ANALOGICTECH AAT4672ITP-T1

PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
General Description
Features
The AAT4672 SmartSwitch™ is a member of AnalogicTech’s
Application Specific Power Management IC™ family. This
device is a dual input, single output power supply selector switch, designed to operate from USB ports, AC
adapter inputs, batteries, or any other power supply with
an input voltage up to 6V.
• Input Voltage Supply Range: 2.5V to 6V
• High Level of Integration:
▪ Reverse Blocking Diode
▪ Current Sensing
▪ Programmable Current Limiting
▪ Automatic Power Supply Switching
• Break-Before-Make Switch-Over
▪ Minimum Output Voltage Drop During Change-Over
• Shutdown Current < 1µA
• Thermal Protection
• TSOPJW-12 Package
The AAT4672 connects the supply on the MAIN pin to the
OUT pin through a very low on-resistance power MOSFET
when the device is enabled, the MAIN pin voltage is
higher than the under voltage lockout (UVLO) threshold,
and MAIN pin voltage is greater than the AUX pin voltage
plus 200mV. The AUX pin connects to the OUT pin only
when the MAIN pin voltage drops 0.2V below the AUX pin
voltage and the AUX pin voltage is greater than the
UVLO threshold. If both input supplies (MAIN/AUX) are
below the UVLO threshold, then the OUT pin floats.
The two internal power switches are current limited and
the thresholds can be programmed through resistors on
the IMAIN and IAUX pins respectively. A power level
selection pin, PWRSEL, is provided to toggle the AUX
current limit between 100% and 20% of the current limit
setting programmed by the resistor on the IAUX pin. This
is particularly useful for USB applications where the
power supply can be powered by either a 500mA or a
100mA USB port.
Applications
•
•
•
•
•
Bluetooth™ Headsets
Cell Phones
Digital Still Cameras
MP3 Players
Personal Data Assistants (PDAs)
The AAT4672 is available in a thermally enhanced,
space-saving, Pb-free 12-pin TSOPJW package and is
specified for operation over the -40°C to +85°C temperature range.
Typical Application
AC Adapter
MAIN
OUT
USB Port
System Load
AUX
IMAIN
USB H/L select
PWRSEL
IAUX
RIAUX
Enable
RIMAIN
EN
GND
4672.2008.04.1.0
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1
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Pin Descriptions
Pin Number
Name
Type
1, 2
3, 4
5
6, 7
MAIN
AUX
EN
GND
I
I
I
I/O
8
PWRSEL
I
9
10
11, 12
IAUX
IMAIN
OUT
I
I
O
Function
Power supply 1 input.
Power supply 2 input.
Enable pin, active low.
Ground.
Power level select input for AUX-OUT switch.
Logic “0”: 20% of the current limit programmed by RIAUX
Logic “1”: 100% of the current limit programmed by RIAUX
AUX-OUT switch current limit set input.
MAIN-OUT switch current limit set input.
Output pin.
Pin Configuration
TSOPJW-12
(Top View)
MAIN
MAIN
AUX
AUX
EN
GND
2
1
12
2
11
3
10
4
9
5
8
6
7
OUT
OUT
IMAIN
IAUX
PWRSEL
GND
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Absolute Maximum Ratings1
Symbol
VN
VX
TLEAD
IOUT
Description
[MAIN, AUX] to GND
[OUT, EN, IMAIN, IAUX, PWRSEL] to GND
Maximum Soldering Temperature (at Leads)
Maximum Output Current
Value
Units
-0.3 to 6.5
-0.3 to VN + 0.3
300
3
V
V
°C
A
Value
Units
160
625
-40 to 150
°C/W
mW
°C
Thermal Information2
Symbol
θJA
PD
TJ
Description
Maximum Thermal Resistance
Maximum Power Dissipation
Operating Junction Temperature Range
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. Mounted on a FR4 board.
4672.2008.04.1.0
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3
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Electrical Characteristics1
VMAIN/AUX = 5V, TA = -40 to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Operation
VMAIN
VAUX
VMAIN-AUX
Description
Conditions
MAIN Operating Voltage Range
AUX Operating Voltage Range
MAIN Switch-Over Threshold (Input Voltage
Difference)
VUVLO_MAIN
MAIN Under-Voltage Lockout
VUVLO_AUX
AUX Under-Voltage Lockout
MAIN-to-OUT FET On-Resistance
RDS(ON) AUX
AUX-to-OUT FET On-Resistance
OUT Voltage Droop from the Lower Voltage of MAIN and AUX, When Switching Over
Between MAIN and AUX
Current Regulation
tSOFT_START
Soft-Start Delay
ILIM_MAIN_range MAIN Current Limit Range
VDROOP_OUT
ILIM_AUX_range
ILIM_MAIN
ILIM_AUX
MAIN, AUX > 2.5V
MAIN Current Limit Accuracy
AUX Current Limit Accuracy
VAUX
+ 0.2
1
10
1
150
Delay of start from EN , or UVLO
RIMAIN = 100kΩ
Units
6
6
VAUX
+0.25
2.3
V
V
2.3
0.1
10
IO(OUT) = 0.5A, CO(OUT) = 10µF
PWRSEL = 5V
PWRSEL = 0V
Max
0.1
0.12
0.14
0.12
0.14
PWRSEL = 5V
PWRSEL = 0V
RIAUX = 100kΩ
AUX Current Limit Range
Typ
VMAIN = 5.0V
VMAIN = 3.5V
VAUX = 5.0V
VAUX = 3.5V
Logic Control / Protection
VIH(EN)
Logic High Threshold
VIL(EN)
Logic Low Threshold
TSHDN
2.5
2.5
VAUX
+ 0.15
Rising edge
Hysteresis
Rising edge
Hysteresis
VMAIN = 5V, VEN = 0V
VMAIN = VEN = 5V, OUT open
VMAIN = 2.5V, VAUX = 5V, VEN = 0V
VAUX = 5V, VEN = 0V
VAUX = VEN = 5V, OUT open
VMAIN = 5V, VAUX = 2.5V, VEN = 0V
IMAIN_OP
MAIN Normal Operating Current
IMAIN_SHDN
MAIN Shutdown Mode Current
IMAIN_SLP
MAIN Sleep Current
AUX Normal Operating Current
IAUX_OP
IAUX_SHDN
AUX Shutdown Mode Current
IAUX_SLP
AUX Sleep Current
Power Switches
RDS(ON) MAIN
Min
30
1
5
30
1
5
1
1
0.2
140
15
µA
µA
µA
µA
µA
µA
mV
2.0
2.0
0.4
1.2
1.2
0.22
0.4
Threshold
Hysteresis
V
Ω
1.6
Chip Thermal Shutdown Temperature
V
Ω
100
0.2
0.2
0.04
0.8
0.8
0.18
V
µs
A
A
A
A
V
V
°C
1. The output charge voltage accuracy is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C temperature range is guaranteed by
design.
4
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Typical Characteristics
IAUX Shutdown Current vs. Temperature
0.8
IAUX Shutdown Current (µA)
IMAIN Shutdown Current (µA)
IMAIN Shutdown Current vs. Temperature
0.6
0.4
VMAIN = 6.5V
0.2
VMAIN = 5V
0
VMAIN = 3.6V
-0.2
-0.4
-40
VMAIN = 4.2V
-15
10
35
60
85
0.8
0.6
VAUX = 6.5V
0.4
VAUX = 5V
0.2
0
VAUX = 3.6V
-0.2
VAUX = 4.2V
-0.4
-40
-15
10
IAUX Operation Current vs. Temperature
(IOUT = 0A)
(IOUT = 0A)
18
VMAIN = 6.5V
16
VMAIN = 5V
14
12
VMAIN = 4.2V
10
VMAIN = 3.6V
8
6
4
-40
-15
10
35
60
20
VAUX = 6.5V
18
VAUX = 5V
16
14
12
10
VAUX = 3.6V
8
4
-40
85
-15
10
35
60
85
Temperature (°C)
RDS(ON) vs. Temperature
Enable Threshold vs. Input Voltage
250
1.1
VMAIN/AUX = 3.5V
Enable Threshold (V)
RDS(ON) (mΩ)
VAUX = 4.2V
6
Temperature (°C)
VMAIN/AUX = 2.5V
150
100
VMAIN/AUX = 6.5V
VMAIN/AUX = 5V
50
0
85
IMAIN Operation Current vs. Temperature
20
200
60
Temperature (°C)
IAUX Operation Current (µA)
IMAIN Operation Current (µA)
Temperature (°C)
35
-40
-15
10
35
60
85
110
1.05
1
0.9
0.85
VIL(EN)
0.8
0.75
0.7
0.65
0.6
Temperature (°C)
4672.2008.04.1.0
VIH(EN)
0.95
2.5
3
3.5
4
4.5
5
5.5
6
6.5
Input Voltage (V)
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PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Typical Characteristics
IMAIN Sleep Current vs. VMAIN Voltage
IAUX Sleep Current vs. VAUX Voltage
(VAUX = 6.5V)
(VMAIN = 6.5V)
2.5
2
IAUX Sleep Current (µA)
IMAIN Sleep Current (µA)
2.5
85°C
25°C
1.5
1
-40°C
0.5
0
2.5
3
3.5
4
4.5
5
6
5.5
85°C
2
25°C
1.5
1
-40°C
0.5
0
2.5
3
3.5
VMAIN Voltage (V)
4
4.5
5
5.5
6
VAUX Voltage (V)
Current Limit vs. RIMAIN/IAUX
Turn-On/Off Response
(ROUT = 10Ω
Ω; VMAIN = 5V)
(VMAIN = 5V; VAUX = 3.3V; VOUT = VMAIN or VOUT = VAUX)
2.25
Current Limit (A)
2
VEN
(2V/div)
1.75
2V
0V
1.5
1.25
1
0.75
VOUT
(5V/div)
0V
IOUT
(500mA/div)
0A
0.5
0.25
0
50
100
150
200
250
300
350
400
450
500
Ω)
RIMAIN/IAUX (kΩ
Time (100µs/div)
Short Circuit Through 0.3Ω
Ω Response
VIN
(2V/div)
5V
IOUT
(5A/div)
0A
VOUT
(5V/div)
5V
Short Circuit Through 0.6Ω
Ω Response
VIN
(2V/div)
5V
2A
IOUT
(5A/div)
0A
0.6V
VOUT
(5V/div)
Time (10µs/div)
6
5V
2A
1.2V
Time (10µs/div)
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Typical Characteristics
Thermal Shutdown Response
(VMAIN = 5V)
VEN
(2V/div)
VOUT
(2V/div)
IOUT
(2A/div)
2V
0V
0V
0A
Time (40ms/div)
4672.2008.04.1.0
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PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Functional Block Diagram
Switch 1
MAIN
OUT
IMAIN
Thermal
and Current
Sense
PWRSEL
Logic
Control
EN
IAUX
GND
AUX
Switch 2
Truth Table
Y = Yes, N = No, X = don’t care.
Input Conditions
VMAIN > UVLO
VAUX > UVLO
VMAIN > VAUX + 0.2V
VOUT
N
Y
N
Y
Y
N
N
Y
Y
Y
X
X
X
Y
N
Floating
VMAIN
VAUX
VMAIN
VAUX
Functional Description
Applications Information
To power the OUT pin, at least one of the two input supplies (MAIN/AUX) must be greater than the UVLO threshold. If only one supply is greater than the UVLO threshold, the load will be connected to that particular supply
when the device is enabled. If both supplies are above
the UVLO threshold, the AAT4672 will connect the supply
from the MAIN pin to the OUT pin when the device is
enabled and the MAIN voltage is greater than the AUX
voltage plus 0.2V (typical); otherwise, the AAT4672 will
connect the supply from the AUX pin to the OUT pin.
The two internal power switches are current limited; the
current limits are programmed by the resistors on the
IMAIN and IAUX pins respectively.
8
AAT4672
Input Capacitors
A 1µF or greater capacitor is generally recommended
between MAIN and GND (CMAIN), and between AUX and
GND (CAUX). An input capacitor is not required for basic
operation; however, it is useful in preventing load transients from affecting up-stream circuits. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected
for CMAIN/CAUX. There is no specific capacitor equivalent
series resistance (ESR) requirement for CMAIN/CAUX.
However, for higher current operation, ceramic capacitors are recommended for CMAIN/CAUX due to their inherent capability over tantalum capacitors to withstand
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
input current surges from low impedance sources such
as batteries in portable devices.
For MAIN (power supply 1 input):
⎛ VIMAIN ⎞
RIMAIN = ⎝ I
⎠ · 200k
Output Capacitor
CLMAIN
A 1µF or greater capacitor is required between OUT and
GND (COUT). As with the input capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be
increased to accommodate any load transient condition.
⎛0.5V⎞
= ⎝ 2A ⎠ · 200k
= 50kΩ (49.9kΩ standard value)
For AUX (power supply 2 input):
EN Input
The AAT4672 is enabled when VEN is ≤ 0.4V (logic ‘0’);
conversely, the AAT4672 is disabled when VEN is ≥ 1.6V
(logic ‘1’).
⎛ VIAUX ⎞
RIAUX = ⎝ I
⎠ · 200k
CLAUX
⎛0.5V⎞
= ⎝0.2A⎠ · 200k
PWRSEL Input
When VPWRSEL is ≤ 0.4V (logic ‘0’) the AUX-OUT current
limit is 20% of the current limit value programmed by
RIAUX; when VPWRSEL is ≥ 1.6V (logic ‘1’), the AUX-OUT
current limit is 100% of the current limit value programmed by RIAUX.
Current Limit Resistor Selection
The current limits for power supply 1 and power supply
2 inputs are set by resistors between IMAIN/IAUX and GND.
The following equation can be used to select the appropriate resistor for a particular current limit:
⎛ VIMAIN/IAUX ⎞
ICLMAIN/AUX = ⎝ R
· 200k
IMAIN/IAUX ⎠
ICLIMAIN/AUX Current limit for MAIN and/or AUX pins
respectively
VIMAIN/IAUX Internally Regulated Voltage [0.5V ± 20%]
on the IMAIN and IAUX pins respectively
RIMAIN/IAUX IMAIN and/or IAUX Resistor
200k
Internal Gain Factor
Design Example
A particular application requires that the current limit for
MAIN be set to 2A and the current limit for AUX be set
to 0.2A. What value of resistor is required for the IMAIN
and IAUX pins respectively?
4672.2008.04.1.0
= 500kΩ (499.9kΩ standard value)
Thermal Considerations
Since the AAT4672 has an internal current limit and overtemperature protection(thermal shutdown), junction temperature is rarely a concern. However, if the application
requires large currents in a high temperature 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).
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
AAT4672 at high temperatures (consult the “RDSON vs.
Temperature” performance graph in the “Typical
Characteristics” section of this datasheet). For estimating the RDS(ON)(MAX) use the data on the “RDSON vs
Temperature” performance graph and increase the value
from the performance graph by 50%. RθJA is the thermal
resistance between the AAT4672 die and the printed
circuit board (PCB) onto which it is mounted; RθJA is the
thermal resistance of the TSOPJW-12 package. TA(MAX) is
the maximum ambient temperature that the PCB under
the AAT4672 would be if the AAT4672 were not dissipating power. Equation 1 can be rearranged to solve for IMAX,
into Equation 2 (Eq. 2).
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9
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Eq. 2: IMAX =
Power Supply Selector Switch
PCB Layout Recommendations
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) · RΘJA
TSD(MIN) is the minimum temperature required to activate
the AAT4672 over-temperature protection (thermal
shutdown). With typical specification of 140°C, 125°C is
a safe minimum value to use.
For example, for a 2.5V input power supply application
that is specified to operate in 50°C environments where
the PCB operates at temperatures as high as 85°C. The
application is sealed and its PCB is small, causing RθJA to
be approximately 160°C/W. The RDS(ON)(MAX) is estimated
to be 300mΩ (from the “RDS(ON) vs. Temperature” performance graph, where VIN = 2.5V at 85°C plus 50%). To
find the maximum current (IMAX) for this application, use
Equation 2:
IMAX =
10
For proper thermal management, to minimize PCB trace
resistance, and to take advantage of the low RDS(ON) values of the two internal power switches in the AAT4672,
certain circuit board layout rules should be followed:
MAIN, AUX, and OUT should be routed using wider than
normal traces. The two MAIN pins (1 and 2) and two
AUX pins (3 and 4) should be connected to the same
wide PCB trace; and GND should be connected to a
ground plane. For best performance, input capacitors
(CMAIN, CAUX) and output capacitor (COUT) should be placed
as close to the package pins as possible. The AAT4672
evaluation board layout follows the printed circuit board
layout recommendations and can be used as an example
of an optimal board layout.
125°C - 85°C
300mΩ · 160°C/W = 0.913A
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Evaluation Board Schematic
C1
4.7µF
MAIN
AUX
J1
C2
4.7µF
2
1
Header 2
C3
4.7µF
U1
1
2
3
4
5
6
MAIN
MAIN
AUX
AUX
EN
GND
OUT
OUT
IMAIN
IAUX
SELECT
GND
12
11
10
9
8
7
AAT4672
IMAIN
IAUX
R3
49.9K
EN
GND
R1
100K
OUT
R2
49.9K
PWRSEL
Figure 1: AAT4672 Evaluation Board Schematic.
Evaluation Board Layout
Figure 2: AAT4672 Evaluation Board
Top Side Layout.
4672.2008.04.1.0
Figure 3: AAT4672 Evaluation Board
Bottom Side Layout.
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11
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TSOPJW-12
ZWXYY
AAT4672ITP-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/about/quality.aspx.
Package Information
TSOPJW-12
2.85 ± 0.20
2.40 ± 0.10
0.20 + 0.10
- 0.05
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
7° NOM
0.04 REF
0.055 ± 0.045
0.15 ± 0.05
+ 0.10
1.00 - 0.065
0.9625 ± 0.0375
3.00 ± 0.10
4° ± 4°
0.45 ± 0.15
0.010
2.75 ± 0.25
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.
3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© 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. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
12
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
General Description
Features
The AAT4672 SmartSwitch™ is a member of AnalogicTech’s
Application Specific Power Management IC™ family. This
device is a dual input, single output power supply selector switch, designed to operate from USB ports, AC
adapter inputs, batteries, or any other power supply with
an input voltage up to 6V.
• Input Voltage Supply Range: 2.5V to 6V
• High Level of Integration:
▪ Reverse Blocking Diode
▪ Current Sensing
▪ Programmable Current Limiting
▪ Automatic Power Supply Switching
• Break-Before-Make Switch-Over
▪ Minimum Output Voltage Drop During Change-Over
• Shutdown Current < 1µA
• Thermal Protection
• TSOPJW-12 Package
The AAT4672 connects the supply on the MAIN pin to the
OUT pin through a very low on-resistance power MOSFET
when the device is enabled, the MAIN pin voltage is
higher than the under voltage lockout (UVLO) threshold,
and MAIN pin voltage is greater than the AUX pin voltage
plus 200mV. The AUX pin connects to the OUT pin only
when the MAIN pin voltage drops 0.2V below the AUX pin
voltage and the AUX pin voltage is greater than the
UVLO threshold. If both input supplies (MAIN/AUX) are
below the UVLO threshold, then the OUT pin floats.
The two internal power switches are current limited and
the thresholds can be programmed through resistors on
the IMAIN and IAUX pins respectively. A power level
selection pin, PWRSEL, is provided to toggle the AUX
current limit between 100% and 20% of the current limit
setting programmed by the resistor on the IAUX pin. This
is particularly useful for USB applications where the
power supply can be powered by either a 500mA or a
100mA USB port.
Applications
•
•
•
•
•
Bluetooth™ Headsets
Cell Phones
Digital Still Cameras
MP3 Players
Personal Data Assistants (PDAs)
The AAT4672 is available in a thermally enhanced,
space-saving, Pb-free 12-pin TSOPJW package and is
specified for operation over the -40°C to +85°C temperature range.
Typical Application
AC Adapter
MAIN
OUT
USB Port
System Load
AUX
IMAIN
USB H/L select
PWRSEL
IAUX
RIAUX
Enable
RIMAIN
EN
GND
4672.2008.04.1.0
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1
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Pin Descriptions
Pin Number
Name
Type
1, 2
3, 4
5
6, 7
MAIN
AUX
EN
GND
I
I
I
I/O
8
PWRSEL
I
9
10
11, 12
IAUX
IMAIN
OUT
I
I
O
Function
Power supply 1 input.
Power supply 2 input.
Enable pin, active low.
Ground.
Power level select input for AUX-OUT switch.
Logic “0”: 20% of the current limit programmed by RIAUX
Logic “1”: 100% of the current limit programmed by RIAUX
AUX-OUT switch current limit set input.
MAIN-OUT switch current limit set input.
Output pin.
Pin Configuration
TSOPJW-12
(Top View)
MAIN
MAIN
AUX
AUX
EN
GND
2
1
12
2
11
3
10
4
9
5
8
6
7
OUT
OUT
IMAIN
IAUX
PWRSEL
GND
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Absolute Maximum Ratings1
Symbol
VN
VX
TLEAD
IOUT
Description
[MAIN, AUX] to GND
[OUT, EN, IMAIN, IAUX, PWRSEL] to GND
Maximum Soldering Temperature (at Leads)
Maximum Output Current
Value
Units
-0.3 to 6.5
-0.3 to VN + 0.3
300
3
V
V
°C
A
Value
Units
160
625
-40 to 150
°C/W
mW
°C
Thermal Information2
Symbol
θJA
PD
TJ
Description
Maximum Thermal Resistance
Maximum Power Dissipation
Operating Junction Temperature Range
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. Mounted on a FR4 board.
4672.2008.04.1.0
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3
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Electrical Characteristics1
VMAIN/AUX = 5V, TA = -40 to +85°C, unless otherwise noted. Typical values are at TA = 25°C.
Symbol
Operation
VMAIN
VAUX
VMAIN-AUX
Description
Conditions
MAIN Operating Voltage Range
AUX Operating Voltage Range
MAIN Switch-Over Threshold (Input Voltage
Difference)
VUVLO_MAIN
MAIN Under-Voltage Lockout
VUVLO_AUX
AUX Under-Voltage Lockout
MAIN-to-OUT FET On-Resistance
RDS(ON) AUX
AUX-to-OUT FET On-Resistance
OUT Voltage Droop from the Lower Voltage of MAIN and AUX, When Switching Over
Between MAIN and AUX
Current Regulation
tSOFT_START
Soft-Start Delay
ILIM_MAIN_range MAIN Current Limit Range
VDROOP_OUT
ILIM_AUX_range
ILIM_MAIN
ILIM_AUX
MAIN, AUX > 2.5V
MAIN Current Limit Accuracy
AUX Current Limit Accuracy
VAUX
+ 0.2
1
10
1
150
Delay of start from EN , or UVLO
RIMAIN = 100kΩ
Units
6
6
VAUX
+0.25
2.3
V
V
2.3
0.1
10
IO(OUT) = 0.5A, CO(OUT) = 10µF
PWRSEL = 5V
PWRSEL = 0V
Max
0.1
0.12
0.14
0.12
0.14
PWRSEL = 5V
PWRSEL = 0V
RIAUX = 100kΩ
AUX Current Limit Range
Typ
VMAIN = 5.0V
VMAIN = 3.5V
VAUX = 5.0V
VAUX = 3.5V
Logic Control / Protection
VIH(EN)
Logic High Threshold
VIL(EN)
Logic Low Threshold
TSHDN
2.5
2.5
VAUX
+ 0.15
Rising edge
Hysteresis
Rising edge
Hysteresis
VMAIN = 5V, VEN = 0V
VMAIN = VEN = 5V, OUT open
VMAIN = 2.5V, VAUX = 5V, VEN = 0V
VAUX = 5V, VEN = 0V
VAUX = VEN = 5V, OUT open
VMAIN = 5V, VAUX = 2.5V, VEN = 0V
IMAIN_OP
MAIN Normal Operating Current
IMAIN_SHDN
MAIN Shutdown Mode Current
IMAIN_SLP
MAIN Sleep Current
AUX Normal Operating Current
IAUX_OP
IAUX_SHDN
AUX Shutdown Mode Current
IAUX_SLP
AUX Sleep Current
Power Switches
RDS(ON) MAIN
Min
30
1
5
30
1
5
1
1
0.2
140
15
µA
µA
µA
µA
µA
µA
mV
2.0
2.0
0.4
1.2
1.2
0.22
0.4
Threshold
Hysteresis
V
Ω
1.6
Chip Thermal Shutdown Temperature
V
Ω
100
0.2
0.2
0.04
0.8
0.8
0.18
V
µs
A
A
A
A
V
V
°C
1. The output charge voltage accuracy is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C temperature range is guaranteed by
design.
4
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Typical Characteristics
IAUX Shutdown Current vs. Temperature
0.8
IAUX Shutdown Current (µA)
IMAIN Shutdown Current (µA)
IMAIN Shutdown Current vs. Temperature
0.6
0.4
VMAIN = 6.5V
0.2
VMAIN = 5V
0
VMAIN = 3.6V
-0.2
-0.4
-40
VMAIN = 4.2V
-15
10
35
60
85
0.8
0.6
VAUX = 6.5V
0.4
VAUX = 5V
0.2
0
VAUX = 3.6V
-0.2
VAUX = 4.2V
-0.4
-40
-15
10
IAUX Operation Current vs. Temperature
(IOUT = 0A)
(IOUT = 0A)
18
VMAIN = 6.5V
16
VMAIN = 5V
14
12
VMAIN = 4.2V
10
VMAIN = 3.6V
8
6
4
-40
-15
10
35
60
20
VAUX = 6.5V
18
VAUX = 5V
16
14
12
10
VAUX = 3.6V
8
4
-40
85
-15
10
35
60
85
Temperature (°C)
RDS(ON) vs. Temperature
Enable Threshold vs. Input Voltage
250
1.1
VMAIN/AUX = 3.5V
Enable Threshold (V)
RDS(ON) (mΩ)
VAUX = 4.2V
6
Temperature (°C)
VMAIN/AUX = 2.5V
150
100
VMAIN/AUX = 6.5V
VMAIN/AUX = 5V
50
0
85
IMAIN Operation Current vs. Temperature
20
200
60
Temperature (°C)
IAUX Operation Current (µA)
IMAIN Operation Current (µA)
Temperature (°C)
35
-40
-15
10
35
60
85
110
1.05
1
0.9
0.85
VIL(EN)
0.8
0.75
0.7
0.65
0.6
Temperature (°C)
4672.2008.04.1.0
VIH(EN)
0.95
2.5
3
3.5
4
4.5
5
5.5
6
6.5
Input Voltage (V)
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5
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Typical Characteristics
IMAIN Sleep Current vs. VMAIN Voltage
IAUX Sleep Current vs. VAUX Voltage
(VAUX = 6.5V)
(VMAIN = 6.5V)
2.5
2
IAUX Sleep Current (µA)
IMAIN Sleep Current (µA)
2.5
85°C
25°C
1.5
1
-40°C
0.5
0
2.5
3
3.5
4
4.5
5
6
5.5
85°C
2
25°C
1.5
1
-40°C
0.5
0
2.5
3
3.5
VMAIN Voltage (V)
4
4.5
5
5.5
6
VAUX Voltage (V)
Current Limit vs. RIMAIN/IAUX
Turn-On/Off Response
(ROUT = 10Ω
Ω; VMAIN = 5V)
(VMAIN = 5V; VAUX = 3.3V; VOUT = VMAIN or VOUT = VAUX)
2.25
Current Limit (A)
2
VEN
(2V/div)
1.75
2V
0V
1.5
1.25
1
0.75
VOUT
(5V/div)
0V
IOUT
(500mA/div)
0A
0.5
0.25
0
50
100
150
200
250
300
350
400
450
500
Ω)
RIMAIN/IAUX (kΩ
Time (100µs/div)
Short Circuit Through 0.3Ω
Ω Response
VIN
(2V/div)
5V
IOUT
(5A/div)
0A
VOUT
(5V/div)
5V
Short Circuit Through 0.6Ω
Ω Response
VIN
(2V/div)
5V
2A
IOUT
(5A/div)
0A
0.6V
VOUT
(5V/div)
Time (10µs/div)
6
5V
2A
1.2V
Time (10µs/div)
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Typical Characteristics
Thermal Shutdown Response
(VMAIN = 5V)
VEN
(2V/div)
VOUT
(2V/div)
IOUT
(2A/div)
2V
0V
0V
0A
Time (40ms/div)
4672.2008.04.1.0
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7
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Functional Block Diagram
Switch 1
MAIN
OUT
IMAIN
Thermal
and Current
Sense
PWRSEL
Logic
Control
EN
IAUX
GND
AUX
Switch 2
Truth Table
Y = Yes, N = No, X = don’t care.
Input Conditions
VMAIN > UVLO
VAUX > UVLO
VMAIN > VAUX + 0.2V
VOUT
N
Y
N
Y
Y
N
N
Y
Y
Y
X
X
X
Y
N
Floating
VMAIN
VAUX
VMAIN
VAUX
Functional Description
Applications Information
To power the OUT pin, at least one of the two input supplies (MAIN/AUX) must be greater than the UVLO threshold. If only one supply is greater than the UVLO threshold, the load will be connected to that particular supply
when the device is enabled. If both supplies are above
the UVLO threshold, the AAT4672 will connect the supply
from the MAIN pin to the OUT pin when the device is
enabled and the MAIN voltage is greater than the AUX
voltage plus 0.2V (typical); otherwise, the AAT4672 will
connect the supply from the AUX pin to the OUT pin.
The two internal power switches are current limited; the
current limits are programmed by the resistors on the
IMAIN and IAUX pins respectively.
8
AAT4672
Input Capacitors
A 1µF or greater capacitor is generally recommended
between MAIN and GND (CMAIN), and between AUX and
GND (CAUX). An input capacitor is not required for basic
operation; however, it is useful in preventing load transients from affecting up-stream circuits. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected
for CMAIN/CAUX. There is no specific capacitor equivalent
series resistance (ESR) requirement for CMAIN/CAUX.
However, for higher current operation, ceramic capacitors are recommended for CMAIN/CAUX due to their inherent capability over tantalum capacitors to withstand
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
input current surges from low impedance sources such
as batteries in portable devices.
For MAIN (power supply 1 input):
⎛ VIMAIN ⎞
RIMAIN = ⎝ I
⎠ · 200k
Output Capacitor
CLMAIN
A 1µF or greater capacitor is required between OUT and
GND (COUT). As with the input capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be
increased to accommodate any load transient condition.
⎛0.5V⎞
= ⎝ 2A ⎠ · 200k
= 50kΩ (49.9kΩ standard value)
For AUX (power supply 2 input):
EN Input
The AAT4672 is enabled when VEN is ≤ 0.4V (logic ‘0’);
conversely, the AAT4672 is disabled when VEN is ≥ 1.6V
(logic ‘1’).
⎛ VIAUX ⎞
RIAUX = ⎝ I
⎠ · 200k
CLAUX
⎛0.5V⎞
= ⎝0.2A⎠ · 200k
PWRSEL Input
When VPWRSEL is ≤ 0.4V (logic ‘0’) the AUX-OUT current
limit is 20% of the current limit value programmed by
RIAUX; when VPWRSEL is ≥ 1.6V (logic ‘1’), the AUX-OUT
current limit is 100% of the current limit value programmed by RIAUX.
Current Limit Resistor Selection
The current limits for power supply 1 and power supply
2 inputs are set by resistors between IMAIN/IAUX and GND.
The following equation can be used to select the appropriate resistor for a particular current limit:
⎛ VIMAIN/IAUX ⎞
ICLMAIN/AUX = ⎝ R
· 200k
IMAIN/IAUX ⎠
ICLIMAIN/AUX Current limit for MAIN and/or AUX pins
respectively
VIMAIN/IAUX Internally Regulated Voltage [0.5V ± 20%]
on the IMAIN and IAUX pins respectively
RIMAIN/IAUX IMAIN and/or IAUX Resistor
200k
Internal Gain Factor
Design Example
A particular application requires that the current limit for
MAIN be set to 2A and the current limit for AUX be set
to 0.2A. What value of resistor is required for the IMAIN
and IAUX pins respectively?
4672.2008.04.1.0
= 500kΩ (499.9kΩ standard value)
Thermal Considerations
Since the AAT4672 has an internal current limit and overtemperature protection(thermal shutdown), junction temperature is rarely a concern. However, if the application
requires large currents in a high temperature 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).
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
AAT4672 at high temperatures (consult the “RDSON vs.
Temperature” performance graph in the “Typical
Characteristics” section of this datasheet). For estimating the RDS(ON)(MAX) use the data on the “RDSON vs
Temperature” performance graph and increase the value
from the performance graph by 50%. RθJA is the thermal
resistance between the AAT4672 die and the printed
circuit board (PCB) onto which it is mounted; RθJA is the
thermal resistance of the TSOPJW-12 package. TA(MAX) is
the maximum ambient temperature that the PCB under
the AAT4672 would be if the AAT4672 were not dissipating power. Equation 1 can be rearranged to solve for IMAX,
into Equation 2 (Eq. 2).
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9
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Eq. 2: IMAX =
Power Supply Selector Switch
PCB Layout Recommendations
TSD(MIN) - TA(MAX)
RDS(ON)(MAX) · RΘJA
TSD(MIN) is the minimum temperature required to activate
the AAT4672 over-temperature protection (thermal
shutdown). With typical specification of 140°C, 125°C is
a safe minimum value to use.
For example, for a 2.5V input power supply application
that is specified to operate in 50°C environments where
the PCB operates at temperatures as high as 85°C. The
application is sealed and its PCB is small, causing RθJA to
be approximately 160°C/W. The RDS(ON)(MAX) is estimated
to be 300mΩ (from the “RDS(ON) vs. Temperature” performance graph, where VIN = 2.5V at 85°C plus 50%). To
find the maximum current (IMAX) for this application, use
Equation 2:
IMAX =
10
For proper thermal management, to minimize PCB trace
resistance, and to take advantage of the low RDS(ON) values of the two internal power switches in the AAT4672,
certain circuit board layout rules should be followed:
MAIN, AUX, and OUT should be routed using wider than
normal traces. The two MAIN pins (1 and 2) and two
AUX pins (3 and 4) should be connected to the same
wide PCB trace; and GND should be connected to a
ground plane. For best performance, input capacitors
(CMAIN, CAUX) and output capacitor (COUT) should be placed
as close to the package pins as possible. The AAT4672
evaluation board layout follows the printed circuit board
layout recommendations and can be used as an example
of an optimal board layout.
125°C - 85°C
300mΩ · 160°C/W = 0.913A
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4672.2008.04.1.0
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Evaluation Board Schematic
C1
4.7µF
MAIN
AUX
J1
C2
4.7µF
2
1
Header 2
C3
4.7µF
U1
1
2
3
4
5
6
MAIN
MAIN
AUX
AUX
EN
GND
OUT
OUT
IMAIN
IAUX
SELECT
GND
12
11
10
9
8
7
AAT4672
IMAIN
IAUX
R3
49.9K
EN
GND
R1
100K
OUT
R2
49.9K
PWRSEL
Figure 1: AAT4672 Evaluation Board Schematic.
Evaluation Board Layout
Figure 2: AAT4672 Evaluation Board
Top Side Layout.
4672.2008.04.1.0
Figure 3: AAT4672 Evaluation Board
Bottom Side Layout.
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11
PRODUCT DATASHEET
AAT4672
SmartSwitchTM
Power Supply Selector Switch
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TSOPJW-12
ZWXYY
AAT4672ITP-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/about/quality.aspx.
Package Information
TSOPJW-12
2.85 ± 0.20
2.40 ± 0.10
0.20 + 0.10
- 0.05
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
7° NOM
0.04 REF
0.055 ± 0.045
0.15 ± 0.05
+ 0.10
1.00 - 0.065
0.9625 ± 0.0375
3.00 ± 0.10
4° ± 4°
0.45 ± 0.15
0.010
2.75 ± 0.25
All dimensions in millimeters.
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
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3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© 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. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
12
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