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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
General Description
The AAT4674/4674-1 are members of AnalogicTech's Application Specific Power Management SmartSwitchTM family. These devices are dual input single output power supply selector switches designed to operate from batteries, or any other power supply with an input voltage up to 6V. The AAT4674/4674-1 connects the supply voltage on IN1 to OUT, or IN2 to OUT, through a very low RDS(ON) power MOSFET that minimizes voltage drops and power dissipation. The enable (EN) and select (SEL) pin voltages control the operational state of the internal power MOSFET switches. Once enabled, the SEL pin will switch between the IN1 and IN2 inputs. If both input voltages are below the UVLO, then the AAT4674 output floats. In the case of the AAT4674-1, if one of the input voltages is above the UVLO threshold then that input voltage that is above the UVLO threshold is passed through to the output. The two power switches are current limited and the current limit thresholds can be programmed through the resistors on IIN1 and IIN2 pins respectively. The AAT4674/4674-1 are available in thermally enhanced, space-saving Pb-free 12-pin TSOPJW packages. The AAT4674/4674-1 are specified for operation over the -40C to +85C temperature range.
Power Supply Selector Switch
Features
* Input Voltage Supply Range: 2.5V to 6V * High Level of Integration: Reverse Blocking Diode Current Sensing Programmable Current Limit Single Control Pin Switching * Break-Before-Make Switch-Over Minimum Output Voltage Drop During Change-Over * Shutdown Current < 1A * Thermal Protection * TSOPJW-12 Package
Applications
* * * * * * BluetoothTM Headsets Cell Phones Digital Still Cameras MP3 Players Personal Data Assistants (PDAs) Set Top Boxes
Typical Application
+5V +3.3V IN1/IN2 Select
IN1 OUT IN2 IIN1 SEL IIN2 RIIN2 RIIN1 System Load
Enable
EN GND
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Pin Descriptions
Pin Number
1, 2 3, 4 5 6, 7 8 9 10 11, 12
Power Supply Selector Switch
Name
IN1 IN2 EN GND SEL IIN2 IIN1 OUT
Type
I I I/O I I I O
Function
Power supply 1 input. Power supply 2 input. Enable pin, active low. Ground. IN2 or IN1 select input. Logic `0' OUT = IN1 Logic `1' OUT = IN2 IN2-OUT switch current limit set resistor input. IN1-OUT switch current limit set resistor input. Output pin.
Pin Configuration
TSOPJW-12 (Top View)
IN1 IN1 IN2 IN2 EN GND
1 2 3 4 5 6
12 11 10 9 8 7
OUT OUT IIN1 IIN2 SEL GND
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PRODUCT DATASHEET
AAT4674
Units
V V C A
SmartSwitchTM
Absolute Maximum Ratings1
Symbol
VINX VN TLEAD IOUT
Power Supply Selector Switch
Description
[IN1, IN2] to GND [OUT, EN, IIN1, IIN2, SEL] to GND Maximum Soldering Temperature (at Leads) Maximum Output Current
Value
-0.3 to 6.5 -0.3 to VINX + 0.3 300 3
Thermal Information2
Symbol
JA PD TJ
Description
Maximum Thermal Resistance Maximum Power Dissipation Operating Junction Temperature Range
Value
160 625 -40 to 150
Units
C/W mW C
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.
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Electrical Characteristics1
Power Supply Selector Switch
VINX = 5V, TA = -40 to +85C, unless otherwise noted. Typical values are at TA = 25C. Symbol Description Conditions Min
2.5 2.5 Rising edge Hysteresis Rising edge Hysteresis VIN1 = 5V, VEN = 0V VIN1 = VEN = 5V, OUT open VIN1 = 2.5V, VIN2 = 5V, VEN =0V VIN2 = 5V, VEN = 0V VIN2 = VEN = 5V, OUT open VIN1 = 5V, VIN2 = 2.5V, VEN = 0V VIN1 VIN1 VIN2 VIN2 = = = = 5.0V 3.5V 5.0V 3.5V 0.1 2.3 0.1 10 1 10 1 0.12 0.14 0.12 0.14 150 100 0.2 0.8 1.6 0.4 Threshold Hysteresis 140 15 1 2.0 1.2 30 1 5 30 1 5 0.15 0.18 0.15 0.18
Typ
Max
6 6 2.3
Units
V V V V A A A A A A mV s A A V V C
Operation IN1 Operating Voltage Range VIN1 VIN2 IN2 Operating Voltage Range VUVLO_IN1 VUVLO_IN2 IN1 Under-Voltage Lockout IN2 Under-Voltage Lockout
IIN1_OP IN1 Normal Operating Current IIN1_SHDN IN1 Shutdown Mode Current IIN1_SLP IN1 Sleep Current IIN2_OP IN2 Normal Operating Current IIN2_SHDN IN2 Shutdown Mode Current IN2 Sleep Current IIN2_SLP Power Switches RDS(ON) IN1 RDS(ON) IN2 VDROOP_OUT IN1-to-OUT FET On-Resistance IN2-to-OUT FET On-Resistance
OUT Voltage Droop From the Lower Voltage of IN1 and IN2, When Switching Over Between IN1 and IN2 Current Regulation tSOFT_START Soft-Start Delay ILIM_range IN1/IN2 Current Limit Range IN1/IN2 Current Limit Accuracy ILIM_ACC Logic Control / Protection VIH(EN) Logic High Threshold VIL(EN) Logic Low Threshold TSHDN Chip Thermal Shutdown Temperature
IO(OUT) = 0.5A, CO(OUT) = 10F Delay of start from EN, or UVLO RIIN1/IIN2 = 100k
1. The AAT4674 is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is assured by design, characterization, and correlation with statistical process controls.
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Typical Characteristics
IIN1 Shutdown Current vs. Temperature
IIN1 Shutdown Current (A) IIN2 Shutdown Current (A)
0.8 0.6 0.4 0.2 0 -0.2 -0.4 -40 0.8 0.6 0.4 0.2 0 -0.2 -0.4 -40
Power Supply Selector Switch
IIN2 Shutdown Current vs. Temperature
VIN1 = 6.5V VIN1 = 5V
VIN2 = 6.5V VIN2 = 5V VIN2 = 3.6V VIN2 = 4.2V
-15 10 35 60 85
VIN1 = 3.6V VIN1 = 4.2V
-15 10 35 60 85
Temperature (C)
Temperature (C)
IIN1 Operation Current vs. Temperature
(IOUT = 0A) IIN1 Operation Current (A)
18 16 14 12 10 8 6 4 -40 -15 10 35 60 85
IIN2 Operation Current vs. Temperature
(IOUT = 0A) IIN2 Operation Current (A)
20 18 16 14 12 10 8 6 4 -40 -15 10 35 60 85
20
VIN1 = 6.5V VIN1 = 5V
VIN2 = 6.5V VIN2 = 5V VIN2 = 4.2V VIN2 = 3.6V
VIN1 = 3.6V
VIN1 = 4.2V
Temperature (C)
Temperature (C)
RDS(ON) vs. Temperature
250 200 1.1
Enable Threshold vs. Input Voltage
Enable Threshold (V)
VIN = 3.5V VIN = 2.5V
1.05 1 0.95 0.9 0.85 0.8 0.75 0.7 0.65 0.6 2.5 3 3.5 4 4.5 5 5.5 6 6.5
RDS(ON) (m)
VIH(EN)
150 100 50 0
VIN = 5V
VIN = 6.5V
VIL(EN)
-40
-15
10
35
60
85
110
Temperature (C)
Input Voltage (V)
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Typical Characteristics
IIN1 Sleep Current vs. VIN1 Voltage
(VIN2 = 6.5V)
2.5 2.5
Power Supply Selector Switch
IIN2 Sleep Current vs. VIN2 Voltage
(VIN1 = 6.5V) IIN2 Sleep Current (A)
IIN1 Sleep Current (A)
2 1.5 1 0.5 0 2.5 3 3.5 4
85C 25C
2 1.5 1 0.5 0
85C 25C -40C
-40C
4.5
5
5.5
6
2.5
3
3.5
4
4.5
5
5.5
6
VIN1 Voltage (V)
VIN2 Voltage (V)
Current Limit vs. RIIN1/IIN2
(VIN1 = 5V; VIN2 = 3.3V; VOUT = VIN2 or VOUT = VIN1)
2.25 2 1.75 1.5 1.25 1 0.75 0.5 0.25 0 50 100 150 200 250 300 350 400 450 500 2V
Turn-On/Off Response
(ROUT = 10; VIN = 5V)
Current Limit (A)
VEN (2V/div)
0V
VOUT (5V/div) IOUT (500mA/div) RIIN1/IIN2 (k)
0V
0A
Time (100s/div)
3.3V to 5V Transition Response
(IOUT = 500mA, COUT = 10F)
5V
5V to 3.3V Transition Response
(IOUT = 500mA, COUT = 10F)
5V
VOUT (1V/div)
VOUT (1V/div)
3.3V
3.3V
VSEL (2V/div)
2V 0V
VSEL (2V/div)
2V 0V
Time (40s/div)
Time (40s/div)
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Typical Characteristics
3.6V to 3.6V Transition Response
(IOUT = 500mA, COUT = 10F) VIN (2V/div)
3.6V 3.6V
Power Supply Selector Switch
Short Circuit Through 0.3 Response
VOUT (1V/div)
5V
IOUT (5A/div)
2V 0V
0A
2A
VSEL (2V/div)
VOUT (5V/div)
5V
0.6V
Time (40s/div)
Time (10s/div)
Short Circuit Through 0.6 Response
VIN (2V/div)
Thermal Shutdown Response
(VIN = 5V)
2V 0V
5V
VEN (2V/div)
IOUT (5A/div) VOUT (5V/div)
0A
2A
VOUT (2V/div) IOUT (2A/div)
0V
5V
1.2V
0A
Time (10s/div)
Time (40ms/div)
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Functional Block Diagram
Switch 1
Power Supply Selector Switch
IN1
OUT
IIN1
Thermal and Current Sense Logic Control
SEL IIN2
EN
IN2
Switch 2
GND
Truth Table
Y = Yes, N = No, X = don't care. Input Conditions VIN1 > UVLO
N Y N Y Y
VIN2 > UVLO
N N Y Y Y
SEL
X X X 0 1
AAT4674 VOUT
Floating Floating Floating VIN1 VIN2
AAT4674-1 VOUT
Floating VIN1 VIN2 VIN1 VIN2
Functional Description
To power the output, both input supplies (IN1 and IN2) must be above the UVLO threshold. If either supply input is below the UVLO threshold then the output will float or, in the case of the AAT4674-1 the output will be the input supply that is above the UVLO threshold. If both supplies are above the UVLO threshold and the device is enabled, the AAT4674/AAT4674-1 will connect the supply from IN1 to OUT when the SEL pin is LOW (logic `0'), and when the SEL pin is HIGH (logic `1') then the supply on IN2 is connected to the OUT pin. Consult the above "Truth Table" for the summarized AA4674/4674-1 operational details. The two internal power switches are current limited and the limiting thresholds can be programmed through the resistors on the IIN1 and IIN2 pins respectively.
Applications Information
Input Capacitors
A 1F or greater capacitor is generally recommended between IN1 and GND (CIN1), and between IN2 and GND (CIN2). 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 CIN1/ CIN2. There is no specific capacitor equivalent series resistance (ESR) requirement for CIN1/CIN2. However, for higher current operation, ceramic capacitors are recommended for CIN1/CIN2 due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices.
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Output Capacitor
A 1F 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.
Power Supply Selector Switch
For IN2 (power supply 2 input):
VIIN2 RIIN2 = I * 200k
CLIN2
0.5V = 0.2A * 200k = 500k (499.9k standard value)
EN Input
The AAT4674/4674-1 is enabled when VEN is 0.4V (logic `0'), conversely the AAT4674/4674-1 is disabled when VEN is 1.6V (logic `1').
Thermal Considerations
Since the AAT4674/4674-1 have an internal current limit and over-temperature 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) * RJA + 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 AAT4674/4674-1 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%. RJA is the thermal resistance between the AAT4674/4674-1 and the printed circuit board (PCB) onto which it is mounted; RJA is the thermal resistance of the TSOPJW-12 package. TA(MAX) is the maximum ambient temperature that the PCB under the AAT4674/4674-1 would be if the AAT4674/4674-1 were not dissipating power. Equation 1 can be rearranged to solve for IMAX, into Equation 2 (Eq. 2).
SEL Input
When VSEL is 0.4V (logic `0') the output voltage equals power supply 1 input (VOUT = VIN1), and conversely when VSEL is 1.6V (logic `1') the output voltage equals power supply 2 input (VOUT = VIN2).
Current Limit Resistor Selection
The current limits for power supply 1 and power supply 2 inputs are set by resistors connected between IIN1/IIN2 and GND. The following equation can be used to select the appropriate resistor for a particular current limit:
VIINX ICLINX = R * 200k IINX
ICLINX Current limit for IN1 and/or IN2 pins respectively VIINX Internally Regulated Voltage [0.5V 20%] on the IIN1 and IIN2 pins respectively RIINX IIN1 and/or IIN2 Resistor 200k Internal Gain Factor
Design Example
A particular application requires that the current limit for IN1 be set to 2A and the current limit for IN2 be set to 0.2A. What value of resistor is required for the IIN1 and IIN2 pins respectively? For IN1 (power supply 1 input):
VIIN1 RIIN1 = I * 200k CLIN1 0.5V = 2A * 200k = 50k (49.9k standard value)
Eq. 2: IMAX =
TSD(MIN) - TA(MAX) RDS(ON)(MAX) * RJA
TSD(MIN) is the minimum temperature required to activate the AAT4674/4674-1 over-temperature protection (thermal shutdown). With typical specification of 140C, 125C is a safe minimum value to use.
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
For example, for a 2.5V input power supply application that is specified to operate in 50C environments where the PCB operates at temperatures as high as 85C. The application is sealed and its PCB is small, causing RJA to be approximately 160C/W. The RDS(ON)(MAX) is estimate to be 300m (from the "RDS(ON) vs. Temperature" performance graph, where VIN = 2.5V at 85C plus 50%). To find the maximum current (IMAX) for this application use Equation 2:
Power Supply Selector Switch
PCB Layout Recommendations
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 AAT4674/4674-1, certain circuit board layout rules should be followed: IN1, IN2, and OUT should be routed using wider than normal traces. The two IN1 pins (1 and 2) and two IN2 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, the input capacitors (CIN1/CIN2) and output capacitors (COUT) should be placed as close to the package pins as possible. The AAT4674/4674-1 evaluation board layout follows the printed circuit board layout recommendations and can be used as an example of an optimal board layout.
IMAX =
125C - 85C 300m * 160C/W = 0.913A
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Evaluation Board Schematic
C1 2.2F U1 MAIN AUX C2 2.2F J1 2 1 Header 2
1 2 3 4 5 6
Power Supply Selector Switch
IN1 IN1 IN2 IN2 EN GND
OUT OUT IIN1 IIN2 SEL GND
12 11 10 9 8 7
OUT IMAIN IAUX
C3 2.2F
AAT4674/4674-1 EN R1 100K GND PWRSEL
R3 49.9K R2 49.9K
Figure 1: AAT4674/AAT4674-1 Evaluation Board Schematic.
Evaluation Board Layout
Figure 2: AAT4674/AAT4674-1 Evaluation Board Top Side Layout.
Figure 3: AAT4674/AAT4674-1 Evaluation Board Bottom Side Layout.
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PRODUCT DATASHEET
AAT4674
SmartSwitchTM
Ordering Information
Package
TSOPJW-12 TSOPJW-12
Power Supply Selector Switch
Marking1
ZVXYY YTXYY
Part Number (Tape and Reel)2
AAT4674ITP-T1 AAT4674ITP-1-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
0.20 + 0.10 - 0.05
2.40 0.10
0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC
2.85 0.20
7 NOM 3.00 0.10
0.9625 0.0375 + 0.10 1.00 - 0.065
0.04 REF
0.15 0.05
0.055 0.045
4 4
0.010
0.45 0.15 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
(c) 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.
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