PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch General Description Features The AAT4674/4674-1 are members of AnalogicTech’s Application Specific Power Management SmartSwitch™ 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. • 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 < 1μA • Thermal Protection • TSOPJW-12 Package 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. Applications • • • • • • Bluetooth™ Headsets Cell Phones Digital Still Cameras MP3 Players Personal Data Assistants (PDAs) Set Top Boxes 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 -40°C to +85°C temperature range. Typical Application +5V IN1 +3.3V IN2 IN1/IN2 Select SEL System Load OUT IIN1 IIN2 RIIN2 Enable 4674.2008.02.1.1 RIIN1 EN GND www.analogictech.com 1 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Pin Descriptions Pin Number Name Type 1, 2 3, 4 5 6, 7 IN1 IN2 EN GND I I I/O 8 SEL I 9 10 11, 12 IIN2 IIN1 OUT 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 2 1 12 2 11 3 10 4 9 5 8 6 7 OUT OUT IIN1 IIN2 SEL GND www.analogictech.com 4674.2008.02.1.1 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Absolute Maximum Ratings1 Symbol VINX VN TLEAD IOUT Description [IN1, IN2] to GND [OUT, EN, IIN1, IIN2, SEL] to GND Maximum Soldering Temperature (at Leads) Maximum Output Current Value Units -0.3 to 6.5 -0.3 to VINX + 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. 4674.2008.02.1.1 www.analogictech.com 3 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Electrical Characteristics1 VINX = 5V, TA = -40 to +85°C, unless otherwise noted. Typical values are at TA = 25°C. Symbol Description Conditions Operation IN1 Operating Voltage Range VIN1 VIN2 IN2 Operating Voltage Range VUVLO_IN1 IN1 Under-Voltage Lockout VUVLO_IN2 IN2 Under-Voltage Lockout IN1-to-OUT FET On-Resistance RDS(ON) IN2 IN2-to-OUT FET On-Resistance 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 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 VDROOP_OUT TSHDN Chip Thermal Shutdown Temperature Typ 2.5 2.5 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 Min = = = = Units 6 6 2.3 V V 0.1 2.3 0.1 10 1 30 1 5 30 1 5 0.12 0.14 0.12 0.14 0.15 0.18 0.15 0.18 1 10 5.0V 3.5V 5.0V 3.5V IO(OUT) = 0.5A, CO(OUT) = 10μF 150 Delay of start from EN, or UVLO RIIN1/IIN2 = 100kΩ Max 1 140 15 μA μA μA μA μA μA Ω Ω 2.0 1.2 μs A A 0.4 V V 1.6 Threshold Hysteresis V mV 100 0.2 0.8 V °C 1. The AAT4674 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 4 www.analogictech.com 4674.2008.02.1.1 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Typical Characteristics IIN2 Shutdown Current vs. Temperature 0.8 0.6 IIN2 Shutdown Current (µA) IIN1 Shutdown Current (µA) IIN1 Shutdown Current vs. Temperature VIN1 = 6.5V 0.4 VIN1 = 5V 0.2 0 VIN1 = 3.6V -0.2 -0.4 -40 VIN1 = 4.2V -15 10 35 60 85 0.8 0.6 0.4 VIN2 = 6.5V 0.2 VIN2 = 5V 0 VIN2 = 3.6V -0.2 VIN2 = 4.2V -0.4 -40 -15 10 IIN2 Operation Current vs. Temperature (IOUT = 0A) (IOUT = 0A) VIN1 = 6.5V 18 VIN1 = 5V 16 14 12 10 VIN1 = 3.6V 8 VIN1 = 4.2V 6 4 -40 -15 10 35 60 20 18 VIN2 = 6.5V 16 VIN2 = 5V 14 12 VIN2 = 4.2V 10 VIN2 = 3.6V 8 6 4 85 -40 -15 10 Temperature (°C) 60 85 Enable Threshold vs. Input Voltage 250 1.1 VIN = 3.5V Enable Threshold (V) RDS(ON) (mΩ) 35 Temperature (°C) RDS(ON) vs. Temperature VIN = 2.5V 150 100 VIN = 6.5V VIN = 5V 50 0 85 IIN1 Operation Current vs. Temperature 20 200 60 Temperature (°C) IIN2 Operation Current (µA) IIN1 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) 4674.2008.02.1.1 VIH(EN) 0.95 2.5 3 3.5 4 4.5 5 5.5 6 6.5 Input Voltage (V) www.analogictech.com 5 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Typical Characteristics IIN1 Sleep Current vs. VIN1 Voltage IIN2 Sleep Current vs. VIN2 Voltage (VIN2 = 6.5V) (VIN1 = 6.5V) 2.5 IIN2 Sleep Current (µA) IIN1 Sleep Current (µA) 2.5 85°C 2 25°C 1.5 1 -40°C 0.5 2 85°C 25°C 1.5 1 -40°C 0.5 0 0 2.5 3 3.5 4 4.5 5 5.5 2.5 6 3 3.5 VIN1 Voltage (V) 4 4.5 5 5.5 6 VIN2 Voltage (V) Current Limit vs. RIIN1/IIN2 Turn-On/Off Response (ROUT = 10Ω Ω; VIN = 5V) (VIN1 = 5V; VIN2 = 3.3V; VOUT = VIN2 or VOUT = VIN1) 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) RIIN1/IIN2 (kΩ 3.3V to 5V Transition Response 5V to 3.3V Transition Response (IOUT = 500mA, COUT = 10µF) (IOUT = 500mA, COUT = 10µF) 5V VOUT (1V/div) VSEL (2V/div) Time (100µs/div) VOUT (1V/div) 3.3V 3.3V 2V 0V VSEL (2V/div) Time (40µs/div) 6 5V 2V 0V Time (40µs/div) www.analogictech.com 4674.2008.02.1.1 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Typical Characteristics Short Circuit Through 0.3Ω Ω Response 3.6V to 3.6V Transition Response (IOUT = 500mA, COUT = 10µF) VOUT (1V/div) VSEL (2V/div) 3.6V VIN (2V/div) 5V IOUT (5A/div) 0A 3.6V VOUT (5V/div) 2V 0V 2A 5V 0.6V Time (40µs/div) Time (10µs/div) Short Circuit Through 0.6Ω Ω Response Thermal Shutdown Response (VIN = 5V) VIN (2V/div) IOUT (5A/div) VOUT (5V/div) 5V VEN (2V/div) 0A 5V 2A VOUT (2V/div) 1.2V IOUT (2A/div) 0V 0V 0A Time (40ms/div) Time (10µs/div) 4674.2008.02.1.1 2V www.analogictech.com 7 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Functional Block Diagram Switch 1 IN1 OUT IIN1 Thermal and Current Sense SEL Logic Control EN IIN2 GND IN2 Switch 2 Truth Table Y = Yes, N = No, X = don’t care. Input Conditions VIN1 > UVLO VIN2 > UVLO SEL AAT4674 VOUT AAT4674-1 VOUT N Y N Y Y N N Y Y Y X X X 0 1 Floating Floating Floating VIN1 VIN2 Floating VIN1 VIN2 VIN1 VIN2 Functional Description Applications Information 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. 8 Input Capacitors A 1μF 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. www.analogictech.com 4674.2008.02.1.1 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Output Capacitor For IN2 (power supply 2 input): 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. ⎛ VIIN2 ⎞ RIIN2 = ⎝ I ⎠ · 200k CLIN2 ⎛0.5V⎞ = ⎝0.2A⎠ · 200k EN Input = 500kΩ (499.9kΩ standard value) 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’). 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? 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) · 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 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%. RθJA is the thermal resistance between the AAT4674/4674-1 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 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). For IN1 (power supply 1 input): Eq. 2: IMAX = ⎛ VIIN1 ⎞ RIIN1 = ⎝ I · 200k CLIN1⎠ ⎛0.5V⎞ = ⎝ 2A ⎠ · 200k = 50kΩ (49.9kΩ standard value) 4674.2008.02.1.1 TSD(MIN) - TA(MAX) RDS(ON)(MAX) · RΘJA TSD(MIN) is the minimum temperature required to activate the AAT4674/4674-1 over-temperature protection (thermal shutdown). With typical specification of 140°C, 125°C is a safe minimum value to use. www.analogictech.com 9 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch 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 estimate 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 = 10 125°C - 85°C 300mΩ · 160°C/W = 0.913A 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. www.analogictech.com 4674.2008.02.1.1 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Evaluation Board Schematic C1 2.2μF U1 MAIN 1 2 AUX C2 2.2μF 3 4 5 6 J1 2 1 Header 2 IN1 IN1 IN2 IN2 EN GND OUT OUT IIN1 IIN2 SEL GND OUT 12 11 10 9 IMAIN IAUX 8 7 R3 49.9K R2 49.9K AAT4674/4674-1 EN R1 100K C3 2.2μF GND PWRSEL Figure 1: AAT4674/AAT4674-1 Evaluation Board Schematic. Evaluation Board Layout Figure 2: AAT4674/AAT4674-1 Evaluation Board Top Side Layout. 4674.2008.02.1.1 Figure 3: AAT4674/AAT4674-1 Evaluation Board Bottom Side Layout. www.analogictech.com 11 PRODUCT DATASHEET AAT4674 SmartSwitchTM Power Supply Selector Switch Ordering Information Package Marking1 Part Number (Tape and Reel)2 TSOPJW-12 TSOPJW-12 ZVXYY YTXYY 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 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 www.analogictech.com 4674.2008.02.1.1