AAT4682_06 [ANALOGICTECH]
Dual Electronic Resettable Switch; 双电复位开关
| 型号： | AAT4682_06 |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | Dual Electronic Resettable Switch |
| 文件： | 总10页 (文件大小：221K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT4682
Dual Electronic Resettable Switch
™
SmartSwitch
General Description
Features
The AAT4682 dual electronic resettable fuse is a
member of AnalogicTech’s Application Specific
Power MOSFET™ (ASPM™) product family. It has
two 1A current limited P-channel MOSFET power
devices that remain fully enhanced as long as the
input power supply is above an under-voltage lock-
out threshold and the load is below the current limit
setting. If the load increases above the current limit
setting, as is the case during a short circuit, the
MOSFET effectively becomes a constant current
source equal to the current limit. If the current limit
condition persists long enough to heat the MOSFET
to an extreme temperature, both devices will ther-
mal cycle off and on until the current limit condition
is removed. Independent open drain FAULT flags
signal an over-current or over-temperature condi-
tion. Quiescent current typically is a low 10µA.
•
•
•
•
•
•
Dual P-Channel MOSFETs
500mA Steady State Load Current
600mA Minimum Current Limit Trip Point
Low Quiescent Current, Typically 10µA
Over-Temperature Protection
Fast Transient Response:
— <1µs Response to Short Circuit
400mΩ Typical RDS(ON)
Under-Voltage Lockout
•
•
•
•
•
Temperature Range: -40°C to +85°C
FAULT Flag with 2ms Blanking
6-Pin SOT23 Package
Applications
The AAT4682 is available in a Pb-free, 6-pin
SOT23 package and is specified over the -40°C to
+85°C temperature range.
•
•
•
•
Cell Phone Ports
Desktop PCs
Peripheral Ports
USB Ports
Typical Application
AAT4682
5
6
IN
OUTA
OUTB
INPUT
OUTA
OUTB
4
1
3
FAULTA
FAULTB
FAULTA
FAULTB
GND
2
CIN
1μF
COUTA
1μF
COUTB
1μF
GND
GND
4682.2006.05.1.2
1
AAT4682
Dual Electronic Resettable Switch
Pin Descriptions
Pin # Symbol
Function
1
2
3
4
5
6
FAULTA
GND
Channel A open drain output; signals over-current and over-temperature condition.
Ground connection.
FAULTB
OUTB
IN
Channel B open drain output; signals over-current and over-temperature condition.
Channel B P-channel MOSFET drain.
Channel A and Channel B P-channel MOSFET sources.
Channel A P-channel MOSFET drain.
OUTA
Pin Configuration
SOT23-6
FAULTA
GND
OUTA
IN
1 6
2
5
3 4
OUTB
FAULTB
2
4682.2006.05.1.2
AAT4682
Dual Electronic Resettable Switch
Absolute Maximum Ratings1
TA = 25°C, unless otherwise noted.
Symbol
Description
Value
Units
VIN
VOUT
VFLG
IOUT
TJ
IN to GND
-0.3 to 6
-0.3 to 6
V
V
OUTA or OUTB to GND
FAULTA or FAULTB to GND
Output Current
-0.3 to 6
V
Internally Limited
-40 to 150
5000
A
Operating Junction Temperature Range
ESD Rating2 - HBM
°C
V
VESD
TLEAD
Maximum Soldering Temperature (at Leads)
300
°C
Thermal Characteristics3
Symbol
Description
Value
Units
ΘJA
PD
Maximum Thermal Resistance
Maximum Power Dissipation
150
667
°C/W
mW
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at condi-
tions 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 a demo board.
4682.2006.05.1.2
3
AAT4682
Dual Electronic Resettable Switch
Electrical Characteristics
VIN = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C; bold values desig-
nate full temperature range.
Symbol
Description
Conditions
Min
1.8
Typ
Max Units
VIN
IQ
Operation Voltage
5.5
20
V
µA
V
Quiescent Current
VIN = 5V, IOUT = 0
VIN Falling
10
1.5
VUVLO
VUVLO(HYS)
Under-Voltage Lockout
Under-Voltage Lockout Hysteresis
0.3
V
V
IN = 5.0V, TA = 25°C
400
525
0.875
500
500
650
1.25
RDS(ON)
On Resistance
mΩ
VIN = 3.V, TA = 25°C
OUT < IN to 0.5V
VIN = 5V
ILIM
tRESP
Current Limit
0.6
A
ns
V
Current Loop Response
FAULT Logic Output Low
FAULT Logic Output High
Leakage Current
VFAULTLOW
ISINK = 1mA
0.4
1
ISINK
VFAULT = 5.5V
0.5
µA
Tblank
TSD
FAULT Blanking Time
Over-Temperature Threshold
2
ms
°C
125
4
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AAT4682
Dual Electronic Resettable Switch
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Quiescent Current vs. Input Voltage
Quiescent Current vs. Temperature
12
20
18
16
14
12
10
8
10
8
6
4
6
2
0
4
2
0
1
2
3
4
5
6
0
-40
-20
0
20
40
60
80
100
120
Input Voltage (V)
Temperature (°C)
RDS(ON) vs. Temperature
Current Limit vs. Output Voltage
1.0
0.8
0.6
0.4
0.2
0.0
600
550
500
450
400
350
300
VIN = 3V
VIN = 5V
0
1
2
3
4
5
-40
-20
0
20
40
60
80
100
120
Output Voltage (V)
Temperature (°C)
Short Circuit Through 0.3Ω
Short Circuit Through 0.6Ω
6
4
7
6
4
2
0
5
Input Voltage
Input Voltage
5
3
2
3
Output Current
Output Voltage
Output Voltage
Output Current
1
0
1
-2
-1
-1
-0.5
0.0
0.5
1.0
1.5
2.0
-0.5
0.0
0.5
1.0
1.5
2.0
Time (μs)
Time (μs)
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5
AAT4682
Dual Electronic Resettable Switch
Typical Characteristics
Unless otherwise noted, VIN = 5V, TA = 25°C.
Thermal Shutdown Response
Fault Delay
FAULTA (5V/div)
OUTA (5V/div)
FAULTA (5V/div)
OUTA (5V/div)
FAULTB
(5V/div)
FAULTB (5V/div)
OUTB (5V/div)
OUTB
(5V/div)
IIN (1A/div)
IIN (1A/div)
Time (500µs/div)
Time (50ms/div)
6
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AAT4682
Dual Electronic Resettable Switch
Functional Block Diagram
INA
OUTB
ILIM
UVLO
OTMP
ILIM
OUTB
FAULTA
FAULTB
3ms Blanking
3ms Blanking
GND
will thermal cycle indefinitely until the over-current
condition is removed. Due to the high thermal con-
ductivity of silicon and the size of the die, the tem-
perature across the die is relatively uniform at high
temperatures; therefore, as a precaution, both
power devices are switched off when the thermal
threshold is reached. The AAT4682 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 AAT4682 internal MOSFETs are protected from
entering the saturated region of operation by being
automatically shut down by an under-voltage lock-
out circuit.
Functional Description
The AAT4682 is a dual channel electronic reset-
table fuse that protects against short-circuit condi-
tions by current limiting to a preset level. A patent-
ed fast acting current limit loop limits load current in
a fraction of a microsecond and instantly resets
back to a low impedance state once the short-cir-
cuit condition is removed. A current limit condition
is reported by the open drain FAULT output after a
two millisecond blanking interval. The blanking
prevents false reporting during the charging of a
capacitive load, which typically occurs when a load
is connected. The AAT4682 is internally protected
from thermal damage by an over-temperature
detection circuit. If the die temperature reaches the
internal thermal limit, both power devices are
switched off until the die temperature cools to a
level below the thermal limit threshold. The device
The AAT4682 is ideally suited for protection of
peripheral ports such as USB, RS232, and parallel
ports.
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7
AAT4682
Dual Electronic Resettable Switch
FAULT Outputs
Applications Information
FAULT flags are provided to alert a system if a
AAT4682 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 two milliseconds, the corre-
sponding FAULT output is pulled to ground through
approximately 100Ω. Removal of voltage or cur-
rent transients of less than two milliseconds pre-
vents capacitive loads connected to the AAT4682
output from activating the FAULT flag when they
are initially attached. Pull-up resistances of 10kΩ
to 100kΩ are recommended. Since the FAULT out-
puts are open drain terminals, they may be pulled
up to any voltage rail less than the maximum oper-
ating voltage of 5.5V, allowing for level shifting
between circuits.
Input Capacitor
The input capacitor protects the power supply from
current transients generated by the loads attached
to the AAT4682. If a short circuit is suddenly
applied to a AAT4682 output, there is a 500
nanosecond long period during which a large cur-
rent can flow before current limit circuitry activates.
(See characteristic curve "Short Circuit Through
0.3Ω.") In this event, a properly sized input capac-
itor can dramatically reduce the voltage transient
seen by the power supply and other circuitry
upstream from the AAT4682.
CIN should be located as close to the device VIN
pin 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 CIN due to their
inherent capability over tantalum capacitors to with-
stand input current surges from low impedance
sources such as batteries in portable devices.
Thermal Considerations
Since the AAT4682 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 combined current avail-
able without risk of an over-temperature condition
can be calculated. The maximum internal temper-
ature while current limit is not active can be calcu-
lated using Equation 1.
Output Capacitors
In order to insure stability while current limit is
active, a small output capacitance of approximately
1µF is required at each output. No matter how big
the output capacitor, output current is limited to the
value set by the AAT4682 current limiting circuitry,
allowing very large output capacitors to be used.
TJ(MAX) = IMAX2 · RDS(ON)(MAX) · RΘJA + TA(MAX)
Eq. 1:
For example, USB ports are specified to have at
least 120µF of capacitance downstream from their
controlling power switch. The current limiting circuit
will allow an output capacitance of 1000µF or more
without disturbing the upstream power supply.
In Equation 1, IMAX is the maximum current
required by the load. RDS(ON)(MAX) is the maximum
rated RDS(ON) of the AAT4682 at high temperature.
RθJA is the thermal resistance between the
AAT4682 die and the board onto which it is mount-
ed. TA(MAX) is the maximum temperature that the
PCB under the AAT4682 would be if the AAT4682
were not dissipating power. Equation 1 can be
rearranged to solve for IMAX; Equation 2.
Attaching Loads
Capacitive loads attached to the AAT4682 will charge
at a rate no greater than the current limit setting.
TSD(MIN) - TA(MAX)
DS(ON)(MAX) · RΘJA
=
IMAX
Eq. 2:
R
8
4682.2006.05.1.2
AAT4682
Dual Electronic Resettable Switch
TSD(MIN) is the minimum temperature required to
activate the AAT4682 over-temperature protection.
The typical over-temperature threshold specifica-
tion is 125°C; therefore, 115°C is a safe minimum
value to use.
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:
115 - 85
600 · 150
For example, if an application is specified to oper-
ate in 50°C environments, the PCB operates at
=
IMAX
= 575mA
Eq. 3:
To prevent thermal limiting, the combined operating
load current of each output in the application must
be less than 575mA.
4682.2006.05.1.2
9
AAT4682
Dual Electronic Resettable Switch
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
AAT4682IGU-T1
SOT23-6
BXXYY
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/pbfree.
Package Information
0.15
1.90 BSC
0.95 BSC
2.85
0.15 0.07
GAUGE PLANE
10° 5°
0.60 REF
0.45
0.40 0.10 × 6
0.15
0.10 BSC
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
© 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.
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AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are regis-
tered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
10
4682.2006.05.1.2
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