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fn9004 rev 2.00 page 1 of 11 november 12, 2004 fn9004 rev 2.00 november 12, 2004 isl6121 single supply integrated current limiting controller datasheet the isl6121 is a single supp ly overcurrent (oc) fault protection ic for 2. 5v to 5v applications where 2a current limiting is desired. this devi ce features int ernal current monitoring and limit ing along with a 50m ? integrated power switch and a current limited time out to la tch-off feature for system protection. the time to latch- off is independent of device temperature, and magnitude of oc. each isl6121 incorporates in a 8 lead soic package a 50m ? n-channel mosfet power sw itch for power control. the switch is driven by a cons tant current source giving a controlled ramp up of the output v oltage. this provides a soft start turn-on eliminating bus voltage drooping caused by in- rush current while charging heavy load capacitances. (enable high (isl6121h) and enable low (isl6121l) options are) available with a fault repo rting output co mpatible with 3v and 5v logic level signals allowing for external control and monitoring. the under voltage (uvlo) locko ut feature pre vents turn-on of the output unless the corre ct enable signal and vin > 2.5v are both present. durin g initial turn-on the isl6121 design prevents a fault from being presented by blanking the fault signal, unlike other ven dor devices needing additional external circuitry to accomplish this. rising and falling output is a current-limited voltage ramp so that both the inrush current and voltage slew rate are limited, independent of load. this reduces supply droop due to surge and eliminates the need for external emi filters. during operation once an oc condition is detected the output is current l imited to 2a to allow for a transient condition to pass. if still in c urrent limit after the current limit period has elapsed the output is latched off and the fault is reported by pu lling the fault low. the fault signal is latched low until reset by the enable signal being deasserted at which time the fault signal will clear. see figure 1 for typical application configuration . features ?0.05 ? integrated power n-c hannel mosfet switch ? accurate current sensing and limiting ? 12ms timed fault latch-off, no thermal dependency ? 2.5v to 5.5v operating range ? under voltage lockout ? disabled output internally pulled low ? controlled turn on/off ramp times ? fault output signal ? logic level enable high inpu ts (isl6121h) or enable low inputs (isl6121l) ? logic level compatible enable input and fault output ? pb-free available (rohs compliant) applications ? fibre channel ? industrial power control ? hot plug figure 1. isl6121 typical application 1 2 3 4 8 7 6 5 en fault vin out out vin out r l c l gnd ordering information part number temp. range (c) package pkg. dwg. # isl6121hib -40 to 85 8 ld soic m8.15 isl6121hibza (see note) -40 to 85 8 ld soic (pb-free) m8.15 isl6121hib-t -40 to 85 8 ld soic tape and reel isl6121hibza-t (see note) -40 to 85 (pb-free) 8 ld soic tape and reel isl6121lib -40 to 85 8 ld soic m8.15 isl6121libza (see note) -40 to 85 8 ld soic (pb-free) m8.15 isl6121lib-t -40 to 85 8 ld soic tape and reel isl6121libza-t (see note) -40 to 85 8 ld soic tape and reel (pb-free) ISL6121HEVAL1 evaluation platform note: intersil pb-free products employ special pb-free material sets; molding compounds/die attach materials and 100% matte tin plate termination finish, which are rohs compliant and compatible wit h both snpb and pb-free soldering operations. intersil pb-free pr oducts are msl classified at pb-free peak reflow temperatures that mee t or exceed the pb-free requirements of ipc/jedec j std-020c.
isl6121 fn9004 rev 2.00 page 2 of 11 november 12, 2004 simplified block diagram gnd vin vin en fault out out out q-pump current and temp. por monitoring, gate and output control logic logic pin # symbol function description 1 gnd ic gnd reference 2, 3 vin chip bias, controlled supply input, undervoltage lock-out vin provides chip bias voltage . at vin < 2.5v chip functionalit y is disabled, fault latch is cleared and floating. out is pulled and held low. 4 enable / enable enable / enable not input enables chip when vin and enable > 2. 5v or enable < 0.6v 5 fault over current fault indicator overcurrent fault indicator. fault is disabled for 12ms after turn-on. this output is pulled low to gnd after the current lim it time-out period has expired and stays latched until enable is deasserted. 6, 7, 8 vout controlled supply output voltage output, connect to l oad to protect. upon an overcurrent condition vout is current limited to 2a. current limit response time is within 200 ? s. this output will remain in current limit for approximately 12ms before being latched off.
isl6121 fn9004 rev 2.00 page 3 of 11 november 12, 2004 absolute maximum ratings thermal information supply voltage (v+ to v-). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0v en, fault . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 6v out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . gnd-0.3v to vin +0.3v dc input voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v supply output current . . . . . . . . . . . . . . . . . . . . . . . sh ort circuit protected esd rating human body model (per mil-std-883 method 3015.7) . . . . 3kv operating conditions temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . -40 o c to 85 o c supply voltage range (typical). . . . . . . . . . . . . . . . . . 2.5v to 5.5v thermal resistance (typical, note 1) ? ja ( o c/w) 8 lead soic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 maximum junction temperat ure (plastic package) . . . . . . . . 150 o c maximum storage temperature range . . . . . . . . . . -65 o c to 150 o c maximum lead temperature (soldering 10s) . . . . . . . . . . . . .300 o c caution: stresses above those listed in ?absolute maximum ratings? may cause permanent damage to the device. this is a stress o nly rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not implied. note: 1. ? ja is measured with the component mounted on a high effective the rmal conductivity test board in free air. see tech brief tb379 for details. electrical specifications v supply = 5v, unless otherwise specified. parameter symbol test conditions min typ max units power switch isl6121 on resistance at 2.7v r ds(on)_27 vin = 2.7v, iout = 0.8a, t a = t j = 25 o c-6070m ? t a = t j = 85 o c--80m ? isl6121 on resistance at 3.3v r ds(on)_33 vin = 3.3v, iout = 0.8a, t a = t j = 25 o c-5060m ? t a = t j = 85 o c--75m ? isl6121 on resistance at 5.0v r ds(on)_50 vin = 5v, iout = 0.8a, t a = t j = 25 o c-5060m ? t a = t j = 85 o c--75m ? disabled output voltage v out_dis vin = 5v, switch disabled, 50 ? a load - 300 450 mv output voltage rising rate t_vout_rt r l = 10 ? , c l = 0.1 ? f, 10%-90% - 10 - v/ms slow vout turn-off rate t_svout_offt r l = 10 ? , c l = 0.1 ? f, 90%-10% - 10 - v/ms fast vout turn-off rate t_fvout_offt r l = 1 ? , c l = 0.1 ? f, 90%-10% - 3 - v/ ? s current control current limit, vin = 5v ilim vout = 3.3v 1.5 2 2.5 a oc regulation settling time tsett ilim r l = 1.6 ??? c l = 0.1 ? f to within 10% of cr - 1 - ms severe oc regulation settling time tsett ilim_sev r l < 1 ??? c l = 0.1 ? f to within 10% of cr - 100 - ? s over current latch-off time t oc_loff t j = 25 o c-12-ms i/o parameters fault output voltage vfault fault output current = 10ma - - 0.4 v enable high threshold ven_vih vin = 5.5v 2.0 - - v enable low threshold ven_vil vin = 2.7v - - 0.6 v enable low threshold ven_vil vin = 4.5v - - 0.8 v enable input current ien_i enable = 0v to 5v, vin = 5v, t j >25 o c -0.5 0 0.5 ? a bias parameters enabled vin current i vdd switch closed, output = open, t j > 0 o c - 120 200 ? a disabled vin current i vdd switch open, output = open - - 5 ? a under voltage lockout threshold v uvlh vin rising, switch enabled 1.7 2.25 2.5 v uv hysteresis uv hys 50 100 - mv over temperature disable temp_dis - 150 - o c
isl6121 fn9004 rev 2.00 page 4 of 11 november 12, 2004 introduction the isl6121 is a single chan nel overcurrent (oc) fault protection ic for the +2.5v to +5v environment. each isl6121 incorporates in a single 8 lead soic package a 50m ? n channel mosfet power switch for power control. see figure 3 for switch resista nce curves. with an enabling input and fault reporting outpu t compatible with 3v and 5v logic allowing for external control and monitoring. see figure 2 for ic operational waveforms. this device features internal current monitoring, consist ent current limiting and an integrated power switch with a current limiting timed delay to latch-off feature for system protection. key feature description and operation uv lock out the isl6121 undervoltage lockout feature prevents functionality of the device unle ss the correct enable state and vin > 2.5v are present. soft start a constant 500na current source ramps up the switchs gate causing a voltage follower effect on the output voltage. this provides a soft start turn-on and eliminates bus voltage drooping caused by inrush current charging heavy load capacitances. the rising and falling output is a current limited voltage ram p so that both the inrush current and voltage slew rate are limit ed, independent of load. this reduces supply droop due to s urge and also eliminates the need for external emi filters necessary on other ic products. see figure 4 for turn-on wave forms. fault blanking on start-up during initial turn-on the isl6121 prevents nuisance faults being reported to the system controller by blanking the fault signal for 12ms. this blanki ng eliminates the need for external rc filters necessary fo r other vendor products that assert a fault signal upon initial turn-on into a temporary hig h current condition. see figures 11 through 13 for waveform examples. current regulation the isl6121 has integrated current sensing on the power mosfet that allows for rapid control of oc events. once an oc is detected the isl6121 goes into its current regulation (cr) control mode. the isl6121 cr level is set to a nominal 2a. this current regulation is ? 20% over the full operating temperature and voltage bias range. see figures 5 and 6 for illustrative curves. the speed of this control is proportional to the magnitude of the oc fault. thus a hard ov er current is more quickly controlled than a marginal condition. see figure 7 for waveforms illustrating th is and figure 8 for an accompanying graph. latch-off time delay the primary functi on of any oc protec tion device is to quickly isolate the voltage bus from a faulty load. unlike many other manufacturers ic products that sense the ic thermal condition (the monito red ic junction temperature depends on a number of factors the most important of which are power dissipation of the faulted swit ch and the package temp) to isolate a f aulty load, the isl6121 uses an internal 12ms timer that starts upon o c detection. once an oc condition is detecte d the output is cu rrent limited for a nominal 12ms to allow transien t conditions to pass before latch-off. the time to latch-off is independent of the devices thermal condition. if, after the isl6121 has latched off, and the fault has asserted and the enable is not deasserted but the oc condition still exists, the isl 6121 unlike other ic devices does not send to the controller a continuous string of fault pulses. the isl6121s single fault signal is sent at the time of latch off. slow and fast shutdown the isl6121 has two shutdown modes. when disabled with a load current less than the cr level the isl6121 shuts down in a controlled manner u sing a 500na constant current source controlled ramp. when latched-off during cr or if the timer has expired the isl6121 quickly pulls down the output thereby quickly removing the f aulted load from the voltage bus. see figures 9 and 10 fo r waveforms of each mode. temperature shutdown although the isl6121 has a t hermal shutdown feature, because of the 12ms timed shutdown this will only be invoked in extremely hig h ambient temperatures. active output pulldown another unique isl6121 featur e is the active pull down on the outputs to within 300mv of gnd when the device is disabled.
isl6121 fn9004 rev 2.00 page 5 of 11 november 12, 2004 typical performance curves figure 2. operational waveforms figure 3. switch resistance at 1a figure 4. vout soft start vs cloa d figure 5. current regulation vs vout (vin = 3.3v) figure 6. current regulation vs vout (vin = 5.0v) figure 7. oc to cr settling time waveforms on off enable latch-off set reset by enable current regulation settling time (1.4ms) over current fault vout iout 12ms current regulation period 2a current limit -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 temperature ( o c) 35 40 45 50 55 60 65 70 75 vin = 2.7v vin = 5v vin = 3.3v switch on resistance (mw) enable c l = 100 ? f cl = 0.1 ? f, 10 ? f vout vout (1v/div.) time (200 ? s/div.) 1.25 1.5 1.75 2.0 2.25 2.5 2.75 3.0 vout (v) 3.1 iout (ma) 1600 1800 2000 2200 2400 85 o c 25 o c -40 o c 1.3 1.5 2.0 2.5 3.0 3.5 4.0 4.5 vout (v) 4.8 iout (ma) 1600 1800 2000 2200 2400 85 o c -40 o c 25 o c time (200 ? s /div.) output current (1a/div) current regulated level nominal current
isl6121 fn9004 rev 2.00 page 6 of 11 november 12, 2004 figure 8. cr settling time vs fault current figure 9. slow turn-of f vs c load figure 10. fast turn-off vs c load figure 11. isl6121 turn-on into 3a oc figure 12. isl6121 turn-on into a 6ms momentary oc figure 13. vend or turn-on into a 6ms momentary oc typical performance curves (continued) 3456 78910112 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0 fault current (a) time to current regulation (ms) c l = 0.1 ? f, 1 0 ? f vout enable c l = 100 ? f vout (1v/div.) time (200 ? s/div.) vout (1v/div.) time (400 ? s /div.) c l = 10 ? f c l =100 ? f vout c l = 0.1 ? f vout enable iout 12ms vout time (2ms/div.) enable fault vout iout time (1ms/div.) vout fault enable time (2ms /div.)
isl6121 fn9004 rev 2.00 page 7 of 11 november 12, 2004 using the isl6121eval1 platform general and biasing information the isl6121eval1 platform, figure 17, allows evaluation of the isl6121 power supply con trol ic and comparison against a suitably sized (1. 85a hold current rating) pptc component. the evaluation platform is biased and monitored through numerous test points (tp#). see table 1 for test point assignments and descriptions. upon proper bias the pptc, f1, has a nominal 1.5a load current passing through it which is the below the hold current rating for that parti cular device. removal of the pptc is necessary to isolate the isl6121 as the pptc load current is common to the isl6121eval1 bias connections. by enabling the isl6121h switches by signaling tp4 high (> 2.4v) the ic is also loaded with a nominal 1.5a current. provided test points enable the evaluation of voltage loss across the pptc (tp9 - tp10 ) and likewise across the isl6121 enabled switch (tp9 - tp6). expect to see 10% - 30% greater voltage loss a cross the pptc than the isl6121. an overcurrent (oc) condition can be invoke d on both the isl6121 and the pptc by drivi ng tp11 to +6v, causing sw1 to close and a nominal 3a load is imposed on each. this represents a current o verload to the isl6121 and is thus quickly current regulat ed to the 2a li mit. if the oc duration extends be yond the nominal 12m s of the internal isl6121 timer then the output is latched off and the fault output is asserted by being pulled low, turning on the fault_ led. the primary functi on of any oc protec tion device is to quickly isolate the voltage bus f rom a faulty load. unlike the pptc and some other vendor available ic products, the isl6121 internal timer that starts upon oc detection provides consistent protection that is independent of temperature. figures 14 through 16 illustrate the comparative efficiency and effectiveness of the isl6121 vs the pptc in protectin g and isolating a f aulty load capable from drooping the system bus in that system. table 1. isl6121eval1 test point assignments tp # description tp1 eval board and ic gnd tp2 eval board +5v bias tp4 enable tp5 fault tp6 vout tp9 ic vin pin tp10 pptc load side tp11 invoke over current figure 14. isl6121 vs pptc into 3.3 ? load figure 15. isl6121 vs pptc into 1.6 ? load vin = 5.07v isl6121 vout = 5v pptc vout = 4.96v vout (100mv/div.) pptc vout isl6121 vout 12ms oc latch-off time vout (1v/div.) time (2ms/div.)
isl6121 fn9004 rev 2.00 page 8 of 11 november 12, 2004 figure 16. isl6121 vs pptc with extended 1.6 ? load pptc vout 29s pptc oc response time isl6121 vout vout (1v/div.) time (4s/div.) figure 17. isl6121eval1 schematic and photograph 1 2 3 4 8 7 6 5 en fault_out vin out out vin out isl6121h vin c1 r1 r2 r5 f1 c2 d1 d2 r3 r4 r7 c3 d3 q1a q1b 0 5v oc r8 r9 c4 r10 r11 r6
isl6121 fn9004 rev 2.00 page 9 of 11 november 12, 2004 table 2. isl6121eval1 board component listing component designator component function component description dut1 isl6121h intersil, isl6121h, integrated fet hot plug control ler r1 - r4 load resistors yageo, 3.3 ?? 5%, 10w, 3.3w-10-nd r5-r7 led current limiting resistor 470 ? , 0805 c1 chip decoupling capacitor 0.1 ? f, 0805 c2 - c3 load capacitor 100 ? f 16v electrolytic, radial lead d1 - d3 indicating leds 0805, smd leds red f1 1.85a hold current poly-fuse raychem, rusb185 or equivalent c4 bulk filter capacitor 100 ? f 16v electrolytic, radial lead q1 over current switch intersil , itf86110dk8t, 7.5a, 30v, 0.025 ? dual n-channel mosfets r8 - r9 gate series resistors 47 ? , 0805 r10 - r11 enable pullup/pulldown resistors 1.2k ? , 0805, r10 not populated
isl6121 fn9004 rev 2.00 page 10 of 11 november 12, 2004 implementing autor eset on the isl6121 hot swap controller. abstract in applications where the cost, complexity or requirement for a system controller is avoi ded and an autonomous power control function is desired, a device t hat can monitor and protect against excessive current failures is needed. this tech brief shows how to implement such an autonomous controller using the isl6121hib. this application works only with the h version of this devic e. the h version refers to the enable function being asserted upon a high input. introduction the isl6118, isl6119 and isl6121 are all 2.5v to 5v power supply controllers, each having a different level of current regulation (cr). the is l6118 and isl6119 have 2 independent controllers with c r levels of 0.6a and 1.0a respectively whereas the isl6121 is a single supply controller with a 2a cr level. e ach of these devices features integrated power switch(es) fo r power control. each switch is driven by a constant curren t source giving a controlled ramp up of the output voltage . this provides a soft start turn-on eliminating bus volta ge drooping caused by in-rush current while charging heavy load capacitances. the independent enabling inputs and fault reporting outputs for each channel are available and necessary for the autonomous autoreset application. the undervoltage (uv) feature prevents turn-on of the outputs unless the enable pin and vin are > 2.5v. during initial turn-on the isl6121 prevents fault reporting by blanking the fault signal. rising and falling outputs are current-limited voltage ramps so that both the inrush current and voltage slew rate are limited, independent of load. this reduces supply droop due to surge and eliminates the need for exte rnal emi filters. during operation, once an oc condition is detected the appropriate output is current limited to the appropriate level for 10ms to allow transient c onditions to pass. if still in current limit after th e current limit period has elapsed, the output is latched off and the fault is reported by pulling the corresponding fault low. the fault signal is latched low until reset by the enable s ignal being de-asserted at which time the fault signal will clear. it is this described sequence of events that allows for the autoreset function t o be implemented in a cost efficient manner requiring the addition of only an rc network per channel to the typical application. figure 18 illustrates the rc network needed with suggested component values and the confi guration of the relevant pins for each autoreset channel. description of operation initially as voltage is applied to vin, the pull up resistor (r pu) provides for pull up to vin on both the enable pin asserting the output once vin > 2.5v and on the fltn pin. once turned on and an overcurrent (oc) cond ition occurs the ic provides cr protection for 10ms and then the fltn pin pulls low through rpu and also pulling the enable low thus resetting the device fault condition. at this time t he rpu charges the cap and the voltage on the enable / fltn node rises until the enable > 2.0 and the output is asserted o n once again. this automatic reset cycle will continue until th e oc fault no longer exists o n the output. after several seconds in this mode of operation the ic thermal protection invokes adjusting the timing of the on-of f cycle to prevent excessi ve thermal dissipat ion in the power switch protecting itself and su rrounding circuitry. see figure 19 for operation waveform. . applications ?usb ? 2.5v to 5v up to 10w power port protection figure 18. vin enable fltn gnd isl6121h rpu = 2k c = 0.1 ? f figure 19. auto reset operation iout 1a / div vout 2v / div vin / fltn 5v / div 0a 0v 4ms/div
fn9004 rev 2.00 page 11 of 11 november 12, 2004 isl6121 intersil products are manufactured, assembled and tested utilizing iso9001 quality systems as noted in the quality certifications found at www.intersil.com/en/suppor t/qualandreliability.html intersil products are sold by description on ly. intersil may modify the circuit design an d/or specifications of products at any time without notice, provided that such modification does not, in intersil's sole judgment, affect the form, fit or function of the product. accordingly, the reader is cautioned to verify that datasheets are current before placing orders. information fu rnished by intersil is believed to be accu rate and reliable. however, no responsib ility is assumed by intersil or its subsidiaries for its use; nor for any infrin gements of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of intersil or its subsidiaries. for information regarding intersil corporation and its products, see www.intersil.com for additional products, see www.intersil.com/en/products.html ? copyright intersil americas llc 2001-2004. all rights reserved. all trademarks and registered trademarks are the property of their respective owners. small outline plast ic packages (soic) index area e d n 123 -b- 0.25(0.010) c a m bs e -a- l b m -c- a1 a seating plane 0.10(0.004) h x 45 o c h 0.25(0.010) b m m ? notes: 1. symbols are defined in the mo series symbol list in section 2.2 of publication number 95. 2. dimensioning and tolerancing per ansi y14.5m - 1982. 3. dimension d does not include mold flash, protrusions or gat e burrs. mold flash, protrusion and gate burrs shall not exceed 0.15mm ( 0.006 inch) per side. 4. dimension e does not include interlead flash or protrusions . inter- lead flash and protrusions shall not exceed 0.25mm (0.010 inch) per side. 5. the chamfer on the body is optional. if it is not present, a visual index feature must be located within the crosshatched area. 6. l is the length of terminal for soldering to a substrate. 7. n is the number of terminal positions. 8. terminal numbers are shown for reference only. 9. the lead width b, as measured 0.36mm (0.014 inch) or greate r above the seating plane, shall not exceed a maximum value of 0.61mm (0.024 inch). 10. controlling dimension: millime ter. converted inch dimensions are not necessarily exact. m8.15 (jedec ms-012-aa issue c) 8 lead narrow body small outline plastic package symbol inches millimeters notes min max min max a 0.0532 0.0688 1.35 1.75 - a1 0.0040 0.0098 0.10 0.25 - b 0.013 0.020 0.33 0.51 9 c 0.0075 0.0098 0.19 0.25 - d 0.1890 0.1968 4.80 5.00 3 e 0.1497 0.1574 3.80 4.00 4 e 0.050 bsc 1.27 bsc - h 0.2284 0.2440 5.80 6.20 - h 0.0099 0.0196 0.25 0.50 5 l 0.016 0.050 0.40 1.27 6 n8 87 ? 0 o 8 o 0 o 8 o - rev. 0 12/93

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