19-1153; Rev 0; 10/96 Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown The MAX894L/MAX895L smart, dual, 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 currentlimiting circuitry protects the input supply against overload. Thermal-overload protection limits power dissipation and junction temperature. The MAX894L/MAX895L’s maximum current limits are 500mA and 250mA, respectively. The current limit through the switches is programmed with resistors from SET A/SET B to ground. When the switches are on, the quiescent supply current is a low 16µA. When the switches are off, the supply current decreases to 0.1µA. The MAX894L/MAX895L are available in an 8-pin SO package. ____________________________Features ♦ +2.7V to +5.5V Input Range ♦ Programmable Current Limits ♦ Low Supply Current: 16µA IQ at VIN = 3.3V 0.1µA with Switch Off ♦ Thermal Shutdown ______________Ordering Information PART* ________________________Applications PCMCIA Slots Access Bus Slots TEMP. RANGE MAX894LC/D 0°C to +70°C MAX894LESA -40°C to +85°C MAX895LC/D 0°C to +70°C MAX895LESA -40°C to +85°C PINPACKAGE CURRENT LIMIT Dice** 500mA 8 SO 500mA Dice** 250mA 8 SO 250mA *To order these units in tape and reel, add (-T) to the end of the part number. **Dice are tested at TA = +25°C. Portable Equipment __________Typical Operating Circuit __________________Pin Configuration TOP VIEW OUTPUT A OUT A ONB ON/OFF 0.1µF OUTPUT B IN OUT B MAX894L MAX895L 0.1µF SET A INPUT 1µF OUT B 2 SET A 3 SET B RSET A OUT A 1 RSET B MAX894L MAX895L ONA 4 8 ONB 7 IN 6 SET B 5 GND SO ON/OFF ONA GND ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX894L/MAX895L _______________General Description MAX894L/MAX895L Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown ABSOLUTE MAXIMUM RATINGS IN to GND ...................................................................-0.3V to 6V ONA, ONB to GND .....................................................-0.3V to 6V SET A, SET B, OUT A, OUT B to GND ........-0.3V to (VIN + 0.3V) Maximum Continuous Switch Current MAX894L ..........................................................................0.75A MAX895L ........................................................................0.375A Continuous Power Dissipation (TA = +70°C) SO (derate 5.88mW/°C above +70°C) .......................471mW Operating Temperature Range MAX89_LESA .................................................-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 CONDITION Operating Voltage V 30 µA 0.03 1 µA 0.04 3 µA 2.4 2.6 V MAX894L 120 225 MAX895L 250 420 MAX894L 150 300 ONA = ONB = IN, VIN = VOUT A = VOUT B = 5.5V Off-Switch Current ONA = ONB = IN, VIN = 5.5V, VOUT A = VOUT B = 0 Undervoltage Lockout Rising edge, 1% hysteresis On-Resistance VIN = 3.0V Slow-Current-Loop Response Time Turn-Off Time 500 1.302 250 945 1085 1270 MAX895L, IOUT = 125mA 910 1050 1235 0.8 VIN = 2.7V to 3.6V 2.0 VIN = 4.5V to 5.5V 2.4 V ONA = V ONB = 5.5V 0.01 1 0.5 3 VSET B = 1.24V, ONB = 0, ONA = VIN, IOUT B = 0 0.5 3 V µA µA µs 2 µs 100 VIN = 3V, IOUT = 250mA (MAX894L), 125mA (MAX895L) 150 1.2 200 µs 20 µs Note 1: Tested with IOUT = 50mA for the MAX894L and 25mA for the MAX895L, and VSET raised until VIN - VOUT ≥ 0.8V. 2 A/A 5 VIN = 5V, IOUT = 250mA (MAX894L), 125mA (MAX895L) 0.8 V V VSET A = 1.24V, ONA = 0, ONB = VIN, IOUT A = 0 20% current overdrive, VCC = 5V mΩ mA MAX894L, IOUT = 250mA Fast-Current-Loop Response Time Turn-On Time 300 1.240 MAX895L VIN = 2.7V to 5.5V ISETA, ISETB Bias Current 1.178 500 ONA, ONB Input Low Voltage ONA, ONB Input Leakage MAX895L MAX894L VOUT = 1.6V to 2.8V ONA, ONB Input High Voltage 2.0 VSET required to turn the switch off (Note 1) IOUT to ISET Current Ratio UNITS 5.5 Off-Supply Current VIN = 4.5V MAX 18 VIN = 5V, ONA = ONB = GND, IOUT A = IOUT B = 0 Maximum Output Current TYP 2.7 Quiescent Current Current-Limit-Amplifier Threshold MIN _______________________________________________________________________________________ Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown MAX894L/MAX895L ELECTRICAL CHARACTERISTICS (Note 2) (VIN = 3V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER CONDITION Operating Voltage MIN 3.0 TYP MAX UNITS 5.5 V Quiescent Current VIN = 5V, ONA = ONB = GND, IOUT A = IOUT B = 0 50 µA Off-Supply Current ONA = ONB = IN, VIN = VOUT A = VOUT B = 5.5V 2.2 µA Off-Switch Current ONA = ONB = IN, VIN = 5.5V, VOUT A = VOUT B = 0 8 µA Undervoltage Lockout Rising edge, 1% hysteresis 2.9 V VIN = 4.5V On-Resistance VIN = 3.0V Current-Limit-Amplifier Threshold 250 MAX895L 420 MAX894L 300 MAX895L VSET_ required to turn the switch off (Note 1) IOUT to ISET Current Ratio VSET = 1.24V, VOUT = 1.6V to 2.8V Turn-On Time VIN = 5V 2.0 MAX894L 500 1.14 1.34 MAX894L, IOUT = 250mA 910 1360 MAX895L, IOUT = 125mA 880 1315 Turn-Off Time mΩ 0.25 V A/A 200 µs 20 µs Note 2: Specifications to -40°C are guaranteed by design, not production tested. _______________________________________________________________________________________ 3 __________________________________________Typical Operating Characteristics (Typical Operating Circuit, TA = +25°C, unless otherwise noted.) QUIESCENT CURRENT vs. TEMPERATURE 16 12 8 18 VIN = 5V 16 VIN = 3V 0.04 0.03 0.02 0.01 2 1 3 5 4 0 -40 6 -20 0 20 40 60 80 INPUT VOLTAGE (V) TEMPERATURE (°C) OFF-SWITCH CURRENT vs. TEMPERATURE NORMALIZED ON-RESISTANCE vs. TEMPERATURE MAX894 TOC-04 0.07 0.06 1.3 100 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) IOUT/ISET vs. ILIMIT MAX894 TOC-05 0 MAX894 TOC-03 0.05 12 0 IOUT = 1/2 ILIMIT 1.2 1600 1400 1200 0.03 0.02 0.01 0 1000 1.0 0.9 800 600 0.8 400 0.7 200 0 0.6 0 20 40 60 80 -40 100 -20 0 20 40 60 TEMPERATURE (°C) TEMPERATURE (°C) NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE TURN-ON TIME vs. TEMPERATURE 260 MAX894 TOC-06A 1.4 VIN = 5V 1.2 240 tON (µs) 0.6 ILOAD = ILIMIT 180 VIN = 3V 160 120 VIN = 5V 2 3 4 OUTPUT VOLTAGE (V) 5 6 100 120 140 7 ILOAD = ILIMIT 6 VIN = 5V 4 3 VIN = 3V 0 60 1 80 1 80 0 60 2 100 0.2 40 5 140 0.4 20 TURN-OFF TIME vs. TEMPERATURE 200 0.8 0 0 100 ILIMIT (%) 220 ILIMIT 1.0 80 tOFF (µs) -20 MAX894 TOC-07 -40 MAX894 TOC-08 0.04 1.1 IOUT/ISET RATIO 0.05 NORMALIZED RON OFF-SWITCH CURRENT (µA) 20 0.06 14 4 4 22 0.07 MAX894 TOC-06 20 24 MAX894 TOC-02 24 QUIESCENT CURRENT (µA) MAX894 TOC-01 ONA = ONB = GND IOUT A = IOUT B = 0 QUIESCENT CURRENT (µA) 28 OFF-SUPPLY CURRENT vs. TEMPERATURE OFF-SUPPLY CURRENT (µA) QUIESCENT CURRENT vs. INPUT VOLTAGE NORMALIZED OUTPUT CURRENT MAX894L/MAX895L Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown -40 -20 0 20 40 60 TEMPERATURE (°C) 80 100 -40 -20 0 20 40 60 TEMPERATURE (°C) _______________________________________________________________________________________ 80 100 Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown (Typical Operating Circuit, TA = +25°C, unless otherwise noted.) CURRENT-LIMIT RESPONSE (MAX894L, RL = 0.7Ω) CURRENT-LIMIT RESPONSE (MAX894L, RL = 1Ω) A 5V 5V A B B C 0A 0A 0V C 0V MAX894/895/896 TOC-10 MAX894/895/896 TOC-9 1µs/div 2µs/div CIN = 47µF, COUT = 0.1µF A: VIN, 500mV/div, AC coupled B: IOUT, 2A/div C: VOUT, 5V/div CIN = 47µF, COUT = 0.1µF A: VIN, 500mV/div, AC coupled LOAD-TRANSIENT RESPONSE (MAX894L) B: IOUT, 2A/div C: VOUT, 5V/div A 0A B 0V MAX494/495/496 TOC-13 2ms/div VIN = 5V A: IOUT = 0 to 500mA, 0.2A/div B: VOUT RIPPLE, 200mV/div, AC COUPLED SWITCH TURN-ON TIME A SWITCH TURN-OFF TIME A 0V B B 0V MAX894/895/896 TOC-11 20µs/div VIN = 5V, IOUT = ILIMIT A: VON, 2V/div B: VOUT, 2V/div 2µs/div MAX894/895/896 TOC-12 VIN = 5V, IOUT = ILIMIT A: VON, 2V/div B: VOUT, 2V/div _______________________________________________________________________________________ 5 MAX894L/MAX895L ____________________________Typical Operating Characteristics (continued) MAX894L/MAX895L Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown ______________________________________________________________Pin Description PIN NAME FUNCTION 1 OUT A Switch A Output. P-channel MOSFET drain. Bypass OUT A with a 0.1µF capacitor to ground. 2 OUT B Switch B Output. P-channel MOSFET drain. Bypass OUT B with a 0.1µF capacitor to ground. 3 SET A Set Current-Limit Input. A resistor from SET A to ground sets the current limit for switch A. See Setting the Current Limit section. 4 ONA Active-Low Switch A On Input. A logic low turns switch A on. 5 GND Ground 6 SET B Set Current-Limit Input. A resistor from SET B to ground sets the current limit for switch B. See Setting the Current Limit section. 7 IN 8 ONB Input, Switches A and B. P-channel MOSFET source. Bypass IN with a 1µF capacitor to ground. Active-Low Switch B On Input. A logic low turns switch B on. P IN OUT A OUT B P P P MAX894L MAX895L REPLICA AMPLIFIER B ON ON REPLICA AMPLIFIER A P P SET B SET A ON RSET A CURRENT-LIMIT AMPLIFIER B ON CURRENT-LIMIT AMPLIFIER A RSET B 1.24V 1.24V ONB GND ONA CONTROL CIRCUITRY Figure 1. Functional Diagram 6 _______________________________________________________________________________________ Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown The MAX894L/MAX895L 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 also increases through the replica switch (IOUT/1050) (MAX895) 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. Setting the Current Limit The MAX894L/MAX895L feature internal current-limiting circuitry with maximum programmable values (IMAX) of 500mA, and 250mA, respectively. For best performance, set the current limit (ILIMIT) between 0.2IMAX ≤ I LIMIT ≤ I MAX . This current limit remains in effect throughout the input supply-voltage range. Program the current limit with a resistor (RSET_) connected from SET_ to ground (Figure 2) as follows: ISET = ILIMIT / IRATIO RSET = 1.24V / ISET = (1.24V x IRATIO) / ILIMIT where ILIMIT is the desired current limit for either switch and IRATIO is the IOUT to ISET current ratio (1085mA for the MAX894L and 1050mA for the MAX895L. Short-Circuit Protection The MAX894L/MAX895L are short-circuit-protected switches. In the event of an output short circuit or current-overload condition, the current through either 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. 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 ISET. When the fault condition is removed, the current limit is set back to ILIMIT. Refer to Output Short-Circuit Fast-Loop Response and Output Short-Circuit Slow-Loop Response in the Typical Operating Characteristics. Thermal Shutdown The MAX894L/MAX895L feature 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 cycles on and off, resulting in a pulsed output. SET MAX894L MAX895L RSET GND Figure 2. Setting the Current Limit __________Applications Information Input Capacitor To limit input voltage drop during momentary output short-circuit conditions, place a capacitor from IN to GND. A 1µF ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce voltage drop at the input. Output Capacitor Connect a 0.1µF capacitor from OUT to GND. This capacitor prevents inductive parasitics from pulling OUT negative during turn-off. 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, reducing 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 = I2LIMITA x R ONA + I2LIMITB x R ONB where R ONA and R ONB are the on-resistances of switches A and B, respectively. When one or both outputs are 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 to further dissipate heat. _______________________________________________________________________________________ 7 MAX894L/MAX895L _______________Detailed Description MAX894L/MAX895L Dual, Current-Limited, High-Side P-Channel Switches with Thermal Shutdown ___________________Chip Information TRANSISTOR COUNT: 453 SUBSTRATE CONNECTED TO GND. __________________________________________________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. 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 © 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.