AAT4618
DATA SHEET
Current Limited Load Switch
1
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Typical Application
AAT4618
ON (ON)
IN OUT
FAULT
GND
ON
(ON)
100k
INPUT
GND GND
CIN
1μF
COUT
0.47μF
OUTPUT
FAULT
General Description
The AAT4618 SmartSwitch is a member of Skyworks'
Application Specific Power MOSFET™ (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, making
it ideal for 2.5V, 3V, and 5V systems. An integrated
current-limiting circuit protects the input supply from
large currents which may cause the supply to fall out of
regulation. In addition, the AAT4618 thermal overload
protection limits power dissipation and junction temper-
atures 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 the supply current decreases
to less than 1μA in shutdown mode.
The AAT4618 is available in a Pb-free 5-pin SOT-23 or a
8-pin SC70JW package and is specified over the -40°C to
+85°C temperature range.
The AAT4600 series is a family of adjustable and fixed
voltage SmartSwitch products with a range of current
handling capabilities. Single versions with adjustable
current limit (AAT4610, AAT4601) or fixed current limit
(AAT4625) are available, as well as dual versions 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
125m Typical RDS(ON)
FAULT Flag with 4ms Blanking
Under-Voltage Lockout
Thermal Shutdown
Temperature Range: -40°C to +85°C
4kV ESD Rating
5-Pin SOT23 or 8-Pin SC70JW Package
Applications
Hot Swap Supplies
Notebook Computers
Peripheral Ports
Personal Communication Devices
USB Ports
AAT4618
DATA SHEET
Current Limited Load Switch
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Pin Descriptions
Pin #
Symbol Function
SOT23-5 SC70JW-8
1 5 OUT P-channel MOSFET drain.
2 6, 7, 8 GND Ground connection.
31
FAULT Open-drain FAULT output.
42
ON (ON) Enable input: AAT4618 active low, AAT4618-1 active high.
5 3, 4 IN P-channel MOSFET source.
Pin Configuration
SOT23-5 SC70JW-8
(Top View) (Top View)
1
2
3ON (ON)
FAULT
IN
4
5
GND
OUT
ON (ON)
IN
IN
1 2
GND
GND
GND
OUT
FAULT
1
2
3
4
8
7
6
5
AAT4618
DATA SHEET
Current Limited Load Switch
3
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
201942A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 14, 2012
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions
specified is not implied. Only one Absolute Maximum Rating should be applied at any one time.
2. Human body model is a 100pF capacitor discharged through a 1.5k resistor into each pin.
3. Mounted on a demo board.
Absolute Maximum Ratings1
TA = 25°C, unless otherwise noted.
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 Rating2—HBM 4000 V
TLEAD Maximum Soldering Temperature (at Leads) 300 °C
Thermal Characteristics3
Symbol Description Value Units
JA Maximum Thermal Resistance 150 °C/W
PDMaximum Power Dissipation 667 mW
AAT4618
DATA SHEET
Current Limited Load Switch
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1. For VIN outside this range, consult Typical ON (ON) Threshold curve.
Electrical Characteristics
VIN = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C; bold values denote full tem-
perature range.
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
μAIQ(OFF) Off Supply Current ON (ON) = Inactive, VIN = 5.5V 1
ISD(OFF) Off Switch Current ON (ON) = Inactive, VIN = 5.5V, VOUT = 0 0.1 1
VUVLO Under-Voltage Lockout VIN Falling 1.9 V
VUVLO(hys) Under-Voltage Lockout Hysteresis 0.3
RDS(ON) On Resistance VIN = 5.0V, TA = 25°C 125 175 m
VIN = 3.0V, TA = 25°C 155 225
TCRDS On Resistance Temperature Coef cient 2800 ppm/°C
ILIM Current Limit VOUT = VIN to 0.5V
AAT4618-0.4 400 500 600
mAAAT4618-0.5 500 750 1000
AAT4618-1.0 1000 1500 2000
VON(L) ON (ON) Input Low Voltage VIN = 2.7V to 5.5V10.8
V
VON(H) ON (ON) Input High Voltage VIN = 2.7V to 4.2V12.0
VIN = > 4.2V to 5.0V12.4
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 = 205μs
TON Turn-On Time VIN = 5V, RL = 201
VFAULTLOW FAULT Logic Output Low ISINK = 1mA 0.4 V
ISINK FAULT Logic Output High Leakage Current VFAULT = 5.5V 0.5 1μA
Tblank FAULT Blanking Time 4ms
TSD Over-Temperature Threshold VIN = 5V 125 °C
AAT4618
DATA SHEET
Current Limited Load Switch
5
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Quiescent Current vs. Temperature
0
5
10
15
20
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
Quiescent Current (μA)
Quiescent Current vs. Input Voltage
0
5
10
15
20
0 123456
Input Voltage (V)
Quiescent Current (μA)
Current Limit vs. VOUT
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
012345
VOUT (V)
Current Limit (A)
RDS(ON) vs. Temperature
0
20
40
60
80
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
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)
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)
AAT4618
DATA SHEET
Current Limited Load Switch
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Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Turn-On
(RL = 20Ω; CL = 0.47μF)
-1
0
1
2
3
4
5
6
-0.5 0.0 0.5 1.0 1.5 2.0
Time (μs)
Voltage (V)
ON OUT
Turn-Off
(RL = 20Ω; CL = 0.47μF)
-1
0
1
2
3
4
5
6
-10 0 10 20 30 40 50
Time (μs)
Voltage (V)
ON OUT
Short Circuit Through 0.3Ω
0
1
2
3
4
5
6
-10 123 45
Time (μs)
Input and Output Voltage (V)
0
2
4
6
8
10
12
Output Current (A)
Output Current
Output Voltage
Input Voltage
Thermal Shutdown Response
Time (50ms/div)
Output Voltage (5V/div)
Output Current (1A/div)
Fault Delay from Short Circuit
Time (1ms/div)
Output Voltage (5V/div)
Output Current (1A/div)
FAULT (5V/div)
ON (ON) Threshold vs. Input Voltage
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
2.2
2.4
22.533.544.555.5
Input Voltage (V)
ON (ON) Threshold (V)
VON(H)
VON(L)
AAT4618
DATA SHEET
Current Limited Load Switch
7
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Functional Description
The AAT4618 is a single channel current limited load
switch that protects against short circuits by current limit-
ing to a preset level. A patented fast-acting current limit
loop limits the current in a fraction of a microsecond 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 ther-
mal 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 automatically shut down by an
under-voltage lockout circuit. A current limit condition is
reported by the open drain FAULT output. A 4ms blanking
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 periph-
eral 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 current limit circuitry activates. (See charac-
teristic curve “Short Circuit Through 0.3.") 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 extreme-
ly fast short-circuit response time of the AAT4618 reduc-
es the size requirement of CIN.
CIN should be located as close to the device VIN pin as
practically possible. Ceramic, tantalum, or aluminum
electrolytic capacitors are appropriate for CIN. There is no
specific capacitor ESR requirement for CIN. However, for
higher current operation, ceramic capacitors are recom-
mended for CIN due to their inherent capability over tan-
talum capacitors to withstand input current surges from
low impedance sources such as batteries in portable
devices.
Functional Block Diagram
IN OUT
ON (ON)
GND
Under-Voltage
Lockout
Over-Temperature
Protection
Current
Limit
FAULT
4ms Delay
AAT4618
DATA SHEET
Current Limited Load Switch
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Output Capacitor
In order to insure stability while current limit is active, a
low capacitance (approximately 0.47μF) is required. No
matter how large the output capacitor, 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 downstream 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 inte-
grated 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 5V TTL and 2.5V to 5V 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 set-
ting.
FAULT Output
The FAULT flag is provided to alert the system if an
AAT4618 load is not receiving sufficient voltage to oper-
ate properly. If current limit or over-temperature circuits
in any combination are active for more than approxi-
mately 4ms, the FAULT flag is pulled to ground through
approximately 100. The filtering of voltage or current
transients of less than 4ms prevents capacitive loads
connected to the AAT4618 output from activating the
FAULT flag when they are initially attached. Pull-up resis-
tances of 1k to 100k are recommended. Since FAULT
is an open drain terminal, it may be pulled up to any
unrelated voltage less than the maximum operating volt-
age 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 cur-
rents in a hot environment, it is possible that tempera-
ture, rather than current limit, will be the dominant
regulating condition. In these applications, the maxi-
mum current available without risk of an over-tempera-
ture condition must be calculated. The maximum inter-
nal temperature while current limit is not active can be
calculated using Equation 1.
Eq. 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 maximum rated RDS(ON) of the
AAT4618 at high temperature. RJA is the thermal resis-
tance between the AAT4618 die and the board onto
which it is mounted. 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 rear-
ranged to solve for IMAX, as shown in Equation 2.
Eq. 2: =
IMAX
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) · RΘJA
TSD(MIN) is the minimum temperature required to activate
the AAT4618 over-temperature protection. With the
typical specification of 125°C, 115°C is a safe minimum
value to use.
For example, if an application is specified to operate in
50°C environments, the PCB operates at temperatures
as high as 85°C. The application is sealed and its PCB is
small, causing RJA to be approximately 150 °C/W. Using
Equation 2,
Eq. 3: =
IMAX = 950m
A
115 - 85
220 · 150
The AAT4618 is safe to operate at the minimum current
limit level of 500mA at 85°C.
AAT4618
DATA SHEET
Current Limited Load Switch
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1. XYY = assembly and date code.
2. Sample stock is generally held on all part numbers listed in BOLD.
Ordering Information
Package Enable Current Limit Marking1Part Number (Tape and Reel)2
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
SC70JW-8 Active High 0.4
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
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
Package Information
SOT23-5
°
±
±
°
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°
°
±
°
GAUGE PLANE
0.075
±
0.075
0.60 REF
All dimensions in millimeters
AAT4618
DATA SHEET
Current Limited Load Switch
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Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved.
Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a
service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Sky-
works may change its documentation, products, services, speci cations or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
responsibility whatsoever for con icts, incompatibilities, or other dif culties arising from any future changes.
No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided here-
under, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale.
THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES
NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, IN-
CLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM
THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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vironmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper
use or sale.
Customers are responsible for their products and applications using Skyworks products, which may deviate from published speci cations as a result of design defects, errors, or operation of products outside of pub-
lished parameters or design speci cations. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
design, or damage to any equipment resulting from the use of Skyworks products outside of stated published speci cations or parameters.
Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
identi cation purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.
SC70JW-8
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
All dimensions in millimeters.