AAT4618IGV-1.0-T1 - AnalogicTech

SmartSwitch™

AAT4618

Current Limited Load Switch

Preliminary Information

4618.2002.4.0.91 1

General Description

The AAT4618 SmartSwitch™ is a member of

AnalogicTech's Application Specific Power MOS-

FET™ (ASPM™) product family. It is a Current

Limited P-channel MOSFET power switch designed

for high-side load-switching applications operating

with inputs ranging from 2.4V to 5.5V which makes it

ideal for 2.5V, 3V and 5V systems. An integrated cur-

rent-limiting circuit protects the input supply from large

currents which potentially cause the supply to fall out

of regulation. In addition, the AAT4618 thermal over-

load protection limits power dissipation and junction

temperatures associated with prolonged periods of

operation in current limit. Due to its low RDS(ON), the

AAT4618 can be used to control loads that require up

to factory preset 400mA, 500mA, or 1A. The ultra fast

current-limit response to a sudden short circuit is a

mere 400ns which reduces the requirements of local

supply bypassing. An open drain FAULT flag signals

an over current or over temperature condition after a

4ms timeout. Quiescent current is a low 10µA and in

shutdown mode, the supply current decreases to less

than 1µA.

The AAT4618 is available in a 5 pin SOT-23, and an

8 pin SC70JW specified over a -40 to 85°C temper-

ature range.

The AAT4600 Series is a family of adjustable and

fixed SmartSwitch™ products with a range of current

handling capabilities. Available are single versions

with adjustable current limit (AAT4610, AAT4601) as

well as fixed current limit (AAT4625), and dual ver-

sions with fixed current limit (AAT4626, AAT4670).

Features

• 2.4V to 5.5V Input voltage range

• Current limit trip threshold options:

• 400mA min

• 500mA min

• 1A min

• Fast transient response:

• 400ns response to short circuit

• Low quiescent current

• 10µA typical

• < 1µA with Switch off

• 125mΩtypical RDS(ON)

• FAULT flag with 4ms blanking

• Undervoltage Lockout

• Thermal shutdown

• Temp range -40 to 85°C

• 4kV ESD Rating

• 5 pin SOT23 package

• 8 pin SC70JW package

Applications

• Peripheral ports

• USB Ports

• Notebook computers

• Personal communication devices

• Hot swap supplies

Typical Application

AAT4618

ON (ON)

IN OUT

FAULT

GND

(ON)

100k

INPUT

GND GND

CIN

1µF

COUT

0.47µF

OUTPUT

FAULT

AAT4618

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Pin Descriptions

Pin Configuration

SOT23-5 SC70JW-8

ON (ON)

1 2

GND

OUT

FAULT

3ON (ON)

FAULT

GND

OUT

Pin #

SOT23-5 SC70JW-8 Symbol Function

1 5 OUT P-channel MOSFET drain

2 6, 7, 8 GND Ground connection

3 1 FAULT Open-drain FAULT output

4 2 ON (ON) Enable Input: 4618 active low, 4618-1 active high

5 3, 4 IN P-channel MOSFET source

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Absolute Maximum Ratings (TA=25°C unless otherwise noted)

Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con-

ditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any one time.

Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩresistor into each pin.

Thermal Characteristics

Note 2: Mounted on a demo board.

Electrical Characteristics (VIN = 5V, TA= -40 to 85°C unless otherwise noted. Typical values

are at TA=25°C; bold values denote full temperature range)

Note 3: For VIN outside this range consult Typical ON (ON) Threshold curve.

Symbol Description Conditions Min Typ Max Units

VIN Operation Voltage 2.4 5.5 V

IQQuiescent Current VIN = 5V, ON (ON) = active, IOUT = 0 10 25 µA

IQ(OFF) Off Supply Current ON (ON) = inactive, VIN = 5.5V 1µA

ISD(OFF) Off Switch Current ON (ON) = inactive, VIN = 5.5V, VOUT = 0 0.1 1µA

VUVLO Undervoltage Lockout VIN falling 1.9 V

VUVLO(hys) Undervoltage Lockout Hysteresis 0.3 V

RDS(ON) On-Resistance VIN = 5.0V, TA= 25°C 125 175 mΩ

VIN = 3.0V, TA= 25°C 155 225

TCRDS ON-Resistance Temp-co 2800 ppm/°C

AAT4618-0.4 400 500 600

ILIM Current Limit VOUT = VIN - 0.5V AAT4618-0.5 500 750 1000 mA

AAT4618-1.0 1000 1500 2000

VON(L) ON (ON) Input Low Voltage VIN = 2.7V to 5.5V 30.8 V

VON(H) ON (ON) Input High Voltage VIN = 2.7V to ≤4.2V 32.0 V

VIN = > 4.2V to 5.0V 32.4 V

ION(SINK) ON (ON) Input leakage VON (ON) = 5.5V 0.01 1µA

tRESP Current Loop Response VIN = 5V 400 ns

TOFF Turn-Off Time VIN = 5V, RL= 20Ω5µs

TON Turn-On Time VIN = 5V, RL= 20Ω1µs

VFAULTLOW FAULT Logic Output Low ISINK = 1mA 0.4 V

ISINK FAULT Logic Output High VFAULT = 5.5V 0.5 1µA

Leakage Current

Tblank Fault Blanking Time 4 ms

TSD Over-temperature threshold VIN = 5V 125 °C

Symbol Description Value Units

ΘJA Maximum Thermal Resistance 2(SOT23-5, SC70JW-8) 150 °C/W

PDMaximum Power Dissipation 2(SOT23-5, SC70JW-8) 667 mW

Symbol Description Value Units

VIN, FAULT IN, FAULT to GND -0.3 to 6 V

VON ON (ON) to GND -0.3 to VIN+1 V

VOUT OUT to GND -0.3 to VIN+0.3 V

IOUT Output Current Internally Limited A

TJOperating Junction Temperature Range -40 to 150 °C

VESD ESD Rating1—HBM 4000 V

TLEAD Maximum Soldering Temperature (at Leads) 300 °C

Typical Characteristics

(Unless otherwise noted, VIN = 5V, TA= 25ºC)

Off-Switch Current vs. Temperature

0.00

0.01

0.10

1.00

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

Off-Switch Current (µA)

Off-Supply Current vs. Temperature

0.00

0.01

0.10

1.00

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

Off-Supply Current (µA)

RDS(ON) vs. Temperature

100

120

140

160

180

200

220

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

RDS(ON) (mΩ)

VIN=3V

VIN=5V

Normalized Current Limit vs. VOUT

0.2

0.4

0.6

0.8

1.2

0 12 345

VOUT (V)

Normalized Current Limit

Quiescent Current vs. Input Voltage

0 123456

IN (V)

Quiescent Current (µA)

Quiescent Current vs. Temperature

-40 -20 0 20 40 60 80 100 120

Temperature (°C)

Quiescent Current (µA)

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Typical Characteristics

(Unless otherwise noted, VIN = 5V, TA= 25ºC)

ON (ON) Threshold vs. VIN

0.4

0.6

0.8

1.2

1.4

1.6

1.8

2.2

2.4

2 2.5 3 3.5 4 4.5 5 5.5

VIN (V)

ON (ON) Threshold (V)

VON(H)

VON(L)

Fault Delay from Short Circuit

Time (1ms/div)

Output Voltage (5V/div)

Output Current (1A/div)

FAULT (5V/div)

Thermal Shutdown Response

Time (50ms/div)

Output Voltage (5V/div)

Output Current (1A/div)

Short Circuit through 0.3 Ω

-10 123 45

Time (µs)

Input and Output (V)

Output (A)

Output Current

Output Voltage

Input Voltage

Turn-Off

RL=20Ω, CL=0.47µF

-1

-100 1020304050

Time (µs)

Voltage (V)

ON OUT

Turn-On

RL=20Ω, CL=0.47µF

-1

-0.5 0.0 0.5 1.0 1.5 2.0

Time (µs)

Voltage (V)

ON OUT

Functional Block Diagram

IN OUT

ON (ON)

GND

Under-Voltage

Lockout

Over-Temp

Protection

Current

Limit

FAULT

4ms Delay

AAT4618

Current Limited Load Switch

64618.2002.4.0.91

Functional Description

The AAT4618 is a single channel current limited

load switch that protects against short circuits by

current limiting to a preset level. A patented fast

acting current limit loop limits the current in a frac-

tion of a micro second and instantly resets to low

impedance once the short circuit condition is

removed. The AAT4618 is internally protected

from thermal damage by an over temperature

detection circuit. If the die temperature reaches

the internal thermal limit, the power device is

switched off until the die temperature cools to a

level below the thermal limit threshold. The device

will thermal cycle indefinitely until the over current

condition is removed. The AAT4618 operates with

input voltages ranging from 2.4V to 5.5V which,

along with its extremely low operating current,

makes it ideal for battery-powered applications. In

cases where the input voltage drops below 2.4V,

the AAT4618 MOSFET is protected from entering

the saturated region of operation by being auto-

matically shut down by an under voltage lockout

circuit. A current limit condition is reported by the

open drain FAULT output. A four millisecond blank-

ing interval prevents false reporting during the

charging of a capacitive load, which typically

occurs during device turn-on, but may also occur

during a port hot plug-in event.

The AAT4618 is ideally suited for protection of

peripheral ports such as USB, RS232 and parallel

ports.

Applications Information

Input Capacitor

The input capacitor, CIN protects the power supply

from current transients generated by the load

attached to the AAT4618. When a short circuit is

suddenly applied to the output of the AAT4618, a

large current, limited only by the RDS(ON) of the

MOSFET, will flow for less than 1µs before the cur-

rent limit circuitry activates. (See characteristic

curve "Short Circuit Through 0.3Ω.") In this event,

a moderately sized CIN will dramatically reduce the

voltage transient seen by the power supply and by

other circuitry upstream from the AAT4618. The

extremely fast short circuit response time of the

AAT4618 reduces the size requirement of CIN.

CIN should be located as close to the device VIN pin

as practically possible. Ceramic, tantalum or alu-

minum electrolytic capacitors are appropriate for

CIN. There is no specific capacitor ESR requirement

for CIN. However, for higher current operation,

ceramic capacitors are recommended for CIN due to

their inherent capability over tantalum capacitors to

withstand input current surges from low impedance

sources such as batteries in portable devices.

Output Capacitor

In order to insure stability while current limit is

active, a small capacitance of approximately

0.47µF is required. No matter how large the output

capacitor however, output current is limited to the

value set by the AAT4618 current limiting circuitry,

so very large output capacitors can be used.

For example, USB ports are specified to have at

least 120µF of capacitance down stream from their

controlling power switch. The current limiting circuit

will allow an output capacitance of 1000µF or more

without disturbing the upstream power supply.

ON (Enable Input)

In many systems, power planes are controlled by

integrated circuits which run at lower voltages than

the power plane itself. The enable input (ON) of

the AAT4618 has low and high threshold voltages

that accommodate this condition. The threshold

voltages are compatible with 5 volt TTL, and 2.5

volt to 5 volt CMOS systems.

When switching the AAT4618 on into a capacitive

load, the AAT4618 will charge the output capacitive

load at a rate no greater than the current limit setting.

Attaching Loads

Capacitive loads attached to an enabled AAT4618 will

charge at a rate no greater than the current limit setting.

FAULT Output

The FAULT flag is provided to alert the system if an

AAT4618 load is not receiving sufficient voltage to

operate properly. If current limit or over tempera-

ture circuits in any combination are active for more

than approximately four milliseconds, the FAULT

flag is pulled to ground through approximately

100Ω. The filtering of voltage or current transients

of less than four milliseconds prevents capacitive

loads connected to the AAT4618 output from acti-

vating the FAULT flag when they are initially

attached. Pull up resistances of 1kΩto 100kΩare

recommended. Since FAULT is an open drain ter-

minal, it may be pulled up to any unrelated voltage

less than the maximum operating voltage of 5.5V,

allowing for level shifting between circuits.

Thermal Considerations

Since the AAT4618 has internal current limit and

over temperature protection, junction temperature

is rarely a concern. However, if the application

requires large currents in a hot environment, it is

possible that temperature rather than current limit

will be the dominant regulating condition. In these

applications, the maximum current available with-

out risk of an over temperature condition must be

calculated. The maximum internal temperature

while current limit is not active can be calculated

using Equation 1.

TJ(MAX) = IMAX2×RDS(ON)(MAX) ×RθJA + TA(MAX)

In Equation 1, IMAX is the maximum current

required by the load. RDS(ON)(MAX) is the maxi-

mum rated RDS(ON) of the AAT4618 at high temper-

ature. RθJA is the thermal resistance between the

AAT4618 die and the board onto which it is mount-

ed. TA(MAX) is the maximum temperature that the

PCB under the AAT4618 would be if the AAT4618

were not dissipating power. Equation 1 can be

rearranged to solve for IMAX; Equation 2.

IMAX=TSD(MIN) - TA(MAX)

RDS(ON)(MAX) ×RθJA

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TSD(MIN) is the minimum temperature required to

activate the AAT4618 over temperature protection.

With typical specification of 125°C, 115°C is a safe

minimum value to use.

For example, if an application is specified to oper-

ate in 50°C environments, the PCB operates at

temperatures as high as 85°C. The application is

sealed and its PCB is small, causing RθJA to be

approximately 150 °C/W. Using Equation 2,

IMAX=115 - 85 = 950 mA

220m ×150

The AAT4618 is safe to operate at the minimum

current limit level of 500mA at 85°C.

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84618.2002.4.0.91

Ordering Information

Note: Sample stock is generally held on all part numbers listed in BOLD.

Note 1: XYY = assembly and date code.

Package Information

SOT23-5

All dimensions in millimeters

4° ± 4°

0.15 ± 0.07

0.45 ± 0.15 0.10 BSC

1.20

0.25

1.575 ± 0.125

2.80 ± 0.20

0.40

0.10

0.60 REF

2.85 ± 0.15

1.90 BSC

0.95

BSC

1.10

0.20

10°

5°

GAUGE PLANE

0.075

0.60 REF

Package Enable Current Limit Marking1Part Number (Tape and Reel)

SOT23-5 Active Low 0.5 AVXYY AAT4618IGV-0.5-T1

SOT23-5 Active High 0.5 DWXYY AAT4618IGV-0.5-1-T1

SOT23-5 Active Low 1.0 EVXYY AAT4618IGV-1.0-T1

SOT23-5 Active High 1.0 EIXYY AAT4618IGV-1.0-1-T1

SC70JW-8 Active Low 0.4 AAT4618IJS-0.4-T1

SC70JW-8 Active High 0.4 AAT4618IJS-0.4-1-T1

SC70JW-8 Active Low 0.5 AVXYY AAT4618IJS-0.5-T1

SC70JW-8 Active High 0.5 DWXYY AAT4618IJS-0.5-1-T1

SC70JW-8 Active Low 1.0 EVXYY AAT4618IJS-1.0-T1

SC70JW-8 Active High 1.0 EIXYY AAT4618IJS-1.0-1-T1

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SC70JW-8

All dimensions in millimeters.

0.225 ± 0.075

0.45 ± 0.10

0.05 ± 0.05

2.10 ± 0.30

2.00 ± 0.20

7° ± 3°4° ± 4°

1.75 ± 0.10

0.85 ± 0.15

0.15 ± 0.05

1.10 MAX

0.100

2.20 ± 0.20

0.048REF

0.50 BSC 0.50 BSC 0.50 BSC

AAT4618

Current Limited Load Switch

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Advanced Analogic Technologies, Inc.

830 E. Arques Avenue, Sunnyvale, CA 94085

Phone (408) 737-4600

Fax (408) 737-4611

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other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily

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