_______________________________________________________________ maxim integrated products 1 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxims website at www.maxim-ic.com. ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 general description the max16914/MAX16915 low-quiescent-current over - voltage and reverse-battery protection controllers are designed for automotive and industrial systems that must tolerate high-voltage transient and fault conditions. these conditions include load dumps, voltage dips, and reversed input voltages. the controllers monitor the input voltage on the supply line and control two external pfets to isolate the load from the fault condition. the external pfets are turned on when the input supply exceeds 4.5v and stay on up to the programmed overvoltage threshold. during high-voltage fault conditions, the con - trollers regulate the output voltage to the set upper threshold voltage (MAX16915), or switch to high resis - tance (max16914) for the duration of the overvoltage transient to prevent damage to the downstream circuitry. the overvoltage event is indicated through an active-low, open-drain output, ov . the reverse-battery pfet behaves as an ideal diode, minimizing the voltage drop when forward biased. under reverse bias conditions, the pfet is turned off, prevent - ing a downstream tank capacitor from being discharged into the source. shutdown control turns off the ic completely, discon - necting the input from the output and disconnecting term from its external resistor-divider to reduce the quiescent current to a minimum. both devices are available in a 10-pin f max m package and operate over the automotive -40 n c to +125 n c tem - perature range. applications automotive industrial features s 4.5v to 19v input voltage operation s transient voltage protection up to +44v and -75v s adjus table overvoltage limit with resistor- divider shut off in shutdown s ideal diode reverse-battery protection s low voltage drop when used with properly sized external pfets s back-charge prevention s overvoltage indicator s shutdown input s 29a low operating current s 6a low shutdown current s thermal-overload protection s -40 n c to +125 n c operating temperature range s small 10-pin max package s aec-q100 qualified 19-4964; rev 0; 9/09 pin configuration ordering information + denotes a lead(pb)-free/rohs-compliant package. /v denotes an automotive qualified device. max is a registered trademark of maxim integrated products, inc. 1 + 2 3 4 5 10 9 8 7 6 gate2 sense out term set shdn sense in gate1 v cc max16914 MAX16915 top view gnd ov v cc v batt v out p2 p1 gate1 sense in r1 r2 shdn on off max16914 MAX16915 gate2 sense out ov term set gnd ov part temp range pin-package max16914 aub/v+ -40 n c to +125 n c 10 f max MAX16915 aub/v+ -40 n c to +125 n c 10 f max typical operating circuit
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 2 ______________________________________________________________________________________ stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc , sense out, term, shdn, ov to gnd for p 400ms ............................................................. -0.3v to +44v v cc , sense out, term, shdn, ov to gnd for p 90s ............................................................. -0.3v to +28v v cc , sense out, term, shdn, ov to gnd ..... -0.3v to +20v sense in to gnd for p 2ms .................................. -75v to +44v sense in to gnd for p 90s .................................. -18v to +44v sense in to gnd ................................................. -0.3v to +20v gate1, gate2 to v cc .......................................... -16v to +0.3v gate1, gate2 to gnd ........................... -0.3v to (v cc + 0.3v) set to gnd ............................................................. -0.3v to +8v continuous power dissipation (t a = +70 n c) 10-pin f max (derate 8.8mw/ n c above t a = +70 n c) (note 1) ....................................................................... 707mw operating temperature range ........................ -40 n c to +125 n c junction temperature ..................................................... +150 n c storage temperature range ............................ -65 n c to +150 n c lead temperature (soldering, 10s) ................................ +300 n c electrical characteristics (v cc = 14v, c gate1 = 32nf, c gate2 = 32nf, shdn = high, t a = -40 n c to +125 n c, unless otherwise noted. typical values are at t a = +25 n c.) (note 2) absolute maximum ratings note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four- layer board. for detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial . parameter symbol conditions min typ max units operating voltage range v cc (note 3) 4.5 19 v shutdown supply current (i sense in + i sense out + i ov + i shdn + i vcc ) i shdn shdn = low, v sense out = 0v, v term = 0v t a = +25 n c 6.0 12 f a t a = +85 n c (note 3) 6.1 12 t a = +125 n c (note 3) 6.2 12 quiescent supply current (i sense in + i sense out + i ov + i shdn + i vcc ) i q shdn = high t a = +25 n c 29 53 f a t a = +85 n c (note 3) 30 55 t a = +125 n c (note 3) 31 57 v cc undervoltage lockout v uvlo v cc rising, v set = 1v , shdn = high 4.06 4.35 v v cc undervoltage-lockout hysteresis 8 % set threshold voltage v setth v set rising -3% +1.20 +3% v set threshold voltage hysteresis v sethy 4 % set input current i set v set = 1v 0.02 0.2 f a shdn low threshold v shdnl 0.4 v shdn high threshold v shdnh 1.4 v shdn pulldown current i shdn v shdn = 14v, internally pulled to gnd 0.5 1.0 f a v cc to gate output low voltage v gvcc1 v cc = 14v 6.25 7.5 8.5 v v cc to gate clamp voltage v gvcc2 v cc = 42v 14 v
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 _______________________________________________________________________________________ 3 electrical characteristics (continued) (v cc = 14v, c gate1 = 32nf, c gate2 = 32nf, shdn = high, t a = -40 n c to +125 n c, unless otherwise noted. typical values are at t a = +25 n c.) (note 2) note 2: all parameters are production tested at t a = +25nc. limits over the operating temperature range are guaranteed by design and characterization. note 3: guaranteed by design and characterization. note 4: the back-charge voltage, v bc , is defined as the voltage at sense out minus the voltage at sense in. note 5: defined as the time from when v bc exceeds v bcth (25mv typ) to when v gate1 exceeds v cc - 3.5v. note 6: defined as the time from when v bc falls below v bcth - 50mv to when v gate1 falls below v cc - 3.5v. note 7: defined as the time from when v set exceeds v setth (1.20v typ) to when v gate2 exceeds v cc - 3.5v. note 8: defined as the time from when v set falls below v setth - 5% (1.14v typ) to when v gate2 falls below v cc - 3.5v. note 9: the external pfets can turn on t start after the ic is powered up and all input conditions are valid. note 10: defined as the time from when v cc exceeds the undervoltage-lockout threshold (4.3v max) to when v gate1 and v gate2 fall below 1v. note 11: defined as the time from when v cc falls below v sense out - 25mv to when v gate1 reaches v cc - 1.75v. parameter symbol conditions min typ max units term on-resistance r term shdn = high 150 500 i term output current i term shdn = low, v term = 0v 1.0 f a back-charge voltage fault threshold v bcth v sense out = 14v (note 4) 18 25 32 mv back-charge voltage threshold hysteresis v bchy v sense out = 14v 50 mv back-charge turn-off time (gate1) t bc v cc = 9.5v, v sense in = 9v, v sense out stepped from 4.9v to 9.5v (note 5) 6 10 f s back-charge recovery time (gate1) t bcrec v cc = 9.5v, v sense in = 9v, v sense out stepped from 9.5v to 4.9v (note 6) 18 30 f s gate2 turn-off time v cc = 9.5v, v set rising from 1v to 1.5v (note 7) 3 f s gate2 turn-on time v cc = 9.5v, v set falling from 1.5v to 1v (note 8) 20 f s startup response time (v shdn rising) t start1 v cc = 9.5v, from v shdn rising to v gate_ falling (note 9) 100 f s startup response time (v cc rising) t start2 v cc rising from 2v to 4.5v, shdn = high (note 10) 0.150 ms reverse-battery voltage turn-off time/uvlo turn-off time t reverse v cc and v sense in falling from 4.25v to 3.25v, v sense out = 4.25v (note 11) 30 f s thermal-shutdown temperature +170 n c thermal-shutdown hysteresis 20 n c ov output low voltage v ovbl i sink = 600 f a 0.4 v ov open-drain leakage current i ovb v set = 1.0v 1.0 f a sense in input current i sense in v shdn = 0/14v 1 5 f a sense out input current i sense out v shdn = 0/14v 2 5 f a set to ov output low propagation delay t ovbpd v cc = 9.5v, v set rising from 1v to 1.5v to v ov falling 3 f s
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 4 ______________________________________________________________________________________ typical operating characteristics (v cc = 14v, v shdn = 14v, max16914/MAX16915 evaluation kit, t a = +25 n c, unless otherwise noted.) supply current vs. supply voltage max16914 toc01 supply voltage (v) supply current (a) 17.0 12.0 14.5 9.5 7.0 15 20 25 30 10 4.5 19.0 term = open shdn = high set = 0v no load max16914 MAX16915 supply current vs. temperature max16914 toc02 temperature (nc) supply current (fa) 110 85 60 35 10 -15 15 20 25 30 35 40 10 -40 125 term = open shdn = high set = 0v, v cc = 14v no load MAX16915 max16914 shutdown supply current vs. supply voltage max16914 toc03 supply voltage (v) supply current (fa) 17.0 14.5 12.0 9.5 7.0 2 4 6 8 10 0 4.5 19.0 shdn = low set = 0v MAX16915 max16914 uvlo threshold vs. temperature max16914 toc04 temperature (nc) uvlo treshold (v) 110 85 -15 10 35 60 3.6 3.7 3.8 3.9 4.0 4.1 4.2 4.3 3.5 -40 125 rising falling set threshold vs. temperature max16914 toc05 temperature (nc) set threshold (v) 110 85 60 35 10 -15 1.15 1.20 1.25 1.10 -40 125 rising falling power-up response max16914 toc06 40s/div v cc 10v/div v out 10v/div v gate1 10v/div v gate2 10v/div 22f input and output capacitor, r out = 100i, shdn = high startup from shutdown response max16914 toc07 20s/div 100f input capacitor, 122f output capacitor, r out = 100i v shdn 2v/div v out 10v/div v gate1 10v/div 14v 14v 0v 0v v gate2 10v/div overvoltage limiter response (MAX16915) max16914 toc08 400s/div 100f input capacitor, 22f output capacitor, r out = 100i c ov = 10nf v cc = 14v to 30v trip threshold = 22v v cc 20v/div v out 20v/div 0v 14v 14v 14v 30v v gate2 20v/div v ov 20v/div overvoltage switch-off response (max16914) max16914 toc09 1.0s/div 100f input capacitor, 22f output capacitor, r out = 100i v cc 10v/div v out 10v/div 14v 30v 30v 14v 14v 0v 0v 20v v gate2 20v/div v ov 20v/div v cc = 14v to 30v trip threshold = 22v
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 _______________________________________________________________________________________ 5 typical operating characteristics (continued) (v cc = 14v, v shdn = 14v, max16914/MAX16915 evaluation kit, t a = +25 n c, unless otherwise noted.) pin description pin name function 1 v cc positive supply input voltage. bypass v cc to gnd with a 0.1 f f or greater ceramic capacitor. 2 gate1 gate-driver output. connect gate1 to the gate of an external p-channel fet pass switch to pro - vide low drain-to-source voltage drop, reverse voltage protection, and back-charge prevention. 3 sense in differential voltage sense input (input side of ic). used with sense out to provide back-charge prevention when the sense in voltage falls below the sense out voltage by 25mv. 4 shdn active-low shutdown/wake input. drive shdn high to turn on the voltage detectors. gate2 is shorted to v cc when shdn is low. shdn is internally pulled to gnd through a 0.5 f a current sink. connect shdn to v cc for always-on operation. 5 ov open-drain overvoltage indicator output. connect a pullup resistor from ov to a positive supply such as v cc . ov is pulled low when the voltage at set exceeds the internal threshold. 6 gnd ground 7 set controller overvoltage threshold programming input. connect set to the center of an external resistive divider network between term and gnd to adjust the desired overvoltage switch-off or limiter threshold. 8 term voltage-divider termination output. term is internally connected to sense out in the MAX16915 and to v cc in the max16914. term is high impedance when shdn is low, forcing the current to zero in the resistor-divider connected to term. 9 sense out differential voltage sense input (output side of ic). used with sense in to provide back-charge prevention when the sense in voltage falls below the sense out voltage by 25mv. 10 gate2 gate-driver output. connect gate2 to the gate of an external p-channel fet pass switch. gate2 is driven low during normal operation and quickly regulated or shorted to v cc during an overvolt - age condition. gate2 is shorted to v cc when shdn is low. back-charge response max16914 toc10 1.0s/div 2.2f input capacitor, 400i input resistor, 22f output capacitor v cc 5v/div v out 5v/div 0v 5v 5v v gate1 5v/div v cc - v gate_ vs. input voltage max16914 toc11 supply voltage (v) gate drive voltage (v) 40.5 36.0 27.0 31.5 13.5 18.0 22.5 9.0 1.5 3.0 4.5 6.0 7.5 9.0 10.5 12.0 13.5 15.0 0 4.5 44.0 gate1 gate2 set = gnd shdn = high gate-drive voltage vs. temperature max16914 toc12 temperature (nc) gate-drive voltage (v) 110 85 60 35 10 -15 6.3 6.4 6.5 6.6 6.2 -40 125 gate1 gate2 v cc = 14v set = gnd shdn = high
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 6 ______________________________________________________________________________________ detailed description the max16914/MAX16915 are ultra-small, low-quies - cent, high load-current, overvoltage-protection circuits for automotive or industrial applications. these devices monitor the input and output voltages and control two p-channel mosfets to protect downstream loads from reverse-battery, overvoltage, and high-voltage transient conditions and prevent downstream tank capacitors from discharging into the source (back-charging). one mosfet (p1) eliminates the need for external diodes, thus minimizing the input voltage drop and provides back-charge and reverse-battery protection. the second mosfet (p2) isolates the load or regulates the output voltage during an overvoltage condition. these ics allow system designers to size the external p-channel mosfet to their load current, voltage drop, and board size. overvoltage switch-off controller (max16914) in the max16914, the input voltage is monitored (term is internally shorted to v cc see the functional diagram ) making the device an overvoltage switch-off controller. as the v cc voltage rises, and the programmed overvolt - age threshold is tripped, the internal fast comparator turns off the external p-channel mosfet (p2), pulling gate2 to v cc to disconnect the power source from the load. when the monitored voltage goes below the adjusted overvoltage threshold, the max16914 enhanc - es gate2, reconnecting the load to the power source. functional diagram reg gate2 1.20v gate1 sense in shdn ov v cc sense out set term gnd term switch to v cc for max16914 to sense out for MAX16915 bandgap bias ov1 ov1 max16914 MAX16915
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 _______________________________________________________________________________________ 7 overvoltage limiter controller (MAX16915) in the MAX16915, term is internally connected to sense out (see the functional diagram ) allowing the ic to operate in voltage-limiter mode. during normal operation, gate2 is pulled low to fully enhance the mosfet. the external mosfets drain voltage is monitored through a resistor-divider between term, set, and gnd. when the output voltage rises above the adjusted overvoltage threshold, an internal comparator pulls gate2 to v cc turning off p2. when the monitored voltage goes below the overvoltage threshold (-4% hysteresis), the p-channel mosfet (p2) is turned on again. during a continuous overvoltage condition, mosfet (p2) cycles on and off (between the overvoltage threshold and the hysteresis), generating a sawtooth waveform with a frequency dependent on the load capacitance and load current. this process contin - ues to keep the voltage at the output regulated to within approximately a 4% window. the output voltage is regu - lated during the overvoltage transients and mosfet (p2) continues to conduct during the overvoltage event, operating in switched-linear mode. caution must be exercised when operating the MAX16915 in voltage-limiting mode for long durations due to the mosfets power-dissipation consideration (see the mosfet selection section). shutdown the max16914/MAX16915 feature an active-low shut - down input ( shdn ). drive shdn low to switch off fet (p2), disconnecting the input from the output, thus placing the ic in low-quiescent-current mode. reverse- battery protection is still maintained. reverse-battery protection the max16914/MAX16915 feature reverse-battery pro - tection to prevent damage to the downstream circuitry caused by battery reversal or negative transients. the reverse-battery protection blocks the flow of current into the downstream load and allows the circuit designer to remove series-protection diodes. back-charge switch-off the max16914/MAX16915 monitor the input-to-output differential voltage between sense in and sense out. it turns off the external fet (p1) when (v sense out - v sense in ) > 25mv (see figure 1) to prevent discharg - ing of a downstream tank capacitor into the battery sup - ply during an input voltage drop, such as a cold-crank condition or during a superimposed sinusoidal voltage on top of the supply voltage. it turns on the fet (p1) again if the back-charge voltage threshold hysteresis of 50mv is satisfied. figure 1. back-charge turn-off time i out v out - v batt = 0v v out - v batt = 50mv t bc = 10s (max) v batt = 9v 50% (25mv) 50%
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 8 ______________________________________________________________________________________ overvoltage indicator output ( ov ) the max16914/MAX16915 include an active-low, open-drain overvoltage-indicator output ( ov ). for the max16914, ov asserts low when v cc exceeds the pro - grammed overvoltage threshold. ov deasserts when the overvoltage condition is over. for the MAX16915, ov asserts if v out exceeds the programmed overvoltage threshold. ov deasserts when v out drops 4% (typ) below the overvoltage threshold level. if the overvoltage condition continues, ov may toggle with the same frequency as the overvoltage limiter fet (p2). if the p2 device is turned on for a very short period (less than t ovbpd ), the ov pin may not toggle. to obtain a logic-level output, connect a 45k i pullup resistor from ov to a system voltage less than 44v. a capacitor connected from ov to gnd helps extend the time that the logic level remains low. applications information load dump most automotive applications run off a multicell 12v lead-acid battery with a nominal voltage that swings between 9v and 16v (depending on load current, charg - ing status, temperature, battery age, etc.). the battery voltage is distributed throughout the automobile and is locally regulated down to voltages required by the differ - ent system modules. load dump occurs when the alter - nator is charging the battery and the battery becomes disconnected. the alternator voltage regulator is tem - porarily driven out of control. power from the alternator flows into the distributed power system and elevates the voltage seen at each module. the voltage spikes have rise times typically greater than 5ms and decays within several hundred milliseconds but can extend out to 1s or more depending on the characteristics of the charg - ing system. these transients are capable of destroying sensitive electronic equipment on the first fault event. setting overvoltage thresholds term and set provide an accurate means to set the overvoltage level for the max16914/MAX16915. use a resistive divider to set the desired overvoltage condition (see the typical operating circuit ). v set has a rising 1.20v threshold with a 4% falling hysteresis. begin by selecting the total end-to-end resistance: r total = r1 + r2 for high accuracy, choose r total to yield a total cur - rent equivalent to a minimum 100 x i set where i set is the input bias current at set. for example: with an overvoltage threshold (v ov ) set to 20v, r total < 20v/(100 x i set ), where i set = 1 f a (max). r total < 200k i use the following formula to calculate r2: r2 = (v th x r total )/v ov where v th is the 1.20v set rising threshold and v ov is the desired overvoltage threshold. then, r2 = 12.0k i . use the nearest standard-value resistor lower than the calculated value. a lower value for total resistance dissi - pates more power but provides slightly better accuracy. to determine r1: r total = r2 + r1 then, r1 = 188k i . use the nearest standard-value resistor lower than the calculated value. a lower value for total resistance dissi - pates more power but provides slightly better accuracy. mosfet selection output p-channel mosfet (p2) select the external output mosfet according to the application current level. the mosfets on-resistance (r ds(on) ) should be chosen low enough to have a minimum voltage drop at full load to limit the mosfet power dissipation. determine the device power rating to accommodate an overvoltage fault when operating the MAX16915 in overvoltage-limiting mode. during normal operation for either ic, the external mosfet dissipates little power. the power dissipated in the mosfet during normal operation is: p norm = i load 2 x r ds(on) where p norm is the power dissipated in the mosfet in normal operation, i load is the output load current, and r ds(on) is the drain-to-source resistance of the mosfet. worst-case power dissipation in the output mosfet occurs during a prolonged overvoltage event when operating the MAX16915 in voltage-limiting mode. the power dissipated across the mosfet is as follows: p ovlo = v ds x i load where p ovlo is the power dissipated in the mosfet in overvoltage-limiting operation, v ds is the voltage across the mosfets drain and source, and i load is the load current.
ideal diode, reverse-battery, and overvoltage protection switch/limiter controllers with external mosfets max16914/MAX16915 maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 9 ? 2009 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. reverse-polarity protection mosfet (p1) most battery-powered applications must include reverse- voltage protection. many times this is implemented with a diode in series with the battery. the disadvantage in using a diode is the forward-voltage drop of the diode, which reduces the operating voltage available to down - stream circuits (v load = v battery - v diode ). the max16914/MAX16915 include high-voltage gate1 drive circuitry allowing users to replace the high-voltage drop series diode with a low-voltage-drop mosfet device (as shown in the typical operating circuit ). the forward-voltage drop is reduced to i load x r ds(on) of p1. with a suitably chosen mosfet, the voltage drop can be reduced to millivolts. in normal operating mode, internal gate1 output cir - cuitry enhances p1. the constant enhancement ensures p1 operates in a low r ds(on) mode, but the gate-source junction is not overstressed during high battery-voltage applications or transients (many mosfet devices specify a q 20v v gs absolute maximum). as v cc drops below 10v, gate1 is limited to gnd, reducing p1 v gs to v cc . in normal operation, the p1 power dissipation is very low: p1 = i load 2 x r ds(on) during reverse-battery conditions, gate1 is limited to gnd and the p1 gate-source junction is reverse biased. p1 is turned off and neither the max16914/MAX16915 nor the load circuitry is exposed to the reverse-battery voltage. care should be taken to place p1 (and its inter - nal drain-to-source diode) in the correct orientation for proper reverse-battery operation. thermal shutdown the max16914/MAX16915 thermal-shutdown feature turns off both mosfets if the ic junction temperature exceeds the maximum allowable thermal dissipation. when the junction temperature exceeds t j = +170 n c, the thermal sensor signals the shutdown logic, turning off both gate1 and gate2 outputs and allowing the device to cool. the thermal sensor turns gate1 and gate2 on again after the ics junction temperature cools by 20 n c. for continuous operation, do not exceed the absolute maximum junction-temperature rating of t j = +150 n c. chip information process: bicmos package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . package type package code document no. 10 f max u10+2 21-0061
|
