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SmartSwitch
™
General Description
The AAT4250 SmartSwitch is a member of
AnalogicTech’s Application Specific Power MOSFET™ (ASPM™) product family. It is a slew rate
controlled P-channel MOSFET power switch
designed for high-side load switching applications.
This switch operates with an input voltage range
from 1.8V to 5.5V, making it ideal for 2.5V, 3.3V, or
5V systems. The part features 1.5ms turn-on and
10µs turn-off time. The AAT4250 has an undervoltage lockout which turns off the switch when an
under-voltage condition exists. Input logic levels
are TTL compatible. The quiescent supply current
is very low, typically 2µA. In shutdown mode, the
supply current is typically reduced to 0.1µA or less.
The AAT4250 is available in a Pb-free, 5-pin SOT23
(SOT25) package or a Pb-free, 8-pin SC70JW package and is specified over the -40°C to +85°C temperature range.
Features
• 1.8V to 5.5V Input Voltage Range
• 120mΩ (5V) Typical R
DS(ON)
• Low Quiescent Current:
• Typical 2µA
• Typical 0.1µAwith Enable Off
• Only 2.0V Needed for ON/OFF Control
• Temperature Range: -40°C to +85°C
• 5kV ESD Rating
• SOT23-5 or SC70JW-8 Package
Applications
• Hot Swap Supplies
• Notebook Computers
• Personal Communication Devices
AAT4250
Slew Rate Controlled Load Switch
Typical Application
4250.2006.03.1.3 1
INPUT
IN OUT
AAT4250
C
IN
1µF 0.1µF
GND GND
ON
ON/OFF
GND
C
OUT
OUTPUT
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Pin Descriptions
Pin Configuration
SOT23-5 (SOT25)
(Top View)
SC70JW-8
(Top View)
Pin #
SOT23-5 SC70JW-8
Symbol Function
1 1 OUT P-channel MOSFET drain.
2 2, 3, 4, 5 GND Ground connection.
3 N/A N/C Not internally connected.
4 6 ON/OFF Active-high enable input. Logic high turns the switch on.
5 7, 8 IN P-channel MOSFET source.
AAT4250
Slew Rate Controlled Load Switch
2 4250.2006.03.1.3
OUT
GND
N/C
OUT
GND
GND
GND
1
2
3
5
IN
4
ON/OFF
1
2
3
45
8
IN
7
IN
6
ON/OFF
GND
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AAT4250
Slew Rate Controlled Load Switch
8 4250.2006.03.1.3
Functional Description
The AAT4250 is a slew rate controlled P-channel
MOSFET power switch designed for high-side load
switching applications. It operates with input voltages ranging from 1.8V 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 1.8V, the AAT4250 MOSFET is protected from entering the saturated region
of operation by automatically shutting down. In
addition, the TTL compatible ON/OFF pin makes
the AAT4250 an ideal level-shifted load switch. The
slew rate controlling feature eliminates inrush current when the MOSFET is turned on, allowing the
AAT4250 to be used with a small input capacitor, or
no input capacitor at all. During slewing, the current
ramps linearly until it reaches the level required for
the output load condition. The proprietary control
method works by careful control and monitoring of
the MOSFET gate voltage. When the device is
switched ON, the gate voltage is quickly increased
to the threshold level of the MOSFET. Once at this
level, the current begins to slew as the gate voltage
is slowly increased until the MOSFET becomes fully
enhanced. Once it has reached this point, the gate
is quickly increased to the full input voltage and
R
DS(ON)
is minimized.
Applications Information
Input Capacitor
A 1µF or larger capacitor is typically recommended
for CINin most applications. A CINcapacitor is not
required for basic operation; however, it is useful in
preventing load transients from affecting upstream
circuits. CINshould be located as close to the
device VINpin as practically possible. Ceramic,
tantalum, or aluminum electrolytic capacitors may
be selected for CIN. There is no specific capacitor
equivalent series resistance (ESR) requirement for
CIN. However, for higher current operation, ceramic capacitors are recommended for CINdue to their
inherent capability over tantalum capacitors to withstand input current surges from low-impedance
sources, such as batteries in portable devices.
Output Capacitor
For proper slew operation, a 0.1µF capacitor or
greater is required between V
OUT
and GND.
Likewise, with the output capacitor , there is no specific capacitor ESR requirement. If desired, C
OUT
may be increased without limit to accommodate
any load transient condition without adversely
affecting the slew rate.
Functional Block Diagram
IN
UnderVoltage
Lockout
ON/OFF
GND
OUT
Slew Rate
Control
Level
Shift
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AAT4250
Slew Rate Controlled Load Switch
4250.2006.03.1.3 13
SC70JW-8
All dimensions in millimeters.
0.50 BSC 0.50 BSC 0.50 BSC
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights,
or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice.
Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicT ech
warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and 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 performed.
7° ± 3°
2.00 ± 0.20
0.225 ± 0.075
1.75 ± 0.10
2.20 ± 0.20
1.10 MAX
0.85 ± 0.15
0.100
0.048REF
0.15 ± 0.05
0.45 ± 0.10
2.10 ± 0.30
4° ± 4°
0.05 ± 0.05
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