19-5037; Rev 0; 1/10 28V-Capable, ILIM VBUS Accessory Switch The MAX14544/MAX14545 are overcurrent detection switches that can provide power to external accessories while preventing the host device from damage due to faulty overload conditions. These analog switches feature a 270mω (typ) on-resistance and operate from a +2.3V to +5.5V input voltage range. The selectable current limit of 200mA or 400mA makes them ideal for load-switching applications. The MAX14544 has an autoretry feature, whereas the MAX14545 has a latchoff feature. When the switch is off, OUT can withstand 28V maximum. When the switch is on and a load is connected to the port, a blanking time of 10.5ms ensures that the transient voltage settles down. After this blanking time, if the voltage across the switch is greater than the FLAG assertion voltage, the switch turns off and then a FLAG is issued to the microprocessor. After the retry time, the device recloses for the duration of the blanking time to check if the load current is lower than the limit. The MAX14544 repeats this cycle if the overload condition is present. During the cycle, FLAG remains asserted. The MAX14544 remains on after the overload condition is removed and FLAG deasserts. For the MAX14545, after the blanking time, the switch turns off and then a FLAG is issued to the microprocessor. The switch can be turned on again by cycling the power or the EN input. The MAX14544/MAX14545 have additional safety features that include thermal shutdown protection, reversecurrent blocking, and overvoltage protection. The MAX14544/MAX14545 are offered in a space-saving, 8-pin, 2mm x 2mm TDFN package, and operate over the -40NC to +85NC extended temperature range. Features S 200mA or 400mA Selectable Current Limit S Output Capable of Withstanding +28V S Reverse-Current Shutdown Protection S +2.3V to +5.5V Input Operation Range S Undervoltage Lockout S Autoretry or Latchoff Option S Thermal Shutdown Protection S 0.1µA (typ) Shutdown Current S 5µs Fast Current-Limit Detect S 8-Pin TDFN (2mm x 2mm) Package S -40NC to +85NC Operating Temperature Range Ordering Information/ Selector Guide PINPACKAGE PART 8 TDFN-EP* ACY Autoretry MAX14545ETA+T 8 TDFN-EP* ACZ Latchoff Note: All devices are specified over the -40°C to +85°C temperature range. +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad. Pin Configuration TOP VIEW + Cell Phones IN 1 MP3 Players IN 2 ISET 3 GND 4 Digital Cameras eBook RETRY/ LATCHOFF MAX14544ETA+T Applications PDAs TOP MARK MAX14544 MAX14545 *EP 8 OUT 7 OUT 6 EN 5 FLAG MID Typical Operating Circuit appears at end of data sheet. TDFN *CONNECT EXPOSED PAD TO GND. ________________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. MAX14544/MAX14545 General Description MAX14544/MAX14545 28V-Capable, ILIM VBUS Accessory Switch ABSOLUTE MAXIMUM RATINGS (Voltages referenced to GND.) OUT........................................................................-0.3V to +30V IN, FLAG, EN, ISET...............................................-0.3V to +6.0V Continuous Power Dissipation (TA = +70NC) 8-Pin TDFN (derate 11.9mW/NC above +70NC)............953mW Junction-to-Ambient Thermal Resistance BJA (Note 1)...............................................................83.9NC/W Junction-to-Case Thermal Resistance BJC (Note 1)..................................................................37NC/W Operating Temperature Range........................... -40NC to +85NC Storage Temperature Range............................. -65NC to +150NC Junction Temperature ...................................... -40NC to +150NC Lead Temperature (soldering, 10s).................................+300NC Soldering Temperature (reflow).......................................+260NC Note 1: Package thermal resistances were obtained using the method described in JEDEC specifications. For detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial. 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 = +2.3V to +5.5V, TA = -40NC to +85NC, unless otherwise noted. Typical values are at VIN = +3.3V, TA = +25NC.) (Note 2) PARAMETER Operating Voltage Range Undervoltage Lockout SYMBOL CONDITIONS VIN VUVLO VIN falling MIN MAX UNITS 2.3 5.5 V 1.8 2.2 V Undervoltage Lockout Hysteresis IN Overvoltage Trip Level 100 VOVLO VIN rising 5.5 IN Overvoltage Hysteresis Quiescent Current OUT Voltage OUT Leakage Current IQ VOUT IOUTL ISHDN Switch On-Resistance RON Current Limit ILIM FLAG Assertion Voltage Reverse-Current Detection Threshold 2 mV 6.0 1 IN Shutdown Current Reverse-Current Detection Hysteresis TYP VEN = VIN = 3.3V, IOUT = 0A 225 Switch off VEN = VIN = 5V, VOUT = 5V after an overcurrent fault 0.2 V % 380 FA 28 V 1 FA VEN = VIN = 5V, VOUT = 10V after an overcurrent fault 3.5 VEN = 0V, VIN = 5V, VOUT = 0V, VISET = 0V 0.1 1.1 VEN = 0V, VIN = 5V, VOUT = 10V, VISET = 0V 0.1 1.1 IOUT = 100mA, VIN = 2.3V IOUT = 100mA, VIN > 3.3V 370 600 270 450 FA mI VISET = 0V, VIN - VOUT = 1V 200 250 300 VISET = VIN, VIN - VOUT = 1V 400 500 600 VFA VFA = VIN - VOUT, where overcurrent is detected and FLAG asserted 0.30 0.45 0.60 V IDET VEN = VIN = 3.3V, VOUT rising until reversecurrent shutdown protection trips 0 155 350 mA After a reverse overcurrent event, VOUT falls below VIN until switch turns on, measure VIN - VOUT 100 200 300 mV mA 28V-Capable, ILIM VBUS Accessory Switch MAX14544/MAX14545 ELECTRICAL CHARACTERISTICS (continued) (VIN = +2.3V to +5.5V, TA = -40NC to +85NC, unless otherwise noted. Typical values are at VIN = +3.3V, TA = +25NC.) (Note 2) PARAMETER SYMBOL Input Logic-High Voltage VIH Input Logic-Low Voltage VIL Input Leakage Output Logic-Low Voltage IIN VOL CONDITIONS MIN TYP MAX UNITS 1.4 VEN = VISET = 0V or 5V V -1 0.4 V +1 FA ISINK = 1mA 0.4 V 1 FA Thermal Shutdown VFLAG = 5V VIN = 5V 150 NC Thermal Shutdown Hysteresis VIN = 5V 15 NC Output High Leakage Current TIMING CHARACTERISTICS (Note 3) Turn-On Time tON VEN from low to high, VIN = 3.3V, RL = 100I Turn-Off Time tOFF VEN from high to low, VIN = 3.3V, RL = 100I 1 ms Current-Limit Reaction Time tLIM VEN = VIN = 3.3V, output high and then short circuit applied, CIN = 10FF ceramic, COUT = 1µF ceramic 5 Fs Blanking Time tBLANK VEN = VIN = 3.3V, Figures 1 and 2 Autoretry Time tRETRY MAX14544, Figure 1 Reverse-Current Detection Time tDET VIN = 3.3V, IREVERSE = 250mA, CIN = 10FF ceramic, COUT = 1FF ceramic Reverse-Current Recovery Time tREC VOUT = VIN + 500mV to VOUT = VIN - 500mV 0.3 ms 4 10.5 30 ms 252 661.5 1890 ms 5 Fs 0.1 ms Note 2: All devices are production tested at TA = +25NC. Specifications over temperature limits are guaranteed by design. Note 3: All timing characteristics are measured using 20% and 80% levels. 3 MAX14544/MAX14545 28V-Capable, ILIM VBUS Accessory Switch tBLANK tBLANK tRETRY CURRENT LIMIT LOAD CURRENT ON SWITCH OFF FLAG ON EN OFF Figure 1. MAX14544 Timing Diagram (Waveforms Not to Scale) tBLANK CURRENT LIMIT LOAD CURRENT ON SWITCH OFF FLAG ON EN OFF Figure 2. MAX14545 Timing Diagram (Waveforms Not to Scale) 4 tBLANK tBLANK tRETRY tBLANK 28V-Capable, ILIM VBUS Accessory Switch SUPPLY CURRENT (µA) 300 250 200 150 200 0 0 3.1 3.5 3.9 4.3 4.7 5.1 VIN = 3.3V 150 50 2.7 VIN = 5V 250 50 5.5 MAX14544/5 toc03 1.01 1.00 0.99 0.98 0.97 0.96 0.95 -15 -40 10 35 60 85 2.3 2.7 3.1 3.5 3.9 4.3 4.7 5.1 0.99 0.98 0.97 VOUT = 5V 800 700 600 500 VIN = 5V 400 300 200 VIN = 2.3V 100 0.96 0.95 -15 10 35 60 900 SHUTDOWN FORWARD CURRENT (nA) MAX14544/5 toc04 1.00 900 0 85 VOUT = 0V 800 700 600 500 VIN = 5V 400 300 200 VIN = 2.3V 100 0 -40 -15 10 35 60 85 -40 -15 10 35 60 SHUTDOWN REVERSE CURRENT vs. TEMPERATURE NORMALIZED ON-RESISTANCE vs. SUPPLY VOLTAGE NORMALIZED ON-RESISTANCE vs. TEMPERATURE 800 750 1.3 1.2 1.1 1.0 0.9 0.8 0.7 10 35 TEMPERATURE (°C) 60 85 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.5 0.5 -15 IOUT = 100mA 1.4 0.6 0.6 700 1.5 NORMALIZED ON-RESISTANCE 850 IOUT = 100mA 1.4 NORMALIZED ON-RESISTANCE 900 1.5 85 MAX14544/5 toc09 TEMPERATURE (°C) MAX14544/5 toc08 TEMPERATURE (°C) MAX14544/5 toc07 TEMPERATURE (°C) VIN = 2.3V VOUT = 5V 5.5 MAX14544/5 toc06 SHUTDOWN FORWARD CURRENT vs. TEMPERATURE MAX14544/5 toc05 SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE 1.01 -40 1.02 NORMALIZED CURRENT LIMIT vs. TEMPERATURE 1.02 950 1.03 SUPPLY VOLTAGE (V) 1.03 1000 1.04 TEMPERATURE (°C) 1.04 -40 1.05 SUPPLY VOLTAGE (V) 1.05 NORMALIZED CURRENT LIMIT 300 100 2.3 SHUTDOWN REVERSE CURRENT (nA) 350 100 SHUTDOWN SUPPLY CURRENT (nA) SUPPLY CURRENT (µA) 350 VEN = VIN 400 NORMALIZED CURRENT LIMIT vs. SUPPLY VOLTAGE NORMALIZED CURRENT LIMIT VEN = VIN 400 450 MAX14544/5 toc01 450 QUIESCENT SUPPLY CURRENT vs. TEMPERATURE MAX14544/5 toc02 QUIESCENT SUPPLY CURRENT vs. SUPPLY VOLTAGE 2.3 2.7 3.1 3.5 3.9 4.3 SUPPLY VOLTAGE (V) 4.7 5.1 5.5 -40 -15 10 35 60 85 TEMPERATURE (°C) 5 MAX14544/MAX14545 Typical Operating Characteristics (VIN = +3.3V, CIN = 10FF, COUT = 1FF, TA = +25NC, unless otherwise noted.) Typical Operating Characteristics (continued) (VIN = +3.3V, CIN = 10FF, COUT = 1FF, TA = +25NC, unless otherwise noted.) SWITCH TURN-ON TIME vs. TEMPERATURE SWITCH TURN-OFF TIME vs. TEMPERATURE 94 93 92 91 90 89 88 87 POWER-UP RESPONSE MAX14544/5 toc12 MAX14544/5 toc11 VIN = 5V RL = 100Ω 1000 VIN = 5V RL = 100Ω 990 SWITCH TURN-OFF TIME (µs) MAX14544/5 toc10 95 SWITCH TURN-ON TIME (µs) MAX14544/MAX14545 28V-Capable, ILIM VBUS Accessory Switch 980 VIN 5V/div 970 960 VOUT 5V/div 950 940 IOUT 50mA/div 930 86 85 -40 -15 10 35 60 920 85 -40 TEMPERATURE (°C) -15 10 35 60 200µs/div 85 TEMPERATURE (°C) FLAG RESPONSE REVERSE OVERVOLTAGE PROTECTION MAX14544/5 toc13 VIN = 5V RL = 100Ω ISET HIGH VEN = 0V 10V CURRENT LIMIT RESPONSE MAX14544/5 toc14 VOUT 2V/div MAX14544/5 toc15 ISET HIGH IOUT 200mA/div IOUT 200mA/div 5V 0V VIN 2V/div 3.3V 100ms/div CURRENT LIMIT RESPONSE 6 BLANKING TIME MAX14544/5 toc17 ISET HIGH 100ms/div 20ms/div OVERCURRENT DURATION TIME MAX14544/5 toc16 VFLAG 2V/div VFLAG 5V/div 0V 10µs/div VOUT 2V/div VOUT 5V/div MAX14544 ISET HIGH IOUT 200mA/div IOUT 200mA/div VOUT 2V/div VOUT 2V/div VFLAG 2V/div VFLAG 2V/div 200ms/div MAX14544/5 toc18 MAX14544 ISET HIGH IOUT 200mA/div VOUT 2V/div 10ms/div VFLAG 2V/div 28V-Capable, ILIM VBUS Accessory Switch PIN NAME FUNCTION 1, 2 IN Input Voltage. Connect IN pins 1 and 2 together and bypass IN to GND with a 10FF ceramic capacitor as close to the device as possible. 3 ISET Current-Limit Setting. Drive ISET low to have a 200mA current limit. Drive ISET high to have a 400mA current limit. 4 GND Ground 5 FLAG Active-Low Fault Open-Drain Output. FLAG goes low when the forward output current is exceeded for longer than the blanking time, the reverse current limit is exceeded, the OVP threshold on IN is reached, or the part goes into thermal shutdown. FLAG is high impedance when EN is low or a fault is not present. 6 EN Active-High Switch-Enable Input. Drive EN high to turn on the device. Drive EN low to turn off the device. 7, 8 OUT Output Voltage. Connect OUT pins 7 and 8 together and bypass OUT to GND with a 1FF ceramic capacitor as close to the device as possible. — EP MAX14544/MAX14545 Pin Description Exposed Pad. Connect EP to GND. For enhanced thermal dissipation, connect EP to a large copper ground plane. Do not use EP as the sole ground connection. Functional Diagram IN OUT REVERSE CURRENT CHARGE PUMP FORWARD CURRENT UVLO CONTROL MAX14544 MAX14545 OVLO EN ISET FLAG GND 7 MAX14544/MAX14545 28V-Capable, ILIM VBUS Accessory Switch Detailed Description The MAX14544/MAX14545 are overcurrent detection switches that prevent host devices from being damaged due to faulty load conditions. The switch opens if current exceeds the current limit for longer than the blanking time or if a reverse-current condition is detected. The switch also disconnects if VIN exceeds OVLO, VIN falls below UVLO, thermal shutdown occurs, or EN is driven low. Current limit can be set to either 200mA or 400mA. When the switch is open, the output (OUT) can withstand 28V maximum. When the switch is on and a load is connected to the port, a blanking time of 10.5ms ensures that the inrush current settles down. After this blanking time, if the voltage across the switch is greater than the FLAG assertion voltage, the part is turned off and issues a FLAG to the microprocessor. After the retry time elapses, the MAX14544 switch is closed for the duration of the blanking time to check if the load current is lower than the limit. Cycle the power or EN input to turn the MAX14545 switch back on. Current-Limit Threshold The MAX14544/MAX14545 ISET logic input sets the desired minimum current-limit threshold to 200mA or 400mA. Connect ISET low for a 200mA current limit and high for a 400mA current limit. If 400mA is selected as the current limit, the input supply current at shutdown can be reduced by connecting ISET to EN. This is due to the fact that the device consumes the lower supply current in ISET = low mode than in ISET = high mode. Reverse-Current Protection The MAX14544/MAX14545 monitor the reverse current (VOUT to VIN) from exceeding the maximum IDET value. If the reverse-current detection threshold is exceeded, the switch turns off and FLAG is asserted without waiting for tBLANK to elapse. This feature prevents excessive reverse currents from flowing through the device. FLAG Indicator The MAX14544/MAX14545 feature a fault output (FLAG). Whenever VIN - VOUT > VFA, the MAX14544 asserts FLAG low after the blanking time and keeps it low until the condition is removed. During this time, the switch cycles on and off in the autoretry mode. When the condition is removed, FLAG deasserts and the switch turns on (Figure 1). The MAX14545 asserts FLAG low after the blanking time and turns the switch off when FLAG assertion voltage is exceeded (Figure 2). 8 FLAG is an open-drain output and requires an external pullup resistor. During shutdown (EN is low), the pulldown on FLAG output is released to limit power dissipation. FLAG goes low when one of the following occurs: 1) T he temperature exceeds the thermal shutdown temperature, +150NC (typ). 2) T he device is in current limit for more than the fault blanking period. 3) The switch is in autoretry. 4) The reverse current limit is exceeded. 5) The input is over the OVLO. Autoretry (MAX14544) When the FLAG assertion voltage is exceeded, the tBLANK timer begins counting (Figure 1). The timer resets if the condition disappears before tBLANK has elapsed. A retry time delay (tRETRY) is started immediately after tBLANK has elapsed and during that time the switch is turned off and FLAG is asserted. At the end of tRETRY, the device is turned on again. If the fault still exists, the cycle is repeated. If the fault is removed, the device stays on and FLAG deasserts. The autoretry feature saves system power in the case of a continuous overcurrent or short-circuit condition. During tBLANK, when the switch is on, the supply current is at the current limit. During tRETRY, when the switch is off, the current through the switch is zero. Instead of observing the full load current, the device sees the equivalent load current times duty cycle or: ISUPPLY = ILOAD x tBLANK /(tBLANK + tRETRY) With a typical tBLANK = 10.5ms and typical tRETRY = 661.5ms, the duty cycle is 1.6%, resulting in a 98.4% power savings over the switch being on the entire time. Latchoff (MAX14545) When the FLAG assertion voltage is exceeded, the tBLANK timer begins counting. The device turns off after the blanking time. The timer resets if the condition is removed before the end of the blanking time. Reset the device by toggling EN (Figure 2). Fault Blanking The MAX14544/MAX14545 feature a 10.5ms (typ) fault blanking. Fault blanking allows current-limit faults, including momentary short-circuit faults that occur when plugging a capacitive load, and also ensures that no fault is issued during power-up. When a load transient causes the device to enter current limit, an internal counter starts. If the load-transient fault persists beyond the 28V-Capable, ILIM VBUS Accessory Switch A reverse current-limit fault, thermal fault, or OVP fault causes FLAG to assert immediately and does not wait for the blanking time. Thermal Shutdown The MAX14544/MAX14545 have a thermal-shutdown feature to protect the devices from overheating. The device turns off and FLAG goes low immediately (no fault blanking) when the junction temperature exceeds +150NC. The MAX14544/MAX14545 turns back on when the device temperature drops approximately 15NC. OVLO and UVLO The MAX14544/MAX14545 feature an overvoltage protection. When IN goes above VOVLO (6.0V max), the switch turns off and FLAG goes low immediately with no fault-blanking time. When IN drops below VUVLO (1.8V min), the switch turns off but FLAG stays high. The MAX14544/MAX14545 turns back on when IN is in the operating range. Applications Information Input Capacitor To limit the input-voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 10FF ceramic capacitor is adequate for most applications; however, higher capacitor values further reduce the voltage drop at the input and are recommended for lower voltage applications. Output Capacitor Connect a 1FF ceramic capacitor from OUT to GND. This capacitor helps prevent inductive parasitics from pulling OUT negative during turn-off, thus preventing the MAX14544/MAX14545 from tripping erroneously. If the load capacitance is too large, then current may not have enough time to charge the capacitance and the device assumes that there is faulty load condition. The maximum capacitive load value that can be driven from OUT is obtained by the following formula: I ×t C MAX < FWD_MIN BLANK_MIN VIN Layout and Thermal Dissipation To optimize the switch response time to output shortcircuit 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. IN and OUT must be connected with short traces to the power bus. During normal operation, the power dissipation is small and the package temperature change is minimal. If the output is continuously shorted to ground at the maximum supply voltage, the operation of the switches with the autoretry option does not cause problems because the total power dissipated during the short is scaled by the duty cycle: V ×I ×t PMAX = IN_MAX OUT_MAX BLANK = 51.6mW t RETRY + t BLANK where VIN_MAX = 5.5V, IOUT_MAX = 600mA, tBLANK = 10.5ms, and tRETRY = 661.5ms. Attention must be given to the MAX14545 where the latchoff condition can be manually reset by toggling EN from high to low. If the latchoff time duration is not sufficiently high, it is possible for the device to reach the thermal-shutdown threshold and never be able to turn the device on until it cools down. 9 MAX14544/MAX14545 fault-blanking timeout, FLAG asserts low. FLAG is not asserted when load-transient fault is less than tBLANK. The fault blanking time only applies to forward currentlimit faults. 28V-Capable, ILIM VBUS Accessory Switch MAX14544/MAX14545 Typical Operating Circuit CURRENT Li+ BATTERY CHARGER D+ BATT VCC IN IN OUT OUT GND MINI-B USB JACK EN GND OR PERIPHERAL DEVICE CURRENT VCC FLAG µC D- MAX14544 MAX14545 10kI CHARGER POWER SOURCE VBUS ISET NOTE: DRIVE ISET HIGH TO HAVE A 400mA CURRENT LIMIT. DRIVE ISET LOW TO HAVE A 200mA CURRENT LIMIT. Chip Information PROCESS: BiCMOS Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 8 TDFN-EP T822+2 21-0168 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. 10 © 2010 Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.