1 ? charging system safety circuit the ISL9211 is an integrated circ uit (ic) optimized to provide a redundant safety protection to a li-ion battery charging system. the ic monitors the input voltage, the battery voltage, and the charge current. when any of the three parameters exceeds its limit, the ic turns off an internal n-channel mosfet to remove the power from the charging system to the battery. in addition to the above protected parameters, the ic also mo nitors its own internal temperature and turns off the n-channel mosfet when the temperature exceeds +150c. together with the battery charger ic and the protection module in a battery pack, the charging system using the is l9211 has tr iple-level protection and is two-fault tolerant. the ic is designed to turn on the internal nfet slowly to avoid inrush current at power up but will turn off the nfet quickly when the input is overvoltage in order to remove the power before any damage occurs. the ISL9211 has a logic flag output to indicate a fault condition. typical application circuit features ? 24v max input voltage ? supports up to 1.5a input current ? fully integrated protection circuit for three protected variables ? high accuracy protection thresholds ? user programmable overcurrent protection threshold ? responds to input overvoltage in less than 1s ? high immunity of false triggering under transients ? fault indication for various fault occurrence ? easy to use ? pb-free (rohs compliant) applications ? cell phones ? digital still cameras ? pdas and smart phones ? portable instruments ? desktop chargers related literature ? technical brief tb363 ?guidelines for handling and processing moisture sensit ive surface mount devices (smds)? ? technical brief tb379 ?thermal characterization of packaged semiconductor devices? ? technical brief tb389 ?pcb land pattern design and surface mount guidelines for qfn packages? pinout ISL9211 (8 ld 2x2 tdfn) top view ordering information part number part marking temp range (c) package (pb-free) pkg. dwg. # ISL9211iru58xz-t* 15x -40 to +85 8 ld tdfn l8.2x2 ISL9211iru68xz-t* 16x -40 to +85 8 ld tdfn l8.2x2 *please refer to tb347 for detai ls on reel specifications. note: these intersil pb-free pl astic packaged products employ special pb-free material sets; molding compounds/die attach materials and nipdau plate - e4 te rmination finish, which is rohs compliant and compatible with both snpb and pb-free soldering operations. intersil pb-free produc ts are msl classified at pb-free peak reflow temperatures that meet or exceed the pb-free requirements of ipc/jedec j std-020. input isl6292 battery charger r vb ISL9211 c 1 ilim r ilim fault vin gnd vb out battery pack c 2 2 3 4 1 7 6 5 8 vin gnd nc fault out ilim vb gnd fn6658.4 ISL9211 data sheet january 13, 2009 caution: these devices are sensitive to electrosta tic discharge; follow proper ic handling procedures. 1-888-intersil or 1-888-468-3774 | intersil (and design) is a registered trademark of intersil americas inc. copyright ? intersil americas inc. 2008, 2009. all rights reserved. all other trademarks mentioned are the property of their respective owners.
2 fn6658.4 january 13, 2009 absolute maximum rati ngs thermal information supply voltage (vin) . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 26v output and vb pin (out, vb) (note 1) . . . . . . . . . . . . . . -0.3v to 8v other pins (ilim, fault) . . . . . . . . . . . . . . . . . . . . . . . -0.3v to 5.5v recommended operating conditions ambient temperature range . . . . . . . . . . . . . . . . . . .-40c to +85c supply voltage, vin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3v to 24v operating current range. . . . . . . . . . . . . . . . . . . . . . . . . 0a to 1.5a thermal resistance (typical, note 2) ja (c/w) 8 ld 2x2 tdfn package . . . . . . . . . . 120 maximum junction temperature (plastic package) . . . . . . . +150c maximum storage temperature range . . . . . . . . . .-65c to +150c pb-free reflow profile. . . . . . . . . . . . . . . . . . . . . . . . .see link below http://www.intersil.com/pbfree/pb-freereflow.asp caution: do not operate at or near the maximum ratings listed fo r extended periods of time. exposure to such conditions may adv ersely impact product reliability and result in failures not covered by warranty. notes: 1. the maximum voltage rating for the vb pin under continuous operatin g conditions is 5.5v. all other pins are allowed to operat e continuously at the absolute maximum ratings. 2. ja is measured in free air with the component mounted on a high ef fective thermal conductivity te st board with ?direct attach? fe atures. see tech brief tb379. electrical specifications typical values are tested at vin = 5v and +25c am bient temperature, maximum and minimum values are established over the recommended operating conditions; pa rameters with min and/or max limits are 100% tested at +25c, unless otherwise specified. temperat ure limits established by characterization and are not production tested. parameter symbol test conditions min typ max units power-on reset rising vin threshold v por rising - - 2.47 v falling 2.20 - - v vin bias current i vin r ilim = 24.9k - - 1000 a protections input overvoltage protection v ovp ISL9211iru58 5.6 5.8 6.0 v ISL9211iru68 6.6 6.8 6.95 v input ovp falling threshold ISL9211iru58 5.55 - - v ISL9211iru68 6.55 - - v input ovp response time (note 3) --1s overcurrent protection i ocp v vb = 3v, r ilim = 24.9k 0.93 1.0 1.07 a overcurrent protection blanking time bt ocp - 180 - s battery overvoltage protection threshold v bovp 4.25 4.34 4.40 v battery ovp threshold hysteresis -3050mv battery ovp blanking time bt bovp - 180 - s vb pin leakage current v vb = 4.34v - - 20 na over-temperature protecti on rising threshold - 150 - c over-temperature protection falling threshold - 110 - c logic fault output logic low sink 5ma current - 0.4 0.8 v fault output logic high leakage current - - 1.5 a power mosfet on-resistance (note 3) r ds(on) measured at 200ma - 170 280 m note: 3. limits should be considered ty pical and are not production tested. ISL9211
3 fn6658.4 january 13, 2009 pin descriptions vin (pin 1) the input power source. the vin can withstand 24v input. gnd (pins 2, 5) system ground reference. nc (pin 3) no connection and must be left floating. fault (pin 4) fault is an open-drain logic output that turns low when any protection event occurs. vb (pin 6) battery voltage monitoring input. this pin is connected to the battery pack positive terminal via an isolation resistor. ilim (pin 7) overcurrent protection threshold setting pin. connect a resistor between this pin and gnd to set the ocp threshold. out (pin 8) output pin. typical application block diagram part description r ilim 24.9k r vb 200k to 1m c 1, c 2 1f/25v x5r ceramic capacitor input isl6292 battery charger r vb ISL9211 c 1 ilim r ilim fault vin gnd vb out battery pack c 2 figure 1. block diagram por pre-reg ref vin vb gnd 1.2v 0.8v r 1 r 2 q 1 input cp1 isl6292 battery charger out r ilim ilim fet driver logic ea r vb cp3 q 2 q 3 fault q 4 cp2 r 3 r 4 ISL9211
4 fn6658.4 january 13, 2009 typical operating performance the test conditions for the typica l operating performance are: v in = 5v, t a = +25c, r ilim = 24.9k , r vb = 200k , unless otherwise noted. figure 2. captured waveforms for power-up. the output is loaded with a 10 resistor figure 3. captured waveforms when the input voltage steps from 5.5v to 9.5v figure 4. captured waveforms when the input gradually rises to the input overvoltage threshold figure 5. transient when the input voltage steps from 6.5v to 5.5v figure 6. transient waveforms when input steps from zero to 9v figure 7. battery overvoltage protection. the ic is latched off after 16 counts of protection. vb voltage varies between 4.3v to 4.5v time - 4ms/div v in ( 2v/div ) out(2v/div) load current(200ma/div) time - 20s/div v in(2v/div) out(2v/div) fault ( 5v/div ) time - 2s/div vin(2v/div) out(2v/div) fault ( 5v/div ) time - 4ms/div vin(2v/div) out(2v/div) fault(5v/div) time - 40s/div vin ( 5v/div ) out(2v/div) fault ( 2v/div ) time - 20s/div vin(1v/div) vb(1v/div) out(1v/div) fault(2v/div) ISL9211
5 fn6658.4 january 13, 2009 figure 8. power-up waveforms when output is short-circuited figure 9. zoomed-in view of figure 8 figure 10. v por vs temperature figure 11. input overvotlage protection vs temperature figure 12. overcurrent protection vs temperature at various input voltages figure 13. i lim pin voltage vs temperature typical operating performance the test conditions for the typica l operating performance are: v in = 5v, t a = +25c, r ilim = 24.9k , r vb = 200k , unless otherwise noted. (continued) time - 40 0 ms/div fault(2v/div ) out(2v/div) load current(500ma/div) vin(2v/div) time - 1ms/div fault(2v/div ) out(2v/div) load current(500ma/div) vin(2v/div) 2.20 2.24 2.28 2.32 2.36 2.40 2.44 2.48 2.52 -50-30-101030507090 temperature (c) v por (v) rising threshold falling threshold 5.60 5.65 5.70 5.75 5.80 5.85 -50-30-101030507090 temperature (c) v ovp (v) rising threshold falling threshold 0.95 0.96 0.97 0.98 0.99 1.00 1.01 1.02 1.03 1.04 -50 -30 -10 10 30 50 70 90 110 130 overcurrent protection (a) temperature (c) 5.0v 3.0v 4.3v 0.972 0.974 0.976 0.978 0.980 0.982 0.984 0.986 0.988 -50 -30 -10 10 30 50 70 90 110 130 i lim pin voltage (v) temperature (c) ISL9211
6 fn6658.4 january 13, 2009 theory of operation the ISL9211 is an integrated circ uit (ic) optimized to provide a redundant safety protection to a li-ion battery from charging system failures. the ic monitors the in put voltage, the battery voltage, and the charge current. when any of the above three parameters exceeds its limit, the ic turns off an internal n-channel mosfet to remove the power from the charging system. in addition to the above protected parameters, the ic also mo nitors its own internal temperature and turns off the n-channel mosfet when the temperature exceeds +150c. together with the battery charger ic and the protection module in a battery pack, the charging system has triple-l evel protection from overcharging the li-ion battery and is two-fault tolerant. the ISL9211 protects up to 26v input voltage. power-up the ISL9211 has a power-on reset (por) threshold of 2.47v (max). before the input voltage reaches the por threshold, the internal power nfet is off. approximately 10ms after the input voltage exceeds the por threshold, the ic resets itself and begins the soft-start. the 10ms delay allows any transients at the input during a hot insertion of the power supply to settle down before the ic starts to operate. the soft-start slowly turns on the power nfet to reduce the inrush current as well as the input voltage drop during the transition. the power-up sequence is illustrated in figure 2. input overvoltage protection (ovp) the input voltage is monitored by the comparator cp1 in the block diagram (figure 1). cp1 has an accurate reference of 1.2v from the bandgap reference. the ovp threshold is set by the resistive divider consisting of r 1 and r 2 . when the input voltage exceeds the threshold, the cp1 outputs a logic signal to turn off the power nfet within 1s (see figure 3) to prevent the high input voltage from damaging the electronics in the handheld system. the hysteresis for the input ovp threshold is given in the ?ele ctrical specifications? table on page 2. when the input overvo ltage condition is removed, the ISL9211 re-enables the out put by running through the soft-start, as shown in figure 5. because of the 10ms second delay before the soft-start, the output is never enabled if the input rises above the ovp threshold quickly, as shown in figure 6. battery overvoltage protection the battery voltage ovp is realized with the vb pin. the comparator cp3, as shown in figure 1, monitors the vb pin and issues an overvoltage signal when the battery voltage exceeds the 4.34v battery ovp threshold. the threshold has 30mv built-in hysteresis. the comparator cp3 has a built-in 180s blanking time to prevent any transient voltage from triggering the ovp. if the ovp situation still exists after the blanking time, the power nfet is turned off. the control logic contains a 4-bit binary counter that if the battery overvoltage event occurs 16x, the power nfet is turned off permanently, as shown in figure 7. recycling the input power will reset the counter and restart the ISL9211. the resistor between the vb pin and the battery, r vb , as shown in the ?typical application circuit? on page 1, is an important component. this resist or provides a current limit in case the vb pin is shorted to the input voltage under a failure mode. the vb pin leakage current under normal operation is negligible to allow a resistance of 200k to 1m be used. overcurrent protection (ocp) the current in the power nfet is limited to prevent charging the battery with an excessive current. the current is sensed using the voltage drop across the power fet after it is turned on. the reference of the ocp is generated using a sensing fet q 2 (mirror to q 1 ), as shown in figure 1. the current in the sensing fet is forced to match the value programmed by the ilim pin. the size of the power fet q 1 is 31,250x the size of the sens ing fet. therefore, when the current in the power fet is 31,250x the current in the sensing fet, the drain voltage of the power fet falls below figure 14. on-resistance vs temperat ure at different input voltages typical operating performance the test conditions for the typica l operating performance are: v in = 5v, t a = +25c, r ilim = 24.9k , r vb = 200k , unless otherwise noted. (continued) 0 50 100 150 200 250 300 350 -50-30-101030507090110130 temperature (c) r ds(on) (m ) 4.3v 5.0v 3.0v ISL9211
7 fn6658.4 january 13, 2009 that of the sensing fet. the comparator cp2 then outputs a signal to turn off the power fet. the ocp threshold can be calculated using equation 1: where the 0.8v is the regulated voltage at the ilim pin. the ocp comparator cp2 has a built-in 170s delay to prevent false triggering by transient si gnals. the ocp function also has a 4-bit binary counter that accumulates during an ocp event. when the total count reaches 8, the power nfet is turned off permanently until the input power is recycled or the enable pin is toggled. figures 8 and 9 illustrate the waveforms during the power-up when the output is shorted to ground. internal over-temperature protection the ISL9211 monitors its own internal temperature to prevent thermal failures. w hen the internal temperature reaches +150c, the ic turns off the n-channel power mosfet. the ic does not resume operation until the internal temperature drops below +110c. fault indication output the fault pin is an open-drain output that indicates a low signal when any of the three fault events happens. this provides a signal to the microprocessor to take further action to enhance the safety of th e charging system. applications information the ISL9211 is designed to meet the ?lithium-safe? criteria when operating together wit h a qualified li-ion battery charger. the ?lithium-safe? criteria requires the charger output to fall within the green region shown in figure 15 under normal operating conditions and not to fall in the red region when there is a single fault in the charging system. taking into account the safety circuit in a li-ion battery pack, the charging system is allowed to have two faults without creating hazardous conditions fo r the battery cell. the output of the li-ion charger, such as the isl6292, isl6292c, has a typical i-v curve shown with the blue lines under normal operation, which is within the gr een region. the function of the ISL9211 is to add a redundant protection layer such that, under any single fault conditio n, the charging system output does not exceed the i-v limits shown with the red lines. as a result, the charging system adopting the ISL9211 and the isl6292, isl6292c chip set can easily pass the ?lithium- safe? criteria test procedures. the ISL9211 is a simple device that requires only three external components, in addition to the isl6292 charger circuit, to meet the ?lithium-safe? criteria, as shown in the ?typical application circuit? on page 1. the selection of the current limit resistor r ilim is given in ?overcurrent protection (ocp)? on page 6. r vb selection the r vb prevents a large current from the vb pin to the battery terminal, in case the ISL9211 fails. the recommended value should be between 200k to 1m . with 200k resistance, the worst ca se current flowing from the vb pin to the charger output is shown in equation 2, assuming the vb pin voltage is 24v under a failure mode and the battery voltage is 4.2v. such a small current can be easily absorbed by the bias current of other components in the handheld system. increasing the r vb value reduces the worst case current, but at the same time increases the error for the 4.34v battery ovp threshold. the error of the battery ovp threshold is the original accuracy at the vb pin given in the ?electrical specifications? table on page 2 plus the voltage built across the r vb by the vb pin leakage current. the vb pin leakage current is less than 20na, as given in the ?ele ctrical specifications? table. with the 200k resistor, the worst-case additional error is 4mv and with a 1m resistor, the worst-case additional error is 20mv. capacitor selection the input capacitor (c 1 in the ?typical application circuit? on page 1) is for decoupling. higher value reduces the voltage drop or the overshoot during transients. two scenarios can cause the input voltage overshoot. the first one is when the ac adapter is inserted live (hot insertion) and the second one is when the current in the power nfet of the ISL9211 has a step-down change. figure 16 shows an equivalent circuit for the ISL9211 input. the cable between the ac/ dc converter output and the handheld system input has a parasitic inductor. the parasitic resistor is the lumped sum of various components, such as the cable, the adapt er output capacitor esr, the connector contact resistance, and so on. i lim 0.8v r ilim --------------- 31250 25000 r ilim ---------------- = ? = (eq. 1) 24v 4.2v ? () 200k () ? 99 a = (eq. 2) figure 15. lithium-safe operating regions 5 0 1000 battery voltage (v) charge current (ma) 13 4 ISL9211 limits isl6292c limits 6 2 ISL9211
8 all intersil u.s. products are manufactured, asse mbled and tested utilizing iso9000 quality systems. intersil corporation?s quality certifications ca n be viewed at www.intersil.com/design/quality intersil products are sold by description only. intersil corpor ation reserves the right to make changes in circuit design, soft ware and/or specifications at any time without notice. accordingly, the reader is cautioned to verify that data sheets are current before placing orders. information furnishe d by intersil is believed to be accurate and reliable. however, no responsibility is assumed by intersil or its subsidiaries for its use; nor for any infringements of paten ts 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 subsidiari es. for information regarding intersil corporation and its products, see www.intersil.com fn6658.4 january 13, 2009 during the load current step-down transient, the energy stored in the parasitic inductor is used to charge the input decoupling capacitor c 2 . the ISL9211 is designed to turn off the power nfet slowly during the ocp and the battery ovp event. because of such desig n, the input overshoot during those events is not significant. during an input ovp, however, the nfet is turned in less than 1s and can lead to significant overshoot. higher capacitance reduces the overshoot. the overshoot caused by a hot insertion is not very dependent on the decoupling capacitance value. especially when ceramic type capacitors are used for decoupling. in theory, the over-shoot can rise up to twice of the dc output voltage of the ac adapter. the actual peak voltage is dependent on the damping factor that is mainly determined by the parasitic resistance (r in figure 16). in practice, the input decoupling capacitor is recommended to use a 25v, x5r dielectric ceramic capacitor with a value between 0.1f to 1f. the output of the ISL9211 and the input of the charging circuit typically share one decoupling capacitor. the selection of that capacitor is mainly determined by the requirement of the charging ci rcuit. when using the isl6292 family chargers, a 1f, 6.3v, x5r capacitor is recommended. layout recommendation the ISL9211 uses a 2x2 dfn package. use some copper on the component layer if possible to improve the thermal performance if possible. figure 16. equivalent circuit for the ISL9211 input ac/dc ISL9211 adapter cable handheld system c1 l r c2 ISL9211
9 fn6658.4 january 13, 2009 ISL9211 package outline drawing l8.2x2 8 lead ultra thin dual flat no-lead col plastic package (utdfn col) rev 3, 11/07 typical recommended land pattern detail "x" top view bottom view side view located within the zone indicated. the pin #1 identifier may be unless otherwise specified, tolerance : decimal 0.05 tiebar shown (if present) is a non-functional feature. the configuration of the pin #1 id entifier is optional, but must be between 0.15mm and 0.30mm from the terminal tip. dimension b applies to the metallized terminal and is measured dimensions in ( ) for reference only. dimensioning and tolerancing conform to amse y14.5m-1994. 6. either a mold or mark feature. 3. 5. 4. 2. dimensions are in millimeters. 1. notes: 2.00 7x 0.4 0.1 0.15 ( 1 . 8 ) (4x) ( 8x 0 . 25 ) ( 1x 0 .70 ) ( 6x 0 . 5 ) 0 . 55 max base plane c seating plane 0.08 c 0.10 c 0.25 +0.05 / -0.07 see detail "x" 0.10 4 ca mb index area 6 pin 1 2.00 a b pin #1 index area 0.50 2x 1.5 6x 6 ( 7x 0 . 60 ) 0 . 00 min. 0 . 05 max. c 0 . 2 ref 5 4 8 1 1x 0.5 0.1
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