19-1223; Rev 0; 4/97 Current-Limited, High-Side P-Channel Switches with Thermal Shutdown The MAX891L/MAX892L smart, low-voltage, P-channel, MOSFET power switches are intended for high-side load-switching applications. These switches operate with inputs from 2.7V to 5.5V, making them ideal for both 3V and 5V systems. Internal current-limiting circuitry protects the input supply against overload. Thermaloverload protection limits power dissipation and junction temperatures. The MAX891L/MAX892L's maximum current limits are 500mA and 250mA, respectively. The current limit through the switch is programmed with a resistor from SET to ground. When the switch is on, the quiescent supply current is a low 13A. When the switch is off, the quiescent current decreases to 0.1A. ____________________________Features Ultra-Small MAX Package--Only 1.11mm High 2.7V to 5.5V Input Range Programmable Current Limit Low 13A Quiescent Current at VIN = 3.3V, 0.1A Switch Off Thermal Shutdown FAULT Indicator Output On-Resistances: 0.12 (MAX891L) 0.25 (MAX892L) The MAX891L/MAX892L are available in 8-pin MAX packages. ________________________Applications PCMCIA Slots ______________Ordering Information PART TEMP. RANGE MAX891LC/D MAX891LEUA* MAX892LC/D MAX892LEUA* 0C to +70C -40C to +85C 0C to +70C -40C to +85C Access Bus Slots Portable Equipment PINCURRENT PACKAGE LIMIT Dice** 8 MAX Dice** 8 MAX 500mA 500mA 250mA 250mA * To order these units in tape and reel, add (-T) to the end of the part number. ** Dice are tested at TA = +25C. __________Typical Operating Circuit __________________Pin Configuration TOP VIEW INPUT IN OUT OUTPUT 0.1F 100k 1F IN MAX891L MAX892L FAULT ON GND SET 8 OUT IN 1 OUT ON/OFF IN 2 ON 3 MAX891L MAX892L 7 OUT 6 FAULT 5 SET GND 4 MAX ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX891L/MAX892L _______________General Description MAX891L/MAX892L Current-Limited, High-Side P-Channel Switches with Thermal Shutdown ABSOLUTE MAXIMUM RATINGS IN to GND ..................................................................-0.3V to 6V ON, FAULT to GND.................................................... -0.3V to 6V SET, OUT to GND ........................................-0.3V to (VIN + 0.3V) Maximum Continuous Switch Current MAX891L ..........................................................................0.75A MAX892L ........................................................................0.375A Continuous Power Dissipation (TA = +70C) MAX (derate 4.1mW/C above +70C) .......................330mW Operating Temperature Range MAX891LEUA/MAX892LEUA ............................-40C to +85C Storage Temperature Range ............................-65C to +150C Lead Temperature (soldering, 10sec) ........................... +300C 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 (VIN = 3V, TA = 0C to +85C, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER CONDITIONS MIN Operating Voltage V 20 A 0.02 1 A 0.02 3 A 2.3 2.6 V MAX891L 120 225 MAX892L 250 420 MAX891L 150 300 MAX892L 300 500 1.240 1.302 Off-Supply Current ON = IN, VIN = VOUT = 5.5V Off-Switch Current ON = IN, VIN = 5.5V, VOUT = 0V Undervoltage Lockout Rising edge, 1% hysteresis VIN = 4.5V VIN = 3.0V Maximum Output Current 2.0 VSET required to turn the switch off (Note 1) 1.178 MAX891L 500 MAX892L 250 IOUT to ISET Current Ratio VOUT = 1.6V to 2.8V ON Input Low Voltage VIN = 2.7V to 5.5V 840 965 1130 MAX892L, IOUT = 125mA 840 965 1130 0.8 2.0 VIN = 4.5V to 5.5V 2.4 ON Input Leakage V ON = 5.5V -1 ISET Bias Current VSET = 1.24V, IOUT = 0mA FAULT Logic Output Low Voltage ISINK = 1mA, VSET = 1.4V Slow-Current-Loop Response Time Turn-On Time Turn-Off Time VIN = 5V VIN = 5V 100 VIN = 3V 150 0.8 A/A V A 3 A 0.4 V 1 A s 2 IOUT = 250mA (MAX891L), or 125mA (MAX892L) V 1 5 Fast-Current-Loop Response Time 2 0.01 0.05 20% current overdrive, VIN = 5V m V 0.5 FAULT Logic Output High Leakage V FAULT = 5.5V, VSET = 1V m mA MAX891L, IOUT = 250mA VIN = 2.7V to 3.6V ON Input High Voltage UNITS 13 VIN = 5V, ON = GND, IOUT = 0mA On-Resistance MAX 5.5 Quiescent Current Current-Limit-Amplifier Accuracy TYP 2.7 2 _______________________________________________________________________________________ s 200 20 s s Current-Limited, High-Side P-Channel Switches with Thermal Shutdown MAX891L/MAX892L ELECTRICAL CHARACTERISTICS (VIN = 3V, TA = -40C to +85C, unless otherwise noted.) (Note 2) PARAMETER CONDITIONS Operating Voltage MIN 3.0 TYP MAX UNITS 5.5 V Quiescent Current VIN = 5V, ON = GND, IOUT = 0mA 50 A Off-Supply Current ON = IN, VIN = VOUT = 5.5V 2.2 A Off-Switch Current ON = IN, VIN = 5.5V, VOUT = 0V 8 A Undervoltage Lockout Rising edge, 1% hysteresis 2.9 V VIN = 4.5V On-Resistance 2.0 MAX891L 225 MAX892L 420 MAX891L 300 MAX892L 500 On-Resistance VIN = 3.0V Current-Limit-Amplifier Accuracy VSET required to turn the switch off (Note 1) 1.14 1.34 MAX891L, IOUT = 250mA 805 1210 MAX892L, IOUT = 125mA 805 1210 m m V IOUT to ISET Current Ratio VOUT = 1.6V to 2.8V FAULT Logic Output Low Voltage ISINK = 1mA, VSET = 1.4V 0.4 V Turn-On Time VIN = 5V 200 s Turn-Off Time VIN = 5V 20 s 0.25 A/A Note 1: Tested with IOUT = 50mA for the MAX891L, 25mA for the MAX892L, and VSET raised until VIN - VOUT 0.8V. Note 2: Parameters to -40C are guaranteed by design, not production tested. _______________________________________________________________________________________ 3 __________________________________________Typical Operating Characteristics (Typical Operating Circuit, TA = +25C, unless otherwise noted.) QUIESCENT CURRENT vs. TEMPERATURE 4 2 VIN = 3V 10 9 1 2 3 4 5 -20 20 0 40 60 80 INPUT VOLTAGE (V) TEMPERATURE (C) OFF-SWITCH LEAKAGE CURRENT vs. TEMPERATURE NORMALIZED ON-RESISTANCE vs. TEMPERATURE 0.03 0.02 0.01 0 -40 -20 20 0 40 60 80 1.2 1200 1.1 1000 1.0 0.9 60 400 0.7 200 -20 0 20 40 60 80 100 0 20 40 60 80 100 ILIMIT (%) NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE TURN-ON TIME vs. TEMPERATURE TURN-OFF TIME vs. TEMPERATURE MAX890-06A 260 ILOAD = ILIM 240 4 MAX981/2/3-07 1.0 VIN = 3V 160 140 120 VIN = 5V 100 0.2 VIN = 5V VIN = 3V 180 tOFF (s) tON (s) 0.4 2 1 80 0 60 1 ILOAD = ILIM 140 3 200 0.6 120 VIN = 5V 220 0.8 100 0 -40 TEMPERATURE (C) ILIMIT 80 600 TEMPERATURE (C) 1.2 0 40 800 0.8 100 20 0 1400 0.6 -40 -20 IOUT/ISET RATIO vs. ILIMIT IOUT/ISET RATIO NORMALIZED RON 0.04 100 MAX980-05 ILOAD = 1/2ILIM 0.05 0.02 TEMPERATURE (C) 1.3 MAX980-04 0.06 0.03 0 -40 6 0.04 0.01 7 0 LEAKAGE CURRENT (A) 11 8 0 2 3 4 OUTPUT VOLTAGE (V) 4 12 0.05 MAX981/2/3-06 6 VIN = 5V MAX981/2/3-08 8 OFF-SUPPLY CURRENT (A) 10 0.06 MAX981/2/3-02 13 QUIESCENT CURRENT (A) 12 QUIESCENT CURRENT (A) 14 MAX981/2/3-01 14 OFF-SUPPLY CURRENT vs. TEMPERATURE MAX980-03 QUIESCENT CURRENT vs. INPUT VOLTAGE NORMALIZED OUTPUT CURRENT MAX891L/MAX892L Current-Limited, High-Side P-Channel Switches with Thermal Shutdown 5 6 0 -40 -20 0 20 40 60 TEMPERATURE (C) 80 100 -40 -20 0 20 40 60 TEMPERATURE (C) _______________________________________________________________________________________ 80 100 Current-Limited, High-Side P-Channel Switches with Thermal Shutdown (Typical Operating Circuit, TA = +25C, unless otherwise noted.) CURRENT-LIMIT RESPONSE (MAX891L, RL = 0.8) CURRENT-LIMIT RESPONSE (MAX891L, RL = 0.5) A 5V B B C 5V A 0A 0A C 0V 0V 2s/div CIN = 47F, COUT = 0.1F A: VIN, 500mV/div, AC COUPLED 1s/div CIN = 47F, COUT = 0.1F A: VIN, 500mV/div, AC COUPLED B: IOUT, 2A/div C: VOUT, 5V/div B: IOUT, 2A/div C: VOUT, 5V/div SWITCH TURN-ON TIME A B 20s/div VIN = 5V, IOUT = ILIM A: VON, 2V/div B: VOUT, 2V/div SWITCH TIMING CHARACTERISTICS SWITCH TURN-OFF TIME A 0A A B 0V 0V C 0V B D 0V 0V 2s/div VIN = 5V, IOUT = ILIM A: VON, 2V/div B: VOUT, 2V/div 50s/div VIN = 5V A: ILOAD, 0.1A/div B: VON, 5V/div C: VOUT, 5V/div D: VFAULT, 5V/div _______________________________________________________________________________________ 5 MAX891L/MAX892L ____________________________Typical Operating Characteristics (continued) MAX891L/MAX892L Current-Limited, High-Side P-Channel Switches with Thermal Shutdown ______________________________________________________________Pin Description PIN NAME FUNCTION 1, 2 IN Input. P-channel MOSFET source. Bypass IN with a 1F capacitor to ground. 3 ON Active-Low Switch On Input. A logic low turns the switch on. 4 GND Ground 5 SET Set Current-Limit Input. A resistor from SET to ground sets the current limit for the switch. See Setting the Current Limit section. 6 FAULT Fault-Indicator Output. This open-drain output goes low when in current limit or when the die temperature exceeds +135C. 7, 8 OUT Switch Output. P-channel MOSFET drain. Bypass OUT with a 0.1F capacitor to ground. _______________Detailed Description The MAX891L/MAX892L P-channel MOSFET power switches limit output current to a user-programmed level. When the output current is increased beyond the set current level, the current is also increased through the replica switch (I OUT /965) and through RSET (Figure 1). The current-limit error amplifier compares the voltage across RSET to the internal 1.24V reference and regulates the current back to the lesser of the programmed current limit (ILIMIT) or the maximum current limit (IMAX). These switches are not bidirectional; therefore, the input voltage must be higher than the output voltage. MAX891L MAX892L P IN OUT P FAULT N REPLICA AMPLIFIER ON P Setting the Current Limit SET The MAX891L/MAX892L feature internal current-limiting circuitry with maximum programmable values (IMAX) of 500mA and 250mA, respectively. For best performance, set the current limit (I LIMIT ) between 0.2IMAX ILIMIT IMAX. This current limit remains in effect throughout the input supply-voltage range. Program the current limit with a resistor (R SET) from SET to ground (Figure 2) as follows: ISET = ILIMIT / IRATIO RSET = 1.240 / ISET where ILIMIT is the desired current limit, and IRATIO is the IOUT to ISET current ratio (965). Short-Circuit Protection The MAX891L/MAX892L are short-circuit-protected switches. In the event of an output short circuit or current-overload condition, the current through the switch is limited by the internal current-limiting error amplifier to 1.5 x ILIMIT. When the fault condition is removed, the replica error amplifier sets the current limit back to ILIMIT. 6 ON CURRENT-LIMIT AMPLIFIER 1.24V RSET HOT ON CONTROL CIRCUITRY GND Figure 1. Functional Diagram For a high VDS/t during an output short-circuit condition, the switch turns off and disconnects the input supply from the output. The current-limiting amplifier then slowly turns the switch on with the output current limited to 1.5 x ILIMIT. When the fault condition is removed, the current limit is set back to ILIMIT. Refer to the CurrentLimit Response graphs in the Typical Operating Characteristics. _______________________________________________________________________________________ Current-Limited, High-Side P-Channel Switches with Thermal Shutdown MAX891L MAX892L Layout and Thermal-Dissipation Consideration SET RSET GND Figure 2. Setting the Current Limit Thermal Shutdown The MAX891L/MAX892L feature thermal shutdown. The switch turns off when the junction temperature exceeds +135C. Once the device cools by 10C, the switch turns back on. If the fault short-circuit condition is not removed, the switch will cycle on and off, resulting in a pulsed output. Fault Indicator The MAX891L/MAX892L provide a fault output (FAULT). This open-drain output goes low when in current limit or when the die temperature exceeds +135C. During start-up, FAULT is low until the switch is fully on and no over-current condition exists. A 100k pull-up resistor from FAULT to IN provides a logic-control signal. To take full advantage of the switch-response time to output short-circuit conditions, it is very important to keep all traces as short as possible to reduce the effect of undesirable parasitic inductance. Place input and output capacitors as close as possible to the device (no more than 5mm). Under normal operating conditions, the package dissipates and channels heat away. Calculate maximum power as follows: P = I2LIM x RON where RON is the on-resistance of the switch. When the output is short circuited, voltage drop across the switch equals the input supply. Hence, the power dissipated across the switch increases, as does the die temperature. If the fault condition is not removed, the thermal-overload-protection circuitry turns the switch off until the die temperature falls by 10C. A ground plane in contact with the device helps dissipate additional heat. ___________________Chip Information TRANSISTOR COUNT: 396 SUBSTRATE CONNECTED TO GND __________Applications Information Input Capacitor To limit input voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 1F ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce voltage drop at the input. _______________________________________________________________________________________ 7 MAX891L/MAX892L Output Capacitor Connect a 0.1F capacitor from OUT to GND. One function of this capacitor is to prevent inductive parasitics from pulling OUT negative during turn-off. __________________________________________________Tape-and-Reel Information 4.0 0.1 1.0 0.1 2.0 0.05 1.5 +0.1/-0.0 DIAMETER 1.75 0.1 A 3.5 0.05 8.0 0.3 2.2 0.1 0.5 RADIUS TYPICAL 4.0 0.1 A0 A Bo 0.30 0.05 0.8 0.05 1.0 MINIMUM Ko Ao = 3.1mm 0.1 Bo = 2.7mm 0.1 Ko = 1.2mm 0.1 NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD. 0.30R MAX. ________________________________________________________Package Information 8LUMAXD.EPS MAX891L/MAX892L Current-Limited, High-Side P-Channel Switches with Thermal Shutdown 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. 8 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.