cc auxon gnd 12v gate 12v out 12pgoodfault auxout auxpgood en timer t jmax = 125c, ja = 110c/w 1615 14 13 12 11 10 9 17 12 3 4 5 6 7 8 12v gate 12v out 12pgoodfault auxout auxpgood en timer 12v sense 12v in 12imon 12on auxin v cc auxon gnd top view dhd package 16-lead (5mm 4mm) plastic dfn exposed pad (pin 17) pcb gnd connection optional must be soldered to pcb to obtain ja = 43c/w, otherwise ja = 140c/w, t jmax = 125c pin configuration order information 12v gate ................................................. C0.3v to 25v 12v out - 12v gate (note 3) ................... C4.5v to 0.3v auxout ................................................. C0.3v to 10v operating temperature range LTC4223-1c/ LTC4223-2c ....................... 0c to 70c LTC4223-1i/ LTC4223-2i ..................... C40c to 85c storage temperature range gn package ....................................... C65c to 150c dhd package ..................................... C65c to 125c lead temperature (soldering, 10sec) gn package ...................................................... 300c lead free finish tape and reel part marking* package description temperature range LTC4223cdhd-1#pbf LTC4223cdhd-1#trpbf 42231 16-lead (5mm 4mm) plastic dfn 0c to 70c LTC4223cdhd-2#pbf LTC4223cdhd-2#trpbf 42232 16-lead (5mm 4mm) plastic dfn 0c to 70c LTC4223idhd-1#pbf LTC4223idhd-1#trpbf 42231 16-lead (5mm 4mm) plastic dfn C40c to 85c LTC4223idhd-2#pbf LTC4223idhd-2#trpbf 42232 16-lead (5mm 4mm) plastic dfn C40c to 85c LTC4223cgn-1#pbf LTC4223cgn-1#trpbf 42231 16-lead plastic ssop 0c to 70c LTC4223cgn-2#pbf LTC4223cgn-2#trpbf 42232 16-lead plastic ssop 0c to 70c LTC4223ign-1#pbf LTC4223ign-1#trpbf 4223i1 16-lead plastic ssop C40c to 85c LTC4223ign-2#pbf LTC4223ign-2#trpbf 4223i2 16-lead plastic ssop C40c to 85c consult ltc marketing for parts speci? ed with wider operating temperature ranges. *the temperature grade is identi? ed by a label on the shipping container. consult ltc marketing for information on non-standard lead based ? nish parts. for more information on lead free part marking, go to: http://www.linear.com/leadfree/ for more information on tape and reel speci? cations, go to: http://www.linear.com/tapeandreel/ downloaded from: http:///
LTC4223-1/LTC4223-2 3 422312f electrical characteristics the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are t a = 25c, v cc = 3.3v, v auxin = 3.3v, v 12vin =12v, unless otherwise speci? ed. (note 2) symbol parameter conditions min typ max units supplies v dd input supply range v cc auxin12v in 2.72.7 10 66 14 vv v i dd input supply current v cc auxin12v in 0.80.4 0.6 21 1 mama ma v dd(uvlo) input supply undervoltage lockout v cc rising v auxin rising v 12vin rising 2.32.4 9.4 2.45 2.59.7 2.62.6 10 vv v v dd(uvlo, hyst) input supply undervoltage lockout hysteresis v cc auxin12v in 4070 70 110110 110 180150 150 mvmv mv current limit v sense(cb) circuit breaker trip sense voltage, (v 12vin C v 12vsense ) 47.5 50 52.5 mv v sense(acl) active current limit sense voltage, (v 12vin C v 12vsense ) 54 60 66 mv i aux(acl) auxout active current limit v auxout = 0v 165 240 330 ma integrated switchr ds(on) switch resistance(v auxin C v auxout )/i auxout i auxout = 150ma (note 4) 0.3 0.5 gate drive v gate external n-channel gate drive(v 12vgate C v 12vout ) (note 3) 4.5 6.2 7.9 v i gate(up) external n-channel gate pull-up current gate drive on, v 12vgate = 0v C7 C10 C14 a i gate(dn) external n-channel gate pull-down current gate drive off v 12vgate = 17v, v 12vout = 12v 0.5 1 2 ma i gate(fpd) external n-channel gate fast pull-down current fast turn off v 12vgate = 17v, v 12vout = 12v 90 160 250 ma current senseg 12imon 12imon pin gain ratio v 12imon / (v 12vin C v 12vsense ) (v 12vin C v 12vsense ) = (75mv, 25mv) 30 33 36 v/v v 12imon 12imon pin output voltage (v 12vin C v 12vsense ) = 75mv, v cc = 2.7v 2.25 2.475 2.7 v v sense(max) 12imon pin maximum input sense voltage 82.5 mv v 12imon(clp) 12imon pin clamp voltage (v 12vin C v 12vsense ) = 150mv, v cc = 2.7v 2.9 3.2 3.5 v r 12imon 12imon pin output resistance (v 12vin C v 12vsense ) = 0v 115 165 215 k v 12imon(min) 12imon pin minimum output voltage (v 12vin C v 12vsense ) = 0v 0 130 mv comparator inputsv pg(th) power good threshold voltage v 12vout falling v auxout falling 10 2.8 10.3 2.885 10.62.97 vv v pg(hyst) power good hysteresis v 12vout v auxout 20 5 6016 110 30 mvmv v tmr(th) timer pin threshold voltage v timer rising v timer falling 1.198 0.15 1.235 0.2 1.272 0.25 vv downloaded from: http:///
LTC4223-1/LTC4223-2 4 422312f symbol parameter conditions min typ max units i tmr(up) timer pull-up current v timer = 1v, initial timing cycle v timer = 0v, in aux fault mode v timer = 0v, in 12v fault mode C7C7 C140 C10C10 C200 C13C13 C260 aa a i tmr(dn) timer pull-down current v timer = 2v, no faults v timer = 2v, in reset mode 1.3 2 28 2.6 16 a ma open drain outputsv ol output low voltage ( ? f ? a ? u ? l ? t, ? 1 ? 2 ? p ? g ? o ? o ? d, ? a ? u ? x ? p ? g ? o ? o ? d) i ol = 3ma 0.15 0.4 v v oh output high voltage ( ? f ? a ? u ? l ? t, ? 1 ? 2 ? p ? g ? o ? o ? d, ? a ? u ? x ? p ? g ? o ? o ? d) (note 5) v cc C 1 v i pu output pin pull-up current ( ? f ? a ? u ? l ? t, ? 1 ? 2 ? p ? g ? o ? o ? d, ? a ? u ? x ? p ? g ? o ? o ? d) v pu = 1.5v C6 C10 C14 a logic inputsv in(th) logic input threshold (12on, auxon, ? e ? n) 0.8 2 v i in(leak) input leakage current (12on, auxon) v in = v cc 1 a r pu ? e ? n pin pull-up resistance 60 100 140 k other pin functionsi 12vsense 12v sense pin input current v 12vsense = 12v 10 50 100 a i 12vout 12v out pin input current gate drive on, v 12vout = 12v 20 50 100 a r out(dis) out pin discharge resistance12v out auxout gate drive offv 12vout = 6v v auxvout = 2v 400375 800750 16001500 ? propagation delayst cb aux circuit breaker trip delay after power up 12 25 50 s t phl(sense) sense voltage, (12v in C 12v sense ) high to 12v gate low v sense = 300mv, c 12vgate = 10nf v sense = 100mv, c 12vgate = 10nf 0.5 5 1 12 ss t phh(auxon) auxon high to auxout high 15 30 s t phh(12on) 12on high to 12v gate high 30 60 s t rst(on) input low (12on, auxon) to ? f ? a ? u ? l ? t high 20 40 s t rst(vcc) v cc low to ? f ? a ? u ? l ? t high 80 150 s t pll(uvlo) 12v in low to 12v gate low 61 21 8 s auxin low to ? a ? u ? x ? p ? g ? o ? o ? d high 61 21 8 s t phl(gate) ? e ? n high to 12v gate low 20 40 s t plh(pg) 12v out low to ? 1 ? 2 ? p ? g ? o ? o ? d high 20 40 s auxout low to ? a ? u ? x ? p ? g ? o ? o ? d high 20 40 s t p(12imon) input sense voltage step to 12imon propagation delay v sense = 100mv 26 s note 1: stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2: all currents into device pins are positive; all currents out of the device pins are negative. all voltages are referenced to gnd unless otherwise speci? ed. note 3: an internal clamp limits the 12v gate pin to a minimum of 4.5v above 12v out . driving this pin to voltages beyond the clamp may damage the device.note 4: for the dfn package, the aux switch on resistance, r ds(on) limit is guaranteed by correlation to wafer test measurements.note 5: the output pins ? f ? a ? u ? l ? t, ? 1 ? 2 ? p ? g ? o ? o ? d and ? a ? u ? x ? p ? g ? o ? o ? d have an internal pull-up to v cc of 10a. however, an external pull-up resistor may be used when faster rise time is required or for v oh voltages greater than v cc . electrical characteristics the denotes the speci? cations which apply over the full operating temperature range, otherwise speci? cations are t a = 25c, v cc = 3.3v, v auxin = 3.3v, v 12vin =12v, unless otherwise speci? ed. (note 2) downloaded from: http:///
LTC4223-1/LTC4223-2 5 422312f v cc (v) 2.5 0 i cc (ma) 0.4 0. 8 1.2 1.6 3.0 3.5 4.0 4.5 422312 g01 5.0 5.5 6.0 temperature ( c) ?50 0 s upply current (ma) 0.2 0.4 0.6 0. 8 1.0 ?25 02 55 0 422312 g02 75 100 12v in v cc auxin temperature ( c) 12imon gain ratio (v/v) 422312 g03 ?50 31 32 33 34 35 ?25 0 25 50 70 100 s en s e voltage (mv) 0 0 12imon output voltage (v) 1 2 3 4 20 40 60 8 0 422312 g04 100 120 140 temperature ( c) 12v out power-good thre s hold (v) 422312 g05 ri s ing falling ?50 10.0 10.1 10.2 10.3 10.4 ?25 0 25 50 75 100 temperature ( c) auxout power-good thre s hold (v) 422312 g06 ri s ing falling ?50 2. 8 4 2. 8 6 2. 88 2.90 2.92 ?25 0 25 50 75 100 temperature ( c) circuit breaker trip voltage (mv) 422312 g07 ?50 4 8 49 50 51 52 ?25 0 25 50 75 100 temperature ( c) active current limit s en s e voltage (mv) 422312 g0 8 ?50 5 8 59 60 61 62 ?25 0 25 50 75 100 temperature ( c) ?50 200 aux active current limit (ma) 210 220 230 240 250 ?25 02 55 0 422312 g09 75 100 typical performance characteristics i cc vs v cc supply current vs temperature 12imon gain ratio vs temperature 12imon output voltage vs sense voltage 12v out power-good threshold vs temperature auxout power-good threshold vs temperature circuit breaker trip voltage vs temperature active current limit sense voltage vs temperature aux active current limit vs temperature speci? cations are t a = 25c, v cc = 3.3v, v auxin = 3.3v, v 12vin =12v, unless otherwise speci? ed. downloaded from: http:///
LTC4223-1/LTC4223-2 6 422312f temperature ( c) aux s witch-on re s i s tance ( ) 422312 g10 ?50 0.1 0.2 0.3 0.4 0.5 ?25 0 25 50 75 100 temperature ( c) gate drive ( ? v gate ) (v) 422312 g11 ?50 5.9 6.0 6.1 6.2 6.3 ?25 0 25 50 75 100 i gate ( a) 0 76 5 4 3 2 1 0 ?6 ?10 422312 g12 ?2 ?4 ? 8 ?12 gate drive ( ? v gate ) (v) temperature ( c) gate pull-up current ( a) 422312 g13 ?50 ?9.0 ?9.5 ?10.0 ?10.5 ?11.0 ?25 0 25 50 75 100 temperature ( c) ?50 15 aux circuit breaker trip delay ( s ) 20 25 30 ?25 02 55 0 422312 g14 75 100 s en s e voltage (mv) 0.1 active current limit delay ( s ) 1 10 100 50 150 200 250 0.01 100 300 422312 g15 temperature ( c) gate fa s t pull-down current (ma) 422312 g16 ?50 50 100 150 200 250 ?25 0 25 50 75 100 temperature ( c) ?50 200 output di s charge re s i s tance ( ) 400 600 8 00 1000 1200 ?25 02 55 0 422312 g17 75 100 auxout 12v out v cc (v) 2.5 logic input thre s hold (v) 2.0 2.5 3.0 4.0 5.0 422312 g18 1.5 1.0 3.0 3.5 4.5 5.5 6.0 0.5 0 low high typical performance characteristics aux switch on resistance vs temperature gate drive vs temperature gate drive vs i gate gate pull-up current vs temperature aux circuit breaker trip delay vs temperature active current limit delay vs sense voltage gate fast pull-down current vs temperature output discharge resistance vs temperature logic input threshold vs v cc speci? cations are t a = 25c, v cc = 3.3v, v auxin = 3.3v, v 12vin =12v, unless otherwise speci? ed. downloaded from: http:///
LTC4223-1/LTC4223-2 7 422312f pin functions 12v sense (pin 1): 12v current sense input. connect this pin to the output of the current sense resistor. the electronic circuit breaker trips if the voltage across the sense resistor exceeds 50mv for more than a fault ? lter delay. 12v in (pin 2): 12v supply input. undervoltage lockout disables the 12v supply until the input at 12v in exceeds 9.7v. 12imon (pin 3): 12v current sense monitoring output. this pin monitors the sense voltage between 12v in and 12v sense . the gain ratio between this pins voltage and the sense voltage is 33.12on (pin 4): 12v supply on control digital input. a ris- ing edge turns on the external n-channel mosfet if ? e ? n is pulled low and a falling edge turns it off. a high-to-low transition on this pin will clear the 12v supply faults. auxin (pin 5): auxiliary supply input. an internal 0.3 switch is connected between auxin and auxout pins. undervoltage lockout holds the switch off until the input at auxin exceeds 2.5v. v cc (pin 6): bias supply input. this pin provides power to the devices internal circuitry and operates from 2.7v to 6v. undervoltage lockout circuit disables the device until the input at v cc exceeds 2.45v. bypass with 330nf. auxon (pin 7): auxiliary supply on control digital input. a rising edge turns on the internal switch if ? e ? n is pulled low and a falling edge turns it off. a high-to-low transi- tion on both this pin and 12on pin will clear the auxiliary supply faults. gnd (pin 8): device ground. timer (pin 9): timer capacitor terminal. connect a capacitor between this pin and ground to set a 741ms/f duration for initial timing cycle, 123ms/f for aux current limit during power-up and 6ms/f duration for 12v current limit before the external mosfet is turned off. ? e ? n (pin 10): enable input intended for card presence detect. ground this pin to enable the external n-channel mosfet and internal switch to turn on. if this pin is pulled high, the switches are not allowed to turn on. an internal 100k resistor pulls up this pin. a high-to-low transition will clear faults. ? a ? u ? x ? p ? g ? o ? o ? d (pin 11): auxiliary supply power status output. open drain output that is normally pulled high by an internal 10a current source or an external pull-up resistor to v cc . it pulls low when the auxout pin voltage exceeds the power-good threshold of 2.901v. auxout (pin 12): auxiliary supply output. this pin is the output from the internal switch connected between auxin and auxout pins. it signals ? a ? u ? x ? p ? g ? o ? o ? d low when it exceeds 2.901v. a 750 active pull-down discharges auxout to ground when the internal switch is turned off. ? f ? a ? u ? l ? t (pin 13): auxiliary and 12v supply fault status output. open drain output that is normally pulled high by an internal 10a current source or an external pull-up resistor to v cc . it pulls low when the circuit breaker is tripped due to an overcurrent fault on auxiliary or 12v supply. ? 1 ? 2 ? p ? g ? o ? o ? d (pin 14): 12v supply power status output. open drain output that is normally pulled high by an in- ternal 10a current source or an external pull-up resistor to v cc . it pulls low when the 12v out pin voltage exceeds the power-good threshold of 10.36v. 12v out (pin 15): 12v gate drive return and power-good input. connect this pin to the source of the external n- channel mosfet for gate drive return. this pin signals ? 1 ? 2 ? p ? g ? o ? o ? d low when it exceeds 10.36v. when the external mosfet is turned off, 12v out is discharged to ground through a 800 active pull-down. 12v gate (pin 16): gate drive for 12v supply external n- channel mosfet. an internal 10a current source charges the gate of the external n-channel mosfet. an internal clamp limits the gate voltage to 6.2v above 12v out . a resistor and capacitor network from this pin to ground sets the turn-on rate and compensates the active current limit. during turn-off, a 1ma pull-down current discharges 12v gate to ground. during short circuit or undervoltage lockout, a 160ma pull-down current between 12v gate and 12v out is activated. exposed pad (pin 17, dhd package): exposed pad may be left open or connected to device ground. downloaded from: http:///
LTC4223-1/LTC4223-2 8 422312f functional diagram +? +? +? uvlo3 9.7v 12v in 2.45v uvlo2cp2 system control aux fault 12v fault charge pump v cc timer fault +? +? acl v cc 10 a 10 a 1ma +? 2.885v ecb 12v supply control 12v in 12v sense 60mv 12pgood 12v out 12imon 12v gate + ? 50mv + ? v cc 10 a v cc v cc 10 a v cc v cc 10 a 2 a 200 a r2 r out 165k 10 a aux supply control auxon aux fet on gnd auxin auxpgood mfet rsns 422312 fd thermal shutdown charge pump aux pwrgd pg1 +? 10.3v 12v pwrgd pg2 auxout +? uvlo1 2.5v0.2v auxin 6.2v gate driver en card presence +? a1 12on 12v fet on +? 1.235v cp1 r in 5k downloaded from: http:///
LTC4223-1/LTC4223-2 9 422312f operation the LTC4223 is designed to control the power on an ad- vanced mezzanine card (amc) or microtca backplane, allowing boards to be safely inserted and removed. it controls the 12v main and 3.3v auxiliary power through an external n-channel mosfet and integrated pass transistor. these two supplies can be turned on and off independently by their respective on control pins. if either auxon or 12on is pulled high, an initial tim- ing cycle set by the timer capacitor value is initiated once all these conditions are met: input supplies out of undervoltage lockout; timer < 0.2v and ? e ? n low. at the end of the initial timing cycle, if the auxon pin is high, the internal pass transistor turns on. it enters into an active current limit loop if the inrush current charging the load capacitor exceeds 240ma. when the load is in current limit, a 10a pull-up charges the timer pin capacitor. if the load capacitor is fully charged and the switch is no longer in current limit before the timer reaches 1.235v, ? a ? u ? x ? p ? g ? o ? o ? d pulls low indicating that power is good. otherwise the internal switch turns off and ? f ? a ? u ? l ? t pulls low when timer reaches 1.235v. if 12on pin is high at the end of the initial timing cycle, an internal charge pump charges the gate of the external mosfet with 10a pull-up. connecting an external gate capacitor limits the inrush current charging the load ca- pacitor. if the inrush current exceeds its limited current value, an internal analog current limit (acl) ampli? er servos the gate to force 60mv across the external sense resistor connected between 12vin and 12v sense pins. during this period, timer pin capacitor is charged by a 200a pull-up. if the load is fully charged and no longer in current limit before the timer reaches 1.235v, ? 1 ? 2 ? p ? g ? o ? o ? d pulls low. otherwise 12v shuts off and ? f ? a ? u ? l ? t pulls low when timer reaches 1.235v. if an overcurrent fault occurs on the auxiliary supply after power-up, the current is limited to 240ma and after a 25s delay, the circuit breaker trips and ? f ? a ? u ? l ? t pulls low. ther- mal shutdown protects the internal pass transistor from overheating by shutting it off at 150c. if an overcurrent fault occurs on the 12v supply, the current is limited to 60mv/r sense . after a timing cycle delay set by 200a charging the timer capacitor, the circuit breaker trips and ? f ? a ? u ? l ? t pulls low. an overcurrent fault on the auxiliary supply shuts off 12v; a fault on the 12v supply does not affect the auxiliary supply. the LTC4223 provides high side current sensing informa- tion for the 12v supply at the 12imon pin. the 12imon output voltage is 33 times the sense voltage, allowing it to be used with an external adc. in the off condition, 12v out and auxout are discharged to ground by internal n-channel pull downs. downloaded from: http:///
LTC4223-1/LTC4223-2 10 422312f the typical LTC4223 application is in a carrier board for advanced mezzanine cards (amc), delivering 3.3v auxiliary and 12v power to the amc module. a control- ler on the carrier board sequences the turn-on of power supplies and manages the fault and power-good reports from the LTC4223. the LTC4223 detects board presence during insertion and extraction, allowing power to be delivered in a controlled manner without damaging the connector. the typical LTC4223 application circuit is shown in figure 1. external component selection is discussed in detail in the design example section. applications information turn-on sequence the power supplies delivered to an amc module are controlled by the external n-channel pass transistor, q1 in the 12v power path and an internal pass transistor in the 3.3v auxiliary power path. sense resistor r s monitors the 12v load current for fault detection and current sensing information. gate capacitor c g provides gate slew rate control to limit the inrush current. resistor r g with c g compensates the current control loop while r3 prevents parasitic oscillations in q1. 422312 f01 12v out 12v sense 12v gate 12v in v cc auxin auxout en auxon12on auxpgood 12pgood fault 12v 5 21 1 6 1512 10 89 67 4 1113 3 58 23 4 76 1 14 3.3v r s 6m q1 si7336adp pwr mp ps1ps0 carrier amc connector module amc connector timer LTC4223-1 gnd 12v7.4a 3.3v 150ma r3 10 r251 mp enablepwr enable mp good pwr good fault c2330nf bulk supply bypass capacitor c t 0.1 f 1 f r g 47 c g 15nf 3.3v 3.3v intelligent platform management controller enable presence reset 12imon r4*10k 2.2k *optional 3.3v 10k r5*10k r6*10k 3.3v 3.3v 3.3v bulk supply bypass capacitor ltc1197l v ref clkd out cs +in?in v cc gnd 3 figure 1. advanced mezzanine card/microtca application downloaded from: http:///
LTC4223-1/LTC4223-2 11 422312f applications information several conditions must be met before the external and internal switches are allowed to turn on. first v cc and the input supplies (12v in , auxin) must exceed their undervoltage lockout thresholds. next timer must be <0.2v and ? e ? n must be pulled low. once these conditions are met, a debounce timing cycle is initiated when auxon or 12on pin is toggled from low to high. these two control pins turn on/off the 3.3v auxiliary and 12v supplies. at the end of the debounce cycle, the on pins and fault status are checked. if both on pins are high and fault is cleared, the 3.3v auxiliary supply starts up ? rst followed by the 12v supply. note that the turn-on delay for the auxon and 12on pins is 15s and 30s. figure 2 shows the two supplies turning on in sequence after ? e ? n goes low. by default, the internal pass transistor turns on ? rst if both on pins are high and start-up conditions met. the output is current limited at 240ma by its internal acl ampli? er as the load current charging the output capaci- tor increases. this causes the timer to ramp up with a 10a pull-up. normally the auxout voltage exceeds its power-good threshold before timer time-out and then ? a ? u ? x ? p ? g ? o ? o ? d pulls low. once auxout signals power is good and the timer pin returns to <0.2v, the external mosfet is then allowed to turn on by charging up the gate with a 10a current source (figure 2). the voltage at the gate pin rises with a slope equal to 10a/c g and the supply inrush current ? owing into the load capacitor c l1 (see figure 14) is limited to: i c c a inrush l g = 1 10 ? the 12v output follows the gate voltage when the mosfet turns on. if the voltage across the current sense resistor r s becomes too high, the inrush current is limited by the internal current limit circuitry. once the output, 12v out exceeds its power-good threshold, ? 1 ? 2 ? p ? g ? o ? o ? d also pulls low. if only the 12on pin is high at the end of debounce cycle, the external mosfet turns on ? rst. after that, if auxon pulls high, the internal switch turns on only after the 12v output signals power is good and timer <0.2v. figure 2. normal power-up sequence table 1. 12v and auxiliary supply turn-off conditions condition result cleared by aux 12v auxon goes low turns off no effect auxon high 12on goes low no effect turns off 12on high ? e ? n goes high turns off turns off ? e ? n low uvlo on v cc turns off turns off v cc > uvlo uvlo on auxin turns off no effect auxin > uvlo uvlo on 12v in no effect turns off 12v in > uvlo aux overcurrent fault turns off turns off auxon and 12on low, ? e ? n high-to-low, uvlo on v cc 12v overcurrent fault no effect turns off 12on low, ? e ? n high-to- low, uvlo on v cc thermal shutdown turns off turns off auxon and 12on low, ? e ? n high-to-low, uvlo on v cc , temperature < 120c 20m s /div 12pgood 5v/div en 5v/div auxout 5v/div timer 2v/div 12v out 5v/div auxpgood 5v/div 422312 f02 downloaded from: http:///
LTC4223-1/LTC4223-2 12 422312f applications information turn-off sequence the switches can be turned off by various conditions and this is summarized in table 1. when the 12on pin goes low, the external switch is turned off with the gate pin pulled to ground by 1ma current sink. the ? 1 ? 2 ? p ? g ? o ? o ? d pin pulls high indicating that power is no longer good, while an internal n-channel transistor dis- charges the output to ground. similarly, when the auxon pin goes low, the internal switch is turned off, ? a ? u ? x ? p ? g ? o ? o ? d pulls high while its output is discharged to ground through an internal n-channel transistor. figure 3 shows the two supplies being turned off by ? e ? n going high. card presence detectin an amc system, ? p ? s ? 1 and ? p ? s ? 0 signals are used to detect the presence of a card upon insertion or removal. normally ? p ? s ? 1 is connected to the ? e ? n pin with a pull-up resistor. if auxon or 12on is high when the ? e ? n pin goes low, indicating a board insertion, a timing cycle for contact debouncing is initiated. upon insertion, any bounces on the ? e ? n pin will re-start the timing cycle. when timer ? nally reaches its threshold during ramp up, the fault latches will be cleared. if the ? e ? n pin remains low at the end of the timing cycle, the switches are allowed to turn on.if the ? e ? n pin is toggled from low to high, indicating board removal, all the switches will be turned off after a 20s delay. any latched faults will not be cleared. however, removing the card could cause the ? e ? n pin voltage to bounce, clearing the fault latches undesirably. this is prevented by blanking the bounces internally with a timer ramp up period given by c t ? 123[ms/f] as shown in figure 4. timer functions an external capacitor c t connected from the timer pin to ground is used to perform several functions. 1. ignore contact debouncing during card insertion when the device is enabled. the debounce cycle is given by ramping up c t with 10a current to timer high threshold (1.235v) and then ramping down with 2a current to below timer low threshold (0.2v). this gives an average debounce cycle time of c t ? 741[ms/f]. after that, if any on pin is pulled high and ? e ? n pin is low, the switches can be turned on. 2. blanking contact bounce on the ? e ? n pin that might trigger unwanted fault clearing during card removal. the blanking time is given by c t ? 123[ms/f]. 3. fault ? ltering during auxiliary supply power-up in analog current limit. timer pulls up with 10a and pulls down with 2a. the ? lter time is given by c t ? 123[ms/f]. 4. 12v supply fault ? ltering during and after power-up in analog current limit. timer pulls up with 200a and pulls down with 2a. the ? lter time is given by c t ? 6[ms/f]. 5. for cooling off during an auto-retry cycle after an overcurrent fault on auxiliary or 12v supply (LTC4223-2). the cool-off time is given by c t ? 1482 [ms/f] after an auxiliary supply fault and c t ? 1358[ms/ f] after a 12v supply fault. figure 3. normal power-down sequence figure 4. debouncing by timer during card removal 100m s /div 12pgood 5v/div en 5v/div auxout 5v/div 12v out 5v/div auxpgood 5v/div 422312 f03 5m s /div fault 2v/div en 2v/div timer 1v/div 422312 f04 downloaded from: http:///
LTC4223-1/LTC4223-2 13 422312f applications information as the timer capacitor is used for fault ? ltering during power-up for both the auxiliary and 12v supplies, only one supply can be started up at any one time. the other supply waits until the power-good signal is generated by the powering-up supply and the timer pin voltage falls below 0.2v. by default, the 3.3v auxiliary supply starts up ? rst if both auxon and 12on are high at the end of the debounce cycle. whenever both auxon and 12on are pulled low, the de- vice is in reset mode and timer capacitor is discharged to ground by an 8ma current sink. thermal shutdown the internal 3.3v auxiliary supply switch is protected by thermal shutdown. if the switchs temperature reaches 150c, the aux switch will shut off immediately and ? f ? a ? u ? l ? t will pull low. the external 12v supply switch also turns off. the switches are allowed to turn on again by cycling both the auxon and 12on pins low then high after the internal switchs temperature falls below 120c. overcurrent fault the LTC4223 features an adjustable current limit with circuit breaker function that protects the external mosfet against short circuits or excessive load current on 12v supply. the voltage across the external sense resistor is monitored by the analog current limit (acl) ampli? er and the electronic circuit breaker (ecb) comparator. if an overcurrent fault occurs that causes the sense voltage to reach the acl threshold (60mv), the acl ampli? er regulates the mosfet to prevent any further increase in current. this overcurrent condition results in a sense voltage that exceeds the ecb threshold. as a result, the timer capacitor is charged by a 200a current. if the condition persists, the timer pin voltage will reach its threshold (1.235v). when this occurs, the ? f ? a ? u ? l ? t pin pulls low and a 1ma current pulls the gate pin to ground causing the mosfet to turn off. the circuit breaker time delay, the time required for the timer pin capacitor to charge from ground to the timer pin threshold, is given by c t ? 6[ms/f]. after the mosfet turns off, the timer pin capacitor dis- charges with a 2a pull-down current. for the auto-retry version (LTC4223-2), if the timer discharges to below 0.2v, a new start-up cycle will begin. the timer starts ramping up and clears faults when it exceeds 1.235v; thereafter it ramps down (see the section on auto-retry for details). figure 5 shows an overcurrent fault on the 12v output. in the event of a severe short-circuit fault on 12v output as shown in figure 6, the output current can surge to tens of amperes. the LTC4223 responds within a very short time to bring the current under control by pulling the mosfets gate-to-source pin voltage down to zero volts. thereafter, the gate of the mosfet recovers rapidly due to the r g /c g compensation network and enters into active current limiting until the timer times out. due to parasitic supply lead inductance, an input supply without any bypass capacitor will collapse during the high cur- rent surge and then spike upwards when the current is interrupted. an input supply transient protection network comprising of z1, r1 and c1 shown in figure 13 is recom- mended if there is no input capacitance. figure 5. overcurrent fault on 12v output 0.1m s /div 12v gate 5v/div fault 5v/div 12v out 5v/div 422312 f05 i load 5a/div downloaded from: http:///
LTC4223-1/LTC4223-2 14 422312f applications information there are two different modes of fault time-out for the 3.3v auxiliary supply: adjustable delay through timer capacitor during power-up when ? a ? u ? x ? p ? g ? o ? o ? d not asserted; ? xed 25s delay after power-up when ? a ? u ? x ? p ? g ? o ? o ? d asserted low. under the situation whereby auxon toggles low then high for short duration after power-up while ? a ? u ? x ? p ? g ? o ? o ? d still pulling low due to output load capacitor, 25s fault time-out applies. when the auxiliary supply is powered up into an output short, the acl ampli? er will regulate the gate of the internal pass transistor to produce 240ma output cur- rent. at this time a 10a pull-up current starts charging up the timer pin capacitor until it exceeds its threshold (1.235v). the internal pass transistor then turns off and ? f ? a ? u ? l ? t pulls low. thereafter, the timer is discharged by a 2a pull-down current. the fault ? lter delay is given by c t ? 123[ms/f]. after a successful power-up cycle, the acl ampli? er pro- tects the auxiliary supply from overcurrent by pulling down the gate of the internal pass transistor rapidly as shown in figure 7. thereafter, the gate recovers and servos the output current to about 240ma for 25s before pulling down to ground gently, turning the transistor off. at this time, ? f ? a ? u ? l ? t pulls low and the 12v external mosfet is also turned off by the 1ma gate pull-down current. whenever the 3.3v auxiliary supply trips off due to an overcurrent fault, the 12v supply also shuts off. the auxiliary supply is, however, unaffected by faults on the 12v supply. in either case ? f ? a ? u ? l ? t latches low when the affected channels turn off, and ? f ? a ? u ? l ? t is cleared by tog- gling the on pins. faults are cleared automatically in the LTC4223-2 auto-retry version. if there is signi? cant supply lead inductance, a severe output short may collapse the input to ground before the LTC4223 can bring the current under control. in this case the undervoltage lockout will activate after a 12s ? lter delay, and pull the gate down. then the acl ampli? er will take control and regulate the output in active current limit. under this situation, the fault time-out is set by timer delay instead of 25s ? lter delay. undervoltage fault an undervoltage fault occurs if either auxin or 12v in falls below its undervoltage threshold for longer than 12s. this turns off the affected supplys switch instantly, but does not clear the fault latches. further, an undervoltage fault on one supply does not affect the operation of the other supply. if the bias supply input, v cc falls below its uvlo threshold for more than 80s, all supply switches are turned off and the fault latches are cleared. operation resumes from a fresh start-up cycle when v cc is restored. figure 7. short-circuit fault on 3.3v aux output figure 6. short-circuit fault on 12v output 5 s /div 12v gate 5v/div 12v out 5v/div 422312 f06 ? v s en s e 200mv/div 5 s /div auxout 5v/div fault 5v/div 422312 f07 i load 1a/div downloaded from: http:///
LTC4223-1/LTC4223-2 15 422312f applications information power-good monitor internal circuitry monitors the output voltages, auxout and 12v out . the power-good status is reported via their respective open drain outputs, ? a ? u ? x ? p ? g ? o ? o ? d and ? 1 ? 2 ? p ? g ? o ? o ? d. several conditions must be met before the power-good outputs assert low. 1. the monitored output should be above its power- good threshold and hysteresis. 2. the input supply is above undervoltage lockout. 3. ? e ? n is low. 4. the associated on pin is high.5. thermal shutdown is not activated. if any of the supply outputs falls below its power-good threshold for more than 20s, the respective power-good output will be pulled high by the external pull-up resistor or internal 10a pull-up. resetting faults (LTC4223-1) any supply faults tripping the circuit breaker are latched and ? f ? a ? u ? l ? t asserts low. for the latched-off version (LTC4223-1), to reset a fault latch due to overcurrent or thermal shutdown on auxiliary supply, pull both auxon and 12on pins low together for at least 100s, after which the ? f ? a ? u ? l ? t will go high. toggling both the on pins high together again initiates the debounce timing cycle, thereafter the auxiliary supply starts up ? rst followed by 12v supply. to skip the debounce timing cycle, ? rst pull only auxon low then high for at least 50s before toggling 12on low then high. the fault latch clears on the falling edge of 12on and the auxiliary supply powers up. thereafter, the 12v supply powers up if 12on pulls high. to reset a fault on the 12v supply and re-start the output, toggle only the 12on pin low and then high again. tog- gling the ? e ? n pin high then low again or bringing the bias input, v cc below its uvlo threshold for more than 100s will initiate the debounce timing cycle and reset all fault latches before power-up. bringing auxin or 12v in below its undervoltage threshold will not reset the fault latches. for the auto-retry version (LTC4223-2), the latched fault will be cleared automatically after a cool-off timing cycle. auto-retry after a fault (LTC4223-2) at time point 1 in figure 8, if a fault latched-off the 3.3v auxiliary supply after power-up, a cool-off cycle begins. the timer capacitor charges up to 1.235v with a 10a current and then discharges with a 2a current to 0.2v at time point 3. this is followed by a debounce timing cycle whereby the fault latch is cleared, and ? f ? a ? u ? l ? t pulls high when timer reaches its threshold at time point 4. at the end of debounce cycle, the internal switch is allowed to turn on. if the output short persists, the auxiliary supply powers up into a short with active current limiting. at time point 7, the fault ? lter delay begins with timer ramping up with a 10a current. if the timer times out at time point 8, ? f ? a ? u ? l ? t will be pulled low and a new cool-off cycle begins with timer ramping down with a 2a current. the whole process repeats itself until the output-short is removed. in figure 9, a fault latches off the 12v supply at time point 1; a cool-off cycle begins by discharging the timer ca- pacitor with 2a current from 1.235v to 0.2v threshold. at time point 2 a new debounce timing cycle is initiated where the fault latch is cleared, and ? f ? a ? u ? l ? t pulls high when timer reaches its threshold at time point 3. at the end of the debounce cycle, the 12v gate is allowed to start up. if the output short persists, the 12v supply powers up into a short with active current limiting. at time point 6, the fault ? lter delay begins with timer ramping up with a 200a current. the timer times out at time point 7, ? f ? a ? u ? l ? t pulls low and a new cool-off cycle begins with timer ramping down with a 2a current. the whole process repeats itself until the output-short is removed. the auto-retry duty cycle is given by: dutycycle t tt t filter cool debounce filt = ++ ?% 100 e er for example, if timer capacitor, c t = 0.1f, the auto-retry duty cycle for auxiliary and 12v supply is 6.5% and 0.5% respectively. downloaded from: http:///
LTC4223-1/LTC4223-2 16 422312f applications information gate pin voltage the gate drive at 12v gate is compatible with any logic level mosfet. the guaranteed range of gate drive is 4.5v to 7.9v, with a typical of 6.2v. active current loop compensation the compensation network consisting of resistor r g and gate slew rate control capacitor c g stabilizes the internal active current limit circuit. the value of c g is selected based on the inrush current allowed. the suggested value for r g is 47 . the value of c g should be 330nf and r g is between 10 and 100 for optimum performance. high side current sensethe 12v load current is monitored via the voltage across an external sense resistor. the LTC4223 features a high side current sense ampli? er that translates the sense voltage from the positive rail to the negative rail using a resistor ratio of 33 times. the output voltage at 12imon pin can then be fed into an ltc1197l adc as shown in figure 10 for data conversion. the current sense information can be used by the system controller to manage the power budget allocated to the modules on the card. full scale input to the current sense ampli? er is 82.5mv, corresponding to an output of about 2.7v. if the input exceeds 100mv, the output clamps at 3.2v. v cc supply filtering the internal circuitry of the LTC4223 is powered from the v cc pin. bypass v cc with at least 330nf to ground. if v cc is derived from the same supply as is auxin, include a decoupling resistor as shown in figure 11. this rc net- work allows the v cc pin to ride out supply glitches caused by short circuits on the auxiliary output or on adjacent boards, thus preventing an undervoltage lockout condi- tion on v cc . since the absolute maximum rating for v cc is 7v as compared to 10v for auxin, select r2 and c2 to keep the peak voltage seen by v cc below 7v during any voltage spikes. fault timer i auxout 12v out v tmr v tmr v tmr v tmr 422312 f08 10 a 12 34 5678 9 1 0 2 a fault pulls low due to auxovercurrent fault after power up start of cool-off cycle start of debounce cycle reset fault high fault pulls low and restart ofcool-off cycle during power up end of debounce cycle start aux internal gate ramp when startup conditions are met aux output in current limit restart of debounce cycle cool-off cycle debounce cycle filter delay cool-off cycle 2 a2 a2 a 10 a1 0 a1 0 a1 0 a aux internal gate regulates figure 8. auto-retry after aux overcurrent fault downloaded from: http:///
LTC4223-1/LTC4223-2 17 422312f applications information supply transient protection the supply inputs, auxin and 12v in are fed directly from the regulated output of the backplane supply, where bulk bypassing assures a spike-free operating environment. in other applications where the bulk bypassing is located far from the LTC4223, spikes generated during output short circuit events could exceed the absolute maximum ratings for auxin and 12v in . to minimize such spikes, use wider traces or heavier trace plating to reduce the power trace inductance. also, bypass locally with a 10f electrolytic and 100nf ceramic, or alternatively clamp the input with a transient voltage suppressor (z1, z2) as shown in figure 13. a 10 , 100nf snubber damps the response and eliminates ringing. a recommended layout of the 12v transient protection devices z1, r1 and c1 around the LTC4223 is shown in figure 12. figure 9. auto-retry after 12v overcurrent fault fault timer 12v gate 12v out v tmr v tmr v tmr 422312 f08 12v in - 12v sense 200 a 60mv 60mv 12 34 5 6 78 2 a fault pulls low due to12v overcurrent fault start of cool-off cycle start of debounce cycle reset fault high fault pulls low andrestart of cool-off cycle end of debounce cycle start 12v gate ramp when startup conditions are met 12v output in current limit restart ofdebounce cycle cool-off cycle debounce cycle filter delay cool-off cycle 2 a2 a 10 a 200 a1 0 a 12v gate regulates 422312 f10 12v sense v sense ? + q1 LTC4223 12v in 12v gate v out 12imon i load r in 5k 12v to systemcontroller cs 1 f 3.3v ltc1197l v ref clk d out +in?in v cc gnd ? + r out 165k v out = ? v sense = 33 ? v sense r out r in load figure 10. high side current sense with ltc1197l adc downloaded from: http:///
LTC4223-1/LTC4223-2 18 422312f the ? rst step is to select the appropriate value of r sense for the 12v supply. calculating r sense value is based on the maximum load current and the lower limit for the circuit breaker threshold, v sense(cb)(min) . r v i mv sense sense cb min load max = = ()( ) () . . 47 5 74 aa m = 6 if a 1% tolerance is assumed for the 6m sense resistor, the minimum and maximum circuit breaker trip current is calculated as follows: 422312 f11 c2330nf v cc auxin r2 51 figure 11. rc network for v cc filtering applications information pcb layout considerations for proper operation of the LTC4223s circuit breaker, kelvin-connection to the sense resistor is strongly rec- ommended. the pcb layout should be balanced and symmetrical to minimize wiring errors. in addition, the pcb layout for the sense resistor and the power mosfet should include good thermal management techniques for optimal device power dissipation. a recommended pcb layout for the 12v sense resistor and the power mosfet is illustrated in figure 12. in applications where load current exceeds 10a, wide pcb traces are recommended to minimize resistance and temperature rise. the suggested trace width for 1 oz copper foil is 0.03 for each ampere of dc current to keep pcb trace resistance, voltage drop and temperature rise to a minimum. note that the sheet resistance of 1 oz copper foil is approximately 0.5m /square, and voltage drops due to trace resistance add up quickly in high cur- rent applications. in most applications, it will be necessary to use plated- through via to make circuit connections from component layers to power and ground layers internal to the pcb. for 1 oz copper foil plating, a general rule is 1a of dc current per via. consult your pcb fabrication facility for design rules pertaining to other plating thicknesses. it is important to place the v cc bypass capacitor c2 as close as possible between v cc and gnd. the transient voltage suppressors z1 and z2 are also placed between the supply inputs and ground using short wide traces. design example as a design example, consider the amc hot swap ap- plication shown earlier in figure 1 with the power supply requirements given in table 2. current flow to load track width w: 0.03" per ampere on 1oz cu foil sense resistor power pak so-8 12v out 12v in gnd422312 f12 gnd c g 12v gate via tognd plane 16 12 15 LTC4223cgn* ? ? current flow to load w current flow to source *additional details omitted for clarity, drawing not to scale! via tognd plane w w r g r3 r1 z1 c1 8 figure 12. recommended layout for power mosfet, sense resistor and gate components on 12v rail table 2. amc power supply requirements supply voltage maximum load current maximum load capacitance 12v 7.4a 800f 3.3v aux 150ma 150f table 3. microtca power supply requirements supply voltage maximum load current maximum load capacitance 12v 7.6a 1600f 3.3v aux 150ma 150f downloaded from: http:///
LTC4223-1/LTC4223-2 19 422312f p cv t avg l out charge = 1 2 12 2 ? ? the inrush current can be limited by using the gate ca- pacitance (c g ) so that the power dissipated in the mosfet is well within its safe operating area (soa). for i gate = 10a and c l1 = 800f, we choose c g = 15nf to set the inrush current to 0.5a. i ci c a t cv i inrush lgate g charge l out == = 1 1 05 12 ? . ? i inrush ms = 19 this results in p avg = 3w and the mosfet selected must be able to tolerate 3w for 19ms. the increase in steady state junction temperature due to power dissipated in the mosfet is t = p avg ? z th where z th is the thermal impedance. under this condition, the si7336adp datasheets tran- sient thermal impedance plot indicates that the junction temperature will increase by 2.4c using z thjc = 0.8c/w (single pulse).the duration and magnitude of the power pulse that results during a short-circuit condition on the 12v output are a function of the timer capacitance and LTC4223s analog current limit. the short-circuit duration is given as 0.1f ? 6[ms/f] = 600s for c t = 0.1f. the maximum short- circuit current is calculated using the maximum analog current limit threshold, v sense(acl)(max) and minimum r sense value. i v r short max sense acl max sense min () () ( ) () = = 66 m mv m a 594 11 . = so the maximum power dissipated in the mosfet is 11a ? 12v or 132w for 600s. the si7336adp datasheets tran- sient thermal impedance plot indicates that the worse-case increase in junction temperature during the short-circuit condition is 13.2c using z thjc = 0.1c/w (single pulse). this will not cause the maximum junction temperature to be exceeded. the soa curves of the si7336adp are also checked to be safe under this condition. applications information i v r trip min sense cb min sense max () ()( ) () . = = 47 5 m mv m a i v r trip max sense cb max s 606 78 . . () ()( ) = = e ense min mv m a () . . . == 52 5 594 88 for proper operation, i trip(min) must exceed the maximum load current with margin, so r sense = 6m should suf? ce for the 12v supply. the second step is to determine the timer capacitance based on the time required to charge up completely the output load capacitor on auxiliary supply in active current limit without exceeding the fault ? lter delay. the worst- case start-up time is calculated using the minimum active current limit value for the auxiliary supply. t cv i f stup aux la u x aux acl min () () () ?. ? == 2 33 150 3 33 165 3 .v ma ms = for a start-up time of 3ms with a 2x safety margin, the timer capacitance is calculated as: c t ms f ms ms f t stup aux = [] = [] ? 2 123 6 123 00 ? // . () 5 5f considering the tolerances for the timer charging rate and capacitance, a value of 0.1f (10%) for c t should suf? ce. since the timer charging rate during fault time-out is 20 times faster for the 12v supply as compared to the auxiliary supply during start-up, this scheme ensures that the external mosfet will not overheat under any output- short condition. the fault ? lter delay for the 12v supply is given by 0.1f ? 6[ms/f] = 600s versus 12ms for the auxiliary supply. the next step is to verify that the thermal ratings of the selected external mosfet for the 12v supply arent ex- ceeded during power-up or an output-short. assuming the mosfet dissipates power only due to inrush current charging the load capacitor, the energy dissipated in the mosfet during power-up is the same as that stored into the load capacitor. the average power dissipated in the mosfet is given by: downloaded from: http:///
LTC4223-1/LTC4223-2 20 422312f typical application c l1 1000 f 5v 5v r410k 5v r510k 12v10a 5v aux 150ma 12v out 12v sense 12v gate 12v in v cc auxin auxout 12imon faultauxon 12on en auxpgood 12pgood r s 4m q1 si7336adp 12v 5v backplane connector card connector timer LTC4223-1 gnd r3 10 r251 c2330nf c t 0.1 f r g 47 c g 15nf pwrflt r610k r72.7 c3100nf r810k bd_sel gnd pwren r110 z1 smaj13a 422312 ta02 to systemcontroller cs 1 f c1100nf ltc1197 v cc clk d out +in?in v ref gnd z2 smaj7.0a + c l2 150 f + card resident application with 5v auxiliary supply downloaded from: http:///
LTC4223-1/LTC4223-2 21 422312f c l1 1000 f 3.3v 3.3v r410k 12v10a 3.3v aux 150ma 12v out 12v sense 12v gate 12v in v cc auxin auxout 12imon 12onauxon 12pgood fault en auxpgood r s 4m q1 si7336adp 12v 3.3v backplane connector card connector timer LTC4223-1 gnd r3 10 c t 0.1 f r g 47 c g 15nf pwren pwrflt gnd bd_sel r110 r510k r910k z1 smaj13a 422312 ta03 to systemcontroller 3.3v 3.3v cs 1 f c1100nf ltc1197l v cc clk d out +in?in v ref gnd q2 2n7002k + c l2 150 f + r610k 3.3v r8 10k r251 c2330nf r72.7 c3100nf z2 smaj5.0a card resident application with 12v power up first followed by 3.3v auxiliary typical application downloaded from: http:///
LTC4223-1/LTC4223-2 22 422312f gn16 (ssop) 0204 12 3 4 5 6 7 8 .229 ? .244 (5.817 ? 6.198) .150 ? .157** (3.810 ? 3.988) 16 15 14 13 .189 ? .196* (4.801 ? 4.978) 12 11 10 9 .016 ? .050 (0.406 ? 1.270) .015 .004 (0.38 0.10) 45 0 ? 8 typ .007 ? .0098 (0.178 ? 0.249) .0532 ? .0688 (1.35 ? 1.75) .008 ? .012 (0.203 ? 0.305) typ .004 ? .0098 (0.102 ? 0.249) .0250 (0.635) bsc .009 (0.229) ref .254 min recommended solder pad layout .150 ? .165 .0250 bsc .0165 .0015 .045 .005 *dimension does not include mold flash. mold flash shall not exceed 0.006" (0.152mm) per side **dimension does not include interlead flash. interlead flash shall not exceed 0.010" (0.254mm) per side inches (millimeters) note:1. controlling dimension: inches 2. dimensions are in 3. drawing not to scale package description gn package 16-lead plastic ssop (narrow .150 inch) (reference ltc dwg # 05-08-1641) downloaded from: http:///
LTC4223-1/LTC4223-2 23 422312f information furnished by linear technology corporation is believed to be accurate and reliable. however, no responsibility is assumed for its use. linear technology corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. package description 4.00 0.10 (2 sides) 5.00 0.10 (2 sides) note:1. drawing proposed to be made variation of version (wjgd-2) in jedec package outline mo-229 2. drawing not to scale 3. all dimensions are in millimeters 4. dimensions of exposed pad on bottom of package do not include mold flash. mold flash, if present, shall not exceed 0.15mm on any side 5. exposed pad shall be solder plated 6. shaded area is only a reference for pin 1 location on the top and bottom of package 0.40 0.10 bottom view?exposed pad 2.44 0.10 (2 sides) 0.75 0.05 r = 0.115 typ r = 0.20 typ 4.34 0.10 (2 sides) 1 8 16 9 pin 1 top mark (see note 6) 0.200 ref 0.00 ? 0.05 (dhd16) dfn 0504 0.25 0.05 pin 1notch 0.50 bsc 4.34 0.05 (2 sides) recommended solder pad pitch and dimensions 2.44 0.05 (2 sides) 3.10 0.05 0.50 bsc 0.70 0.05 4.50 0.05 packageoutline 0.25 0.05 dhd package 16-lead plastic dfn (5mm 4mm) (reference ltc dwg # 05-08-1707) downloaded from: http:///
LTC4223-1/LTC4223-2 24 422312f linear technology corporation 1630 mccarthy blvd., milpitas, ca 95035-7417 (408) 432-1900 fax: (408) 434-0507 www.linear.com ? linear technology corporation 2007 lt 0807 printed in usa related parts typical application part number description comments ltc1421 dual channel, hot swap controller operates from 3v to 12v, supports C12v, ssop-24 ltc1645 dual channel, hot swap controller operates from 3v to 12v, power sequencing, so-8 or so14 ltc1647-1/ltc1647-2/ ltc1647-3 dual channel, hot swap controller operates from 2.7v to 16.5v, so-8 or ssop-16 ltc4210 single channel, hot swap controller operates from 2.7v to 16.5v, active current limiting, sot23-6 ltc4211 single channel, hot swap controller operates from 2.7v to 16.5v, multifunction current control, msop-8 or msop-10 ltc4215 single channel, hot swap controller operates from 2.9v to 15v, i 2 c compatible monitoring, ssop-16 or qfn-24 (4mm 5mm) ltc4216 single channel, hot swap controller operates from 0v to 6v, msop-10 or dfn-12 (4mm 3mm) ltc4221 dual channel, hot swap controller operates from 1v to 13.5v, multifunction current control, ssop-16 ltc4245 multiple channel, hot swap controller 3.3v, 5v, 12v supplies, i 2 c compatible monitoring, ssop-36 or qfn-38 (5mm 7mm) ltc4252-1/ltc4252-2/ ltc4252a-1/ ltc4252a-2 C48v hot swap controller fast active current limiting with drain accelerated response, supplies from C15v, msop-8 or msop-10 c l1 1000 f 3..3v r410k 3.3v r510k 12v18a 3.3v aux 150ma r610k 12v out 12v sense 12v gate 12v in v cc auxin auxout 12imon auxon12on en auxpgood 12pgood fault r s 2.5m q1 hat2160h 12v 3.3v backplane connector card connector timer LTC4223-1 gnd r3 10 r251 c2330nf c t 0.1 f r g 47 c g 15nf r72.7 c3100nf r810k bd_sel r9 10k r110 z1 smaj13a 422312 ta04 tocontroller cs 1 f c1100nf ltc1197l v cc clk d out +in?in v ref gnd z2 smaj5.0a + c l2 150 f + 12v/18a card resident application downloaded from: http:///

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