AAT4651 5V/3V PC Card Power Switch General Description Features The AAT4651 SmartSwitch is a single channel PC card (PCMCIA) power switch. It is used to select between two different voltage inputs, each between 2.7V and 5.5V. An internal switch powers the circuitry from whichever input voltage is higher. The device's output, VCC, is slew rate controlled and current limited, in compliance with PC card specifications. The current limit response time to a short circuit is typically 1µs. The internal P-channel MOSFET switches are configured to break before make; that is, both switches cannot be closed at the same time. Controlled by a 2-bit parallel interface, the three states for VCC are VCC5, VCC3, or ground. When in the ground state, VCC is pulled to ground by an 200Ω resistor. An open drain FAULT output is asserted during over-current conditions. During power-up slewing, FAULT also signals that VCC is out of tolerance. An internal over-temperature sensor forces VCC to a high impedance state when an over-temperature condition exists. Quiescent current is typically a low 15µA, as long as ICC is less than approximately 500mA. Above this load current, the quiescent current increases to 200µA. • • • • • • • • • SmartSwitch™ 2.7V to 5.5V Input Voltage Range 80mΩ (5V) Typical RDS(ON) Low Quiescent Current: 15µA (Typ) Reverse-Blocking Switches Short-Circuit Protection Over-Temperature Protection FAULT Flag Output Temperature Range: -40°C to +85°C 8-Pin SOP or TSSOP Package Applications • • • Notebook Computer PDA, Subnotebook Power Supply Multiplexer Circuit The AAT4651 is available in a Pb-free, 8-pin SOP or TSSOP package and is specified over the -40°C to +85°C temperature range. Typical Application 8 VCC5 VCC3 5 VCCD1 VCCD0 FAULT CIN5 1μF GND 4651.2006.05.1.2 CIN3 1μF 2 3 4 1 VCC5 VCC3 VCCD1 VCCD0 FAULT GND AAT4651 VCC 6,7 VCC COUT 0.1μF GND 1 AAT4651 5V/3V PC Card Power Switch Pin Descriptions Pin # Symbol 1 2 3 4 5 6, 7 8 GND VCCD1 VCCD0 FAULT VCC3 VCC VCC5 Function Ground connection. Control input (see Control Logic Table below). Control input (see Control Logic Table below). Open drain output; signals over-current condition. 3V supply. Output (see Control Logic Table below). 5V supply. Pin Configuration SOP-8 (Top View) VCCD1 2 VCCD0 FAULT 8 2 1 1 GND TSSOP-8 (Top View) 7 3 4 VCC5 1 8 VCC GND VCC5 VCCD1 2 7 VCC 6 VCC VCCD0 3 6 VCC 5 VCC3 FAULT 4 5 VCC3 Control Logic Table 2 VCCD1 VCCD0 Function Result 0 0 1 1 0 1 0 1 OFF 3.3V 5V OFF 80Ω VCC to GND VCC = VCC3 VCC = VCC5 80Ω VCC to GND 4651.2006.05.1.2 AAT4651 5V/3V PC Card Power Switch Absolute Maximum Ratings1 TA = 25°C, unless otherwise noted. Symbol VCC3, VCC5 VCC IMAX TJ VESD Description IN to GND OUT to GND Maximum Continuous Switch Current Operating Junction Temperature Range ESD Rating2 — HBM Value Units -0.3 to 6 -0.3 to 6 Current Limited -40 to 150 4000 V V A °C V Value Units Thermal Characteristics3 Symbol Description ΘJA Thermal Resistance PD Power Dissipation SOP-8 TSSOP-8 SOP-8 TSSOP-8 120 150 1.0 833 °C/W 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 an FR4 board. 4651.2006.05.1.2 3 AAT4651 5V/3V PC Card Power Switch Electrical Characteristics VCC5 = 5.0V, VCC3 = 3.3V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C; bold values designate full temperature range. Symbol Description Conditions Min Typ Max Units 2.5 A 85 80 110 100 mΩ 80 200 Ω VCC Output Iccsc Short-Circuit Current Limit RDS(ON) On Resistance RCLAMP Clamp Resistance Switch Resistance Temperature Coefficient VCC Switching Time (Refer to Figure 1) t1 Output Turn-On Delay Time t2 Output Turn-On Delay Time t3 Output Rise Time t4 Output Rise Time t5 Output Turn-Off Delay Time t6 Output Turn-Off Delay Time t7 Output Fall Time to Off State t8 Output Fall Time to Off State Power Supply VCC3 VCC3 Operation Voltage VCC5 VCC5 Operation Voltage VCC = VCCIN -0.5V, On Mode VCC3 or VCC5 Selected, TA = 25°C VCC = 3.0V, TA = 25°C VCC = 5.0V, TA = 25°C VCC = Clamped to GND, ICCOUT = 10mA Sinking 1.0 Tcrds ICC3 ICC5 VCC3 Supply Current VCC5 Supply Current Parallel Interface VCCD LOW VCCD Input Low Voltage VCCD Input High Voltage VCCD HI ISINK VCCD VFAULTLOW ISINKFAULT Other OTMP VCCD Input leakage FAULT Logic Output Low Voltage FAULT Logic Output High Leakage Current 2800 VCC VCC VCC VCC VCC VCC VCC VCC = = = = = = = = 0V to 10% of 3.3V, ROUT = 10Ω 0V to 10% of 5.0V, ROUT = 10Ω 10% to 90% of 3.3V, RLOAD = 10Ω 10% to 90% of 5.0V, RLOAD = 10Ω 3.3V to 90% of 3.3V, RLOAD = 10Ω 5.0V to 90% of 5.0V, RLOAD = 10Ω 90% to 10% of 3.3V, RLOAD = 10Ω 90% to 10% of 5.0V, RLOAD = 10Ω 300 300 500 500 1000 1000 2.7 2.7 VCC = 5V or Off, VCC3 < VCC5, ICC Out = 0 VCC = 3.3V, VCC3 < VCC5, ICC Out = 0 VCC = Off, VCC5 > VCC3, ICC Out = 0 VCC = 3.3V, VCC5 > VCC3, ICC Out = 0 VCC = 5V, VCC5 > VCC3, ICC Out = 0 VCC3 or VCC5 = 3.0V to 5.5V1 VCC3 or VCC5 = 2.7V to 3.6V VCC3 or VCC5 = 4.5V to 5.5V VCTL = 5.5V Over-Temperature Shutdown 2000 1500 3000 3000 400 400 200 200 µs 5.5 5.5 V V 1 5 10 15 20 1 40 40 0.8 2.0 2.4 µA µA V V 0.01 ISINK = 1mA VFAULT = 5.5V ppm/°C 0.05 125 1 µA 0.4 V 1 µA °C 1. For VCCD outside this range, consult Typical VCCD Threshold curve. 4 4651.2006.05.1.2 AAT4651 5V/3V PC Card Power Switch Typical Characteristics Unless otherwise noted, TA = 25°C. Current Limit Quiescent Current vs. Temperature (VCC = VCC3) (ICC5) 2 Quiescent Current (μA) 30 VCC3 = 3V VCCD1 = 5V 25 1.5 VCC5 = 5V VCCD0 = 0V 20 1 15 10 0.5 5 0 0 -40 -20 0 20 40 60 80 100 0 120 0.5 1 Current Limit Off-Switch Current (μA) 1.5 1 0.5 0 3 3 (ICC3) 2 2 2.5 Off-Switch Current vs. Temperature (VCC = VCC5) 1 2 Output Voltage (V) Temperature (°C) 0 1.5 4 5 6 1.0000 VCC3 = 3V VCCD1 = 0V 0.1000 VCC5 = 5V VCCD0 = 0V 0.0100 0.0010 0.0001 0.0000 -40 -20 0 Output Voltage (V) 20 40 60 80 100 120 Temperature (°C) RDS(ON) vs. Temperature Off-Switch Current vs. Temperature 1.0000 0.1000 120.0 VCC5 = 5V VCC3 = 3V VCCD1 = 0V VCCD0 = 0V 110.0 RDS(ON) (mΩ) Off-Switch Current (μA) (ICC5) 0.0100 0.0010 0.0001 90.0 VCC = VCC3 = 3.0V 80.0 VCC = VCC5 = 5.0V 70.0 60.0 0.0000 -40 100.0 -20 0 20 40 60 Temperature (°C) 4651.2006.05.1.2 80 100 120 -40 -20 0 20 40 60 80 100 120 Temperature (°C) 5 AAT4651 5V/3V PC Card Power Switch Typical Characteristics Unless otherwise noted, TA = 25°C. Turn-On/Off Response with 15Ω, 1μF Load Turn-On/Off Response with 10Ω, 1µF Load (VCCD0 = 0V) (VCCD1 = 0V) VCCD0 (5V/div) VCCD1 (5V/div) FAULT (5V/div) FAULT (5V/div) VCC (2V/div) VCC (1V/div) IVCC5 (500mA/div) IVCC5 (200mA/div) Time (500µs/div) Time (500µs/div) Thermal Shutdown Response Short Circuit Through 0.3Ω (VCCD0 = 0V) 8 FAULT (5V/div) VCC (1V/div) IVCC5 (500mA/div) 11 Input Voltage 6 4 5 Output Current 2 -1 -2 0 2 Input Voltage 6 4 Output Current 3 2 Output Voltage 0 0 -3 Time (μs) 6 8 10 VCCD Threshold Voltage (V) 6 Output (A) Input and Output (V) 9 4 6 8 10 VCCD Threshold vs. VCC 8 2 4 Time (μs) Short Circuit Through 0.6Ω 0 2 Output Voltage 0 Time (100ms/div) -2 8 Output (A) Input and Output (V) VCCD1 (5V/div) 2.5 2.3 2.1 1.9 1.7 VCCDH 1.5 1.3 VCCDL 1.1 0.9 0.7 0.5 2.5 3.0 3.5 4.0 4.5 5.0 5.5 VCC (V) 6 4651.2006.05.1.2 AAT4651 5V/3V PC Card Power Switch Functional Block Diagram VCC3 VCC5 Body Control VCC OverTemperature VCCD1 VCCD0 OverCurrent OverCurrent Slew Rate Slew Rate 80 Ω FAULT Control Logic GND Functional Description The AAT4651 is a single channel power switch that can be used in any application where dual power supply multiplexing is required. Typical applications for this include PC card applications not requiring a 12V power supply, or applications where power is switched, for example, between 5V for operation and 3.3V for standby mode. The AAT4651 operates with input voltages ranging from 2.7V to 5.5V in any combination and automatically powers its internal circuitry from whichever input voltage is higher. Two identical low RDS(ON) P-channel MOSFETs serve as the power multiplexing circuit with a common drain as the VCC output and independent sources as the two VCC3 and VCC5 inputs. A 2-bit parallel interface determines the state of the multiplexer: VCC = VCC3, VCC = VCC5, or VCC with resistive pull down to ground. When the state is set to either of the two inputs, the multiplexing circuit will slowly slew the 4651.2006.05.1.2 VCC output to the new voltage level which protects the upstream power supply from sudden load transients. When the resistive pull down is chosen for VCC, the VCC output is quickly discharged by the resistive pull down. The AAT4651 always serves as an electronic fuse by limiting the load current if it exceeds the current limit threshold. During powerup into a short, the current will gradually increase until the current limit is reached. During a sudden short circuit on the output, the current limit will respond in 1µs to isolate and protect the upstream power supply from the load short circuit. In most applications, because the response time is so fast, a short circuit to VCC will not affect the upstream supply, so system functionality will not be affected. In the case of an over-current condition, an open drain FAULT flag output will signal the event. The FAULT output is also active during output voltage slew, and becomes inactive once the output is within regulation. 7 AAT4651 5V/3V PC Card Power Switch Applications Information Input Capacitor A 1µF or larger capacitor is typically recommended for CIN. A CIN capacitor is not required for basic operation; however, it is useful in preventing load transients from affecting upstream circuits. 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 withstand input current surges from low impedance sources such as batteries in portable devices. Output Capacitor A 0.1µF or greater capacitor is generally required between VCC and GND. Likewise, with the output capacitor, there is no specific capacitor ESR requirement. If desired, COUT may be increased to accommodate any load transient condition. Parallel Interface / Break Before Make A 2-bit parallel interface determines the state of the VCC output. The logic levels are compatible with CMOS or TTL logic. A logic low value must be less than 0.8V, and a logic high value must be greater than 2.4V. In cases where the interface pins rapidly change state directly from 3V to 5V (or vice versa), internal break-before-make circuitry prevents any backflow of current from one input power supply to the other. In addition, the body connections of the internal P-channel MOSFET switches are always set to the highest potential of VCC3, VCC5, or VCC, which prevents any body diode conduction, power supply backflow, or possible device damage. FAULT Output The FAULT output is pulled to ground by an open drain N-channel MOSFET during an over-current or output slew condition. It should be pulled up to the reference power supply of the controller IC via a nominal 100kΩ resistor. 8 Voltage Regulation The PC card specification calls for a regulated 5V supply tolerance of +/-5%. Of this, a typical power supply will drop less than 2%, and the PCB traces will drop another 1%. This leaves 2% for the AAT4651 as the PC card switch. In the PC card application, the maximum allowable current for the AAT4651 is dominated by voltage regulation rather than by thermal considerations, and is set by either the current limit or the maximum RDS(ON) of the Pchannel MOSFET. The maximum RDS(ON) at 85°C is calculated by applying the RDS(ON) temperature coefficient to the maximum room temperature RDS(ON): RDS(ON)(MAX) = RDS(ON)25 ⋅ (1 + [TC ⋅ ΔT]) -or- RDS(ON)(MAX) = 100mΩ ⋅ (1 + [0.0028 ⋅ 60]) = 116.8mΩ The maximum current is equal to the 2% tolerance of the 5V supply (100mV) across the AAT4651 divided by RDS(ON)(MAX). Or: IMAX5 = 100mV = 856.2mA 116.8mΩ For the 3.3V supply in the PC card application, the conditions are a bit relaxed, with the allowable voltage regulation drop equal to 300mV. With a 2% supply and 1% PCB trace regulation, the PC card switch can have a 200mV drop. So: IMAX3 = 200mV = 1.5A 134mΩ Since 1.5A is the nominal current limit value, the AAT4651 will current limit before IMAX3 is reached. Thermal issues are not a problem in the SOP-8 package since ΘJA, the package thermal resistance, is only 120°C/W. At any given ambient temperature 4651.2006.05.1.2 AAT4651 5V/3V PC Card Power Switch (TA), the maximum package power dissipation can be determined by the following equation: PD(MAX) = TJ(MAX) -TA θJA Constants for the AAT4651 are maximum junction temperature, TJ(MAX) = 125°C, and package thermal resistance, ΘJA = 120°C/W. Worst case conditions are calculated at the maximum operating temperature where TA = 85°C. Typical conditions are calculated under normal ambient conditions where TA = 25°C. At TA = 85°C, PD(MAX) = 333mW. At TA = 25°C, PD(MAX) = 833mW. Maximum current is given by the following equation: IOUT(MAX) = PD(MAX) RDS(ON) For the AAT4651 at 85°C, IOUT(MAX) = 1.65A, a value greater than the internal minimum current limit specification. Over-Current and Over-Temperature Protection Because many AAT4651 applications provide power to external devices, it is designed to protect its host device from malfunctions in those peripherals through slew rate control, current limiting, and thermal limiting. The AAT4651 current limit and thermal limit serve as an immediate and reliable electronic fuse without any increase in RDS(ON) for this function. Other solutions, such as a poly fuse, do not protect the host power supply and system from mishandling or short circuiting peripherals; they will only prevent a fire. The AAT4651 high-speed current limit and thermal limit not only prevent fires, they also isolate the power supply and entire system from any activity at the external port and report a mishap by means of a FAULT signal. Over-current and over-temperature go hand in hand. Once an over-current condition exists, the current supplied to the load by the AAT4651 is limited to the over-current threshold. This results in a voltage drop across the AAT4651 which causes excess power 4651.2006.05.1.2 dissipation and a package temperature increase. As the die begins to heat up, the over-temperature circuit is activated. If the temperature reaches the maximum level, the AAT4651 automatically switches off the P-channel MOSFETs. While they are off, the over-temperature circuit remains active. Once the temperature has cooled by approximately 10°C, the P-channel MOSFETs are switched back on. In this manner, the AAT4651 is thermally cycled on and off until the short circuit is removed. Once the short is removed, normal operation automatically resumes. To save power, the full high-speed over-current circuit is not activated until a lower threshold of current (approximately 500mA) is exceeded in the power device. When the load current exceeds this crude threshold, the AAT4651 quiescent current increases from 15µA to 200µA. The high-speed over-current circuit works by linearly limiting the current when the current limit is reached. As the voltage begins to drop on VCC due to current limiting, the current limit magnitude varies and generally decreases as the VCC voltage drops to 0V. Switching VCC Voltage The AAT4651 meets PC card standards for switching the VCC output by providing a ground path for VCC as well as “off” state. The PC card protocol for determining low voltage operations is to first power the peripheral with 5V and poll for 3.3V operation. When transitioning from 5V to 3.3V, VCC must be discharged to less than 0.8V to provide a hard reset. The resistive ground state (VCCD0 = VCCD1) will accommodate this. The ground state will also guarantee the VCC voltage to be discharged within the specified 100ms amount of time. Printed Circuit Board Layout Recommendations For proper thermal management, to minimize PCB trace resistance, and to take advantage of the low RDS(ON) of the AAT4651, a few circuit board layout rules should be followed: VCC3, VCC5, and VCC should be routed using wider than normal traces; the two VCC pins (Pins 6 and 7) should be connected to the same wide PCB trace; and GND should be connected to a ground plane. For best performance, CIN and COUT should be placed close to the package pins. 9 AAT4651 5V/3V PC Card Power Switch Timing Diagram 5 0 VCCD0,1 5 0 Vcc t1, t2 t3, t4 t5, t6 t7, t8 Figure 1: VCC Switching Time Diagram. Refer to VCC Switching Time specifications in the Electrical Characteristics section of this datasheet for definitions of t1 to t8. Typical PC Card Application Circuit 8 Power 5V Supply 3.3V PC Card Controller VCC 5 2 CIN5 1μF CIN3 1μF 3 4 1 100kΩ VCC5 VCC3 VCCD1 VCCD0 FAULT GND AAT4651 VCC PC Card Slot 6,7 VCC COUT 0.1μF FAULT VCC_EN1 VCC_EN0 10 4651.2006.05.1.2 AAT4651 5V/3V PC Card Power Switch Evaluation Board Layout The AAT4651 evaluation board layout follows the printed circuit board layout recommendations, and can be used for good applications layout. Note: Board layout shown is not to scale. Figure 2: Evaluation Board Top Side Silk Screen Layout / Assembly Drawing. Figure 3: Evaluation Board Component Side Layout. Figure 4: Evaluation Board Solder Side Layout. 4651.2006.05.1.2 11 AAT4651 5V/3V PC Card Power Switch Ordering Information Package Marking Part Number (Tape and Reel)1 SOP-8 TSSOP-8 4651 4651 AAT4651IAS-T1 AAT4651IHS-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 6.00 ± 0.20 3.90 ± 0.10 SOP-8 4.90 ± 0.10 0.42 ± 0.09 × 8 1.27 BSC 45° 4° ± 4° 0.175 ± 0.075 1.55 ± 0.20 0.375 ± 0.125 0.235 ± 0.045 0.825 ± 0.445 All dimensions in millimeters. 1. Sample stock is generally held on part numbers listed in BOLD. 12 4651.2006.05.1.2 AAT4651 5V/3V PC Card Power Switch 6.40 ± 0.20 4.40 ± 0.10 TSSOP-8 12° REF × 4 3.00 ± 0.10 1.05 MAX 0.245 ± 0.055 × 8 1.20 MAX 0.65 BSC 0.145 ± 0.055 4° ± 4° 0.60 ± 0.15 0.10 ± 0.05 DETAIL A 12° 1.00 REF All dimensions in millimeters. 4651.2006.05.1.2 13 AAT4651 5V/3V PC Card Power Switch © 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. Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. 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. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 14 4651.2006.05.1.2