AAT4612
G
Current Limited Load Switch
General Description
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 R
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 10µAand in shutdown mode, the
supply current decreases to less than 1µA.
The AAT4612 is available in a 5-pin SOT23, and an
8-pin SC70JW specified over a -40 to 85°C temperature range.
DS(ON)
, the
SmartSwitch
Features
•2.4V to 5.5V Input voltage range
• 1A current limit trip threshold
• Fast transient response:
• <1µs response to short circuit
• Low quiescent current
•10µAtyp
• 1µA max with Switch off
• 100mΩ typical R
• Undervoltage Lockout
• Thermal Shutdown
• Temp range -40 to 85°C
• 4kV ESD Rating
• 5-pin SOT23 package
• 8-pin SC70JW package
Applications
• Peripheral ports
• Notebook computers
• Personal communication devices
• Hot swap supplies
DS(ON)
™
Preliminary Information
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
1
AAT4612
4
C
IN
1µF
ND GND
ON
ON
SOT23
GND
2
C
OUT
0.47µF
V
CC
4612.2002.1.0.9 1
Pin Descriptions
Pin #
SOT23-5 SC70JW Symbol Function
1 2 OUT P-channel MOSFET drain
2 5, 6, 7, 8 GND Ground connection
3 NC Not internally connected
4 1 ON Active low enable Input
5 3, 4 IN P-channel MOSFET source
Pin Configuration
SOT23-5 SC70JW-8
AAT4612
Current Limited Load Switch
OUT
GND
NC
1 2
IN
IN
1
2
3
4
1
2
4
3
ON
ON
OUT
IN
5
8
7
6
5
GND
GND
GND
GND
2 4612.2002.1.0.9
AAT4612
Current Limited Load Switch
Absolute Maximum Ratings (T
=25°C unless otherwise noted)
A
Symbol Description Value Units
V
IN
V
ON
V
OUT
I
out
T
J
V
ESD
T
LEAD
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.
IN to GND -0.3 to 6 V
ON to GND -0.3 to 6 V
OUT to GND -0.3 to 6 V
Output Current Internally Limited A
Operating Junction Temperature Range -40 to 150 °C
ESD Rating1—HBM 4000 V
Maximum Soldering Temperature (at Leads) 300 °C
Thermal Characteristics
Symbol Description Value Units
Θ
JA
P
D
Note 2: Mounted on a demo board.
Maximum Thermal Resistance 2(SOT23-5, SC70JW-8) 150 °C/W
Maximum Power Dissipation 2(SOT23-5, SC70JW-8) 667 mW
Electrical Characteristics (V
= 5V, TA= -40 to 85°C unless otherwise noted. Typical values
IN
are at TA=25°C; bold values denote full temperature range)
Symbol Description Conditions Min Typ Max Units
V
IN
I
Q
I
Q(OFF)
I
SD(OFF)
V
UVLO
V
UVLO(hys)
R
DS(ON)
I
LIM
V
ON(L)
V
ON(H)
I
ON(SINK)
t
RESP
T
OFF
T
ON
OTMP Over Temperature Shutdown 125 °C
Note 3: For VINoutside this range consult typical ON threshold curve.
Operation Voltage2.45.5V
Quiescent CurrentVIN= 5V, ON = active, I
= 01020µA
OUT
Off Supply Current ON = inactive, VIN= 5.5V 1 µA
Off Switch Current ON = inactive, VIN= 5.5V, V
= 0 0.1 1 µA
OUT
Undervoltage LockoutVINfalling1.9V
Undervoltage Lockout Hysteresis 0.3 V
V
=5.0V, TA = 25ºC 100 150
On-Resistance
Current LimitV
ON Input Low VoltageVIN= 2.7V to 5.5V
ON Input High Voltage
IN
VIN=3.0V, TA= 25ºC 140 180
= VIN- 0.5V11.52.0A
OUT
V
= 2.7V ≤ 4.2V 2.0
IN
V
= > 4.2V to 5.0V
IN
3
3
2.4
0.8V
ON Input leakage VON= 5.5V 0.01 1 µA
Current Loop ResponseV
Turn-Off Time V
Turn-On Time V
= 5V500ns
IN
= 5V, R
IN
= 5V, R
IN
= 10Ω 2.5 µs
L
= 10Ω 1µs
L
mΩ
V
4612.2002.1.0.9 3
Typical Characteristics
AAT4612
Current Limited Load Switch
Quiescent Current vs. Temperature
20
15
10
5
Quiescent Current (µA)
0
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
Current Limit vs. V
1.4
1.2
1.0
0.8
0.6
0.4
Current Limit (A)
0.2
0.0
012345
V
OUT
OUT
(V)
Quiescent Current vs. Input Voltage
20
15
10
5
0
Quiescent Current (µA)
0 1234 56
IN (V)
R
vs. Temperature
DS(ON)
180
160
140
120
100
(mΩ)
80
60
DS(ON)
R
40
20
0
-40 -20 0 20 40 60 80 100 120
V
=3V
IN
Temperature (°C)
VIN=5V
Off-Supply Current vs. Temperature
1.00
0.10
0.01
Off-Supply Current (µA)
0.00
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
Off-Switch Current vs. Temperature
1.00
0.10
0.01
0.00
Off-Switch Current (µA)
-40 -20 0 20 40 60 80 100 120
Temperature (°C)
4 4612.2002.1.0.9
Typical Characteristics
AAT4612
Current Limited Load Switch
Turn-On
R
=10Ω, CL=0.47µF
L
6
5
4
ON OUT
3
2
1
Voltage (V)
0
-1
-0.5 0.0 0.5 1.0 1.5 2.0
Time (µs)
Short Circuit through 0.3 Ω
6.0
5.0
4.0
3.0
2.0
1.0
Input and Output (V)
0.0
-10 12345
Input Voltage
Output Current
Output Voltage
Time (µs)
12
10
8
6
4
2
0
Output (A)
Turn-Off
R
=10Ω, CL=0.47µF
L
6
5
4
3
ON OUT
2
1
Voltage (V)
0
-1
-5 0 5 10 15 20
Time (µs)
Thermal Shutdown Response
Output Voltage (5V/div)
Output Current (1A/div)
Time (50ms/div)
ON Threshold vs. V
2.4
2.2
2
1.8
1.6
1.4
1.2
1
0.8
ON Threshold (V)
0.6
0.4
2 2.5 3 3.5 4 4.5 5 5.5
V
ON(H)
V
ON(L)
IN
VIN (V)
4612.2002.1.0.9 5
Functional Block Diagram
IN OUT
Under-Voltage
Lockout
AAT4612
Current Limited Load Switch
Over-Temp
Protection
Current
Limit
ON
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
GND
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.
6 4612.2002.1.0.9
AAT4612
Current Limited Load Switch
Applications Information
Input Capacitor
The input capacitor, CINprotects 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 R
DS(ON)
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 CINwill 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.
CINshould be located as close to the device VINpin
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 C
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.
of the
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) = I
IN
In Equation 1, I
required by the load. R
mum rated R
ature. R
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 I
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 R
approximately 150 °C/W. Using Equation 2,
The AAT4612 is safe to operate at the maximum
current level of 1A at 85°C.
2
× R
MAX
MAX
DS(ON)
is the thermal resistance between the
θJA
I
=
MAX
I
=
MAX
DS(ON)
(MAX) × R
+ TA(MAX)
θJA
is the maximum current
(MAX) is the maxi-
DS(ON)
of the AAT4612 at high temper-
; Equation 2.
MAX
(MIN) - TA(MAX))
(T
SD
(R
(188m × 150))
(MAX) × R
DS(ON)
((115 - 85)
= 1 A
θJA
)
θJA
to be
4612.2002.1.0.9 7
Ordering Information
c
AAT4612
Current Limited Load Switch
Package Marking
SOT23-5 N/A AAT4612IGV-T1
SC70JW-8 N/A AAT4612IJS-T1
Package Information
SOT23-5
e
S1
H
E
D
A2
S
b
A
A1
Part Number
Bulk Tape and Reel
Dim
Millimeters Inches
Min Max Min Max
A 1.00 1.30 0.039 0.051
A1 0.00 0.10 0.000 0.004
A2 0.70 0.90 0.028 0.035
b 0.35 0.50 0.014 0.020
c 0.10 0.25 0.004 0.010
D 2.70 3.10 0.106 0.122
E 1.40 1.80 0.055 0.071
e 1.90 0.075
H 2.60 3.00 0.102 0.118
L 0.37 0.015
S 0.45 0.55 0.018 0.022
S1 0.85 1.05 0.033 0.041
Θ 1° 9° 1° 9°
I
L
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.
8 4612.2002.1.0.9
SC70JW-8
AAT4612
Current Limited Load Switch
eee
Dim
Millimeters Inches
Min Max Min Max
E 2.10 BSC 0.083 BSC
E1 1.75 2.00 0.069 0.079
E
L 0.23 0.40 0.009 0.016
A 1.10 0.043
A1 0 0.10 0.004
A2 0.70 1.00 0.028 0.039
D 2.00 BSC 0.079 BSC
b
D
c
A2
A
Θ1
L
E1
0.048REF
Θ
A1
e 0.50 BSC 0.020 BSC
b 0.15 0.30 0.006 0.012
c 0.10 0.20 0.004 0.008
Θ 08º08º
Θ1 4º 10º 4º 10º
4612.2002.1.0.9 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
10 4612.2002.1.0.9
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