AAT4650 5V/3V PC Card Power Switch General Description Features The AAT4650 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 four states for VCC are VCC5, VCC3, Hi-impedance, or Ground. When in the ground state, VCC is pulled to ground by a 5kΩ 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 85mΩ (5V) typical RDS(ON) Low quiescent current 15µA (typ) Reverse-blocking switches Short-circuit protection Over-temperature protection FAULT flag output Temp range -40 to 85°C 8 pin SOP or TSSOP package Preliminary Information Applications • • • Notebook Computer PDA, Subnotebook Power Supply Multiplexer Circuit The AAT4650 is available in 8-pin SOP and TSSOP packages specified over -40 to 85°C. Typical Application 8 VCC5 VCC3 5 CTL1 CTL0 FAULT CIN5 1µF GND 4650.2001.10.0.93 CIN3 1µF 3 2 4 1 VCC5 VCC3 VCC CTL1 AAT4650 CTL0 FAULT GND 6,7 VCC COUT 0.1µF GND 1 AAT4650 5V/3V PC Card Power Switch Pin Descriptions Pin # Symbol Function 1 GND Ground connection 2 CTL0 Control input (see Control Logic Table below) 3 CTL1 Control input (see Control Logic Table below) 4 FAULT Open drain output signals over-current condition 5 VCC3 3V supply 6 VCC Output (see Control Logic Table below) 7 VCC Output (see Control Logic Table below) 8 VCC5 5V supply Pin Configuration SO-8 / TSSOP-8 (Top View) 1 8 1 2 7 2 GND CTL0 CTL1 FAULT 3 6 4 5 VCC5 VCC VCC VCC3 Control Logic Table 2 CTL1 CTL0 Function Result 0 0 OFF 5k VCC to GND 0 1 5v VCC=VCC5 1 0 3v VCC=VCC3 1 1 HiZ Both FETs OFF 4650.2001.10.0.93 AAT4650 5V/3V PC Card Power Switch Absolute Maximum Ratings Symbol (TA=25°C unless otherwise noted) Description VCC3, VCC5 VCC IMAX TJ TLEAD VESD IN to GND OUT to GND Maximum Continuous Switch Current Operating Junction Temperature Range Maximum Soldering Temperature (at Leads) ESD Rating1 — HBM Value Units -0.3 to 6 -0.3 to 6 Current Limited -40 to 150 300 4000 V V A °C °C V Note: 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. Note 1: Human body model is a 100pF capacitor discharged through a 1.5kΩ resistor into each pin. Thermal Characteristics Symbol Description ΘJA PD Thermal Resistance (SOP-8)2 Power Dissipation (SOP-8)2 Value Units 100 1.25 °C/W W Note 2: Mounted on an FR4 board. Electrical Characteristics (VIN = 5V, TA = -40 to 85°C unless otherwise noted. Typical values are at TA=25°C; bold values designate full temperature range) Symbol Description VCC Output ICC Hi-Z High impedance Output Leakage Current Iccsc Short Circuit Current Limit RDS(ON) On-Resistance Tcrds Switch Resistance Tempco 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 t9 Output Fall Time to Hi-Z State t10 Output Fall Time to Hi-Z State 4650.2001.10.0.93 Conditions Min Typ OFF mode, VCC=0V 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=0v to 10% of 3.3V, ROUT=10Ω VCC=0v to 10% of 5.0V, ROUT=10Ω VCC=10% to 90% of 3.3V, RLOAD=10Ω VCC=10% to 90% of 5.0V, RLOAD=10Ω VCC=3.3 to 90% of 3.3V, RLOAD=10Ω VCC=5.0 to 90% of 5.0V, RLOAD=10Ω VCC=90% to 10% of 3.3V, RLOAD=10Ω VCC=90% to 10% of 5.0V, RLOAD=10Ω VCC=90% to 10% of 3.3V, RLOAD=10Ω VCC=90% to 10% of 5.0V, RLOAD=10Ω Units 1 µA 2.0 A 85 80 2800 110 100 mΩ mΩ ppm/ºC 500 500 1000 1000 2000 1500 3000 3000 400 400 200 200 1500 2000 µs µs µs µs µs µs µs µs µs µs 1.0 300 300 Max 3 AAT4650 5V/3V PC Card Power Switch Symbol Description Conditions Min Power Supply VCC3 VCC3 Operation Voltage VCC5 VCC5 Operation Voltage ICC3 ICC5 2.7 2.7 VCC=5V or HiZ or OFF, VCC3<VCC5, ICC Out=0 VCC=3.3v, VCC3<VCC5, ICC Out=0 VCC=Off, VCC5>VCC3, ICC Out=0 VCC=HiZ, VCC5>VCC3, ICC Out=0 VCC=3.3v, VCC5>VCC3 ,ICC Out=0 VCC=5v, VCC5>VCC3, ICC Out=0 VCC3 Supply Current VCC5 Supply Current Parallel Interface VCTLLOW CTL Input Low Voltage VCTLHI CTL Input High Voltage ISINKCTL VFAULTLOW ISINKFAULT Other OTMP Typ VCC3 or VCC5=2.7 to 3.6V VCC3 or VCC5=4.5 to 5.5V VCTL = 5.5V ISINK=1mA CTL Input leakage FAULT Logic Output Low Voltage FAULT Logic Output High Leakage Current 5 10 10 15 Max Units 5.5 5.5 1 V V µA 20 1 40 40 40 µA µA µA µA µA 0.8 0.01 1 0.4 V V V µA V 0.05 1 µA 2.0 2.4 VFAULT= 5.5V Over Temperature Shutdown 125 degC Timing Diagram 5 0 CTL0,1 5 Vcc 0 t1, t2 t3, t4 t5, t6 t7, t8 t9, t10 Figure 1: VCC Switching Time Diagram Refer to VCC Switching Time specifications under the Electrical Characteristics section for definitions of t1 to t10. 4 4650.2001.10.0.93 AAT4650 5V/3V PC Card Power Switch Typical Characteristics (Unless otherwise noted, TA = 25°C) Current Limit VCC=VCC3 Quiescent Current vs. Temperature (ICC5) Quiescent Current (µA) 2 30 VCC3=3V VCC5=5V 25 20 Ta=25C 1.5 CTL0=5V CTL1=0V 1 15 10 0.5 5 0 0 -40 -20 0 20 40 60 80 100 120 0 0.5 1 Current Limit VCC=VCC5 Off-Switch Current (µA) Ta=25C 1.5 1 0.5 0 2 3 3 4 5 1.0000 VCC3=3V VCC5=5V 0.1000 0.0100 CTL1=0V CTL0=0V 0.0010 0.0001 0.0000 6 -40 -20 0 Vout 20 40 60 80 100 120 Temperature (C) Rdson vs. Temperature Off-Switch Current vs. Temperature ICC5 Off-Switch Current (µA) 2.5 Off-Switch Current vs. Temperature (ICC3) 2 1 2 Vout Temperature (C) 0 1.5 120.0 1.0000 VCC5=5V VCC3=3V 0.1000 CTL1=0V CTL0=0V 110.0 VCC=VCC3=3.0V 100.0 0.0100 90.0 0.0010 80.0 0.0001 VCC=VCC5=5.0V 70.0 60.0 0.0000 -40 -20 0 20 40 60 Temperature (C) 4650.2001.10.0.93 80 100 120 -40 -20 0 20 40 60 80 100 120 Temperature (C) 5 AAT4650 5V/3V PC Card Power Switch (Unless otherwise noted, TA = 25°C) Turn-ON/OFF Response with 10 Ohm 1µF load CTL0 (5V/div) FAULT (5V/div) FAULT (5V/div) VCC (2V/div) VCC (2V/div) IVCC3 (200mA/div) IVCC5 (200mA/div) 500µs/div 500µs/div Thermal Shutdown Response Short Circuit Through 0.3 Ohm 8 Input and Output (V) CTL1 (5V/div) FAULT (5V/div) VCC (1V/div) 11 Input Voltage 6 8 4 5 Output Current 2 2 Output Voltage 0 IVCC5 (500mA/div) -1 -2 100ms / div Output (A) CTL1 (5V/div) Turn-ON/OFF Response with 15 Ohm 1µF load 0 2 4 6 8 10 Time (µs) Short Circuit Through 0.6 Ohm 9 Input Voltage 6 6 4 Output Current 3 2 Output Voltage 0 0 Output (A) Input and Output (V) 8 -3 -2 0 2 4 6 8 10 Time (µs) 6 4650.2001.10.0.93 AAT4650 5V/3V PC Card Power Switch Functional Block Diagram VCC 3 VCC 5 Body Ctl VCC Over Temperature CTL1 CTL0 Over Current Over Current Slew Rate Slew Rate 5KΩ FAULT Control Logic GND Functional Description The AAT4650 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 12 volt power supply, or applications where power is switched, for example, between 5 volts for operation and 3.3 volts for standby mode. The AAT4650 operates with input voltages ranging from 2.7 to 5.5 volts in any combination and automatically powers its internal circuitry off of whichever input voltage is higher. Two identical low RDS 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 two bit parallel interface determines the state of the multiplexer: Vcc=Vcc3, Vcc=Vcc5, Vcc with resistive pull down to ground, or Vcc hi-impedance. When the state is set to either of the two inputs, the multiplex- 4650.2001.10.0.93 ing circuit will slowly slew the 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 AAT4650 always serves as an electronic fuse by limiting the load current if it exceeds the current limit threshold. During power up 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 1 µs 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 AAT4650 5V/3V PC Card Power Switch Applications Information Input Capacitor Typically a 1µF or larger capacitor is recommended for CIN. A CIN capacitor is not required for basic operation, however, it is useful in preventing load transients from affecting up stream 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 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 two 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 0.8 volts, and a logic high value must be greater than 2.4 volts. In cases where the interface pins rapidly change state directly from 3v to 5v (or vice versa), internal break before make circuitry prevents any back flow 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. Voltage Regulation The PC Card Specification calls for a regulated 5 volt 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 AAT4650 as the PC card switch. In the PC card application, the maximum allowable current for the 8 AAT4650 is dominated by voltage regulation rather than by thermal considerations, and is set by either the current limit or the maximum RDS of the P-channel MOSFET. The maximum RDS at 85°C is calculated by applying the RDS Tempco to the maximum room temperature RDS: RDS(MAX) = RDS25 x (1 + TC x ∆T), or RDS(MAX) = 105mΩ x (1 + 0.0028 x 60) = 122mΩ The maximum current is equal to the 2% tolerance of the 5 volt supply (100mV) across the AAT4650 divided by RDS(MAX). Or IMAX5 = 100mV / 122mΩ = 820mA For the 3.3 volt 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 / 134mΩ = 1.5A Since 1.5A is the nominal current limit value, the AAT4650 will current limit before IMAX3 is reached. Thermal issues are not a problem in the SO-8 package since ΘJA, the package thermal resistance, is only 120°C/W. At any given ambient temperature (TA) the maximum package power dissipation can be determined by the following equation: PD(MAX) = [TJ(MAX) - TA] / Θ JA Constants for the AAT4650 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)1/2 For the AAT4650 at 85°C, IOUT(MAX) = 1.65A, a value greater than the internal minimum current limit specification. Overcurrent and Overtemperature Protection Because many AAT4650 applications provide power to external devices, it is designed to protect its host device from malfunctions in those peripherals 4650.2001.10.0.93 AAT4650 5V/3V PC Card Power Switch through slew rate control, current limiting, and thermal limiting. The AAT4650 current limit and thermal limit serve as an immediate and reliable electronic fuse without any increase in RDS for this function. Other solutions such as a poly fuse do not protect the host power supply and system from mishandling, or short circuited peripherals, they will only prevent a fire. The AAT4650 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. crude threshold, the AAT4650 quiescent current increases from 15µA to 150µA. The high speed overcurrent 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 0 volts. Switching Vcc Voltage The AAT4650 meets PC card standards for switching the Vcc output by providing a ground path for Vcc as well as a hi impedance state. The PC card protocol for determining low voltage operations is to first power the peripheral with 5 volts and poll for 3.3 volt operation. When transitioning from 5 volts to 3.3 volts, Vcc must be discharged to less than 0.8 volts to provide a hard reset. The resistive ground state (CTL1=0, CTL0=0) will accommodate this. The ground state will also guarantee the Vcc voltage to be discharged within the specified 100ms amount of time. Overcurrent and overtemperature go hand in hand. Once an overcurrent condition exists, the current supplied to the load by the AAT4650 is limited to the overcurrent threshold. This results in a voltage drop across the AAT4650 which causes excess power dissipation and a package temperature increase. As the die begins to heat up, the overtemperature circuit is activated. If the temperature reaches the maximum level, the AAT4650 automatically switches off the P-channel MOSFETs. While they are off, the overtemperature circuit remains active. Once the temperature has cooled by approximately 10°C, the P-channel MOSFETs are switched back on. In this manner, the AAT4650 is thermally cycled on and off until the short circuit is removed. Once the short is removed, normal operation automatically resumes. 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 AAT4650, 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 (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. To save power, the full high speed overcurrent circuit is not activated until a lower threshold of current (approximately 700mA) is exceeded in the power device. When the load current exceeds this Typical PC Card Application Circuit 8 Power 5V Supply 3.3V 5 3 CIN5 1µF PC Card Controller VCC CIN3 1µF 2 4 1 100KΩ VCC5 VCC3 CTL1 AAT4650 VCC CTL0 FAULT GND PC Card Slot 6,7 VCC COUT 0.1µF FAULT CTL1 CTL0 4650.2001.10.0.93 9 AAT4650 5V/3V PC Card Power Switch Evaluation Board Layout The AAT4650 evaluation 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 10 Figure 3: Evaluation board component side layout Figure 4: Evaluation board solder side layout 4650.2001.10.0.93 AAT4650 5V/3V PC Card Power Switch Ordering Information Package Marking Part Number Bulk Tape and Reel SO-8 AAT4650IAS-B1 AAT4650IAS-T1 TSSOP-8 AAT4650IHS-B1 AAT4650IHS-T1 Package Information SOP-8 Dim E H D 7 (4x) A c A2 Q b y 4650.2001.10.0.93 e A1 L A A1 A2 B C D E e H L Y θ1 Millimeters Min Max 1.35 1.75 0.10 0.25 1.45 0.33 0.51 0.19 0.25 4.80 5.00 3.80 4.00 1.27 5.80 6.20 0.40 1.27 0.00 0.10 0° 8° Inches Min Max 0.053 0.069 0.004 0.010 0.057 0.013 0.020 0.007 0.010 0.189 0.197 0.150 0.157 0.050 0.228 0.244 0.016 0.050 0.000 0.004 0° 8° Note: 1. PACKAGE BODY SIZES EXCLUDE MOLD FLASH PROTRUSIONS OR GATE BURRS. 2. TOLERANCE 0.1000mm (4mil) UNLESS OTHERWISE SPECIFIED 3. COPLANARITY: 0.1000mm 4. DIMENSION L IS MEASURED IN GAGE PLANE. 5. CONTROLLING DIMENSION IS MILLIMETER; CONVERTED INCH DIMENSIONS ARE NOT NECESSARILY EXACT. 11 AAT4650 5V/3V PC Card Power Switch TSSOP-8 Dim E 1 DETAIL A E1 2 D A A1 A2 b c D-8 D-28 E E1 e L L1 R R1 θ1 θ2 Millimeters Min Max 1.05 1.20 0.05 0.15 1.05 0.25 0.30 0.127 2.90 3.10 9.60 9.80 4.30 4.50 6.20 6.60 0.65 BSC 0.50 0.70 1.0 0.09 0.09 0° 8° Inches Min Max 0.041 0.047 0.002 0.006 0.041 0.010 0.012 0.005 0.114 0.122 0.378 0.386 0.170 0.177 0.244 0.260 0.025 BSC 0.20 0.028 0.039 0.004 0.004 0° 8° 12° E 0.20 e R1 A2 A R 1 A1 b L DETAIL A 2 L1 Advanced Analogic Technologies, Inc. 1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086 Phone (408) 524-9684 Fax (408) 524-9689 12 4650.2001.10.0.93