19-1146; Rev 3; 3/00 1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown ____________________________Features ♦ +2.7V to +5.5V Input Range ♦ Programmable Current Limit ♦ Low Quiescent Current 10µA (typ) at VIN = +3.3V 0.1µA (typ) with Switch Off ♦ Thermal Shutdown ♦ FAULT Indicator Output ♦ 0.09Ω (typ) On-Resistance ________________________Applications Ordering Information PCMCIA Slots PART* Access Bus Slots MAX890LC/D MAX890LESA Portable Equipment TEMP. RANGE 0°C to +70°C -40°C to +85°C PINPACKAGE Dice** 8 SO CURRENT LIMIT 1.2A 1.2A * To order this unit in tape and reel, add (-T) to the end of the part number. ** Dice are tested at TA = +25°C. Typical Operating Circuit Pin Configuration TOP VIEW INPUT IN OUT OUTPUT 0.1µF IN MAX890L IN 2 100kΩ 1µF 8 FAULT IN 1 OUT FAULT ON GND SET ON/OFF RSET MAX890L 7 OUT ON 3 6 OUT GND 4 5 SET SO ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX890L General Description The MAX890L smart, low-voltage, P-channel, MOSFET power switch is intended for high-side load-switching applications. This switch operates with inputs from +2.7V to +5.5V, making it ideal for both +3V and +5V systems. Internal current-limiting circuitry protects the input supply against overload. Thermal-overload protection limits power dissipation and junction temperatures. The MAX890L’s maximum current limit is 1.2A. The current limit through the switch is programmed with a resistor from SET to ground. The quiescent supply current is a low 10µA. When the switch is off, the supply current decreases to 0.1µA. The MAX890L is available in an 8-pin SO package. MAX890L 1.2A, 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 ..................................1.5A Continuous Power Dissipation (TA = +70°C) SO (derate 5.88mW/°C above +70°C) ..........................471mW Operating Temperature Range MAX890LESA ....................................................-40°C to +85°C Storage Temperature Range ........................... -65°C to +150°C Lead Temperature (soldering, 10s) . ...............................+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 MIN TYP 2.7 MAX UNITS 5.5 V Quiescent Current VIN = 5V, ON = GND, IOUT = 0 13 20 µA Off-Supply Current ON = IN, VIN = VOUT = 5.5V 0.03 1 µA Off-Switch Current ON = IN, VIN = 5.5V, VOUT = 0 0.04 15 µA Undervoltage Lockout Rising edge, 1% hysteresis V On-Resistance Current-Limit-Amplifier Threshold 2.4 2.6 VIN = 4.5V 75 130 VIN = 3.0V 90 150 1.240 1.302 VSET required to turn the switch off (Note 1) 2.0 1.178 Maximum Output Current Limit 1.2 IOUT to ISET Current Ratio IOUT = 500mA, VOUT > 1.6V ON Input Low Voltage VIN = 2.7V to 5.5V ON Input High Voltage 970 VIN = 2.7V to 3.6V 2.0 VIN = 4.5V to 5.5V 2.4 1110 mΩ V A 1300 A/A 0.8 V V ON Input Leakage Current V ON = 5.5V 0.01 1 µA ISET Bias Current VSET = 1.24V, IOUT = 0; VIN = VOUT 0.5 3 µA FAULT Logic Output Low Voltage ISINK = 1mA, VSET = 1.4V 0.4 V FAULT Logic Output High Leakage Current V FAULT = 5.5V, VSET = 1V 1 µA Slow-Current-Loop Response Time 20% current overdrive, VCC = 5V 0.05 5 Fast-Current-Loop Response Time Turn-On Time Turn-Off Time 2 µs 2 VIN = 5V, IOUT = 500mA 120 VIN = 3V, IOUT = 500mA 185 VIN = 5V 2 5 _______________________________________________________________________________________ µs 200 µs µs 1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX890L ELECTRICAL CHARACTERISTICS (VIN = +3V, TA = -40°C to +85°C, 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 = 0 50 µA Off-Supply Current ON = IN, VIN = VOUT = 5.5V 2.2 µA Off-Switch Current ON = IN, VIN = 5.5V, VOUT = 0 15 µA Undervoltage Lockout Rising edge, 1% hysteresis 2.9 V On-Resistance 2.0 VIN = 4.5V 130 VIN = 3.0V 150 mΩ Current-Limit-Amplifier Threshold VSET required to turn the switch off (Note 1) 1.14 1.34 V IOUT to ISET Current Ratio IOUT = 500mA, VOUT > 1.6V 925 1390 A/A FAULT Logic Output Low Voltage ISINK = 1mA, VSET = 1.4V 0.4 V Turn-On Time VIN = 5V 200 µs Turn-Off Time VIN = 5V 20 µs 1 Note 1: Tested with IOUT = 100mA and VSET raised until VIN - VOUT ≥ 0.8V. Note 2: 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 2 VIN = 5V 12 11 VIN = 3V 10 9 10 1 0.1 8 0 7 1 2 3 4 5 6 0.01 -40 -20 0 20 40 60 80 -40 100 -20 0 20 40 60 INPUT VOLTAGE (V) TEMPERATURE (°C) TEMPERATURE (°C) OFF-SWITCH CURRENT vs. TEMPERATURE NORMALIZED ON-RESISTANCE vs. TEMPERATURE IOUT/ISET RATIO vs. ILIMIT IOUT = 1/2ILIMIT 1.2 10 1 1.1 1.0 0.9 100 120 140 1400 1200 IOUT/ISET RATIO NORMALIZED RON 100 80 MAX890 toc06 1.3 MAX890 toc04 1000 MAX890 toc05 0 OFF-SWITCH CURRENT (nA) 100 OFF-SUPPLY CURRENT (nA) 13 QUIESCENT CURRENT (µA) ON = GND IOUT = 0 MAX890 toc02 14 MAX890 toc01 QUIESCENT CURRENT (µA) 14 12 OFF-SUPPLY CURRENT vs. TEMPERATURE QUIESCENT CURRENT vs. TEMPERATURE MAX890 toc03 QUIESCENT CURRENT vs. INPUT VOLTAGE 1000 800 600 0.8 400 0.7 200 0.1 0.01 0.6 -20 0 20 40 60 80 100 -20 0 20 40 60 80 100 20 40 60 80 100 TEMPERATURE (°C) ILIMIT (%) NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE TURN-ON TIME vs. TEMPERATURE TURN-OFF TIME vs. TEMPERATURE ILOAD = ILIMIT 240 220 180 160 140 0.4 1 60 1 2 3 4 OUTPUT VOLTAGE (V) 5 6 VIN = 3V 2 80 0 4 3 100 VIN = 5V VIN = 5V 5 VIN = 5V 120 0.2 6 tOFF (µs) tON (µs) 0.6 ILOAD = ILIMIT 7 VIN = 3V 200 0.8 8 MAX890 toc09 260 MAX890 toc07 ILIMIT 1.0 0 0 TEMPERATURE (°C) 1.2 4 0 -40 MAX890 toc08 -40 NORMALIZED OUTPUT CURRENT MAX890L 1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown 0 -40 -20 0 20 40 60 TEMPERATURE (°C) 80 100 -40 -20 0 20 40 60 TEMPERATURE (°C) _______________________________________________________________________________________ 80 100 1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown OUTPUT SHORT-CIRCUIT (FAST LOOP RESPONSE) OUTPUT OVER-LOAD (SLOW LOOP RESPONSE) MAX890 toc11 MAX890 toc10 A A 5V 5V B B 0A C C 0V 0V, 0A 2µs/div CIN = 100µF, COUT = 0.1µF A: VIN, 1V/div, AC-COUPLED 2µs/div CIN = 100µF, COUT = 0.1µF A: VIN, 1V/div, AC-COUPLED B: IOUT, 1A/div C: VOUT, 2V/div B: IOUT, 5A/div C: VOUT, 2V/div SWITCH TURN-ON TIME LOAD-TRANSIENT RESPONSE MAX890 toc13 MAX890 toc12 A A 0A 0V B B 20µs/div 5ms/div VIN = 5V A: IOUT = 0mA TO 750mA, 0.5A/div B: VOUT RIPPLE, 200mV/div, AC COUPLED VIN = 5V, IOUT = ILIMIT A: VON, 2V/div B: VOUT, 2V/div SWITCH TURN-OFF TIME MAX890 toc14 A 0V B 0V 2µs/div VIN = 5V, IOUT = ILIMIT A: VON, 2V/div B: VOUT, 2V/div _______________________________________________________________________________________ 5 MAX890L ____________________________Typical Operating Characteristics (continued) (TA = +25°C, unless otherwise noted.) 1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown MAX890L Pin Description PIN NAME FUNCTION 1, 2 IN Input. P-channel MOSFET source. Bypass IN with a 1µF 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. RSET = 1.38 x 103 / ILIMIT, where ILIMIT is the desired current limit in amperes. 6, 7 OUT Switch Output. P-channel MOSFET drain. Bypass OUT with a 0.1µF capacitor to ground. 8 FAULT Fault-Indicator Output. This open-drain output goes low when in current limit or when the die temperature exceeds +135°C. Detailed Description The MAX890L P-channel MOSFET power switch limits output current to a programmed level. When the output current is increased beyond the programmed current limit, or 1.2A (IMAX), the current also increases through the replica switch (I OUT /1110) and through R SET (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 limit (ILIMIT) or 1.2A. This switch is not bidirectional; therefore, the input voltage must be higher than the output voltage. P IN OUT MAX890L P FAULT N REPLICA AMPLIFIER ON P SET Setting the Current Limit The MAX890L features internal current-limiting circuitry with a maximum programmable value (IMAX) of 1.2A. 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 (RSET) from SET to ground (Figure 2) as follows: ISET = ILIMIT / 1110 RSET = 1.24V / I8 = 1.38 x 103 / ILIMIT where ILIMIT is the desired current limit. Short-Circuit Protection The MAX890L is a short-circuit-protected switch. 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 will set 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 dVDS/dt 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 Output ShortCircuit Fast-Loop Response and Output Over-Load _______________________________________________________________________________________ 1.2A, Current-Limited, High-Side P-Channel Switch with Thermal Shutdown Output Capacitor Connect a 0.1µF capacitor from OUT to GND. One function of this capacitor is to prevent inductive parasitics from pulling OUT negative during turn-off. MAX890L SET RSET GND Figure 2. Setting the Current Limit Slow-Loop Response in the Typical Operating Characteristics. Thermal Shutdown The MAX890L 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 short-circuit condition is not removed, the switch will cycle on and off, resulting in a pulsed output. Fault Indicator The MAX890L 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. Layout and Thermal-Dissipation Consideration 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 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. 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 will help dissipate additional heat. Chip Information TRANSISTOR COUNT: 396 Applications Information Input Capacitor To limit the input voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 1µF ceramic capacitor will be adequate for _______________________________________________________________________________________ 7 MAX890L most applications; however, higher capacitor values will further reduce the voltage drop at the input. ________________________________________________________Package Information SOICN.EPS MAX890L 1.2A, Current-Limited, High-Side P-Channel Switch 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 © 2000 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.