ANALOGICTECH AAT4612

AAT4612
Current Limited Load Switch
General Description
Features
The AAT4612 SmartSwitch™ is a member of
AnalogicTech's 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 which makes it
ideal for both 3V and 5V systems. An integrated current-limiting circuit protects the input supply from large
currents which potentially cause the supply to fall out
of regulation. In addition, the AAT4612 thermal overload protection limits power dissipation and junction
temperatures associated with prolonged periods of
operation in current limit. Due to its low RDS(ON), the
AAT4612 can be used to control loads that require up
to 1A even while operating at high ambient temperatures. The ultra fast current-limit response to a sudden short circuit is a mere 500ns which reduces the
requirements of local supply bypassing. Quiescent
current is a low 10µA and in shutdown mode, the
supply current decreases to less than 1µA.
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2.4V to 5.5V Input voltage range
1A current limit trip threshold
Fast transient response:
• <1µs response to short circuit
Low quiescent current
• 10µA typ
• 1µA max with Switch off
100mΩ typical R DS(ON)
Undervoltage Lockout
Thermal Shutdown
Temp range -40 to 85°C
4kV ESD Rating
5-pin SOT23 package
8-pin SC70JW package
Preliminary Information
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•
•
•
•
•
•
SmartSwitch™
Applications
•
•
•
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The AAT4612 is available in a 5-pin SOT23, and an
8-pin SC70JW specified over a -40 to 85°C temperature range.
Peripheral ports
Notebook computers
Personal communication devices
Hot swap supplies
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 versions with fixed current limit (AAT4626, AAT4670).
Typical Application
INPUT
5
IN
OUT
VCC
1
AAT4612
SOT23
CIN
1µF
ON
4
ON
GND
COUT
0.47µF
2
GND
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GND
1
AAT4612
Current Limited Load Switch
Pin Descriptions
Pin #
SOT23-5
SC70JW
Symbol
1
2
OUT
P-channel MOSFET drain
2
5, 6, 7, 8
GND
Ground connection
3
Function
NC
Not internally connected
4
1
ON
Active low enable Input
5
3, 4
IN
P-channel MOSFET source
Pin Configuration
SOT23-5
IN
ON
ON
OUT
IN
IN
1
8
7
2
2
2
1 5
2
3 4
1
OUT
GND
NC
SC70JW-8
3
6
4
5
GND
GND
GND
GND
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AAT4612
Current Limited Load Switch
Absolute Maximum Ratings
Symbol
(TA=25°C unless otherwise noted)
Description
Value
Units
VIN
IN to GND
-0.3 to 6
V
VON
ON to GND
-0.3 to 6
V
VOUT
OUT to GND
-0.3 to 6
V
Internally Limited
A
-40 to 150
°C
Iout
Output Current
TJ
Operating Junction Temperature Range
VESD
ESD Rating1—HBM
4000
V
TLEAD
Maximum Soldering Temperature (at Leads)
300
°C
Note: 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.
Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin.
Thermal Characteristics
Symbol
ΘJA
PD
Description
Value
Units
150
°C/W
667
mW
Maximum Thermal Resistance 2 (SOT23-5, SC70JW-8)
2
Maximum Power Dissipation (SOT23-5, SC70JW-8)
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)
Symbol
VIN
IQ
IQ(OFF)
ISD(OFF)
VUVLO
VUVLO(hys)
RDS(ON)
Description
Conditions
Operation Voltage
Quiescent Current
Off Supply Current
Off Switch Current
Undervoltage Lockout
Undervoltage Lockout Hysteresis
VIN = 5V, ON = active, IOUT = 0
ON = inactive, VIN = 5.5V
ON = inactive, VIN = 5.5V, VOUT = 0
VIN falling
On-Resistance
ILIM
VON(L)
Current Limit
ON Input Low Voltage
VON(H)
ON Input High Voltage
ION(SINK)
tRESP
TOFF
TON
OTMP
ON Input leakage
Current Loop Response
Turn-Off Time
Turn-On Time
Over Temperature Shutdown
Min
Typ
2.4
VIN=5.0V, TA = 25ºC
VIN=3.0V, TA = 25ºC
VOUT = VIN - 0.5V
VIN = 2.7V to 5.5V 3
VIN = 2.7V ≤ 4.2V
VIN = > 4.2V to 5.0V 3
VON = 5.5V
VIN = 5V
VIN = 5V, RL = 10Ω
VIN = 5V, RL = 10Ω
10
1
0.1
1.9
0.3
100
140
1.5
Max
Units
5.5
20
1
1
V
µA
µA
µA
V
V
150
180
2.0
0.8
2.0
2.4
mΩ
A
V
V
0.01
500
2.5
1
125
1
µA
ns
µs
µs
°C
Note 3: For VIN outside this range consult typical ON threshold curve.
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3
AAT4612
Current Limited Load Switch
Typical Characteristics
Quiescent Current vs. Temperature
Quiescent Current vs. Input Voltage
20
Quiescent Current (µA)
Quiescent Current (µA)
20
15
10
5
0
-40
-20
0
20
40
60
80
100
15
10
5
0
120
0
1
2
3
Temperature (°C)
180
1.2
160
6
VIN=3V
140
1.0
RDS(ON) (mΩ)
Current Limit (A)
1.4
0.8
0.6
0.4
120
100
VIN=5V
80
60
40
0.2
20
0.0
0
0
1
2
3
4
-40
5
-20
0
V OUT (V)
20
40
60
80
100
120
Temperature (°C)
Off-Supply Current vs. Temperature
Off-Switch Current vs. Temperature
1.00
1.00
Off-Switch Current (µA)
Off-Supply Current (µA)
5
RDS(ON) vs. Temperature
Current Limit vs. V OUT
0.10
0.01
0.00
-40
-20
0
20
40
60
Temperature (°C)
4
4
IN (V)
80
100
120
0.10
0.01
0.00
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
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AAT4612
Current Limited Load Switch
Typical Characteristics
Turn-Off
RL=10Ω, CL=0.47µF
6
6
5
5
4
ON
3
Voltage (V)
Voltage (V)
Turn-On
RL=10Ω, CL=0.47µF
OUT
2
1
0
3
ON
2
OUT
1
0
-1
-0.5
-1
0.0
0.5
1.0
1.5
2.0
Time (µs)
-5
0
5
10
15
20
Time (µs)
Short Circuit through 0.3 Ω
Thermal Shutdown Response
6.0
12
Input Voltage
5.0
10
4.0
8
Output Voltage (5V/div)
3.0
6
Output Current
2.0
4
Output (A)
Input and Output (V)
4
Output Voltage
1.0
2
0.0
Output Current (1A/div)
0
-1
0
1
2
3
4
5
Time (µs)
Time (50ms/div)
ON Threshold vs. VIN
2.4
ON Threshold (V)
2.2
2
1.8
VON(H)
1.6
1.4
VON(L)
1.2
1
0.8
0.6
0.4
2
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
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5
AAT4612
Current Limited Load Switch
Functional Block Diagram
IN
OUT
Over-Temp
Protection
Under-Voltage
Lockout
Current
Limit
ON
GND
Functional Description
The AAT4612 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 fraction of a micro second and instantly resets to low
impedance once the short circuit condition is
removed.
The AAT4612 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
6
the thermal limit threshold. The device will thermal
cycle indefinitely until the over current condition is
removed. The AAT4612 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 AAT4612
MOSFET is protected from entering the saturated
region of operation by being automatically shut
down by an under voltage lockout circuit.
The AAT4612 is ideally suited for protection of
peripheral ports such as USB, RS232 and parallel
ports.
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AAT4612
Current Limited Load Switch
Applications Information
Input Capacitor
The input capacitor, CIN protects the power supply
from current transients generated by the load
attached to the AAT4612. When a short circuit is
suddenly applied to the output of the AAT4612, 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 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 AAT4612. The
extremely fast short circuit response time of the
AAT4612 reduces 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 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 AAT4612 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
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 AAT4612 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.
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When switching the AAT4612 on into a capacitive
load, the AAT4612 will charge the output capacitive
load at a rate no greater than the current limit setting.
Attaching Loads
Capacitive loads attached to an enabled AAT4612
will charge at a rate no greater than the current limit
setting.
Thermal Considerations
Since the AAT4612 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 without 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 × R DS(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 AAT4612 at high temperature. RθJA is the thermal resistance between the
AAT4612 die and the board onto which it is mounted. TA(MAX) is the maximum temperature that the
PCB under the AAT4612 would be if the AAT4612
were not dissipating power. Equation 1 can be
rearranged to solve for IMAX; Equation 2.
IMAX=
(TSD(MIN) - TA(MAX))
(RDS(ON)(MAX) × RθJA)
TSD(MIN) is the minimum temperature required to
activate the AAT4612 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 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 RθJA to be
approximately 150 °C/W. Using Equation 2,
IMAX =
((115 - 85)
=1A
(188m × 150))
The AAT4612 is safe to operate at the maximum
current level of 1A at 85°C.
7
AAT4612
Current Limited Load Switch
Ordering Information
Package
Marking
Part Number
Bulk
Tape and Reel
SOT23-5
N/A
AAT4612IGV-T1
SC70JW-8
N/A
AAT4612IJS-T1
Package Information
SOT23-5
e
Dim
S1
H
E
D
A
A2
A1
S
8
b
c
I
L
A
A1
A2
b
c
D
E
e
H
L
S
S1
Θ
Millimeters
Min
Max
1.00
1.30
0.00
0.10
0.70
0.90
0.35
0.50
0.10
0.25
2.70
3.10
1.40
1.80
1.90
2.60
3.00
0.37
0.45
0.55
0.85
1.05
1°
9°
Inches
Min
Max
0.039
0.051
0.000
0.004
0.028
0.035
0.014
0.020
0.004
0.010
0.106
0.122
0.055
0.071
0.075
0.102
0.118
0.015
0.018
0.022
0.033
0.041
1°
9°
Note:
1. PACKAGE BODY SIZES EXCLUDE MOLD FLASH
PROTRUSIONS OR GATE BURRS.
2. TOLERANCE 0.1000mm (4mil) UNLESS
OTHERWISE SPECIFIED
3. COPLANARITY: 0.1000mm
4. DIMENSION L IS MEASURED IN GAGE PLANE.
5. CONTROLLING DIMENSION IS MILLIMETER;
CONVERTED INCH DIMENSIONS ARE NOT
NECESSARILY EXACT.
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AAT4612
Current Limited Load Switch
SC70JW-8
e
e
e
Dim
E
b
D
0.048REF
c
A2 A
E
E1
L
A
A1
A2
D
e
b
c
Θ
Θ1
Millimeters
Min
Max
2.10 BSC
1.75
2.00
0.23
0.40
1.10
0
0.10
0.70
1.00
2.00 BSC
0.50 BSC
0.15
0.30
0.10
0.20
0
8º
4º
10º
Inches
Min
Max
0.083 BSC
0.069
0.079
0.009
0.016
0.043
0.004
0.028
0.039
0.079 BSC
0.020 BSC
0.006
0.012
0.004
0.008
0
8º
4º
10º
A1
Θ1
4612.2002.1.0.9
L
E1
Θ
9
AAT4612
Current Limited Load Switch
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Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone (408) 524-9684
Fax (408) 524-9689
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4612.2002.1.0.9