19-1176; Rev 1; 6/11 High-Side, n-Channel MOSFET Switch Driver The MAX1614 drives high-side, n-channel power MOSFETs to provide battery power-switching functions in portable equipment. The n-channel power MOSFETs typically have one-third the on-resistance of p-channel MOSFETs of similar size and cost. An internal micropower regulator and charge pump generate the high-side drive output voltage, while requiring no external components. The MAX1614 also features a 1.5%-accurate low-battery comparator that can be used to indicate a low-battery condition, provide an early power-fail warning to the system microprocessor, or disconnect the battery from the load, preventing deep discharge and battery damage. An internal latch allows for pushbutton on/off control with very low current consumption. Off-mode current consumption is only 6µA while normal operation requires less than 25µA. The MAX1614 is available in the space-saving µMAX® package that occupies about 60% less space than a standard 8-pin SO. ____________________________Features o Internal On/Off Latch o High-Side, n-Channel Power MOSFET Drive o 25µA (max) Quiescent Current o 6µA (max) Off Current o Requires No External Components o 1.5%-Accurate Low-Battery Detector o Space-Saving µMAX Package o 5V to 26V Input Voltage Range o Drives Single or Back-to-Back MOSFETs o Controlled Turn-On for Low Inrush Current ______________Ordering Information PART MAX1614C/D ________________________Applications Notebook Computers Portable Equipment Hand-Held Instruments Battery Packs µMAX is a registered trademark of Maxim Integrated Products, Inc. __________Typical Operating Circuit N N -40°C to +85°C 8 µMAX MAX1614EUA/V+ -40°C to +85°C 8 µMAX *Contact factory for dice specifications. +Denotes a lead(Pb)-free/RoHS-compliant package. /V denotes an automotive qualified part. Devices are also available in a tape-and-reel package. Specify tape-and-reel by adding “T” to the part number when ordering. __________________Pin Configuration TOP VIEW OFF 2 ON BATT MAX1614 LBO 3 + MAX1614 LBI 4 OFF R1 Dice* MAX1614EUA+ ON 1 SRC PIN-PACKAGE 0°C to +70°C LOAD OPTIONAL FOR REVERSE CURRENT PROTECTION GATE TEMP RANGE 8 BATT 7 SRC 6 GATE 5 GND µMAX LBO LBI R2 GND ________________________________________________________________ Maxim Integrated Products 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. 1 MAX1614 _______________General Description MAX1614 High-Side, n-Channel MOSFET Switch Driver ABSOLUTE MAXIMUM RATINGS BATT, SRC to GND.................................................-0.3V to +30V GATE to SRC ..........................................................-0.3V to +12V GATE to GND .........................................................-0.3V to +36V GATE + SRC Sink Current, Continuous .............................2.7mA LBI, LBO, ON, OFF to GND....................................-0.3V to +12V LBO Current ..........................................................................5mA Continuous Power Dissipation (TA = +70°C) µMAX (derate 4.10mV/°C above +70°C) .....................330mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10s) .................................+300°C Soldering Temperature (reflow) .......................................+260°C 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 (VBATT = 15V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER SYMBOL BATT Operating Range BATT Shutdown Current Quiescent Current CONDITIONS VGATE - VSRC > 3V, SRC = BATT ISHDN IBATT + ISRC MIN TYP 5 MAX UNITS 26 V VBATT = 26V, ON = OFF = unconnected, IGATE = 0A, device latched off, VLBI = 1.5V 4 7 µA VBATT = 15V, ON = OFF = unconnected, IGATE = 0A, device latched on, VLBI = 1.5V, SRC = BATT 17 30 µA µA VBATT = 26V, ON = OFF = unconnected, IGATE = 0A, device latched on, VLBI = 1.5V, SRC = BATT 21 40 8 9.0 INTERNAL CHARGE PUMP GATE Drive Voltage VGS Measured from GATE to SRC, VBATT = 15V, IGATE = 0A Measured from GATE to SRC, VBATT = VSRC = 5V, IGATE = 1.5µA 6.5 V 3 GATE Drive Output Current VGATE = VSRC = 15V 15 60 µA GATE Discharge Current VGATE = 4V, device latched off 0.5 2 mA 1.218 V LOW-BATTERY COMPARATOR LBI Trip Level VTH LBI input falling 1.182 LBI Trip Hysteresis 1.20 0.02VTH Minimum VBATT for Valid LBO Tested at VLBI = VBATT / 4 0.9 V 4 V LBI Input Current ILBI VLBI = 1.3V 10 nA LBO Low Voltage VOL ISINK = 1mA 0.4 V LBO High Leakage VOH VLBO = 11.5V 0.5 µA ON, OFF) CONTROL INPUTS (O Minimum Input Pullup Current Tested at 2V Maximum Input Pullup Current Tested at 0.6V Input Low Voltage VIL VBATT = 5V Input High Voltage VIH VBATT = 26V Minimum Input Pulse Width tPW VBATT = 5V 2 0.5 µA 1.5 2 µA 0.6 V 2.0 V 0.5 _______________________________________________________________________________________ 1.0 µs High-Side, n-Channel MOSFET Switch Driver MAX1614 ELECTRICAL CHARACTERISTICS (VBATT = 15V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER SYMBOL CONDITIONS MIN TYP UNITS BATT Operating Range VGATE - VSRC > 3V, SRC = BATT 26 V BATT Shutdown Current ISHDN VBATT = 26V, ON = OFF = unconnected, IGATE = 0A, device latched off, VLBI = 1.5V 8 µA IBATT + ISAC VBATT = 26V, ON = OFF = unconnected, IGATE = 0A, device latched on, VLBI = 1.5V 40 µA Quiescent Current 5.0 MAX INTERNAL CHARGE PUMP GATE Drive Voltage Measured from GATE to SRC, VBATT = 15V, IGATE = 0A VGS GATE Drive Output Current 6.5 9.0 V Measured from GATE to SRC, VBATT = 5.25V, IGATE = 1.5µA, VSRC = 5.25V 3 VGATE = VSRC = 15V 15 60 µA 1.224 V LOW BATTERY COMPARATOR LOW-BATTERY LBI Trip Level VTH LBI input falling 1.176 1.20 Note 1: Specifications to TA = -40°C are guaranteed by design and not production tested. __________________________________________Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) TA = +25°C TA = -40°C 14 12 10 TA = -40°C 3.0 2.5 2.0 5 10 15 20 VBATT (V) 25 30 MAX1614-05 1.26 VLBI RISING 1.24 1.22 VLBI FALLING 1.18 1.16 1.0 6 VBATT = 15V 1.28 1.20 1.5 8 1.30 MAX1614-02 TA = +25°C 3.5 18 16 TA = +85°C LBI THRESHOLD (V) TA = +85°C SHUTDOWN CURRENT (µA) SUPPLY CURRENT (µA) 20 4.0 MAX1614-01 22 LOW-BATTERY THRESHOLD vs. TEMPERATURE OFF SUPPLY CURRENT vs. VBATT ON SUPPLY CURRENT vs. VBATT 5 10 15 20 VBATT (V) 25 30 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) _______________________________________________________________________________________ 3 ____________________________Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) GATE-DISCHARGE CURRENT vs. GATE VOLTAGE TA = +85°C 1.5 1.0 0.5 0 32 31 30 29 28 27 -0.5 2 4 6 8 10 12 14 16 18 20 29 TA = +85°C 28 27 TA = -40°C 26 25 24 23 26 0 MAX1614-06 MAX1614--03 33 30 22 -40 -20 VGATE (V) 0 20 40 60 80 5 100 10 15 TEMPERATURE (°C) 20 25 GATE AND SOURCE TRANSITIONS FOR TYPICAL MOSFET LOAD MAX1614-07 GATE TURN-ON TRANSITION FOR TYPICAL MOSFET LOAD VGATE VGATE Si9936 MOSFETS ILOAD = 1A VSRC VSRC ON = GND Si9936 MOSFETS ILOAD = 1A Ciss = 400pF ON = GND 5V/div 5V/div 0V VOFF 0V VOFF 1ms/div 100µs/div MAX1614-09 GATE TURN-OFF TRANSITION FOR TYPICAL MOSFET LOAD VGATE Si9936 MOSFETS ILOAD = 1A Ciss = 400pF ON = GND VSRC 5V/div VOFF 20µs/div 4 30 VBATT (V) MAX1614-08 TA = +25°C VBATT = 15V GATE-CHARGING CURRENT (µA) 2.0 GATE-CHARGING CURRENT vs. BATT VOLTAGE 34 GATE-CHARGING CURRENT (µA) TA = -40°C GATE-CHARGING CURRENT vs. TEMPERATURE MAX1614-04 2.5 GATE-DISCHARGE CURRENT (mA) MAX1614 High-Side, n-Channel MOSFET Switch Driver _______________________________________________________________________________________ High-Side, n-Channel MOSFET Switch Driver PIN NAME FUNCTION 1 ON SET Input to the On/Off Latch. Pulse ON low with OFF high to turn on the external MOSFET switch. When both ON and OFF are low, the part is off. 2 OFF RESET Input to the On/Off Latch. Pulse OFF low with ON high to turn off the external MOSFET switch. When both ON and OFF are low, the part is off. 3 LBO Open-Drain, Low-Battery Comparator Output. LBO is low when VLBI is below the trip point. 4 LBI Low-Battery Comparator Input. LBO goes low when VLBI falls below 1.20V (typ). Connect a voltage divider between BATT, LBI, and GND to set the battery undervoltage trip threshold (see Typical Operating Circuit). 5 GND System Ground 6 GATE Gate-Drive Output. Connect to the gates of external, n-channel MOSFETs. When the MAX1614 is off, GATE actively pulls to GND. 7 SRC Source Input. Connect to the sources of external, n-channel MOSFETs. When the MAX1614 is off, SRC actively pulls to GND. 8 BATT Battery Input. Connect to a battery voltage between 5V and 26V. _______________Detailed Description The MAX1614 uses an internal, monolithic charge pump and low-dropout linear regulator to supply the required 8V VGS voltage to fully enhance an n-channel MOSFET high-side switch (Figure 1). The charge pump typically supplies 30µA, charging 800pF of gate capacitance in 400µs (VBATT = 15V). For slower turn-on times, simply add a small capacitor between the GATE and SRC pins. When turned off, GATE and SRC pull low and typically discharge an 800pF gate capacitance in 80µs. The MAX1614 provides separate on/off control inputs (ON and OFF). ON and OFF connect, respectively, to the SET and RESET inputs of an internal flip-flop. When ON is pulsed low (with OFF = high), the internal charge pump turns on, and GATE is pumped to 8V above SRC, turning on the external MOSFETs. The charge pump maintains gate drive to the external MOSFETs until OFF is pulsed low. When this happens, the internal charge pump turns off, and GATE discharges to ground through an internal switch. For slower turn-on times, simply add a small capacitor. __________ Applications Information Connecting ON/OFF to 3V or 5V Logic ON and OFF internally connect to 2µA max pullup current sources (Figure 1). The open-circuit voltage for ON and OFF ranges from 7V to 10.5V (nominally 8.5V). Since the current sources are relatively weak, connecting ON and OFF directly to logic powered from lower voltages (e.g., 3V or 5V) poses no problem if the gate outputs driving these pins can sink at least 2µA while high. Although the MAX1614 shutdown function was designed to operate with a single pushbutton on/off switch, it can also be driven by a single gate. Connect ON to GND and drive OFF directly (Figure 2). Maximum Switching Rate The MAX1614 is not intended for fast switching applications. In fact, it is specifically designed to limit the rate of change of the load current, ∆I/∆t. The maximum switching rate is limited by the turn-on time, which is a function of the charge-pump output current and the total capacitance on GATE (CGATE). Calculate the turnon time as a function of external MOSFET gate capacitance using the Gate Charging Current vs. VBATT graph in the Typical Operating Characteristics. Since turn-off time is small compared to turn-on time, the maximum switching rate is approximately 1/tON. Adding Gate Capacitance The charge pump uses an internal monolithic transfer capacitor to charge the external MOSFET gates. Normally, the external MOSFET’s gate capacitance is sufficient to serve as a reservoir capacitor. If the MOSFETs are located at a significant distance from the MAX1614, place a local bypass capacitor (100pF typ) across the GATE and SRC pins. For slower turn-on times, simply add a small capacitor between GATE and SRC. _______________________________________________________________________________________ 5 MAX1614 ______________________________________________________________Pin Description MAX1614 High-Side, n-Channel MOSFET Switch Driver BATT P GATE 8.5V LDO CPUMP POWER-ON RESET (BATT < 2V) 1.21V P LBI SRC N LBO N 50kHz OSC SOFT START 1µA ON 1µA N OFF ON ON OFF STATE 0 0 OFF 0 1 ON 1 0 OFF 1 1 LAST VALID STATE MAX1614 GND Figure 1. Functional Diagram 6 _______________________________________________________________________________________ High-Side, n-Channel MOSFET Switch Driver A simple undervoltage disconnect circuit is often desirable to prevent damage to secondary batteries due to repeated deep discharge or cell reversal. The Typical Operating Circuit turns off the MAX1614, disconnecting the battery from the load when the battery voltage falls below the minimum battery voltage required, (VLOW BATT). VLOW BATT = (R1 + R2)/R2 x VTH where VTH is the LBI input threshold (1.20V typ). When fresh cells are installed or the batteries are recharged, a µC or pushbutton reconnects the load. MAX1614 SHUTDOWN OFF (CMOS OR TTL LOGIC) ON GND Using LBO to Generate Early Power-Fail Interrupt Figure 2. Single-Line Shutdown Control N N GATE LOAD SRC Many applications require an early warning indicating that power is failing so that the microprocessor (µP) can take care of any “housekeeping” functions (storing current settings in memory, etc.) before the power fails. Connect LBI through a resistor divider across the battery, and connect LBO to the µP nonmaskable interrupt (NMI). Set the threshold so that LBO goes low when the battery decays to a point where regulation begins to degrade (Figure 4). VLOW BATT = (R1 + R2)/R2 x VTH, where VTH is the LBI input threshold (1.20V typ). Once housekeeping is complete, the µP can turn off the load by pulling OFF low. ON BATT MAX1614 OFF TO µC R1 N LBO LBI N LOAD R2 GND GATE SRC ON Figure 3. Single-Pushbutton On/Off Control On/Off Control with a Single Pushbutton Switch The MAX1614’s separate on and off inputs allow maximum flexibility in controlling the external MOSFETs. Connect a pushbutton switch to the ON pin and microcontroller (µC) I/O for single-button control. Connect the OFF pin to another µC I/O pin. On the first button depression, the MAX1614 turns on automatically; the signal is also detected by the µC. When the button is depressed a second time, the µC wraps around and turns off the MAX1614 by pulling low on the OFF pin (Figure 3). BATT MAX1614 TO µC PORT PINS OFF R1 LBO LBI TO µC NONMASKABLE INTERRUPT R2 GND Figure 4. Using LBO to Generate Early Power-Fail Interrupt _______________________________________________________________________________________ 7 MAX1614 Simple Low-Battery Disconnect/Fresh Battery Reconnect Circuit MAX1614 High-Side, n-Channel MOSFET Switch Driver Increasing Low-Battery Comparator Hysteresis The MAX1614 contains an on-chip comparator with 2% hysteresis for low-battery detection. If more than 2% hysteresis is needed on the low-battery comparator and LBO is connected to OFF, use the circuit in Figure 5 to add hysteresis. The circuit of Figure 5 shows LBO controlling an n-channel MOSFET that shorts R2 to add positive feedback to the trip point. This is necessary to prevent loading down the 1µA pullup at OFF (Figure 1). LOAD N BATT GATE SRC MAX1614 Package Information For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO. 8 µMAX U8+1 21-0036 90-0092 OFF R2 2N7002 (SOT23) LBO LBI R3 R1 = 909kΩ R2, R3 = 150kΩ VL = 8.5V VH = 9.8V HYSTERESIS = 6% SUBSTRATE CONNECTED TO GND ON R1 N ___________________Chip Information GND FALLING TRIP POINT VL ( R1 + R3 VL = VTH R3 ) RISING TRIP POINT VH VH = VTH ( R1 + R2 + R3 R3 ) Figure 5. Increasing Hysteresis of the Battery Disconnect Circuit 8 _______________________________________________________________________________________ High-Side, n-Channel MOSFET Switch Driver REVISION NUMBER REVISION DATE 0 12/96 Initial release 1 6/11 Added automotive-qualified part to the Ordering Information, added soldering temperature to the Absolute Maximum Ratings. DESCRIPTION PAGES CHANGED — 1, 2 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 © 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. MAX1614 Revision History