19-4964; Rev 0; 9/09 Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs Features The MAX16914/MAX16915 low-quiescent-current overvoltage 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 controllers regulate the output voltage to the set upper threshold voltage (MAX16915), or switch to high resistance (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. S 4.5V to 19V Input Voltage Operation 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, preventing a downstream tank capacitor from being discharged into the source. S Small 10-Pin µMAX Package Shutdown control turns off the IC completely, disconnecting 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 FMAXM package and operate over the automotive -40NC to +125NC temperature range. Applications S Transient Voltage Protection Up to +44V and -75V S Adjustable Overvoltage Limit with ResistorDivider 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 29µA Low Operating Current S 6µA Low Shutdown Current S Thermal-Overload Protection S -40NC to +125NC Operating Temperature Range S AEC-Q100 Qualified Ordering Information PART TEMP RANGE PIN-PACKAGE MAX16914AUB/V+ -40NC to +125NC 10 FMAX MAX16915AUB/V+ -40NC to +125NC 10 FMAX +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive qualified device. Typical Operating Circuit P1 VBATT P2 VOUT Automotive Industrial Pin Configuration VCC TOP VIEW GATE1 + VCC 1 GATE1 2 SENSE IN 3 MAX16914 MAX16915 10 GATE2 MAX16914 MAX16915 9 SENSE OUT 8 TERM SHDN 4 7 SET OV 5 6 GND SENSE OUT SENSE IN OV OV TERM ON OFF GATE2 SHDN R1 GND SET R2 µMAX is a registered trademark of Maxim Integrated Products, Inc. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX16914/MAX16915 General Description MAX16914/MAX16915 Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs ABSOLUTE MAXIMUM RATINGS VCC, SENSE OUT, TERM, SHDN, OV to GND for P 400ms..............................................................-0.3V to +44V VCC, SENSE OUT, TERM, SHDN, OV to GND for P 90s..............................................................-0.3V to +28V VCC, 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 VCC. .........................................-16V to +0.3V GATE1, GATE2 to GND............................ -0.3V to (VCC + 0.3V) SET to GND..............................................................-0.3V to +8V Continuous Power Dissipation (TA = +70NC) 10-Pin FMAX (derate 8.8mW/NC above TA = +70NC) (Note 1)........................................................................707mW Operating Temperature Range......................... -40NC to +125NC Junction Temperature......................................................+150NC Storage Temperature Range............................. -65NC to +150NC Lead Temperature (soldering, 10s).................................+300NC Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a fourlayer board. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. 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. ELECTRICAL CHARACTERISTICS (VCC = 14V, CGATE1 = 32nF, CGATE2 = 32nF, SHDN = high, TA = -40NC to +125NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2) PARAMETER Operating Voltage Range Shutdown Supply Current (ISENSE IN + ISENSE OUT + IOV + ISHDN + IVCC) Quiescent Supply Current (ISENSE IN + ISENSE OUT + IOV + ISHDN + IVCC) VCC Undervoltage Lockout SYMBOL VCC ISHDN IQ VUVLO CONDITIONS TYP MAX UNITS 19 V TA = +25NC 6.0 12 TA = +85NC (Note 3) 6.1 12 TA = +125NC (Note 3) 6.2 12 TA = +25NC 29 53 TA = +85NC (Note 3) 30 55 TA = +125NC (Note 3) 31 57 4.06 4.35 (Note 3) SHDN = low, VSENSE OUT = 0V, VTERM = 0V SHDN = high MIN 4.5 VCC rising, VSET = 1V , SHDN = high VCC Undervoltage-Lockout Hysteresis 8 SET Threshold Voltage VSETTH SET Threshold Voltage Hysteresis VSETHY SET Input Current ISET SHDN Low Threshold VSHDNL SHDN High Threshold VSHDNH SHDN Pulldown Current ISHDN VSET rising -3% +1.20 0.02 +3% VCC to GATE Output Low Voltage VGVCC1 VCC = 14V VCC to GATE Clamp Voltage VGVCC2 VCC = 42V 6.25 V V % 0.2 FA 0.4 V 0.5 1.0 FA 7.5 8.5 V 14 V 1.4 VSHDN = 14V, internally pulled to GND FA % 4 VSET = 1V FA V 2 _______________________________________________________________________________________ Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs (VCC = 14V, CGATE1 = 32nF, CGATE2 = 32nF, SHDN = high, TA = -40NC to +125NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX 150 500 UNITS I 1.0 FA 32 mV TERM On-Resistance RTERM SHDN = high TERM Output Current ITERM SHDN = low, VTERM = 0V Back-Charge Voltage Fault Threshold VBCTH VSENSE OUT = 14V (Note 4) Back-Charge Voltage Threshold Hysteresis VBCHY VSENSE OUT = 14V 50 18 25 mV Back-Charge Turn-Off Time (GATE1) tBC VCC = 9.5V, VSENSE IN = 9V, VSENSE OUT stepped from 4.9V to 9.5V (Note 5) 6 10 Fs Back-Charge Recovery Time (GATE1) tBCREC VCC = 9.5V, VSENSE IN = 9V, VSENSE OUT stepped from 9.5V to 4.9V (Note 6) 18 30 Fs GATE2 Turn-Off Time VCC = 9.5V, VSET rising from 1V to 1.5V (Note 7) 3 Fs GATE2 Turn-On Time VCC = 9.5V, VSET falling from 1.5V to 1V (Note 8) 20 Fs VCC = 9.5V, from VSHDN rising to VGATE_ falling (Note 9) 100 Fs 0.150 ms Startup Response Time (VSHDN Rising) tSTART1 Startup Response Time (VCC Rising) tSTART2 Reverse-Battery Voltage Turn-Off Time/UVLO Turn-Off Time tREVERSE VCC rising from 2V to 4.5V, SHDN = high (Note 10) VCC and VSENSE IN falling from 4.25V to 3.25V, VSENSE OUT = 4.25V (Note 11) Thermal-Shutdown Temperature Thermal-Shutdown Hysteresis OV Output Low Voltage OV Open-Drain Leakage Current SENSE IN Input Current SENSE OUT Input Current SET to OV Output Low Propagation Delay VOVBL IOVB 30 Fs +170 NC 20 NC ISINK = 600FA 0.4 V VSET = 1.0V 1.0 FA ISENSE IN VSHDN = 0/14V 1 5 FA ISENSE OUT VSHDN = 0/14V 2 5 FA VCC = 9.5V, VSET rising from 1V to 1.5V to VOV falling 3 tOVBPD Fs Note 2: All parameters are production tested at TA = +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, VBC, is defined as the voltage at SENSE OUT minus the voltage at SENSE IN. Note 5: Defined as the time from when VBC exceeds VBCTH (25mV typ) to when VGATE1 exceeds VCC - 3.5V. Note 6: Defined as the time from when VBC falls below VBCTH - 50mV to when VGATE1 falls below VCC - 3.5V. Note 7: Defined as the time from when VSET exceeds VSETTH (1.20V typ) to when VGATE2 exceeds VCC - 3.5V. Note 8: Defined as the time from when VSET falls below VSETTH - 5% (1.14V typ) to when VGATE2 falls below VCC - 3.5V. Note 9: The external pFETs can turn on tSTART after the IC is powered up and all input conditions are valid. Note 10:Defined as the time from when VCC exceeds the undervoltage-lockout threshold (4.3V max) to when VGATE1 and VGATE2 fall below 1V. Note 11:Defined as the time from when VCC falls below VSENSE OUT - 25mV to when VGATE1 reaches VCC - 1.75V. _______________________________________________________________________________________ 3 MAX16914/MAX16915 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (VCC = 14V, VSHDN = 14V, MAX16914/MAX16915 Evaluation Kit, TA = +25NC, unless otherwise noted.) SUPPLY CURRENT vs. SUPPLY VOLTAGE SUPPLY CURRENT vs. TEMPERATURE 20 TERM = OPEN SHDN = HIGH SET = 0V NO LOAD 10 4.5 7.0 9.5 30 25 MAX16915 20 15 12.0 14.5 10 17.0 19.0 MAX16914 TERM = OPEN SHDN = HIGH SET = 0V, VCC = 14V NO LOAD -40 -15 SUPPLY VOLTAGE (V) RISING 10 35 60 85 TEMPERATURE (NC) 110 125 MAX16915 4.0 3.9 3.8 SHDN = LOW SET = 0V 0 4.5 7.0 9.5 12.0 14.5 SUPPLY VOLTAGE (V) 17.0 19.0 POWER-UP RESPONSE MAX16914 toc06 RISING SET THRESHOLD (V) 4.1 MAX16914 toc03 4 2 1.25 MAX16914 toc04 4.3 MAX16914 6 SET THRESHOLD vs. TEMPERATURE UVLO THRESHOLD vs. TEMPERATURE 4.2 8 MAX16914 toc05 15 35 SUPPLY CURRENT (FA) MAX16915 10 MAX16914 toc02 25 SUPPLY CURRENT (FA) SUPPLY CURRENT (µA) MAX16914 SHUTDOWN SUPPLY CURRENT vs. SUPPLY VOLTAGE 40 MAX16914 toc01 30 UVLO TRESHOLD (V) MAX16914/MAX16915 Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs VCC 10V/div VOUT 1.20 10V/div VGATE1 1.15 10V/div 3.7 3.6 FALLING FALLING VGATE2 10V/div 1.10 3.5 -40 -15 10 35 60 85 TEMPERATURE (NC) 110 -40 125 -15 10 35 60 85 TEMPERATURE (NC) 125 40µs/div 22µF INPUT AND OUTPUT CAPACITOR, ROUT = 100I, SHDN = HIGH OVERVOLTAGE SWITCH-OFF RESPONSE (MAX16914) OVERVOLTAGE LIMITER RESPONSE (MAX16915) STARTUP FROM SHUTDOWN RESPONSE MAX16914 toc09 MAX16914 toc08 MAX16914 toc07 VSHDN 30V 2V/div 14V 10V/div VGATE1 VCC 20V/div VCC 30V 10V/div 14V VOUT 14V 110 VOUT 14V 14V 20V/div 14V VOUT 0V 14V VOV 30V VGATE2 10V/div VOV 20V/div 10V/div 20V 0V 20V/div 14V VGATE2 VGATE2 20V/div 10V/div 0V 0V 20µs/div 100µF INPUT CAPACITOR, 122µF OUTPUT CAPACITOR, ROUT = 100I 400µs/div VCC = 14V TO 30V TRIP THRESHOLD = 22V 100µF INPUT CAPACITOR, 22µF OUTPUT CAPACITOR, ROUT = 100I COV = 10nF 20V/div 0V 1.0µs/div VCC = 14V TO 30V TRIP THRESHOLD = 22V 100µF INPUT CAPACITOR, 22µF OUTPUT CAPACITOR, ROUT = 100I 4 _______________________________________________________________________________________ Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs VCC - VGATE_ vs. INPUT VOLTAGE MAX16914 toc11 15.0 5V/div 5V VOUT 5V/div 5V VGATE1 5V/div GATE DRIVE VOLTAGE (V) 13.5 VCC 12.0 10.5 7.5 6.0 4.5 2.2µF INPUT CAPACITOR, 400I INPUT RESISTOR, 22µF OUTPUT CAPACITOR GATE2 3.0 0 1.0µs/div GATE1 9.0 1.5 0V GATE-DRIVE VOLTAGE vs. TEMPERATURE SET = GND SHDN = HIGH 4.5 9.0 13.5 18.0 22.5 27.0 31.5 36.0 40.5 44.0 SUPPLY VOLTAGE (V) 6.6 MAX16914 toc12 MAX16914 toc10 GATE-DRIVE VOLTAGE (V) BACK-CHARGE RESPONSE 6.5 GATE1 6.4 GATE2 6.3 VCC = 14V SET = GND SHDN = HIGH 6.2 -40 -15 10 35 60 85 TEMPERATURE (NC) 110 125 Pin Description PIN NAME FUNCTION 1 VCC 2 GATE1 Gate-Driver Output. Connect GATE1 to the gate of an external p-channel FET pass switch to provide 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 VCC when SHDN is low. SHDN is internally pulled to GND through a 0.5FA current sink. Connect SHDN to VCC for always-on operation. 5 OV 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 VCC 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 VCC during an overvoltage condition. GATE2 is shorted to VCC when SHDN is low. Positive Supply Input Voltage. Bypass VCC to GND with a 0.1FF or greater ceramic capacitor. Open-Drain Overvoltage Indicator Output. Connect a pullup resistor from OV to a positive supply such as VCC. OV is pulled low when the voltage at SET exceeds the internal threshold. _______________________________________________________________________________________ 5 MAX16914/MAX16915 Typical Operating Characteristics (continued) (VCC = 14V, VSHDN = 14V, MAX16914/MAX16915 Evaluation Kit, TA = +25NC, unless otherwise noted.) MAX16914/MAX16915 Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs Functional Diagram VCC 1.20V REG GATE1 OV1 GATE2 SENSE OUT SENSE IN SET TO VCC FOR MAX16914 SHDN BANDGAP BIAS TO SENSE OUT FOR MAX16915 TERM SWITCH OV TERM OV1 MAX16914 MAX16915 Detailed Description The MAX16914/MAX16915 are ultra-small, low-quiescent, 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. GND Overvoltage Switch-Off Controller (MAX16914) In the MAX16914, the input voltage is monitored (TERM is internally shorted to VCC—see the Functional Diagram) making the device an overvoltage switch-off controller. As the VCC voltage rises, and the programmed overvoltage threshold is tripped, the internal fast comparator turns off the external p-channel MOSFET (P2), pulling GATE2 to VCC to disconnect the power source from the load. When the monitored voltage goes below the adjusted overvoltage threshold, the MAX16914 enhances GATE2, reconnecting the load to the power source. 6 _______________________________________________________________________________________ Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs 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 MOSFET’s 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 VCC 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 continues to keep the voltage at the output regulated to within approximately a 4% window. The output voltage is regulated 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 MOSFET’s power-dissipation consideration (see the MOSFET Selection section). Shutdown The MAX16914/MAX16915 feature an active-low shutdown 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. Reversebattery protection is still maintained. Reverse-Battery Protection The MAX16914/MAX16915 feature reverse-battery protection 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 (VSENSE OUT VSENSE IN) > 25mV (see Figure 1) to prevent discharging of a downstream tank capacitor into the battery supply 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. tBC = 10µs (max) VOUT - VBATT = 50mV 50% (25mV) VOUT - VBATT = 0V VBATT = 9V 50% IOUT Figure 1. Back-Charge Turn-Off Time _______________________________________________________________________________________ 7 MAX16914/MAX16915 Overvoltage Limiter Controller (MAX16915) MAX16914/MAX16915 Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs Overvoltage Indicator Output (OV) For example: The MAX16914/MAX16915 include an active-low, open-drain overvoltage-indicator output (OV). For the MAX16914, OV asserts low when VCC exceeds the programmed overvoltage threshold. OV deasserts when the overvoltage condition is over. With an overvoltage threshold (VOV) set to 20V, RTOTAL < 20V/(100 x ISET), where ISET = 1FA (max). For the MAX16915, OV asserts if VOUT exceeds the programmed overvoltage threshold. OV deasserts when VOUT 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 tOVBPD), the OV pin may not toggle. To obtain a logic-level output, connect a 45kI 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. R2 = (VTH x RTOTAL)/VOV 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, charging status, temperature, battery age, etc.). The battery voltage is distributed throughout the automobile and is locally regulated down to voltages required by the different system modules. Load dump occurs when the alternator is charging the battery and the battery becomes disconnected. The alternator voltage regulator is temporarily 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 charging 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). VSET has a rising 1.20V threshold with a 4% falling hysteresis. Begin by selecting the total end-to-end resistance: RTOTAL = R1 + R2 For high accuracy, choose RTOTAL to yield a total current equivalent to a minimum 100 x ISET where ISET is the input bias current at SET. RTOTAL < 200kI Use the following formula to calculate R2: where VTH is the 1.20V SET rising threshold and VOV is the desired overvoltage threshold. Then, R2 = 12.0kI. Use the nearest standard-value resistor lower than the calculated value. A lower value for total resistance dissipates more power but provides slightly better accuracy. To determine R1: RTOTAL = R2 + R1 Then, R1 = 188kI. Use the nearest standard-value resistor lower than the calculated value. A lower value for total resistance dissipates 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 MOSFET’s on-resistance (RDS(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: PNORM = ILOAD2 x RDS(ON) where PNORM is the power dissipated in the MOSFET in normal operation, ILOAD is the output load current, and RDS(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: POVLO = VDS x ILOAD where POVLO is the power dissipated in the MOSFET in overvoltage-limiting operation, VDS is the voltage across the MOSFET’s drain and source, and ILOAD is the load current. 8 _______________________________________________________________________________________ Ideal Diode, Reverse-Battery, and Overvoltage Protection Switch/Limiter Controllers with External MOSFETs 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 ILOAD x RDS(ON) of P1. With a suitably chosen MOSFET, the voltage drop can be reduced to millivolts. In normal operating mode, internal GATE1 output circuitry enhances P1. The constant enhancement ensures P1 operates in a low RDS(ON) mode, but the gate-source junction is not overstressed during high battery-voltage applications or transients (many MOSFET devices specify a Q20V VGS absolute maximum). As VCC drops below 10V, GATE1 is limited to GND, reducing P1 VGS to VCC. In normal operation, the P1 power dissipation is very low: 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 internal 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 TJ = +170NC, 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 IC’s junction temperature cools by 20NC. For continuous operation, do not exceed the absolute maximum junction-temperature rating of TJ = +150NC. Chip Information PROCESS: BiCMOS P1 = ILOAD2 x RDS(ON) 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 FMAX U10+2 21-0061 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 © 2009 Maxim Integrated Products 9 Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX16914/MAX16915 Reverse-Polarity Protection MOSFET (P1) Most battery-powered applications must include reversevoltage 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 downstream circuits (VLOAD = VBATTERY - VDIODE).