19-1278; Rev 0; 8/97 2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown The MAX869L features a 2A, 45mΩ switch controlled by a logic signal. Current-limit accuracy is ±21%, and can be set from 400mA to 2.4A using a single resistor. The device has a low 12µA quiescent supply current, which reduces to 2µA max in shutdown. It features thermal-shutdown protection and a logic-signal output pin (FAULT) that signals when there is an overcurrent or overtemperature condition. For other devices in this family, consult the Selector Guide. _____________________Selector Guide ____________________________Features ♦ Very Small Footprint (16-pin QSOP is the same size as an 8-pin SO) ♦ Low Resistance: 45mΩ at 3V ♦ ±21%-Accurate, User-Set Current Limit ♦ 12µA (typ) Quiescent Current ♦ 0.01µA (typ) Shutdown Current ♦ 0.04µA (typ) Leakage to Output when Switch is Off ♦ 2.7V to 5.5V Input Range ♦ Thermal Shutdown ♦ FAULT Output ______________Ordering Information PART PART RON AT 3V (mΩ) NOMINAL CURRENT (A) COUNT PACKAGE MAX869L 45 2 Single 16 QSOP MAX890L 90 1 Single 8 SO MAX891L 150 0.5 Single 8 µMAX MAX892L 300 0.25 Single 8 µMAX MAX894L 150 0.5 Dual 8 SO MAX895L 300 0.25 Dual 8 SO ________________________Applications Universal Serial Bus (USB) Notebook Computers MAX869LC/D MAX869LEEE TEMP. RANGE PIN-PACKAGE 0°C to +70°C -40°C to +85°C Dice* 16 QSOP *Dice are specified at TA = +25°C. __________Typical Operating Circuit INPUT 2.7V TO 5.5V IN OUTPUT UP TO 2A OUT 0.1µF* 1µF* 100k MAX869L Personal Communicators Palmtop Computers FAULT ON Hand-Held Instruments GND SET Portable Medical Instruments Pin Configuration appears at end of data sheet. ON/OFF RSET *FOR USB APPLICATIONS, CIN = 1µF, COUT = 120µF ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800. For small orders, phone 408-737-7600 ext. 3468. MAX869L _______________General Description The MAX869L P-channel load switch features an accurate user-set current limit and low on-resistance. This switch is designed to protect your power source from shorts and surges by limiting current and preventing the system supply from being pulled low. The input voltage range is 2.7V to 5.5V. MAX869L 2A, Current-Limited, High-Side P-Channel Switch 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 .....................................3A Continuous Power Dissipation (TA = +70°C) QSOP (derate 8.3mW/°C above +70°C) .......................667mW Operating Temperature Range MAX869LEEE.....................................................-40°C to +85°C Storage Temperature Range ........................... -65°C to +150°C Lead Temperature (soldering, 10sec) .............................+300°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 (VIN = 3V, TA = 0°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITIONS Operating Voltage TYP 2.7 MAX UNITS 5.5 V 12 20 µA 0.01 2 µA 0.04 30 µA 2.3 2.6 V VIN = 4.75V 38 70 VIN = 3.0V 45 90 Quiescent Current VIN = 5V, ON = GND, IOUT = 0A 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 On-Resistance MIN 2.0 mΩ Nominal Current-Limit Set Range RSET = 1% tolerance (Note 1) 0.40 2.4 A Current-Limit-Amplifier Threshold VSET required to turn the switch off (Note 2) 1.178 1.240 1.302 V IOUT to ISET Current Ratio IOUT = 1A, VOUT > 1.6V 810 955 1100 A/A ON Input Low Voltage VIN = 2.7V to 5.5V 0.8 V ON Input High Voltage VIN = 2.7V to 3.6V 2.0 VIN = 4.5V to 5.5V 2.4 V ON Input Leakage V ON = 5.5V 0.01 ±1 µA ISET Bias Current VSET = 1.24V, IOUT = 0A 0.05 ±3 µA FAULT Logic Output Low Voltage ISINK = 1mA, VSET = 1.4V FAULT Logic Output High Leakage Current V FAULT = 5.5V, VSET = 1V Slow-Current-Loop Response Time 20% current overdrive, VCC = 5V 0.05 Turn-Off Time V 1 µA 10 Fast-Current-Loop Response Time Turn-On Time 0.4 µs 4 VIN = 5V, IOUT = 500mA 100 VIN = 3V, IOUT = 500mA 200 VIN = 5V, IOUT = 500mA 2 10 µs 300 30 Note 1: Guaranteed by design. Derived from the ISET current ratio; current-limit amplifier and external set resistor accuracies. Note 2: Tested with IOUT = 200mA and VSET raised until (VIN - VOUT) ≥ 0.8V. Note 3: Specifications to -40°C are guaranteed by design, not production tested. 2 _______________________________________________________________________________________ µs µs 2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX869L ELECTRICAL CHARACTERISTICS (VIN = 3V, TA = -40°C to +85°C, unless otherwise noted.) (Note 3) PARAMETER CONDITIONS Operating Voltage MIN 2.9 TYP MAX UNITS 5.5 V Quiescent Current VIN = 5V, ON = GND, IOUT = 0A 25 µA Off-Supply Current ON = IN, VIN = VOUT = 5.5V 2.5 µA Off-Switch Current ON = IN, VIN = 5.5V, VOUT = 0V 30 µA Undervoltage Lockout Rising edge, 1% hysteresis 2.85 V On-Resistance 2.0 VIN = 4.75V 70 VIN = 3.0V 90 mΩ Nominal Current-Limit Set Range RSET = 1% tolerance (Note 1) 0.40 2.4 A Current-Limit-Amplifier Threshold VSET required to turn the switch off (Note 2) 1.14 1.34 V IOUT to ISET Current Ratio IOUT = 1A, VOUT > 1.6V 765 1145 A/A FAULT Logic Output Low Voltage ISINK = 1mA, VSET = 1V 0.4 V Turn-On Time VIN = 5V, IOUT = 500mA 400 µs Turn-Off Time VIN = 5V, IOUT = 500mA 30 µs 2 Note 1: Guaranteed by design. Derived from the ISET current ratio; current-limit amplifier and external set resistor accuracies. Note 2: Tested with IOUT = 200mA and VSET raised until (VIN - VOUT) ≥ 0.8V. Note 3: Specifications to -40°C are guaranteed by design, not production tested. _______________________________________________________________________________________ 3 __________________________________________Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) 10 8 6 4 MAX869-02 13 12 VIN = 5V 11 VIN = 3V 10 2 9 0 8 20 VIN = VOUT = 5.5V IN = ON 18 OFF-SUPPLY CURRENT (nA) ON = GND IOUT = 0A QUIESCENT CURRENT (µA) QUIESCENT CURRENT (µA) 14 MAX869-01 14 12 OFF-SUPPLY CURRENT vs. TEMPERATURE QUIESCENT CURRENT vs. TEMPERATURE MAX869-03 QUIESCENT CURRENT vs. INPUT VOLTAGE 16 14 12 10 8 6 4 2 1 2 3 4 5 6 40 60 80 -40 100 20 40 60 NORMALIZED ON-RESISTANCE vs. TEMPERATURE IOUT/ISET RATIO vs. SWITCH CURRENT IOUT = 1/2ILIMIT 1.3 400 300 1.1 1.0 0.9 200 0.8 100 0.7 20 0 40 60 80 800 600 200 0 -20 0 20 40 60 80 100 0 0.4 0.8 1.2 1.6 2.0 TEMPERATURE (°C) TEMPERATURE (°C) ISWITCH (A) NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE TURN-ON TIME vs. TEMPERATURE TURN-OFF TIME vs. TEMPERATURE tON (µs) 0.8 0.6 0.4 0.2 VIN = 5V 0 1 2 3 4 OUTPUT VOLTAGE (V) 5 6 12 MAX869-08 CIN = 100µF COUT = 0.1µF ILOAD = ILIMIT CIN = 100µF COUT = 0.1µF ILOAD = ILIMIT 10 VIN = 3V VIN = 5V 8 tOFF (µs) ILIMIT 1.0 260 240 220 200 180 160 140 120 100 80 60 40 20 0 MAX869-07 MAX869-06A 1.2 2.8 1000 400 -40 100 2.4 1200 0.6 -20 100 1400 IOUT/ISET RATIO 500 80 MAX890-06 MAX869-04 1.4 1.2 0 0 OFF-SWITCH CURRENT vs. TEMPERATURE VIN = VON = 5.5V OUT = GND -40 -20 TEMPERATURE (°C) NORMALIZED RON OFF-SWITCH CURRENT (nA) 20 0 TEMPERATURE (°C) 0 4 -20 INPUT VOLTAGE (V) 700 600 0 -40 MAX890-05 0 NORMALIZED OUTPUT CURRENT MAX869L 2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown VIN = 5V VIN = 3V 6 4 2 0 -40 -20 0 20 40 60 TEMPERATURE (°C) 80 100 -40 -20 0 20 40 60 TEMPERATURE (°C) _______________________________________________________________________________________ 80 100 2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown SLOW CURRENT-LIMIT RESPONSE A 0V MA869-10 MA869-09 FAST CURRENT-LIMIT RESPONSE A 0V B 0V B 0V C C 0A 0A D D 0V 0V 4µs/div CIN = 100µF, COUT = 0.1µF C: IOUT, 5A/div A: VFAULT, 5V/div D: VIN, 5V/div B: VOUT, 5V/div 2µs/div CIN = 100µF, COUT = 0.1µF C: IOUT, 5A/div A: VFAULT, 5V/div D: VIN, 5V/div B: VOUT, 5V/div MA869-11 LOAD-TRANSIENT RESPONSE A 0A 0V B 10ms/div VIN = 5V A: IOUT = 0mA TO 1A, 0.5A/div B: VOUT RIPPLE, 200mV/div, AC COUPLED SWITCH TURN-ON TIME A 0V MA869-13 MA869-12 SWITCH TURN-OFF TIME A 0V B B 0V C C 0V 0A 0A D D 0V 0V 20µs/div CIN = 100µF, COUT = 0.1µF, VIN = 5V, IOUT = 1A C: IOUT, 0.5A/div A: VON, 5V/div D: VFAULT, 2V/div B: VOUT, 2V/div 2µs/div CIN = 100µF, COUT = 0.1µF, VIN = 5V, IOUT = 1A A: VON, 5V/div C: IOUT, 0.5A/div B: VOUT, 2V/div D: VFAULT, 2V/div _______________________________________________________________________________________ 5 MAX869L ____________________________Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) ____________________________Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) USB* CIRCUIT OUTPUT FALL TIME A 0V MA869-15 USB* CIRCUIT OUTPUT RISE TIME MA869-14 MAX869L 2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown A 0V B B 0V 0V C C 0A 0A D D 0V 0V 500µs/div VIN = 5V, IOUT = 1A, CIN = 1µF, COUT = 120µF A: VON, 5V/div C: IOUT, 0.5A/div B: VOUT, 2V/div D: VFAULT, 2V/div 500µs/div VIN = 5V, IOUT = 1A, CIN = 1µF, COUT = 120µF A: VON, 5V/div C: IOUT, 0.5A/div B: VOUT, 2V/div D: VFAULT, 2V/div *REFER TO TYPICAL OPERATING CIRCUIT _____________________Pin Description PIN NAME 1, 4, 5, 12, 13, 16 IN Input, P-channel MOSFET source. Bypass IN with a 1µF capacitor to ground. 2, 3, 6, 11, 14, 15 OUT Switch output. P-channel MOSFET drain. Bypass OUT with a 0.1µF capacitor to GND. 7 ON Active-Low Switch-On Input. A logic low turns the switch on. 8 GND Ground SET Set Current-Limit Input. A resistor from SET to ground sets the current limit for the switch. RSET = 1,184 / ILIMIT, where ILIMIT is the desired current limit in amperes. FAULT Fault-Indicator Output. This opendrain output goes low when in current limit or when the die temperature exceeds +135°C. FAULT remains low for Turn-On Time + 50µs during startup. 9 10 6 FUNCTION _______________Detailed Description The MAX869L P-channel MOSFET power switch limits output current to a programmed level. When the output current passes through the main switch, a smaller current also passes through the replica switch (IOUT / 955) and through RSET (Figure 1). When the voltage on RSET exceeds the trip voltage of 1.24V, the current-limit error amplifier regulates the output current to the programmed current limit, ILIMIT (400mA to 2.4A). This switch is not bidirectional; therefore, the input voltage must be higher than the output voltage. Setting the Current Limit The MAX869L features internal current-limiting circuitry with a maximum programmable value (IMAX) of 2.4A. For best performance, set the current limit (I LIMIT ) between 0.2 IMAX ≤ 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 / 955 RSET = 1.24V / ISET = 1,184 / ILIMIT where ILIMIT is the desired current limit. _______________________________________________________________________________________ 2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown OUT MAX869L MAX869L P FAULT MAX869L P IN SET N REPLICA AMPLIFIER RSET ON GND P SET ON CURRENT-LIMIT AMPLIFIER 1.24V RSET Figure 2. Setting the Current Limit HOT ON CONTROL CIRCUITRY GND Figure 1. Functional Diagram Fault Indicator The MAX869L provides a fault output (FAULT). This open-drain output goes low when in current limit or when the die temperature exceeds 135°C. A 100kΩ pull-up resistor from FAULT to IN provides a logiccontrol signal. __________Applications Information Short-Circuit Protection Input Capacitor The MAX869L is a short-circuit-protected switch. In the event of an output short circuit (VOUT ≤ 1.6V typical), the current through the switch is limited by the internal current-limiting error amplifier to 1.4 x ILIMIT. When the short-circuit condition is removed, the current-limit amplifier sets the current limit back to ILIMIT. 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 1.4 x I LIMIT . When the short-circuit condition is removed, the current limit is set back to ILIMIT. Refer to the Fast Current-Limit Response and Slow Current-Limit Response graphs in the Typical Operating Characteristics. To limit the input voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 1µF ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce the voltage drop at the input. Thermal Shutdown The MAX869L features thermal shutdown. The switch turns off when the junction temperature exceeds 135°C. Once the device cools by 10°C, the switch turns back on. If the fault condition is not removed, the switch cycles on and off, resulting in a pulsed output. Output Capacitor Connect a 0.1µF capacitor from OUT to GND to prevent inductive parasitics from pulling OUT below GND during turn-off. USB applications require COUT to be at least 120µF. This larger output capacitance slows the output rise and fall times, as shown in the Typical Operating Characteristics , but does not adversely affect the MAX869L’s turn-off response time. Layout and Thermal-Dissipation Considerations 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 (less than 5mm). _______________________________________________________________________________________ 7 MAX869L 2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown Under normal operating conditions, the package can dissipate and channel heat away. Calculate the maximum power as follows: P = I2LIMIT x RON where RON is the on-resistance of the switch. __________________Pin Configuration When the output is short circuited, the 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 10°C. A ground plane in contact with the device helps dissipate additional heat. ___________________Chip Information TRANSISTOR COUNT: 433 TOP VIEW SUBSTRATE CONNECTED TO GND 16 IN IN 1 OUT 2 15 OUT OUT 3 14 OUT IN 4 MAX869L 13 IN 12 IN IN 5 OUT 6 11 OUT ON 7 10 FAULT 9 GND 8 SET QSOP 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 © 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.