Analogic AAT4612 Current limited load switch Datasheet

AAT4612
Current Limited Load Switch
General Description
Features
The AAT4612 SmartSwitch is a current limited Pchannel MOSFET power switch designed for highside load switching applications operating with
inputs ranging from 2.4V to 5.5V, making it ideal for
both 3V and 5V systems. An integrated current
limiting circuit protects the input supply from large
currents which could potentially cause the supply
to fall out of regulation. In addition, the AAT4612’s
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.
•
•
•
The AAT4612 is available in a Pb-free 5-pin SOT23
package or a Pb-free 8-pin SC70JW package and
is specified over the -40°C to +85°C temperature
range.
•
•
•
•
•
•
•
SmartSwitch™
Input Voltage Range: 2.4V to 5.5V
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 RDS(ON)
Under-Voltage Lockout
Thermal Shutdown
4kV ESD Rating
5-Pin SOT23 or 8-Pin SC70JW Package
-40°C to +85°C Temperature Range
Applications
•
•
•
•
Hot Swap Supplies
Notebook Computers
Peripheral Ports
Personal Communication Devices
Typical Application
INPUT
IN
VCC
OUT
AAT4612
CIN
1μF
GND
4612.2006.09.1.3
ON
ON
GND
C OUT
0.47μF
GND
1
AAT4612
Current Limited Load Switch
Pin Descriptions
Pin #
SOT23-5
SC70JW-8
Symbol
1
2
OUT
P-channel MOSFET drain.
2
5, 6, 7, 8
GND
Ground connection.
N/C
Not internally connected.
3
Function
4
1
ON
Active low enable input.
5
3, 4
IN
P-channel MOSFET source.
Pin Configuration
SOT23-5
(Top View)
OUT
GND
N/C
2
1
SC70JW-8
(Top View)
5
IN
2
3
4
ON
ON
OUT
IN
IN
1
8
2
7
3
6
4
5
GND
GND
GND
GND
4612.2006.09.1.3
AAT4612
Current Limited Load Switch
Absolute Maximum Ratings1
TA = 25°C unless otherwise noted.
Symbol
VIN
VON
VOUT
IOUT
TJ
VESD
TLEAD
Description
IN to GND
ON to GND
OUT to GND
Output Current
Operating Junction Temperature Range
ESD Rating2—HBM
Maximum Soldering Temperature (at Leads)
Value
Units
-0.3 to 6
-0.3 to 6
-0.3 to 6
Internally Limited
-40 to 150
4000
300
V
V
V
A
°C
V
°C
Thermal Characteristics3
Symbol
ΘJA
PD
Description
Maximum Thermal Resistance (SOT23-5, SC70JW-8)
Maximum Power Dissipation (SOT23-5, SC70JW-8)
Value
Units
150
667
°C/W
mW
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 a demo board.
4612.2006.09.1.3
3
AAT4612
Current Limited Load Switch
Electrical Characteristics
VIN = 5V, TA = -40°C 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
Operation Voltage
Quiescent Current
Off Supply Current
Off Switch Current
Under-Voltage Lockout
Under-Voltage Lockout Hysteresis
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
Conditions
Min
Typ
2.4
VIN = 5V, ON = Active, IOUT = 0
ON = Inactive, VIN = 5.5V
ON = Inactive, VIN = 5.5V, VOUT = 0
VIN Falling
VIN = 5.0V, TA = 25°C
VIN = 3.0V, TA = 25°C
VOUT = VIN to 0.5V
VIN = 2.7V to 5.5V1
VIN = 2.7V ≤ 4.2V
VIN = > 4.2V to 5.0V1
VON = 5.5V
VIN = 5V
VIN = 5V, RL = 10Ω
VIN = 5V, RL = 10Ω
10
1
0.1
1.9
0.3
130
170
1.5
Max
Units
5.5
20
1
1
V
µA
µA
µA
V
V
175
225
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
1. For VIN outside this range, consult typical ON threshold curve.
4
4612.2006.09.1.3
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
Temperature (°C)
Current Limit vs. Output Voltage
5
6
250
1.4
VIN = 3V
200
1.0
RDS(ON) (mΩ
Ω)
Current Limit (A)
4
RDS(ON) vs. Temperature
1.2
0.8
0.6
0.4
150
VIN = 5V
100
50
0.2
0
0.0
0
1
2
3
4
-40
5
-20
0
20
40
60
80
100
120
Temperature (°°C)
Output Voltage (V)
Off-Supply Current vs. Temperature
Off-Switch Current vs. Temperature
1.00
1.00
Off-Switch Current (µA)
Off-Supply Current (µA)
3
Input Voltage (V)
0.10
0.01
0.00
0.10
0.01
0.00
-40
-20
0
20
40
60
Temperature (°C)
4612.2006.09.1.3
80
100
120
-40
-20
0
20
40
60
80
100
120
Temperature (°C)
5
AAT4612
Current Limited Load Switch
Turn-On
Turn-Off
(RL = 10Ω; CL = 0.47µF)
(RL = 10Ω; CL = 0.47µF)
6
6
5
5
4
ON
3
Voltage (V)
Voltage (V)
Typical Characteristics
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)
Thermal Shutdown Response
Short Circuit Through 0.3Ω
6.0
12
Input Voltage
5.0
10
4.0
8
3.0
6
Output Current
2.0
4
Output Voltage
1.0
2
0.0
Output Current (A)
Input and Output Voltage (V)
4
Output Current (1A/div)
0
-1
0
1
2
3
4
Output Voltage (5V/div)
5
Time (50ms/div)
Time (µs)
ON Threshold vs. Input Voltage
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
Input Voltage (V)
6
4612.2006.09.1.3
AAT4612
Current Limited Load Switch
Functional Block Diagram
IN
OUT
OverTemperature
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 microsecond 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 the ther-
4612.2006.09.1.3
mal 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.
7
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 IN 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 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.
that accommodate this condition. The threshold
voltages are compatible with 5V TTL and 2.5V to
5V CMOS systems.
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.
Eq. 1: TJ(MAX) = IMAX2 · RDS(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:
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
8
Eq. 2: IMAX =
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) · RΘJA
TSD(MIN) is the minimum temperature required to
activate the AAT4612 over-temperature protection.
4612.2006.09.1.3
AAT4612
Current Limited Load Switch
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,
Eq. 3: IMAX =
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) · RΘJA
The AAT4612 is safe to operate at the maximum
current level of 0.93A at 85°C.
4612.2006.09.1.3
9
AAT4612
Current Limited Load Switch
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
SOT23-5
ATXYY
AAT4612IGV-T1
SC70JW-8
ATXYY
AAT4612IJS-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/pbfree.
Package Information
SOT23-5
2.85 ± 0.15
1.90 BSC
0.40 ± 0.10
0.075 ± 0.075
0.15 ± 0.07
4° ± 4°
10° ± 5°
1.10 ± 0.20
0.60 REF
1.20 ± 0.25
2.80 ± 0.20
1.575 ± 0.125
0.95
BSC
0.60 REF
0.45 ± 0.15
GAUGE PLANE
0.10 BSC
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on all part numbers listed in BOLD.
10
4612.2006.09.1.3
AAT4612
Current Limited Load Switch
SC70JW-8
2.20 ± 0.20
1.75 ± 0.10
0.50 BSC 0.50 BSC 0.50 BSC
0.225 ± 0.075
2.00 ± 0.20
0.100
7° ± 3°
0.45 ± 0.10
4° ± 4°
0.05 ± 0.05
0.15 ± 0.05
1.10 MAX
0.85 ± 0.15
0.048REF
2.10 ± 0.30
All dimensions in millimeters.
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4612.2006.09.1.3
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