AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4250.2009.06.1.4 1
www.analogictech.com
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 appli-
cations. 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 under-voltage lockout
which turns off the switch when an under-voltage condi-
tion 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 RDS(ON)
• Low Quiescent Current:
▪ Typical 2μA
▪ Typical 0.1μA with 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
Typical Application
AAT4250
ON/OFF
IN OUT
GND
ON
1µF 0.1µF
INPUT
GND GND
CIN COUT
OUTPUT
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
2 4250.2009.06.1.4
www.analogictech.com
Pin Descriptions
Pin #
Symbol Function
SOT23-5 SC70JW-8
1 1 OUT P-channel MOSFET drain.
2 2, 3, 4, 5 GND Ground connection.
3 N/A N/C Not internally connected.
46
ON/OFF Active-high enable input. Logic high turns the switch on.
5 7, 8 IN P-channel MOSFET source.
Pin Configuration
SOT23-5 (SOT25) SC70JW-8
(Top View) (Top View)
GND
IN
ON/OFF
N/C
OUT
1
2
34
5
GND
GND
GND
IN
IN
ON/OFF
GND
OUT 1
2
3
45
6
7
8
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4250.2009.06.1.4 3
www.analogictech.com
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 1.5kΩ resistor into each pin.
3. Mounted on an AAT4250 demo board in still 25ºC air.
Absolute Maximum Ratings1
TA = 25°C, unless otherwise noted.
Symbol Description Value Units
VIN IN to GND -0.3 to 6 V
VON ON/OFF to GND -0.3 to 6 V
VOUT OUT to GND -0.3 to VIN + 0.3 V
IMAX Maximum Continuous Switch Current 1.7 A
IDM Maximum Pulsed Current IN ≥ 2.5V 4 A
IN < 2.5V 2
TJOperating Junction Temperature Range -40 to 150 °C
TLEAD Maximum Soldering Temperature (at leads) 300 °C
VESD ESD Rating2 - HBM 5000 V
Thermal Characteristics3
Symbol Description Value Units
ΘJA Thermal Resistance SC70JW-8 150 °C/W
SOT23-5 233.4
PDPower Dissipation SC70JW-8 667 mW
SOT23-5 428
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4 4250.2009.06.1.4
www.analogictech.com
1. Part requires minimum start-up of VIN ≥ 2.0V to ensure operation down to 1.8V.
2. For VIN outside this range, consult typical ON/OFF threshold curve.
Electrical Characteristics
VIN = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol Description Conditions Min Typ Max Units
VIN Operation Voltage 1.815.5 V
IQQuiescent Current VIN = 5V, ON/OFF = VIN, IOUT = 0 2 4 μA
IQ(OFF) Off Supply Current ON/OFF = GND, VIN = 5V, OUT Open 1 μA
ISD(OFF) Off Switch Current ON/OFF = GND, VIN = 5V, VOUT = 0 0.1 1 μA
VUVLO Under-Voltage Lockout VIN Falling 1.0 1.5 1.8 V
VUVLO(hys) Under-Voltage Lockout Hysteresis 250 mV
RDS(ON) On Resistance
VIN = 5V, TA = 25°C 120 175
mΩVIN = 3V, TA = 25°C 135 200
VIN = 1.8V 165
TCRDS On Resistance Temperature Coeffi cient 2800 ppm/°C
VIL ON/OFF Input Logic Low Voltage VIN = 2.7V to 5.5V20.8 V
VIH ON/OFF Input Logic High Voltage VIN = 2.7V to 4.2V 2.0 V
VIN = >4.2V to 5.5V 2.4
ISINK ON Input Leakage VON = 5V 0.01 1 μA
TDOutput Turn-On Delay Time 300 μs
TDOFF Turn-Off Delay Time VIN = 5V, RLOAD = 10Ω10 μs
VIN = 3V, RLOAD = 5Ω10
TON Turn-On Rise Time
VIN = 5V, RLOAD = 16.5Ω, TA = 0 to 50°C 1000
μsVIN = 5V, RLOAD = 10Ω, COUT = 0.1μF 1500
VIN = 3V, RLOAD = 5Ω, COUT = 0.1μF 1500
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4250.2009.06.1.4 5
www.analogictech.com
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Quiescent Current vs. Temperature
0
0.5
1
1.5
2
2.5
3
3.5
4
-40 -20 0 20 40 60 80 100
Temperature (
°
C)
Quiescent Current (µA)
VIN = 3V
VIN = 5V
Quiescent Current vs. Input Voltage
0
0.5
1
1.5
2
2.5
3
3.5
4
0 12 3456
Quiescent Current (µA)
Input Voltage (V)
Off-Supply Current vs. Temperature
1
10
100
1000
-40 -20 0 20 40 60 80 100
Temperature (
°
C)
Off-Supply Current (nA)
Off-Switch Current vs. Temperature
1
10
100
1000
10000
-40-20 0 20406080100
Temperature (
°
C)
Off-Switch Current (nA)
Turn-Off Time vs. Temperature
(CIN = 1µF; COUT = 0.1µF)
5
6
7
8
9
10
-40 -20 0 20 40 60 80 100
Temperature (
°
C)
Turn-Off Time (µs)
VIN = 5V
RLOAD = 10Ω
VIN = 3V
RLOAD = 5Ω
Turn-On Time vs. Temperature
(CIN = 1µF; COUT = 0.1µF)
0.5
1.0
1.5
2.0
2.5
3.0
-40 -20 0 20 40 60 80 100
Temperature (°C)
Turn-On Time (ms)
VIN = 5V
RLOAD = 10Ω
VIN = 3V
RLOAD = 5Ω
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
6 4250.2009.06.1.4
www.analogictech.com
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Voltage (V)
-1 0 1 2 3 4
0
1
2
3
4
0
0.5
1
1.5
2
Time (ms)
Turn-On Waveforms
(CIN = 1µF; COUT = 0.1µF; VIN = 3V)
V(ON/OFF)
VOUT
IIN
Current (A)
Voltage (V)
-1 0 1 2 3 4
0
1
2
3
4
0
1
1.2
Time (ms)
Turn-On Waveforms
(CIN = 1µF; COUT = 0.1µF; VIN = 5V)
VOUT 0.8
0.6
0.4
0.2
5
6
IIN
Current (A)
V(ON/OFF)
Voltage (V)
-1 0 1 2 3 4
0
1
2
3
4
0
0.5
1
1.5
2
Time (ms)
Turn-On Waveforms
(CIN = 1µF; COUT = 10µF; VIN = 3V)
VOUT
Current (A)
V(ON/OFF)
IIN
-1 0 1 2 3 4
0
1
1.2
Time (ms)
Turn-On Waveforms
(CIN = 1µF; COUT = 10µF; VIN = 5V)
VOUT 0.8
0.6
0.4
0.2
5
6
IIN
Voltage (V)
4
3
2
1
0
Current (A)
V(ON/OFF)
0
1
2
3
4
Turn-Off Waveforms
(CIN = 1µF; COUT = 1µF; VIN = 3V)
Time (µs)
-1
-1 1 3 5 7 9 11 13 15
VOUT
Voltage (V)
V(ON/OFF)
1
3
5
Turn-Off Waveforms
(CIN = 1µF; COUT = 1µF; VIN = 5V)
Time (µs)
-1
-1 1 3 5 7 9 11 13 15
VOUT
Voltage (V)
V(ON/OFF)
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4250.2009.06.1.4 7
www.analogictech.com
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
RDS(ON) vs. Temperature
80
90
120
110
100
150
140
130
160
-40 -20 0 20 40 60 80 100
Temperature (
°
C)
RDS(ON) (m
Ω
)
VIN = 3V
VIN = 5V
RDS(ON) vs. Input Voltage
110
120
130
140
150
160
170
180
190
1.5 2 2.53 3.54 4.55 5.5
Input Voltage (V)
RDS(ON) (m
Ω
)
IOUT = 100mA
Typical ON/OFF Threshold vs. Input Voltage
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
Input Voltage (V)
ON/OFF Threshold
VIH
VIL
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
8 4250.2009.06.1.4
www.analogictech.com
Functional Description
The AAT4250 is a slew rate controlled P-channel MOSFET
power switch designed for high-side load switching appli-
cations. It operates with input voltages ranging from
1.8V to 5.5V which, along with its extremely low operat-
ing current, makes it ideal for battery-powered applica-
tions. 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 RDS(ON) is
minimized.
Applications Information
Input Capacitor
A 1μF or larger capacitor is typically recommended for
CIN in most applications. A CIN capacitor is not required
for basic operation; however, it is useful in preventing
load transients from affecting upstream circuits. CIN
should be located as close to the device VIN pin as practi-
cally possible. Ceramic, tantalum, or aluminum electro-
lytic capacitors may be selected for CIN. There is no
specific capacitor equivalent series resistance (ESR)
requirement for CIN. However, for higher current opera-
tion, 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
For proper slew operation, a 0.1μF capacitor or greater
is required between VOUT and GND.
Likewise, with the output capacitor, there is no specific
capacitor ESR requirement. If desired, COUT may be
increased without limit to accommodate any load tran-
sient condition without adversely affecting the slew rate.
Functional Block Diagram
Under-
Voltage
Lockout
Level
Shift
Slew Rate
Control
IN
ON/OFF
GND
OUT
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4250.2009.06.1.4 9
www.analogictech.com
Enable Function
The AAT4250 features an enable / disable function. This
pin (ON) is active high and is compatible with TTL or
CMOS logic. To assure the load switch will turn on, the
ON control level must be greater than 2.0V. The load
switch will go into shutdown mode when the voltage on
the ON pin falls below 0.8V. When the load switch is in
shutdown mode, the OUT pin is tri-stated, and quiescent
current drops to leakage levels below 1μA.
Reverse Output-to-Input Voltage
Conditions and Protection
Under normal operating conditions, a parasitic diode
exists between the output and input of the load switch.
The input voltage should always remain greater than the
output load voltage, maintaining a reverse bias on the
internal parasitic diode. Conditions where VOUT might
exceed VIN should be avoided since this would forward
bias the internal parasitic diode and allow excessive cur-
rent flow into the VOUT pin, possibly damaging the load
switch.
In applications where there is a possibility of VOUT
exceeding VIN for brief periods of time during normal
operation, the use of a larger value CIN capacitor is
highly recommended. A larger value of CIN with respect
to COUT will effect a slower CIN decay rate during shut-
down, thus preventing VOUT from exceeding VIN. In appli-
cations where there is a greater danger of VOUT exceeding
VIN for extended periods of time, it is recommended to
place a Schottky diode from VIN to VOUT (connecting the
cathode to VIN and anode to VOUT). The Schottky diode
forward voltage should be less than 0.45V.
Thermal Considerations and
High Output Current Applications
The AAT4250 is designed to deliver a continuous output
load current. The limiting characteristic for maximum
safe operating output load current is package power dis-
sipation. In order to obtain high operating currents,
careful device layout and circuit operating conditions
must be taken into account.
The following discussions will assume the load switch is
mounted on a printed circuit board utilizing the mini-
mum recommended footprint as stated in the Printed
Circuit Board Layout Recommendations section of this
datasheet.
At any given ambient temperature (TA), the maximum
package power dissipation can be determined by the fol-
lowing equation:
PD(MAX) = TJ(MAX) - TA
θJA
Constants for the AAT4250 are maximum junction tem-
perature (TJ(MAX) = 125°C) and package thermal resis-
tance (ΘJA = 150°C/W). Worst case conditions are calcu-
lated at the maximum operating temperature, TA =
85°C. Typical conditions are calculated under normal
ambient conditions where TA = 25°C. At TA = 85°C,
PD(MAX) = 267mW. At TA = 25°C, PD(MAX) = 667mW.
The maximum continuous output current for the AAT4250
is a function of the package power dissipation and the
RDS of the MOSFET at TJ(MAX). The maximum RDS of the
MOSFET at TJ(MAX) is calculated by increasing the maxi-
mum room temperature RDS by the RDS temperature
coefficient. The temperature coefficient (TC) is 2800ppm/
°C. Therefore, at 125°C:
RDS(MAX) = RDS(25°C) · (1 + TC · ΔT)
RDS(MAX) = 175mΩ · (1 + 0.002800 · (125°C - 25°C))
RDS(MAX) = 224mΩ
For maximum current, refer to the following equation:
IOUT(MAX) < PD(MAX)
RDS
1
2
⎛⎞
⎝⎠
For example, if VIN = 5V, RDS(MAX) = 224mΩ, and TA =
25°C, IOUT(MAX) = 1.7A. If the output load current were to
exceed 1.7A or if the ambient temperature were to
increase, the internal die temperature would increase
and the device would be damaged.
Higher peak currents can be obtained with the AAT4250.
To accomplish this, the device thermal resistance must
be reduced by increasing the heat sink area or by oper-
ating the load switch in a duty-cycle manner. Duty cycles
with peaks less than 2ms in duration can be considered
using the method below.
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
10 4250.2009.06.1.4
www.analogictech.com
High Peak Output Current Applications
Some applications require the load switch to operate at
a continuous nominal current level with short duration,
high-current peaks. Refer to the IDM specification in the
Absolute Maximum Ratings table to ensure the AAT4250’s
maximum pulsed current rating is not exceeded. The
duty cycle for both output current levels must be taken
into account. To do so, first calculate the power dissipa-
tion at the nominal continuous current level, and then
add the additional power dissipation due to the short
duration, high-current peak scaled by the duty factor.
For example, a 4V system using an AAT4250 operates at
a continuous 100mA load current level and has short 2A
current peaks, as in a GSM application. The current peak
occurs for 576μs out of a 4.61ms period.
First, the current duty cycle is calculated:
% Peak Duty Cycle: X/100 = 576μs/4.61ms
% Peak Duty Cycle = 12.5%
The load current is 100mA for 87.5% of the 4.61ms
period and 2A for 12.5% of the period. Since the
Electrical Characteristics do not report RDS(MAX) for 4V
operation, it must be approximated by consulting the
chart of RDS(ON) vs. VIN. The RDS reported for 5V RDS can
be scaled by the ratio seen in the chart to derive the RDS
for 4V VIN: 175mΩ · 120mΩ/115mΩ = 183mΩ. Derated
for temperature: 183mΩ · (1 + 0.002800 · (125°C -
25°C)) = 235mΩ. The power dissipation for a 100mA
load is calculated as follows:
PD(MAX) = I2OUT · RDS
PD(100mA) = (100mA)2 · 235mΩ
PD(100mA) = 2.35mW
PD(87.5%D/C) = %DC · PD(100mA)
PD(87.5%D/C) = 0.875 · 2.35mW
PD(87.5%D/C) = 2.1mW
The power dissipation for 100mA load at 87.5% duty
cycle is 2.1mW. Now the power dissipation for the
remaining 12.5% of the duty cycle at 2A is calculated:
PD(MAX) = I2OUT · RDS
PD(2A) = (2A)2 · 235mΩ
PD(2A) = 940mW
PD(12.5%D/C) = %DC · PD(2A)
PD(12.5%D/C) = 0.125 · 940mW
PD(12.5%D/C) = 117.5mW
The power dissipation for 2A load at 12.5% duty cycle is
117mW. Finally, the two power figures are summed to
determine the total true power dissipation under the
varied load.
PD(total) = PD(100mA) + PD(2A)
PD(total) = 2.1mW + 117.5mW
PD(total) = 120mW
The maximum power dissipation for the AAT4250 oper-
ating at an ambient temperature of 85°C is 267mW. The
device in this example will have a total power dissipation
of 120mW. This is well within the thermal limits for safe
operation of the device; in fact, at 85°C, the AAT4250
will handle a 2A pulse for up to 28% duty cycle. At lower
ambient temperatures, the duty cycle can be further
increased.
Printed Circuit Board
Layout Recommendations
For proper thermal management, and to take advantage
of the low RDS(ON) of the AAT4250, a few circuit board lay-
out rules should be followed: VIN and VOUT should be
routed using wider than normal traces, and GND should
be connected to a ground plane. For best performance,
CIN and COUT should be placed close to the package pins.
Evaluation Board Layout
The AAT4250 evaluation layout follows the printed circuit
board layout recommendations, and can be used for
good applications layout.
Note: Board layout shown is not to scale.
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4250.2009.06.1.4 11
www.analogictech.com
Figure 1: AAT4250 Evaluation Board Figure 2: AAT4250 Evaluation Board
Top Side Silk Screen Layout / Component Side Layout.
Assembly Drawing.
Figure 3: AAT4250 Evaluation Board
Solder Side Layout.
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
12 4250.2009.06.1.4
www.analogictech.com
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
Ordering Information
Package Marking1Part Number (Tape and Reel)2
SOT23-5 (SOT25) ACXYY AAT4250IGV-T1
SC70JW-8 ACXYY AAT4250IJS-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor
products that are in compliance with current RoHS standards, including the requirement that lead not exceed
0.1% by weight in homogeneous materials. For more information, please visit our website at
http://www.analogictech.com/about/quality.aspx.
Package Information
SOT23-5 (SOT25)
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
±
0.075
0.60 REF
All dimensions in millimeters.
AAT4250
Slew Rate Controlled Load SwitchSmartSwitchTM
PRODUCT DATASHEET
4250.2009.06.1.4 13
www.analogictech.com
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3230 Scott Boulevard, Santa Clara, CA 95054
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 specifi cations or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fi tness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specifi c testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
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.
