19-1223; Rev 0; 4/97 General Description 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. Thermal- overload protection limits power dissipation and junc- tion 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 13yA. When the switch is off, the quiescent current decreases to 0. 1p/A. The MAX891L/MAX892L. are available in 8-pin pMAX packages. Applications PCMCIA Slots Access Bus Slots Portable Equipment Typical Operating Circuit MAXLAA Current-Limited, High-Side P-Channel Switches with Thermal Shutdown Features # Ultra-Small HMAX PackageOnly 1.11mm High * 2.7V to 5.5V Input Range # Programmable Current Limit @ Low 13pA Quiescent Current at VIN = 3.3V, 0.1pA Switch Off Thermal Shutdown @ FAULT Indicator Output @ On-Resistances: 0.720 (MAXB9S1L) 0.25Q (MAX892L) Ordering information PART TEMP. PIN- CURRENT RANGE PACKAGE LIMIT MAX891LC/D OC to +70C Dice** 500mA MAXS8S1LEUA* -40C to +85C 8 uUMAX 500mA MAX892L.C/D 0C to +70C Dice** 250MmA MAX892LEUA* -40C to +86C 8 MAX 250mA * To order these units in tape and reel, add (-T) ta the end of the part number, Dice are tested at Ta = 428C. Pin Configuration INPUT iN OUT OUTPUT MAAXIAN OApF IN MAXagiL = OUT "00k MAXB921 FAULT GN IF GND SET tL tw | a TOP VIEW * farnaee why a | Our MAXIAA wat axeatt 7] out onTa MAX892L ra] FAULT ano [4 | [5] Set MAX PRAXLUM Maxim integrated Products 4-87 For free samples & the {atest literature: http:/Wwww.maxim-ic.com, or phone 1-800-998-8800 1268XVW/1L68XVWMAX891L/MAX892L Current-Limited, High-Side P-Channel Switches with Thermal Shutdown ABSOLUTE MAXIMUM RATINGS IN tO GND once ccc ececteenenetaceseseentcesereeneeeeanes -0.3V to 6V ON, FAULT to GND.. SET, OUT to GND Maximum Continuous Switch Current MAXB91L oo ceccccerecceteesceetecssenseeesecssseseteseressesecensess 0.75A MAXBG2L occ ereceeccctseeceseeevesessescsseerensniceassterenes 0.375A -0.3V to (Vin + 0.9V) Continuous Power Dissipation (Ta = +70C) MAX (derate 4.1mW/C above +70C) oo... 330mW Operating Temperature Range MAXB91LEUA/MAX892LEUA o.oo. ees -40C to +85C Storage Temperature Range ............ Lead Temperature (soldering, 10sec) Stresses beyond those listed under Absoiute 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 TYP MAX UNITS Operating Voltage 2.7 5.5 Vv Quiescent Current Vin = 5V, ON = GND, lout = OMA 13 20 LA Off-Supply Current ON = IN, Vin = Vout = 5.5V 0.02 1 uA Off-Switch Current ON = IN, Vin = 5.5V, Vout = 0V 0.02 3 pA Undervoitage Lockout Rising edge, 1% hysteresis 2.0 23 26 v Vin = 4.5V MAX891L 120 225 ma . MAX892L 250 420 On-Resistance Vin 2 30V MAX891L 150 300 ma MAX892L 300 500 Current-Limit-Amplifier Accuracy Vset required to tum the switch off (Note 1) 1.178 1.240 1.302 v Maximum Output Current MAXB91L 500 mA MAX892L 250 Jour to Iser Current Ratio Vout = 1.6V to 2.8V MAXGOTL lout = 250mA | 840 968 1130 AIA MAX892L, lout = 125mA | 840 965. 1130 ON Input Low Voltage Vin = 2.7V to 5.5V 0.8 Vv GN input Hi VIN = 2.7V to 3.6V 2.0 V put High Voltage Vin = 4.5V to 5.5V 2A GON Input Leakage VON = 5.5V 4 0.04 1 vA lseT Bias Current VseT = 1.24V, lout = OmA 0.5 3 yA FAULT Logic Output Low Voltage | Isink = 1mA, VseT = 1.4V 0.4 Vv FAULT Logic Output High Leakage} V FAUCT = 5.4V, VseT = 1V 0.05 4 pA Slow-Current-Loop Response Time | 20% current overdrive, Vin = 5V 5 us Fast-Current-Loop Response Time 2 Us . = 4L), or 125mA VIN = SV 100 200 Turn-On Time (waKesay Vin = oV 160 Ws Turn-Off Time Vin = 5V 0.8 2 20 us 4-88 PRAXIARCurrent-Limited, High-Side P-Channel Switches with Thermal Shutdown ELECTRICAL CHARACTERISTICS (VIN = 3V, Ta = -40C to +85C, unless otherwise noted.) (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Operating Voltage 3.0 5.5 Vv Quiescent Current Vin = 5V, ON = GND, four = OmA 50 BA Off-Supply Current ON = IN, Vin = Vout = 5.5V 22 pA Off-Switch Current ON = IN, Vin = 5.5V, Vour = OV 8 LA Undervoltage Lockout Rising edge, 1% hysteresis 2.0 29 Vv MAX891L 225 VIN = 4.5V On Resistance IN MAX892L ao] -Resi esistane Vin a 30v MAXBO1L 300 5 NSS MAXe02L 500 | Current-Limit-Amplifier Accuracy VseT required to turn the switch off (Note 1) 4.14 1.34 Vv . MAX891L, lout = 250mA 805 1210 { iset Current Ratio Vv = 1.6V to 2.8V AIA QUT (0 IseT Current has Our MAX8O2L, lout = 125mA | 805 1210 t FAULT Logic Output Low Voltage | Isink = 1MA, VseT = 1.4V 0.4 Vv Turn-On Time Vin = 5V 200 HS Turn-Off Time VIN = 5V 0.25 20 us Note 1: Tested with lout = S0mA for the MAX891L, 25mA for the MAX892L, and Vs_ET raised until Vin - Vout 2 0.8V. Note 2: Parameters to -40C are guaranteed by design, not production tested. 4-89 MAAXLMA TE68XVW/1L68XVNMAX891L/MAX892L Current-Limited, High-Side P-Channel Switches with Thermal Shutdown (Typical Operating Circuit. Ta = +25C, unless atherwise noted.) QUIESCENT CURRENT v8. MNPUT VOLTAGE QUIESCENT CURRENT (A) 0 4 2 $ 4 6 INPUT VOLTAGE (V} OFF-SWITCH LEAKAGE CURRENT vs. TEMPERATURE LEAKAGE CURRENT (HA) 40-20 0 @ 40 60 a TEMPERATURE (C) NORMALIZED OUTPUT CURRENT vs. OUTPUT VOLTAGE | fuer NORMALIZED OUTPUT CURRENT 0 1 2 3 4 5 OUTPUT VOLTAGE (V} 4-90 rome) 100 : i QUIESCENT CURRENT (A) NORMALIZED Row fon (us) QUIESCENT CURRENT vs. TEMPERATURE 0 2 0 BH 6 8 80 10 TEMPERATURE (C) NORMALIZED ON-RESISTANCE vs. TEMPERATURE lLonp= 40-20 0 2 40 60 80 100 TEMPERATURE (C) TURN-ON TIME vs. TEMPERATURE hoap = lin MaxD6129-407 40-20 0 2 40 60 80 100 TEMPERATURE (C) Typical Operating Characteristics OFF-SUPPLY CURRENT vs. TEMPERATURE Rana 3 z z oa) > & a & 40 20 9 W 40 & 80 100 TEMPERATURE (C) tour/ser RATIO vs. Iuawtr 1400 5 1200 i <> 1000 z : 800 = 2 600 yp OS 8 8 0 0 2m 4 & 938 100 120 140 lumt (%) TURN-OFF TIME vs. TEMPERATURE 4 Ioag = lum g ! i i Vin = SV 4 ! | at Vin = 3V \ \\ \ ! | 40-20 2 40 60 8 100 TEMPERATURE (C) MAAXLAACurrent-Limited, High-Side P-Channel Switches with Thermal Shutdown Typical Operating Characteristics (continued) (Typical Operating Circuit, Ta = +25C, unless otherwise noted.) CURRENT-LIMIT RESPONSE CURRENT-LIMAT RESPONSE {MAXSS1L, Ry = 0.82) (MAXGS1L, Ay = 0.50) B B cv c ov ays/div tpstiv Cin = 47 pF, Cour = 0.1pF B: lout, 2A/div Cin= 47pF, Cour = 0.4pF B: Tout. 2A/div A: Vin, S500mVidiv, AC COUPLED C: Vout. SVidiv A: Vin, 500mV/div, AC COUPLED C: Vout, SV/div SWITCH TURN-ON TIME 20us/div Vin = 5, tout = tum A: Von, 2V/div 8 Your, 2vidiv SWITCH TUAR-OFF TIME A w - B ov ; _ 2psidiv ) Viw= 5V, lour= lum Vu=5 0 A: Von, 2V/div A. tLoap, O.1A/div C Vout. SVAiv B: Your. 2V/div B Van. OV/div D: Veautr, SV/div MAAXIMA 91 1268XVW/1L68XVANMAX891L/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 tyF 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. 5 FAULT Fauit-Indicator Output. This apen-drain output goes low when in current limit or when the die temperature axceeds +135C. 7,8 OUT Switch Output..P-channel MOSFET drain, Bypass OUT with a 0.1yF capacitor te 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 (louT/965) and through Rset (Figure 1). The current-limit error amplifier com- pares the voltage across RseT to the internal 1.24V ref- erence and regulates the current back to the lesser of the programmed current limit (ILimit) or the maximum current limit (IMaAx). These switches are not bidirectional; therefore, the input voltage must be higher than the output voltage. Setting the Current Limit The MAX891L/MAX892L feature internal current-limit- ing circuitry with maximum programmabie values (IMAx) of 50QmA and 250mA, respectively. For best performance, set the current limit (ILimiT) between 0.2IMaAx < 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 = tumit /IRATIO RSET = 1.240 / ISET where Iuiwit is the desired current limit, and IRATiO is the lout to Iser current ratio (965). Short-Circuit Protection The MAX891L/MAX892L are short-circuit-protected switches. In the event of an output short circuit or cur- rent-overload condition, the current through the switch is limited by the internal current-limiting error amplifier to 1.5 x lumit. When the fault condition is removed, the replica error amplifier sets the current limit back to ILIMIT- 4-92 AAAXIAA MAXB9IL N TES MAXA92L e ouT FAULT 4 P UL ~~ N REPLICA \~ + AMPLIFIER + ON SET CURRENT-LIMIT AMPLIFIER 1.24V Rser --~ GND CONTROL CIRCUITRY gi | Ih Figure 1. Functional Diagram For a high AVps/At during an output short-circuit condi- tion, the switch turns off and disconnects the input sup- ply from the output. The current-limiting amplifier then slowly turns the switch on with the output current limited to 1.5 x lumi. When the fault condition is removed, the current limit is set back to ILimrr. Refer to the Current- Limit Response graphs in the Typical Operating Characteristics, PAAXIMACurrent-Limited, High-Side P-Channel Switches with Thermal Shutdown PRAXLAN MAXB89IL MAKE92L cer Rser GND Figure 2. Setting the Current Limit Thermal Shutdown The MAX89 1L/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 100kQ pull-up resistor from FAULT to IN provides a logic-control signal. Applications Information input Capacitor To limit input voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 1uF ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce voltage drop at the input. MAAXILAA Output Capacitor Connect a 0.1pF capacitor from OUT to GND. One function of this capacitor is to prevent inductive para- sitics 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 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 dissi- pates and channels heat away. Calculate maximum power as follows: P = 2.1m 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 4-93 TE6SXVW/TEGESXVI esMAX891L/MAX892L Current-Limited, High-Side P-Channel Switches with Thermal Shutdown Tape-and-Ree!l Information 4.0 20.1 a a ee| ee 1.0 20.1 4.75 20.1 1.5 +0.140.0 DIAMETER > t1- 2.0 0.05 A { \ oo A x &- Co} oot 2220.1 | 4 t +E} +--+ , f+ 4.0401 je |_A0_ 1.0 MINIMUM - A 0.30R MAX. Y Ao 2 3.1mm 26.1 Ko Bo 2.7mm 20.1 Ko = 1.2mm =0.1 NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA461-1 STANDARD. MAAXI AA