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MAX14544ETA+T;中文规格书,Datasheet资料

_______________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, 28V-Capable, I LIM V BUS Accessory Switch

MAX14544/MAX14545

General Description

The MAX14544/MAX14545 are overcurrent detection switches that can provide power to external accesso-ries 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 fea-tures that include thermal shutdown protection, reverse-current blocking, and overvoltage protection.

The MAX14544/MAX14545 are offered in a space-sav-ing, 8-pin, 2mm x 2mm TDFN package, and operate over the -40N C to +85N C extended temperature range.

Applications

Cell Phones MP3 Players PDAs

Digital Cameras eBook MID

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 -40N C to +85N C Operating Temperature Range

19-5037; Rev 0; 1/10

Pin Configuration

Ordering Information/

Selector Guide

Note: All devices are specified over the -40°C to +85°C tem-perature range.

+Denotes a lead(Pb)-free/RoHS-compliant package.T = Tape and reel.*EP = Exposed pad.

Typical Operating Circuit appears at end of data sheet.

PART PIN-PACKAGE TOP MARK RETRY/LATCHOFF MAX14544ETA+T 8 TDFN-EP*ACY Autoretry MAX14545ETA+T

8 TDFN-EP*

ACZ

Latchoff

28V-Capable, I LIM V BUS Accessory Switch M A X 14544/M A X 1454

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.

(Voltages referenced to GND.)

OUT .......................................................................-0.3V to +30V IN, FLAG , EN, ISET ..............................................-0.3V to +6.0V Continuous Power Dissipation (T A = +70N C)

8-Pin TDFN (derate 11.9mW/N C above +70N C) ...........953mW Junction-to-Ambient Thermal Resistance

B JA (Note 1) ..............................................................83.9N C/W

Junction-to-Case Thermal Resistance

B J

C (Note 1) .................................................................37N C/W Operating Temperature Range ..........................-40N C to +85N C Storage Temperature Range ............................-65N C to +150N C Junction Temperature .....................................-40N C to +150N C Lead Temperature (soldering, 10s) ................................+300N C Soldering Temperature (reflow) ......................................+260N C

ELECTRICAL CHARACTERISTICS

(V IN = +2.3V to +5.5V, T A = -40N C to +85N C, unless otherwise noted. Typical values are at V IN = +3.3V, T A = +25N C.) (Note 2)

ABSOLUTE MAXIMUM RATINGS

Note 1: Package thermal resistances were obtained using the method described in JEDEC specifications. For detailed information

on package thermal considerations, refer to https://www.sodocs.net/doc/7416437326.html,/thermal-tutorial .

PARAMETER

SYMBOL CONDITIONS

MIN TYP

MAX UNITS Operating Voltage Range V IN 2.3 5.5V Undervoltage Lockout

V UVLO

V IN falling

1.8

2.2

V Undervoltage Lockout Hysteresis 100

mV IN Overvoltage Trip Level V OVLO

V IN rising

5.5

6.0

V IN Overvoltage Hysteresis 1%Quiescent Current I Q V EN = V IN = 3.3V, I OUT = 0A 225

380F A OUT Voltage

V OUT

Switch off

28V

OUT Leakage Current I OUTL

V EN = V IN = 5V, V OUT = 5V after an overcur-rent fault

0.2

F A

V EN = V IN = 5V, V OUT = 10V after an overcur-rent fault

3.5IN Shutdown Current I SHDN V EN = 0V, V IN = 5V, V OUT = 0V, V ISET = 0V 0.1 1.1F A V EN = 0V, V IN = 5V, V OUT = 10V, V ISET = 0V 0.1 1.1Switch On-Resistance R ON I OUT = 100mA, V IN = 2.3V 370600m I I OUT = 100mA, V IN > 3.3V 270450Current Limit

I LIM V ISET = 0V, V IN - V OUT = 1V 200250300mA V ISET = V IN , V IN - V OUT = 1V

400500600FLAG Assertion Voltage V FA V FA = V IN - V OUT , where overcurrent is detected and FLAG asserted

0.300.450.60V Reverse-Current Detection Threshold

I DET

V EN = V IN = 3.3V, V OUT rising until reverse- current shutdown protection trips

155350

Reverse-Current Detection Hysteresis

After a reverse overcurrent event, V OUT falls below V IN until switch turns on, measure V IN - V OUT

100200300mV

28V-Capable, I LIM V BUS Accessory Switch

MAX14544/MAX14545

3 ELECTRICAL CHARACTERISTICS (continued)

(V IN = +2.3V to +5.5V, T A = -40N C to +85N C, unless otherwise noted. Typical values are at V IN = +3.3V, T A = +25N C.) (Note 2)

Note 2:All devices are production tested at T A = +25N C. Specifications over temperature limits are guaranteed by design.

Note 3:All timing characteristics are measured using 20% and 80% levels.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input Logic-High Voltage V IH 1.4V

Input Logic-Low Voltage V IL0.4V

Input Leakage I IN V EN = V ISET = 0V or 5V-1+1F A

Output Logic-Low Voltage V OL I SINK = 1mA0.4V

Output High Leakage Current V FLAG= 5V1F A Thermal Shutdown V IN = 5V150N C

Thermal Shutdown Hysteresis V IN = 5V15N C

TIMING CHARACTERISTICS (Note 3)

Turn-On Time t ON V EN from low to high, V IN = 3.3V, R L = 100I0.3ms

Turn-Off Time t OFF V EN from high to low, V IN = 3.3V, R L = 100I1ms

Current-Limit Reaction Time t LIM

V EN = V IN = 3.3V, output high and then short

circuit applied, C IN = 10F F ceramic,

C OUT = 1F F ceramic

5F s

Blanking Time t BLANK V EN = V IN = 3.3V, Figures 1 and 2410.530ms Autoretry Time t RETRY MAX14544, Figure 1252661.51890ms Reverse-Current Detection Time t DET

V IN = 3.3V, I REVERSE = 250mA, C IN = 10F F

ceramic, C OUT = 1F F ceramic

5F s Reverse-Current Recovery Time t REC

V OUT = V IN + 500mV to

V OUT = V IN - 500mV

0.1ms

28V-Capable, I LIM V BUS Accessory Switch M A X 14544/M A X 1454

Figure 1. MAX14544 Timing Diagram (Waveforms Not to Scale)

Figure 2. MAX14545 Timing Diagram (Waveforms Not to Scale)

28V-Capable, I LIM V BUS Accessory Switch

MAX14544/MAX14545

Typical Operating Characteristics

(V IN = +3.3V, C IN = 10F F, C OUT = 1F F, T A = +25N C, unless otherwise noted.)

NORMALIZED ON-RESISTANCE

vs. TEMPERATURE

TEMPERATURE (°C)

-15

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

0.5

-4085

NORMALIZED ON-RESISTANCE

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

5.1

4.7

3.9

4.3

3.1 3.5

2.7

0.6

0.7

0.8

0.9

1.0

1.1

1.2

1.3

1.4

1.5

0.5

2.3

5.5

SHUTDOWN REVERSE CURRENT

vs. TEMPERATURE

TEMPERATURE (°C)

(

)

-15

750

800

850

900

950

1000

700

-4085

SHUTDOWN FORWARD CURRENT

vs. TEMPERATURE

TEMPERATURE (°C)

(

)

-15

100

200

300

400

500

600

700

800

900

-4085

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

TEMPERATURE (°C)

(

)

-15

100

200

300

400

500

600

700

800

900

-4085

NORMALIZED CURRENT LIMIT

vs. TEMPERATURE

TEMPERATURE (°C)

-15

0.96

0.97

0.98

0.99

1.00

1.01

1.02

1.03

1.04

1.05

0.95

-4085

NORMALIZED CURRENT LIMIT

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

5.1

4.7

3.9

4.3

3.1 3.5

2.7

0.96

0.97

0.98

0.99

1.00

1.01

1.02

1.03

1.04

1.05

0.95

2.3 5.5

QUIESCENT SUPPLY CURRENT

vs. TEMPERATURE

TEMPERATURE (°C)

(

)

-15

100

150

200

250

300

350

400

450

-4085

QUIESCENT SUPPLY CURRENT

vs. SUPPLY VOLTAGE

SUPPLY VOLTAGE (V)

(

)

5.1

4.7

3.9

4.3

3.1 3.5

2.7

100

150

200

250

300

350

400

450

2.3 5.5

28V-Capable, I LIM V BUS Accessory Switch M A X 14544/M A X 1454

BLANKING TIME

MAX14544/5 toc18

10ms/div

V OUT 2V/div I OUT

200mA/div

V FLAG 2V/div

MAX14544 ISET HIGH

OVERCURRENT DURATION TIME

200ms/div

V OUT 2V/div I OUT

200mA/div

V FLAG 2V/div

MAX14544 ISET HIGH

CURRENT LIMIT RESPONSE

100ms/div

V OUT 2V/div I OUT

200mA/div

V FLAG 2V/div

ISET HIGH

CURRENT LIMIT RESPONSE

20ms/div

V OUT 2V/div I OUT

200mA/div

V FLAG 2V/div

ISET HIGH

FLAG RESPONSE

100ms/div

V OUT 5V/div I OUT

200mA/div

V FLAG

5V/div

REVERSE OVERVOLTAGE PROTECTION

10μs/div

10V

0V 0V

3.3V V OUT 2V/div

V IN 2V/div

POWER-UP RESPONSE

MAX14544/5 toc12

200μs/div

V IN 5V/div V OUT 5V/div I OUT

50mA/div

SWITCH TURN-OFF TIME vs. TEMPERATURE

TEMPERATURE (°C)

S W I T C H T U R N -O F F T I M E (μs )

-15

930

9409509609809709901000

920

-40

SWITCH TURN-ON TIME vs. TEMPERATURE

TEMPERATURE (°C)

S W I T C H T U R N -O N T I M E (μs )

603510-158687888990919293949585-40

Typical Operating Characteristics (continued)

(V IN = +3.3V, C IN = 10F F, C OUT = 1F F, T A = +25N C, unless otherwise noted.)

28V-Capable, I LIM V BUS Accessory Switch

MAX14544/MAX14545

Pin Description

Functional Diagram

PIN NAME FUNCTION

1, 2IN

Input Voltage. Connect IN pins 1 and 2 together and bypass IN to GND with a 10F F ceramic capacitor as

close to the device as possible.

3ISET

Current-Limit Setting. Drive ISET low to have a 200mA current limit. Drive ISET high to have a 400mA current

limit.

4GND Ground

5FLAG

Active-Low Fault Open-Drain Output. FLAG goes low when the forward output current limit 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.

6EN Active-High Switch-Enable Input. Drive EN high to turn on the device. Drive EN low to turn off the device.

7, 8OUT

Output Voltage. Connect OUT pins 7 and 8 together and bypass OUT to GND with a 1F F ceramic capacitor

as close to the device as possible.

—EP

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.

28V-Capable, I LIM V BUS Accessory Switch M A X 14544/M A X 1454

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 V IN exceeds OVLO, V IN 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 volt-age across the switch is greater than the FLAG asser-tion 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 blank-ing 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 (V OUT to V IN ) from exceeding the maximum I DET value. If the reverse-current detection threshold is exceeded, the switch turns off and FLAG is asserted without waiting for t BLANK to elapse. This feature prevents excessive reverse currents from flowing through the device.FLAG Indicator

The MAX14544/MAX14545 feature a fault output (FLAG ). Whenever V IN - V OUT > V FA , 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 condi-tion 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 asser-tion voltage is exceeded (Figure 2).

FLAG is an open-drain output and requires an external pullup resistor. During shutdown (EN is low), the pull-down on FLAG output is released to limit power dissipa-tion. FLAG goes low when one of the following occurs:1) T he temperature exceeds the thermal shutdown tem-perature, +150N C (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 t BLANK timer begins counting (Figure 1). The timer resets if the condition disappears before t BLANK has elapsed. A retry time delay (t RETRY ) is started immediately after t BLANK has elapsed and during that time the switch is turned off and FLAG is asserted. At the end of t RETRY , 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 t BLANK , when the switch is on, the supply current is at the current limit. During t RETRY , 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:

I SUPPLY = I LOAD x t BLANK /(t BLANK + t RETRY )With a typical t BLANK = 10.5ms and typical t RETRY = 661.5ms, the duty cycle is 1.6%, resulting in a 98.4% power savings over the switch being on the entire https://www.sodocs.net/doc/7416437326.html,tchoff (MAX14545)

When the FLAG assertion voltage is exceeded, the t BLANK 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 coun-ter starts. If the load-transient fault persists beyond the

28V-Capable, I LIM V BUS Accessory Switch

MAX14544/MAX14545

fault-blanking timeout, FLAG asserts low. FLAG is not

asserted when load-transient fault is less than t BLANK.

The fault blanking time only applies to forward current-

limit faults.

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

+150N C. The MAX14544/MAX14545 turns back on when

the device temperature drops approximately 15N C.

OVLO and UVLO

The MAX14544/MAX14545 feature an overvoltage pro-

tection. When IN goes above V OVLO(6.0V max), the

switch turns off and FLAG goes low immediately with

no fault-blanking time. When IN drops below V UVLO

(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 10F F ceramic capacitor is adequate for most

applications; however, higher capacitor values further

reduce the voltage drop at the input and are recom-

mended for lower voltage applications.

Output Capacitor

Connect a 1F F 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:

MAX

I t

Layout and Thermal Dissipation

To optimize 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. 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:

IN_MAX OUT_MAX BLANK

MAX

RETRY BLANK

V I t

P51.6mW

t t

××

where V IN_MAX= 5.5V, I OUT_MAX= 600mA, t BLANK=

10.5ms, and t RETRY = 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 suf-

ficiently 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.

分销商库存信息: MAXIM

MAX14544ETA+T

MAX14544ETA+T;中文规格书,Datasheet资料

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