19-2926; Rev 0; 7/03 200mA/500mA Selectable Current-Limit Switches Applications SDIO Features ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ ♦ Guaranteed Current Limit: 200mA or 500mA Thermal-Shutdown Protection Reverse-Current Protection 0.2Ω On-Resistance (SEL = High) 14ms Guaranteed Blanking Time FLAG Function Autoretry (MAX4773) 80µA Supply Current 6µA Latch-Off Current (MAX4772) 0.01µA Shutdown Current 2.0V to 4.5V Supply Range Fast Current-Limit Response Time Tiny SOT23 and TDFN Packages UL Certification Pending Ordering Information PART TEMP RANGE PINPACKAGE TOP MARK MAX4772EUT-T -40°C to +85°C 6 SOT23-6 ABND MAX4772ETT* -40°C to +85°C 6 TDFN-EP** MAX4773EUT-T -40°C to +85°C 6 SOT23-6 MAX4773ETT* -40°C to +85°C 6 TDFN-EP** — ABNE — *Future product—contact factory for availability. **EP—Exposed pad. PDAs and Palmtop Devices Selector Guide Cell Phones PART GPS Systems AUTORETRY MAX4772EUK-T Hand-Held Devices Typical Operating Circuit No MAX4772ETT No MAX4773EUK-T Yes MAX4773ETT Yes 2.0V TO 4.5V Pin Configurations TOP VIEW IN ON MAX4772 MAX4773 µP FLAG IN 1 GND 2 TO SDIO PORT OUT SEL MAX4772 MAX4773 ON 3 6 OUT IN 1 5 SEL OUT 2 4 FLAG SEL 3 6 ON MAX4772 MAX4773 5 GND 4 FLAG GND SOT23 TDFN ________________________________________________________________ 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 MAX4772/MAX4773 General Description The MAX4772/MAX4773 switches feature selectable internal current limiting to prevent damage to host devices due to faulty load conditions. The MAX4772/MAX4773 include a logic input to select a guaranteed 200mA or 500mA current limit, making them ideal for SDIO and other load-switching applications. These analog switches have a low 0.2Ω on-resistance and operate from a 2.0V to 4.5V input voltage range. When the switch is on and a load is connected to the port, a guaranteed blanking time of 14ms ensures that the transient voltage settles down. If, after this blanking time, the load current is greater than the current limit, the MAX4772 switch is turned off and issues a FLAG to the microprocessor. The switch can be turned on again by cycling the power or the ON input. The MAX4773 has an autoretry feature where the switch turns off and issues a FLAG to the microprocessor after the blanking time and then continuously checks to see if the overload condition is present. The switch remains on after the overload condition disappears and FLAG deasserts. The MAX4772/MAX4773 are available in tiny space-saving 6-pin SOT23 and 6-pin TDFN (3mm x 3mm) packages. MAX4772/MAX4773 200mA/500mA Selectable Current-Limit Switches ABSOLUTE MAXIMUM RATINGS IN, ON, FLAG, SEL, OUT to GND.............................-0.3V to +6V OUT Short Circuit to GND .................................Internally Limited Continuous Power Dissipation (TA = +70°C) 6-Pin SOT23 (derate 8.7mW/°C above +70°C)............696mW 6-Pin TDFN (derate 24.4mW/°C above +70°C) .........1951mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°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 = +2.0V to +4.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN = +3.3V, TA = +25°C.) (Note 1) PARAMETER SYMBOL Operating Voltage VIN Quiescent Current IQ CONDITIONS MIN 2.0 UNITS 4.5 V VIN = +3.3V 80 125 µA VIN = +3.3V 6 10 µA 1 µA ILATCH VON = VIN, after an overcurrent fault (MAX4772) Shutdown Current ISHDN VON = 0V, SEL = low or floating Reverse-Current Limit MAX VON = VIN, switch on Latch-Off Current (Note 2) Forward-Current Limit TYP 0.03 SEL = low, VIN = 3.3V, VOUT = GND 200 320 SEL = high, VIN = 3.3V, VOUT = GND 500 800 SEL = low 320 SEL = high 800 ON Input Leakage -1 +1 mA µA Shutdown Forward Leakage VON = 0V, VOUT = 0V Shutdown Reverse Leakage VON = 0V, VIN = 2V, VOUT = 4.5V SEL Pulldown Current After power-up (VIN > 2V, 0V < VSEL < 0.5V) 30 100 µA SEL Input Current Measured after first low-to-high transition -1 +1 µA On-Resistance (Note 3) RON ON, SEL Input Logic High Voltage VIH ON, SEL Input Logic Low Voltage VIL 0.01 mA 1 µA 1 µA SEL = low, ILOAD = 100mA 0.45 0.9 SEL = high, ILOAD = 100mA 0.18 0.36 VIN = 2V to 3.6V VIN > 3.6V FLAG Output Logic Low Voltage ISINK = 1mA FLAG Output High Leakage Current VIN = VFLAG = VON = 4.5V 1.4 Ω V 2 0.5 V 0.4 V 1 µA Thermal Shutdown 150 °C Thermal-Shutdown Hysteresis 15 °C DYNAMIC Turn-On Time (Note 4) VON from low to high, IOUT = 10mA, CL = 0.1µF 120 µs Turn-Off Time (Note 4) VON from high to low, IOUT = 10mA, CL = 0.1µF 100 ns Blanking Time 2 tBLANK Overcurrent fault (Figures 4 and 5) 14 _______________________________________________________________________________________ 60 ms 200mA/500mA Selectable Current-Limit Switches (VIN = +2.0V to +4.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VIN = +3.3V, TA = +25°C.) (Note 1) PARAMETER SYMBOL CONDITIONS Short-Circuit Current-Limit Response Time MIN TYP VON = VIN, short circuit applied to OUT Retry Time (Note 5) tRETRY MAX UNITS 5 MAX4773 (Figure 4) µs 210 900 ms Note 1: All parts are 100% tested at +25°C. Electrical limits across the full temperature range are guaranteed by design and correlation. Note 2: Latch-off current does not include the current flowing into FLAG. Note 3: TDFN parts are guaranteed by design. Note 4: The on-time is defined as the time taken for the current through the switch to go from 0mA to full load. The off-time is defined as the time taken for the current through the switch to go from full load to 0mA. Note 5: Retry time is typically 15 times the blanking time (typ). Typical Operating Characteristics (VIN = 3.3V, TA = +25°C, unless otherwise noted.) 80 60 9 LATCH-OFF CURRENT (µA) 100 VON = VIN 90 SUPPLY CURRENT (µA) 120 10 MAX4772 toc02 VON = VIN 140 80 70 40 8 7 6 5 4 3 2 60 20 1 0 0 50 2.5 3.0 3.5 4.0 4.5 -40 -15 10 35 60 -15 10 35 60 TEMPERATURE (°C) SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE SHUTDOWN LEAKAGE CURRENT vs. TEMPERATURE LATCH-OFF LEAKAGE CURRENT vs. TEMPERATURE 1 0.1 0.01 VON = 0V, VOUT = 0V 1 0.1 0.01 0.001 0.001 -15 10 35 TEMPERATURE (°C) 60 85 100 LATCH-OFF LEAKAGE CURRENT (nA) MAX4772 toc04 10 10 MAX4772 toc05 TEMPERATURE (°C) 100 -40 -40 85 SUPPLY VOLTAGE (V) SHUTDOWN SUPPLY CURRENT (nA) 2.0 SHUTDOWN SUPPLY CURRENT (nA) VON = VIN 85 MAX4772 toc06 SUPPLY CURRENT (µA) 100 MAX4772 toc01 160 LATCH-OFF CURRENT vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE MAX4772 toc03 QUIESCENT SUPPLY CURRENT vs. SUPPLY VOLTAGE 10 1 0.1 0.01 0.001 0.0001 -40 -15 10 35 TEMPERATURE (°C) 60 85 -40 -15 10 35 60 85 TEMPERATURE (°C) ________________________________________________________________________________________ 3 MAX4772/MAX4773 ELECTRICAL CHARACTERISTICS (continued) Typical Operating Characteristics (continued) (VIN = 3.3V, TA = +25°C, unless otherwise noted.) SHUTDOWN REVERSE LEAKAGE CURRENT vs. TEMPERATURE 0.1 0.01 900 800 OUTPUT CURRENT (mA) 1.2 NORMALIZED RON (Ω) 1 1000 MAX4772 toc09 1.4 MAX4772 toc08 VON = 0V, VOUT = 4.5V OUTPUT CURRENT vs. OUTPUT VOLTAGE NORMALIZED ON-RESISTANCE vs. TEMPERATURE MAX4772 toc07 1.0 0.8 0.6 0.4 VSEL = VIN 700 600 500 400 300 VSEL = GND 200 0.001 0.2 0.0001 100 0 0 10 35 60 85 -40 -15 10 TEMPERATURE (°C) 100 MAX4772 toc10 TURN-ON/OFF TIMES (µs) OUT = GND SEL = HIGH 550 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 85 VIN - VOUT (V) SWITCH TURN-ON/OFF TIMES vs. TEMPERATURE 700 600 60 TEMPERATURE (°C) FORWARD CURRENT LIMIT vs. SUPPLY VOLTAGE 650 35 500 450 400 350 300 FLAG-BLANKING TIMEOUT vs. TEMPERATURE ILOAD = 10mA ON 10 1 0.1 50 45 40 35 30 25 OFF 250 MAX4772 toc12 -15 FLAG-BLANKING TIMEOUT (ms) -40 MAX4772 toc11 SHUTDOWN LEAKAGE CURRENT (nA) 10 FORWARD CURRENT LIMIT (mA) MAX4772/MAX4773 200mA/500mA Selectable Current-Limit Switches SEL = LOW 0.01 200 2.0 2.5 3.0 3.5 4.0 4.5 20 -40 SUPPLY VOLTAGE (V) CURRENT-LIMIT RESPONSE MAX4772/3 toc13 -15 10 35 60 85 -40 -15 10 35 60 TEMPERATURE (°C) TEMPERATURE (°C) CURRENT-LIMIT RESPONSE CURRENT-LIMIT RESPONSE (OUT SHORTED TO GND) 85 MAX4772/3 toc15 MAX4772/3 toc14 3.3V 3V VIN 2V/div 0V 3V 3V VIN = VON 1V/div VON 2V/div 0V IOUT 200mA/div 4 VOUT 2V/div IOUT 200mA/div VIN = 3.3V COUT = 1µF CIN = 1µF VSEL = 3.3V 40µs/div 0V 3.3V 0V 0V 0V VIN 2V/div 0V VIN = VON COUT = 1µF CIN = 1µF VSEL = 3.3V CIN = 1µF COUT = 1µF IOUT 5A/div 0V 40µs/div _______________________________________________________________________________________ 4µs/div 200mA/500mA Selectable Current-Limit Switches REVERSE CURRENT LIMIT SWITCH TURN-ON TIME RESPONSE MAX4772/3 toc16 MAX4772/3 toc17 VIN 2V/div 3V 0V 3V VOUT 2V/div 3.3V VON 1V/div 0V 0V IOUT 1A/div 0V CIN = 1µF COUT = 1µF VSEL = 3.3V IOUT 10mA/div 0V 200µs/div 20µs/div FLAG-BLANKING RESPONSE (OVERLOAD CONDITION) SWITCH TURN-OFF TIME RESPONSE MAX4772/3 toc18 MAX4772/3 toc19 3.3V 3.3V VON 1V/div 0V VIN 2V/div 0V 3.3V VOUT 2V/div 0V 3.3V IOUT 10mA/div 0V VFLAG 2V/div 0V VSEL = VIN = 3.3V CIN = 1µF IOUT COUT = 1µF 500mA/div 0V 40ns/div 10ms/div Pin Description PIN NAME FUNCTION SOT23 TDFN 1 1 IN 2 5 GND 3 6 ON 4 4 FLAG Fault Output. This open-drain output goes low when the device stays in forward or reverse current limit for more than the blanking time period. FLAG is high impedance when a fault is not present or when ON is low. 5 3 SEL Current-Limit Threshold Selection. Connect to logic-low level or leave floating to select 200mA currentlimit threshold. Connect to logic-high level to select 500mA current-limit threshold. 6 2 OUT Switch Output. Bypass with a 0.1µF ceramic capacitor to ground. Input. Bypass with a 0.1µF ceramic capacitor to ground. Ground Active-High Switch-On Input. A logic high turns the switch on. _______________________________________________________________________________________ 5 MAX4772/MAX4773 Typical Operating Characteristics (continued) (VIN = 3.3V, TA = +25°C, unless otherwise noted.) MAX4772/MAX4773 200mA/500mA Selectable Current-Limit Switches REVERSE-CURRENT DETECTOR FLAG BLANKING TIME CIRCUITRY N FORWARD-CURRENT DETECTOR N IN OUT ON LOGIC SEL MAX4772/MAX4773 GND Figure 1. Functional Diagram Detailed Description The MAX4772/MAX4773 are forward/reverse currentlimited switches that operate from a 2.0V to 4.5V input voltage range and guarantee a 200mA or 500mA minimum current-limit threshold when driving SEL low or high, respectively. The voltage drop across an internal sense resistor is compared to two reference voltages to indicate a forward or reverse current-limit fault. When the load current exceeds the preset current limit for greater than the fault-blanking time, the switch opens. The MAX4773 has an autoretry function that turns on the switch again after an internal retry time expires. If the faulty load condition is still present after the blanking time, the switch turns off again and the cycle is repeated. If the faulty load condition is not present, the switch remains on. The MAX4772 does not have the autoretry option and the switch remains in latch-off mode until the ON pin or the input power is cycled from high to low and then high again. 6 Current-Limit Threshold Selection The MAX4772/MAX4773 SEL logic input sets the desired minimum current-limit threshold to 200mA or 500mA. Connect SEL low or leave floating for 200mA current limit and high for the 500mA current limit. During power-up, if SEL is low or floating, the current limit is set to 200mA. The MAX4772/MAX4773 uses an internal pulldown resistor (100µA, max) to set the default current limit to 200mA when SEL is floating. After the first low-tohigh transition, the pulldown resistor is internally disconnected and the level on SEL determines the current limit (SEL = low, 200mA and SEL = high, 500mA). During power-up, if SEL and VIN rise together, the current limit is immediately set to 500mA. Figures 2 and 3 illustrate the two different modes of power-up sequence for the MAX4772/MAX4773. In Figure 2, the switch powers up, VIN ≥ 2V, a low-to-high transition on SEL changes the current limit from 200mA to 500mA. In Figure 3, the switch powers up in the 500mA current-limit mode with SEL and IN rising simultaneously. The microprocessor’s GPIO must be able to source the 100µA drive current for the MAX4772/MAX4773 500mA current-limit operation. After the current limit has been set to 500mA, the 100µA driving current is no longer needed. _______________________________________________________________________________________ 200mA/500mA Selectable Current-Limit Switches VIN = 2V VIN VIH 200mA VIN 500mA VSEL 500mA 100µA (MAX) VSEL ISEL ISEL Figure 2. MAX4772/MAX4773 Power-Up Sequence (VSEL Rises after Power-Up) Reverse-Current Protection The MAX4772/MAX4773 limit the reverse current (VOUT to VIN) from exceeding the maximum IREV value. The switch is shut off and FLAG is asserted if the reverse current-limit condition persists for more than the blanking time. This feature prevents excessive reverse currents from flowing through the device. Switch-On/Off Control Toggle ON high to enable the current-limited switches. When a forward/reverse current fault is present or the die exceeds the thermal-shutdown temperature of +150°C, OUT is internally disconnected from IN and the supply current decreases to 8µA (latch off). The switch is now operating in one of its off states. The switch-off state also occurs when driving ON low, thus reducing the supply current (shutdown) to 0.01µA. Table 1 illustrates the ON/OFF state of the MAX4772/MAX4773 current-limit switches. FLAG Indicator The MAX4772/MAX4773 feature a fault output (FLAG). Whenever an overcurrent condition is encountered, the MAX4772 latches FLAG low and turns the switch off. The MAX4773 latches FLAG low and keeps it low until the overcurrent conditon is removed. During this time, the switch cycles on and off in the autoretry mode. Figure 3. MAX4772 Power-Up Sequence (VSEL and VIN Rise Simultaneously) When the overcurrent condition is removed, FLAG deasserts and the switch turns on (Figure 4). FLAG is an open-drain output transistor and requires an external pullup resistor from FLAG to IN. During shutdown (ON is low), the pulldown on FLAG output is released in order to limit power dissipation. FLAG goes low when any of the following conditions occur: • The die temperature exceeds the thermal-shutdown temperature limit of +150°C. • The device is in current limit for more than the faultblanking period. • The switch is in autoretry. Autoretry (MAX4773) When the forward or reverse current-limit threshold is exceeded, tBLANK timer begins counting (Figure 4). The timer resets if the overcurrent 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 latched off and FLAG asserts. At the end of tRETRY, the switch is turned on again. If the fault still exists, the cycle is repeated. If the fault has been removed, the switch stays on and FLAG deasserts. Table 1. MAX4772/MAX4773 Switch Truth Table ON FAULT Low X High Thermal High Current Limit SWITCH ON/OFF OFF SUPPLY CURRENT MODE Shutdown OFF immediately (tBLANK period does not apply) Latch off OFF after tBLANK period has elapsed Latch off ON during tBLANK period, OFF during tRETRY period for the MAX4773 cycle repeats until fault is removed See the Autoretry section _______________________________________________________________________________________ 7 MAX4772/MAX4773 VIN ≥ 2V MAX4772/MAX4773 200mA/500mA Selectable Current-Limit Switches tBLANK tRETRY tBLANK tBLANK tBLANK tBLANK CURRENT LIMIT SHORT CONDITION REMOVED LOAD CURRENT LOAD CURRENT ON ON SWITCH STATUS SWITCH STATUS OFF ON PIN VOLTAGE OFF FLAG PIN STATUS FLAG PIN STATUS (a) Figure 4. MAX4773 Autoretry Fault-Blanking Diagram tBLANK The autoretry feature saves system power in the case of an 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 switch sees the equivalent load current times duty cycle or I SUPPLY = I LOAD ✕ t BLANK /(t BLANK + t RETRY ). With a typical t BLANK = 37ms and typical tRETRY = 555ms, the duty cycle is 6%, which results in a 94% power savings over the switch being on the entire time. The duty cycle is consistent across the process and devices. Latch Off (MAX4772) When the forward or reverse current-limit threshold is exceeded, t BLANK timer begins counting. The timer resets if the overcurrent condition disappears before tBLANK has elapsed. The switch is shut off and FLAG asserts if the overcurrent condition continues up to the end of the blanking time. Reset the switch by either toggling ON (Figure 5) or cycling the input voltage (Figure 5). Fault Blanking The MAX4772/MAX4773 feature 14ms (min) fault blanking. Fault blanking allows current-limit faults, including momentary short-circuit faults that occur when hot swapping 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 fault-blanking timeout, FLAG asserts low. Load-transient faults less than tBLANK do not cause a FLAG output assertion. Only current-limit faults are blanked. 8 tBLANK LOAD CURRENT ON SWITCH STATUS OFF IN PIN VOLTAGE FLAG PIN STATUS (b) Figure 5. MAX4773 Latch-Off Fault Blanking A thermal fault causes FLAG to assert immediately and does not wait for the blanking time. Thermal Shutdown The MAX4772/MAX4773 have a thermal-shutdown feature to protect the devices from overheating. The switch turns off and FLAG goes low immediately (no fault blanking) when the junction temperature exceeds +150°C. The switch with autoretry turns back on when the device temperature drops approximately 15°C. The switch with the latch off requires ON cycling. Applications Information Input Capacitor To limit the input-voltage drop during momentary output short-circuit conditions, connect a capacitor from IN to GND. A 0.1µF ceramic capacitor is adequate for most applications; however, higher capacitor values further _______________________________________________________________________________________ 200mA/500mA Selectable Current-Limit Switches Output Capacitance Connect a 0.1µF capacitor from OUT to GND. This capacitor helps prevent inductive parasitics from pulling OUT negative during turn-off, thus preventing the MAX4772/MAX4773 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 a faulty load condition. The maximum capacitive load value that can be driven from OUT is obtained by the following formula: CMAX < IFWD _ MIN × tBLANK _ 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 (no more than 5mm). IN and OUT pins 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: PMAX = VIN _ MAX × IOUT _ MAX × tBLANK = 211mW tRETRY + tBLANK where VIN = 4.5V, IOUT = 750mA, tBLANK = 14ms, and tRETRY = 210ms. Attention must be given to the MAX4772 where the latch-off condition must be manually reset by toggling ON from high to low. If the latch-off 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. Chip Information TRANSISTOR COUNT: 2539 PROCESS: BiCMOS _______________________________________________________________________________________ 9 MAX4772/MAX4773 reduce the voltage drop at the input and are recommended for lower voltage applications. Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.) 6LSOT.EPS MAX4772/MAX4773 200mA/500mA Selectable Current-Limit Switches PACKAGE OUTLINE, SOT-23, 6L 21-0058 F 1 1 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 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.