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19-5037; Rev 0; 1/10
28V-Capable, ILIM VBUS Accessory Switch
General Description
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 270m (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 0.1A (typ) Shutdown Current S 5s Fast Current-Limit Detect S 8-Pin TDFN (2mm x 2mm) Package S -40NC to +85NC Operating Temperature Range
MAX14544/MAX14545
Ordering Information/ Selector Guide
PART MAX14544ETA+T MAX14545ETA+T PINPACKAGE 8 TDFN-EP* 8 TDFN-EP* TOP MARK ACY ACZ RETRY/ LATCHOFF Autoretry Latchoff
Note: All devices are specified over the -40C to +85C temperature range. +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. *EP = Exposed pad.
Pin Configuration
TOP VIEW
+
IN IN ISET GND 1 2 3 4 8 7 6 *EP 5 OUT OUT EN FLAG
Applications
Cell Phones MP3 Players PDAs Digital Cameras eBook MID
Typical Operating Circuit appears at end of data sheet.
MAX14544 MAX14545
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.
28V-Capable, ILIM VBUS Accessory Switch MAX14544/MAX14545
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 Undervoltage Lockout Hysteresis IN Overvoltage Trip Level IN Overvoltage Hysteresis Quiescent Current OUT Voltage IQ VOUT VEN = VIN = 3.3V, IOUT = 0A Switch off VEN = VIN = 5V, VOUT = 5V after an overcurrent fault VEN = VIN = 5V, VOUT = 10V after an overcurrent fault VEN = 0V, VIN = 5V, VOUT = 0V, VISET = 0V VEN = 0V, VIN = 5V, VOUT = 10V, VISET = 0V IOUT = 100mA, VIN = 2.3V IOUT = 100mA, VIN > 3.3V VISET = 0V, VIN - VOUT = 1V VISET = VIN, VIN - VOUT = 1V VFA = VIN - VOUT, where overcurrent is detected and FLAG asserted VEN = VIN = 3.3V, VOUT rising until reversecurrent shutdown protection trips After a reverse overcurrent event, VOUT falls below VIN until switch turns on, measure VIN - VOUT 200 400 0.30 0 0.1 0.1 370 270 250 500 0.45 155 0.2 VOVLO VIN rising 5.5 1 225 380 28 1 FA 3.5 1.1 1.1 600 450 300 600 0.60 350 FA mI mA V mA SYMBOL VIN VUVLO VIN falling CONDITIONS MIN 2.3 1.8 100 6.0 TYP MAX 5.5 2.2 UNITS V V mV V % FA V
OUT Leakage Current
IOUTL
IN Shutdown Current Switch On-Resistance Current Limit FLAG Assertion Voltage Reverse-Current Detection Threshold Reverse-Current Detection Hysteresis
ISHDN RON ILIM VFA IDET
100
200
300
mV
2
28V-Capable, ILIM VBUS Accessory Switch
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 Input Logic-High Voltage Input Logic-Low Voltage Input Leakage Output Logic-Low Voltage Output High Leakage Current Thermal Shutdown Thermal Shutdown Hysteresis TIMING CHARACTERISTICS (Note 3) Turn-On Time Turn-Off Time Current-Limit Reaction Time Blanking Time Autoretry Time Reverse-Current Detection Time Reverse-Current Recovery Time tON tOFF tLIM tBLANK tRETRY tDET tREC VEN from low to high, VIN = 3.3V, RL = 100I VEN from high to low, VIN = 3.3V, RL = 100I VEN = VIN = 3.3V, output high and then short circuit applied, CIN = 10FF ceramic, COUT = 1F ceramic VEN = VIN = 3.3V, Figures 1 and 2 MAX14544, Figure 1 VIN = 3.3V, IREVERSE = 250mA, CIN = 10FF ceramic, COUT = 1FF ceramic VOUT = VIN + 500mV to VOUT = VIN - 500mV 4 252 1 5 10.5 661.5 5 0.1 30 1890 0.3 ms ms Fs ms ms Fs ms SYMBOL VIH VIL IIN VOL VEN = VISET = 0V or 5V ISINK = 1mA VFLAG = 5V VIN = 5V VIN = 5V 150 15 -1 CONDITIONS MIN 1.4 0.4 +1 0.4 1 TYP MAX UNITS V V FA V FA NC NC
MAX14544/MAX14545
3
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.
28V-Capable, ILIM VBUS Accessory Switch MAX14544/MAX14545
tBLANK CURRENT LIMIT tBLANK tRETRY tBLANK tRETRY tBLANK
LOAD CURRENT
ON SWITCH OFF
FLAG
ON EN OFF
Figure 1. MAX14544 Timing Diagram (Waveforms Not to Scale)
tBLANK CURRENT LIMIT
tBLANK
LOAD CURRENT
ON SWITCH OFF
FLAG
ON EN OFF
Figure 2. MAX14545 Timing Diagram (Waveforms Not to Scale)
4
28V-Capable, ILIM VBUS Accessory Switch
Typical Operating Characteristics
(VIN = +3.3V, CIN = 10FF, COUT = 1FF, TA = +25NC, unless otherwise noted.)
QUIESCENT SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX14544/5 toc01
MAX14544/MAX14545
QUIESCENT SUPPLY CURRENT vs. TEMPERATURE
MAX14544/5 toc02
NORMALIZED CURRENT LIMIT vs. SUPPLY VOLTAGE
1.04 NORMALIZED CURRENT LIMIT 1.03 1.02 1.01 1.00 0.99 0.98 0.97 0.96 0.95
MAX14544/5 toc03
450 400 SUPPLY CURRENT (A) 350 300 250 200 150 100 50 0 2.3
VEN = VIN
450 400 SUPPLY CURRENT (A) 350 300 250 200 150 100 50 0
VEN = VIN
1.05
VIN = 5V
VIN = 3.3V
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40
-15
10
35
60
85
2.3
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
NORMALIZED CURRENT LIMIT vs. TEMPERATURE
MAX14544/5 toc04
SHUTDOWN SUPPLY CURRENT vs. TEMPERATURE
MAX14544/5 toc05
SHUTDOWN FORWARD CURRENT vs. TEMPERATURE
SHUTDOWN FORWARD CURRENT (nA) 800 700 600 500 400 300 200 100 0 -40 -15 10 35
NORMALIZED CURRENT LIMIT
1.03 1.02 1.01 1.00 0.99 0.98 0.97 0.96 0.95 -40 -15 10 35 60
SHUTDOWN SUPPLY CURRENT (nA)
1.04
800 700 600 500 400 300 200 100
VOUT = 5V
VOUT = 0V
VIN = 5V
VIN = 5V
VIN = 2.3V
-40 -15 10 35 60 85
VIN = 2.3V
60 85
85
0 TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
SHUTDOWN REVERSE CURRENT vs. TEMPERATURE
MAX14544/5 toc07
NORMALIZED ON-RESISTANCE vs. SUPPLY VOLTAGE
MAX14544/5 toc08
NORMALIZED ON-RESISTANCE vs. TEMPERATURE
1.4 NORMALIZED ON-RESISTANCE 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5
SHUTDOWN REVERSE CURRENT (nA)
NORMALIZED ON-RESISTANCE
950 900 850 800 750 700 -40
VIN = 2.3V VOUT = 5V
1.4 1.3 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0.5
IOUT = 100mA
IOUT = 100mA
-15
10
35
60
85
2.3
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
-40
-15
10
35
60
85
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
TEMPERATURE (C)
MAX14544/5 toc09
1000
1.5
1.5
MAX14544/5 toc06
1.05
900
900
5
28V-Capable, ILIM VBUS Accessory Switch MAX14544/MAX14545
Typical Operating Characteristics (continued)
(VIN = +3.3V, CIN = 10FF, COUT = 1FF, TA = +25NC, unless otherwise noted.)
SWITCH TURN-ON TIME vs. TEMPERATURE
MAX14544/5 toc10
SWITCH TURN-OFF TIME vs. TEMPERATURE
990 SWITCH TURN-OFF TIME (s) 980 970 960 950 940 930
POWER-UP RESPONSE
MAX14544/5 toc11
95 94 SWITCH TURN-ON TIME (s) 93 92 91 90 89 88 87 86 85 -40
VIN = 5V RL = 100
1000
MAX14544/5 toc12
VIN = 5V RL = 100
VIN 5V/div VOUT 5V/div IOUT 50mA/div
-15
10
35
60
85
920 -40 -15 10 35 60 85 TEMPERATURE (C)
200s/div
TEMPERATURE (C)
REVERSE OVERVOLTAGE PROTECTION
VEN = 0V 10V
FLAG RESPONSE
MAX14544/5 toc13
MAX14544/5 toc14
CURRENT LIMIT RESPONSE
MAX14544/5 toc15
VIN = 5V RL = 100 ISET HIGH VOUT 2V/div
ISET HIGH
IOUT 200mA/div IOUT 200mA/div
5V VOUT 2V/div VFLAG 2V/div 20ms/div
0V 3.3V 0V 10s/div
VIN 2V/div
VOUT 5V/div VFLAG 5V/div 100ms/div
CURRENT LIMIT RESPONSE
MAX14544/5 toc16
OVERCURRENT DURATION TIME
MAX14544/5 toc17
BLANKING TIME
MAX14544/5 toc18
ISET HIGH
IOUT 200mA/div
MAX14544 ISET HIGH
IOUT 200mA/div
MAX14544 ISET HIGH
IOUT 200mA/div
VOUT 2V/div VFLAG 2V/div 100ms/div 200ms/div
VOUT 2V/div VFLAG 2V/div 10ms/div
VOUT 2V/div VFLAG 2V/div
6
28V-Capable, ILIM VBUS Accessory Switch
Pin Description
PIN 1, 2 3 4 5 6 7, 8 -- NAME IN ISET GND FLAG EN OUT EP FUNCTION 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. Current-Limit Setting. Drive ISET low to have a 200mA current limit. Drive ISET high to have a 400mA current limit. Ground 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. Active-High Switch-Enable Input. Drive EN high to turn on the device. Drive EN low to turn off the device. 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. 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.
MAX14544/MAX14545
Functional Diagram
IN
OUT
REVERSE CURRENT FORWARD CURRENT
CHARGE PUMP
UVLO CONTROL MAX14544 MAX14545 OVLO EN ISET
FLAG GND
7
28V-Capable, ILIM VBUS Accessory Switch MAX14544/MAX14545
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. 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) The temperature exceeds the thermal shutdown temperature, +150NC (typ). 2) The 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. 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. 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). 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
Autoretry (MAX14544)
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. 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. 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).
Reverse-Current Protection
Latchoff (MAX14545)
FLAG Indicator
Fault Blanking
8
28V-Capable, ILIM VBUS Accessory Switch
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. A reverse current-limit fault, thermal fault, or OVP fault causes FLAG to assert immediately and does not wait for the blanking time. 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. 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. 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 xt C MAX < FWD_MIN BLANK_MIN VIN 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 xI xt PMAX = IN_MAX OUT_MAX BLANK = 51.6mW t RETRY + t BLANK
MAX14544/MAX14545
Thermal Shutdown
Layout and Thermal Dissipation
OVLO and UVLO
Applications Information
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. Connect a 1FF ceramic capacitor from OUT to GND. This capacitor helps prevent inductive parasitics from pulling OUT negative during turn-off, thus preventing
Input Capacitor
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.
Output Capacitor
9
28V-Capable, ILIM VBUS Accessory Switch MAX14544/MAX14545
Typical Operating Circuit
CURRENT Li+ BATTERY CHARGER BATT VCC IN IN 10kI C FLAG EN GND ISET MAX14544 MAX14545 VCC OUT OUT VBUS D+ DGND MINI-B USB JACK CHARGER POWER SOURCE OR PERIPHERAL DEVICE CURRENT 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 8 TDFN-EP PACKAGE CODE T822+2 DOCUMENT NO. 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
(c)
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