AAT4618 [ANALOGICTECH]
Current Limited Load Switch; 限流负载开关
| 型号： | AAT4618 |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | Current Limited Load Switch |
| 文件： | 总10页 (文件大小：226K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT4618
Current Limited Load Switch
™
SmartSwitch
General Description
Features
The AAT4618 SmartSwitch™ is a member of
AnalogicTech's Application Specific Power MOS-
FET™ (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 2.5V, 3V and 5V systems. An integrated cur-
rent-limiting circuit protects the input supply from large
currents which potentially cause the supply to fall out
of regulation. In addition, the AAT4618 thermal over-
load protection limits power dissipation and junction
temperatures 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 500mA even while operating at high ambient tem-
peratures. 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 tem-
perature condition after a 4ms timeout. Quiescent
current is a low 10µA and in shutdown mode, the sup-
ply current decreases to less than 1µA.
•
•
•
2.4V to 5.5V Input voltage range
500mA min current limit trip threshold
Fast transient response:
•
400ns response to short circuit
•
Low quiescent current
•
•
10µA typical
< 1µA with Switch off
•
•
•
•
•
•
•
•
125mΩ typical RDS(ON)
FAULT flag with 4ms blanking
Undervoltage Lockout
Thermal shutdown
Temp range -40 to 85°C
4kV ESD Rating
5 pin SOT23 package
8 pin SC70JW package
Applications
•
•
•
•
•
Peripheral ports
USB Ports
Notebook computers
Personal communication devices
Hot swap supplies
The AAT4618 is available in a 5 pin SOT-23, and an
8 pin SC70JW specified over a -40 to 85°C temper-
ature range.
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 ver-
sions with fixed current limit (AAT4626, AAT4670).
Typical Application
INPUT
OUTPUT
IN
OUT
AAT4618
100k
FAULT
FAULT
ON
(ON)
ON (ON)
CIN
1µF
COUT
0.47µF
GND
GND
GND
4618.2002.2.0.9
1
AAT4618
Current Limited Load Switch
Pin Descriptions
Pin #
SOT23-5
SC70JW-8
Symbol
OUT
Function
1
2
3
4
5
5
6, 7, 8
1
P-channel MOSFET drain
GND
Ground connection
FAULT
ON (ON)
IN
Open-drain FAULT output
2
Enable Input: 4618 active low, 4618-1 active high
P-channel MOSFET source
3, 4
Pin Configuration
SOT23-5
SC70JW-8
1
2
3
5
4
1
8
OUT
GND
FAULT
IN
GND
GND
GND
OUT
FAULT
ON (ON)
IN
2
3
4
7
6
5
ON (ON)
IN
2
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
Absolute Maximum Ratings (TA=25°C unless otherwise noted)
Symbol
Description
Value
Units
VIN, FAULT
VON
VOUT
IOUT
TJ
VESD
TLEAD
IN, FAULT to GND
ON (ON) to GND
OUT to GND
Output Current
Operating Junction Temperature Range
ESD Rating1—HBM
Maximum Soldering Temperature (at Leads)
-0.3 to 6
-0.3 to VIN+1
-0.3 to VIN+0.3
Internally Limited
-40 to 150
4000
V
V
V
A
°C
V
°C
300
Note: Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at con-
ditions 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
Description
Value
Units
2
ΘJA
PD
Maximum Thermal Resistance
Maximum Power Dissipation
150
667
°C/W
mW
2
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 Description
Conditions
Min Typ Max Units
VIN
IQ
IQ(OFF)
ISD(OFF)
VUVLO
Operation Voltage
Quiescent Current
Off Supply Current
Off Switch Current
Undervoltage Lockout
2.4
5.5
20
1
V
µA
µA
µA
V
VIN = 5V, ON (ON) = active, IOUT = 0
ON (ON) = inactive, VIN = 5.5V
ON (ON) = inactive, VIN = 5.5V, VOUT = 0
VIN falling
10
0.1
1.9
1
VUVLO(hys) Undervoltage Lockout Hysteresis
0.3
V
VIN = 5.0V, TA = 25°C
VIN = 3.0V, TA = 25°C
125
155
2800
175
225
RDS(ON)
On-Resistance
mΩ
TCRDS
ILIM
VON(L)
ON-Resistance Temp-co
Current Limit
ON (ON) Input Low Voltage
ppm/°C
mA
V
VOUT = VIN - 0.5V
VIN = 2.7V to 5.5V
500 750 1000
3
0.8
3
VIN = 2.7V to ≤ 4.2V
VIN = > 4.2V to 5.0V
2.0
2.4
V
V
VON(H)
ON (ON) Input High Voltage
3
ION(SINK)
tRESP
TOFF
ON (ON) Input leakage
Current Loop Response
Turn-Off Time
VON (ON) = 5.5V
VIN = 5V
VIN = 5V, RL = 20Ω
VIN = 5V, RL = 20Ω
ISINK = 1mA
0.01
400
5
1
µA
ns
µs
µs
V
TON
Turn-On Time
1
VFAULTLOW FAULT Logic Output Low
0.4
1
ISINK
FAULT Logic Output High
Leakage Current
V FAULT = 5.5V
0.5
µA
Tblank
TSD
Fault Blanking Time
Over-temperature threshold
4
125
ms
°C
VIN = 5V
Note 3: For VIN outside this range consult Typical ON (ON) Threshold curve.
4618.2002.2.0.9
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AAT4618
Current Limited Load Switch
Typical Characteristics
(Unless otherwise noted, VIN = 5V, TA = 25ºC)
Quiescent Current vs. Temperature
Quiescent Current vs. Input Voltage
20
15
10
5
20
15
10
5
0
0
0
1
2
3
4
5
6
120
120
-40
-20
0
20
40
60
80
100
120
IN (V)
Temperature (°C)
Current Limit vs. VOUT
RDS(ON) vs. Temperature
220
200
180
160
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
VIN=3V
140
120
100
80
VIN=5V
60
40
20
0
1
2
3
4
5
0
-40
-20
0
20
40
60
80
100
VOUT (V)
Temperature (°C)
Off-Switch Current vs. Temperature
Off-Supply Current vs. Temperature
1.00
0.10
0.01
0.00
1.00
0.10
0.01
0.00
-40
-20
0
20
40
60
80
100
120
-40
-20
0
20
40
60
80
100
Temperature (°C)
Temperature (°C)
4
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
Typical Characteristics
(Unless otherwise noted, VIN = 5V, TA = 25ºC)
Turn-Off
Turn-On
RL=20Ω, CL=0.47µF
RL=20Ω, CL=0.47µF
6
5
6
5
4
4
ON
OUT
ON
OUT
3
3
2
2
1
1
0
0
-1
-1
-10
0
10
20
30
40
50
-0.5
0.0
0.5
1.0
1.5
2.0
Time (µs)
Time (µs)
Thermal Shutdown Response
Short Circuit through 0.3 Ω
6
5
4
3
2
1
0
12
10
8
Input Voltage
Output Current
Output Voltage
Output Voltage (5V/div)
6
4
2
Output Current (1A/div)
0
-1
0
1
2
3
4
5
Time (µs)
Time (50ms/div)
Fault Delay from Short Circuit
ON (ON) Threshold vs. VIN
2.4
2.2
2
Output Voltage (5V/div)
Output Current (1A/div)
FAULT (5V/div)
VON(H)
1.8
1.6
1.4
1.2
1
VON(L)
0.8
0.6
0.4
2
2.5
3
3.5
4
4.5
5
5.5
VIN (V)
Time (1ms/div)
4618.2002.2.0.9
5
AAT4618
Current Limited Load Switch
Functional Block Diagram
IN
OUT
Over-Temp
Protection
Under-Voltage
Lockout
Current
Limit
FAULT
ON (ON)
4ms Delay
GND
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 auto-
matically shut down by an under voltage lockout
circuit. A current limit condition is reported by the
open drain FAULT output. A four millisecond blank-
ing 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.
Functional Description
The AAT4618 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 frac-
tion of a micro second 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 thermal 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
The AAT4618 is ideally suited for protection of
peripheral ports such as USB, RS232 and parallel
ports.
6
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
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.
Applications Information
Input Capacitor
Attaching Loads
Capacitive loads attached to an enabled AAT4618
will charge at a rate no greater than the current limit
setting.
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 cur-
rent 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 AAT4618. The
extremely fast short circuit response time of the
AAT4618 reduces the size requirement of CIN.
FAULT Output
The FAULT flag is provided to alert the system if an
AAT4618 load is not receiving sufficient voltage to
operate properly. If current limit or over tempera-
ture circuits in any combination are active for more
than approximately four milliseconds, the FAULT
flag is pulled to ground through approximately
100Ω. The filtering of voltage or current transients
of less than four milliseconds prevents capacitive
loads connected to the AAT4618 output from acti-
vating the FAULT flag when they are initially
attached. Pull up resistances of 1kΩ to 100kΩ are
recommended. Since FAULT is an open drain ter-
minal, it may be pulled up to any unrelated voltage
less than the maximum operating voltage of 5.5V,
allowing for level shifting between circuits.
CIN should be located as close to the device VIN pin
as practically possible. Ceramic, tantalum or alu-
minum 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.
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 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 with-
out 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.
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 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 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.
2
TJ(MAX) = IMAX × RDS(ON)(MAX) × RθJA + TA(MAX)
In Equation 1, IMAX is the maximum current
required by the load. RDS(ON)(MAX) is the maxi-
mum rated RDS(ON) of the AAT4618 at high temper-
ature. RθJA is the thermal resistance between the
AAT4618 die and the board onto which it is mount-
ed. 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
rearranged to solve for IMAX; Equation 2.
ON (Enable Input)
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 AAT4618 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.
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) × RθJA
IMAX
=
4618.2002.2.0.9
7
AAT4618
Current Limited Load Switch
TSD(MIN) is the minimum temperature required to
activate the AAT4618 over temperature protection.
With typical specification of 125°C, 115°C is a safe
minimum value to use.
sealed and its PCB is small, causing RθJA to be
approximately 150 °C/W. Using Equation 2,
115 - 85
IMAX
=
= 950 mA
220m × 150
For example, if an application is specified to oper-
ate in 50°C environments, the PCB operates at
temperatures as high as 85°C. The application is
The AAT4618 is safe to operate at the minimum
current limit level of 500mA at 85°C.
8
4618.2002.2.0.9
AAT4618
Current Limited Load Switch
Ordering Information
Part Number
Package
Enable
Marking
Bulk
N/A
N/A
N/A
N/A
Tape and Reel
AAT4618IGV-T1
AAT4618IGV-1-T1
AAT4618IJS-T1
AAT4618IJS-1-T1
SOT23-5
SOT23-5
Active Low
Active High
Active Low
Active High
SC70JW-8
SC70JW-8
Package Information
SOT23-5
e
Millimeters
Inches
Dim
Min
Max
1.45
0.15
1.30
0.50
0.20
3.00
1.70
Min
Max
S1
A
A1
A2
b
c
D
E
0.95
0.05
0.90
0.35
0.08
2.84
1.50
0.037
0.002
0.035
0.014
0.003
0.112
0.059
0.057
0.006
0.051
0.019
0.078
0.112
0.067
H
E
e
1.90
0.0748
H
L
S
S1
Θ
2.60
0.35
0.47
.95
3.00
0.55
0.55
0.102
.0137
0.019
0.037
0°
0.118
.0216
.0216
D
A
A1
0°
10°
10°
c
I
S
b
L
4618.2002.2.0.9
9
AAT4618
Current Limited Load Switch
SC70JW-8
e
e
e
Millimeters
Min Max
2.10 BSC
Inches
Min Max
0.083 BSC
Dim
E
E1
L
1.75
0.23
2.00
0.40
1.10
0.10
1.00
0.069
0.009
0.079
0.016
0.043
0.004
0.039
E
A
A1
A2
D
0
0.70
0.028
2.00 BSC
0.50 BSC
0.079 BSC
0.020 BSC
b
e
D
b
c
Θ
Θ1
0.15
0.10
0
0.30
0.20
8º
0.006
0.004
0
0.012
0.008
8º
0.048REF
c
A2
A
4º
10º
4º
10º
A1
L
Θ
Θ1
E1
Advanced Analogic Technologies, Inc.
1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086
Phone (408) 524-9684
Fax (408) 524-9689
10
4618.2002.2.0.9
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