AAT4601 1.5A Current Limited P-Channel Switch General Description Features The AAT4601 SmartSwitch™ is part of AnalogicTech's Application Specific Power MOSFET™ (ASPM™) product family. It is a 1.5A Current Limited P-channel MOSFET power switch designed for high-side load-switching applications. This switch operates with inputs ranging from 2.7V to 5.5V, making it ideal for both 3V and 5V systems. An integrated current-limiting circuit protects the input supply against large changes in load current which could cause the supply to fall out of regulation. The AAT4601 has protection from thermal overload which limits power dissipation and junction temperatures. The maximum current limit level is 1.5A; the actual threshold is programmed with a resistor from the SET pin to ground. The quiescent supply current is typically 12µA. In shutdown mode, the supply current decreases to less than 1µA. • • • 2.7V to 5.5V Input voltage range Programmable over current threshold Low quiescent current • 12µA typical • Less than 1µA with Switch off Only 2.5V needed for ON Control Thermal Shutdown Fault Flag 2ms Fault Blanking Undervoltage Lockout Temperature range -40 to 85°C 2kV ESD rating UL Approved—File No. E217765 8-pin SOP or TSSOP package Preliminary Information • • • • • • • • • SmartSwitch™ Applications The AAT4601 is available in 8-pin SOP or TSSOP specified over -40 to 85°C. • • • • USB ports Notebook computers Peripheral ports Hot swap supplies UL Recognized Component Typical Application INPUT 1 2 100kΩ 8 ON 1µF 3 IN IN OUT AAT4601 OUT FAULT SET ON GND OUTPUT 6 7 5 R SET 1uF 4 4601.2001.11.0.92 1 AAT4601 1.5A Current Limited P-Channel Switch Pin Descriptions Pin # Symbol Function 1,2 IN These pins are the input to the P-channel MOSFET source. Connect a 1µF capacitor from IN to GND. 3 ON Active-Low Enable Input. A logic low turns the switch on. 4 GND Ground 5 SET Current-Limit Set Input. A resistor from SET to ground sets the current limit for the switch. 6,7 OUT These pins are the P-channel MOSFET drain connection. Connect a 1µF capacitor from OUT to GND. 8 FAULT Fault-Indication Output. This open-drain output goes low when in current limit or when the die temperature exceeds +135 ºC, with a 2ms delay after the fault event occurs. Pin Configuration SOP-8/TSSOP-8 (Top View) 2 8 7 2 2 1 1 IN IN ON GND 3 6 4 5 FAULT OUT OUT SET 4601.2001.11.0.92 AAT4601 1.5A Current Limited P-Channel Switch Absolute Maximum Ratings Symbol (TA=25°C unless otherwise noted) Description VIN VON, VFAULT VSET, VOUT IMAX TJ TLEAD VESD IN to GND ON, FAULT to GND SET, OUT to GND Maximum Continuous Switch Current Operating Junction Temperature Range Maximum Soldering Temperature (at Leads) ESD Rating—HBM1 Value Units -0.3 to 6 -0.3 to VIN+0.3 -0.3 to VIN+0.3 3 -40 to 150 300 4000 V 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 2 Typical Thermal Resistance Maximum Power Dissipation2 Value Units 100 1.25 °C/W W Note 2: Mounted on an AATI demo board. Electrical Characteristics (VIN = 5V, TA = -40 to 85°C unless otherwise noted. Typical values are at TA=25°C) Symbol VIN IQ Description IQ(OFF) ISD(OFF) VUVLO Operation Voltage Quiescent Current Off Supply Current Off Switch Current Undervoltage Lockout RDS(ON) On-Resistance ILIM ILIM(MIN) TSD VONL Current Limit Minimum Current Limit Shutdown Temperature ON Input Low Voltage VONH IONSINK VFAULTL IFSINK TRESP TBLANK TOFF TON OTMP ON Input High Voltage ON Input leakage FAULT Logic Output Low Voltage FAULT Logic Output High Leakage Current Limit Response Time Fault Blanking Time after Turn-On Turn-Off Time3 Turn-On Time3 Over Temperature Shut Down Conditions Min Typ 2.7 VIN = 5V, ON = GND, IOUT = 0 ON=IN, VIN = 5.5V ON = IN, VIN = 5.5V, VOUT = 0 Rising edge, 1% hysteresis, VIN=5.0V VIN=4.5V VIN=3.0V RSET = 2kΩ 2.0 510 VIN = 5V 12 .004 .07 2.3 70 75 80 715 250 125 Max Units 5.5 30 1 15 2.7 V µA µA µA V mΩ mΩ mΩ mA mA ºC V V V µA V µA µs ms µs µs ºC 130 150 920 0.8 VIN=2.7V to 3.6V VIN=4.5V to 5.5V VON = 5.5V ISINK=1mA VFAULT = 5.5V VIN=5V 2.0 2.4 0.01 0.08 0.05 2 2 VIN=5V VIN=5V 1 0.4 1 20 200 125 Note 3: Guaranteed by design. 4601.2001.11.0.92 3 AAT4601 1.5A Current Limited P-Channel Switch Typical Characteristics (Unless otherwise noted, VIN = 5V, TA = 25°C) Quiescent Current 25 25 20 20 Input (µA) Quiescent Current (µA) Quiescent Current vs. Temperature 15 10 5 15 10 5 0 -40 -20 0 20 40 60 80 100 120 0 0 Temperature (°C) 1 2 3 4 5 6 Input (V) RSET I LIM Product vs I LIM Current Limit 1 2500 2000 0.6 Product (V) Output (A) 0.8 RSET = 2 k W 0.4 Input Voltage = 5 V 1500 1000 0.2 500 0 0 1 2 3 4 0 5 0.5 10 1 0.1 0.01 0.001 0.0001 0 20 40 60 80 Temperature (°C) 4 2 Off-Switch Current vs. Temperature Off-Switch Current (µA) Off-Supply Current (µA) Off-Supply Current vs. Temperature -20 1.5 Typical I LIM (A) Output (V) -40 1 100 120 140 10 1 0.1 0.01 0.001 0.0001 -40 -20 0 20 40 60 80 100 120 140 Temperature (°C) 4601.2001.11.0.92 AAT4601 1.5A Current Limited P-Channel Switch Typical Characteristics (Unless otherwise noted, VIN = 5V, TA = 25°C) Turn-On vs. Temperature Turn-Off vs. Temperature 80 2 Turn-OFF Time (µs) 60 50 40 VIN= 5V 30 20 10 VIN=3V 1.6 1.4 VIN=5V 1.2 1 0.8 0.6 0.4 0.2 0 0 -40 -20 0 20 40 60 80 100 120 -40 -20 0 60 80 100 120 Switch Turn-Off Time Switch Turn-On Time 6 6 IOUT =I LIMIT 5 5 Voltage (V) 4 ON 3 2 Output 1 4 IOUT = ILIMIT ON 3 2 Output 1 0 0 -1 -20 -1 -10 0 40 60 -4 80 -2 0 Short Circuit through 0.3Ω 4 4 2 0 Output Voltage 0 -4 4 Time (µs) 4601.2001.11.0.92 6 8 Output (A) 8 Input Voltage 2 6 8 Input and Output (V) 12 Output Current 0 4 Short Circuit through 0.6Ω 8 6 2 Time ( Time ( Input and Output (V) 40 Temperature ( °C) Temperature (°C) Voltage (V) 20 9 Output Current Input Voltage 6 6 4 3 2 0 Output (A) Turn-ON Time (µs) 1.8 VIN= 3V 70 Output Voltage 0 -3 -20 0 20 40 60 80 100 120 140 Time (µs) 5 AAT4601 1.5A Current Limited P-Channel Switch Typical Characteristics (Unless otherwise noted, VIN = 5V, TA = 25°C) Fault Delay vs. Temperature RDS(ON) vs. Temperature 100 90 2.0 RDS(ON) (mΩ ) Fault Delay (ms) 2.5 1.5 1.0 60 VIN=4.5V 40 -20 0 20 40 Temperature (°C) 6 VIN=3V 70 50 0.5 0 -40 80 60 80 100 -4 0 -20 0 20 40 60 80 Temperature ( °C) 4601.2001.11.0.92 AAT4601 1.5A Current Limited P-Channel Switch Functional Block Diagram IN OUT Undervoltage Lockout Over-temp Protection FAULT ON 1.2V Reference Current Limit SET Functional Description persists, the die temperature will rise causing the over temperature protection circuit to activate. The AAT4601 is an integrated MOSFET load switch with an adjustable current limit, over temperature protection, level shifted input and a fault flag. The current limit control is combined with an over temperature thermal limit circuit to provide a comprehensive system to protect the load switch under short circuit or other adverse operating conditions. The AAT4601 is ideally suited for control and protection of peripheral ports such as USB, RS232 and parallel ports. If the current limit or over temperature protection circuits are active for more then two milliseconds, the system will be informed via the FAULT Flag. The two millisecond delay allows the AAT4601 to be turned on into capacitive loads without activating the FAULT Flag. The open drain FAULT output can be connected directly to system controllers driven by voltage levels less than the IN pin voltage without additional level shifting circuitry. The current limit and over temperature circuits will act independently. The device current limit is activated when the output load current exceeds an internal threshold level. The internal current limit threshold is determined by an external resistor connected between the SET pin and ground. The minimum current limit threshold is specified by ILIM(MIN). If the load switch ambient temperature becomes excessive or if a short circuit condition 4601.2001.11.0.92 The load switch is turned off by applying a logic high level to the ON pin. The AAT4601 typically consumes 12µA when operating, when off, the device draws less then 1µA. In the off state, current is prevented from flowing between the input and output. The ON function has logic level thresholds that allow the AAT4601 to be TTL compatible and may also be controlled by 2.5V to 5.0V CMOS circuits. The voltage level on either ON or FAULT should not exceed the input supply level present on the IN pin. 7 AAT4601 1.5A Current Limited P-Channel Switch Applications Information Current Limit RSET Values Setting Current Limit A simple three-step procedure can be used to adjust the AAT4601's current limit. First, the maximum current required by the load should be determined. Second, select a resistor that guarantees adequate current is available to the load under normal conditions. Finally, the maximum current that can pass through the switch can be calculated and compared to the maximum current available. Step 1: The maximum current required by a load is usually defined in port specifications design application references. For example, USB ports are specified to support loads of up to 500 mA. Step 2: The most convenient method for determining a current limit resistor value is to look it up in the provided table named "Current Limit RSET Values". Find the lowest current value that is greater than the maximum load current in the given application. Refer to the column named "Device will not current limit below". The resistor value needed is in the corresponding row named "RSET". For example, a USB port requires 500 mA. The lowest level where the device will current limit above 500 mA is 516 mA. The corresponding resistor value for RSET would be 2kΩ . Step 3: Now the required resistor value has been determined. The maximum current that can be drawn, even with a short circuit applied to the output, can be determined by reading the column labeled "Device always current limits below". If the power supply connected to the AAT4601's input can provide this current level, the power supply voltage will not collapse when a short circuit is applied to the load switch output. For example, a notebook computer has a USB port which is powered by an AAT4601 with a 2kΩ resistor connected between the SET pin and GND. If the power supply connected to the AAT4601's IN pin can provide more than 917 mA, this supply will remain in regulation even if a short circuit is applied to the USB port. 8 RSET (Ω) Current Limit typ (mA) 470 510 560 620 680 750 820 910 1000 1100 1200 1300 1500 1600 1800 2000 2200 2400 2700 3000 3300 3600 3900 4300 4700 5100 5600 6200 6800 7500 1585 1529 1466 1397 1334 1266 1206 1144 1089 1034 986 941 865 829 769 716 673 633 582 539 502 470 442 410 382 358 332 306 283 268 Device will not current limit below: (mA) 1141 1101 1055 1006 960 911 869 823 784 745 710 677 623 597 554 516 485 456 419 388 362 339 318 295 275 258 239 220 204 193 Device always current limits below: (mA) 2029 1957 1876 1788 1707 1620 1544 1464 1394 1324 1262 1204 1107 1061 985 917 861 811 745 690 643 602 565 524 489 458 424 392 362 343 4601.2001.11.0.92 AAT4601 1.5A Current Limited P-Channel Switch internal temperature while current limit is not active can be calculated using Equation 1: Applications Information Operation in Current Limit If an excessive load is applied to the output of an AAT4601, the load's current will be limited by the AAT4601's current limit circuitry. Refer to the figure named "Overload Operation". If a short circuit were to occur on the load, it would demand more current than what is allowed by the internal current limiting circuit and the voltage at the AAT4601's output will drop. This causes the AAT4601 to dissipate more power than in normal operation, causing the die temperature to increase. When die temperature exceeds the internal over temperature threshold, the AAT4601 will shut down. After shutting down, the AAT4601 cools to a level below the over temperature threshold, at which point it will start up again. The AAT4601 will continue to cycle off and on until one of the following events occurs; the load current is reduced to a level below the AAT4601's current limit setting, the input power is removed, or until the output is turned off by a logic high level applied to the ON pin. Thermal Considerations Since the AAT4601 has internal current limit and over temperature protection, junction temperature is rarely a concern. If an application requires a large load current in a high temperature operating environment, there is the possibility that the over temperature protection circuit rather than the current limit circuit will regulate the current available to the load. In these applications, the maximum current available without risk of activation of the over temperature circuit can be calculated. The maximum TJ(MAX) = IMAX2 × R DS(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 AAT4601 at high temperature. RθJA is the thermal resistance between the AAT4601's die and the board onto which it is mounted. TA(MAX) is the maximum ambient temperature for the printed circuit board assembly under the AAT4601 when the load switch is not dissipating power. Equation 1 can be transformed to provide IMAX; Refer to Equation 2. IMAX= TSD(MIN) - TA(MAX) RDS(ON)(MAX) × RθJA TSD(MIN) is the minimum temperature required to activate the AAT4601's over temperature protection. With typical specification of 125°C, 115°C is a safe minimum value to use. For example, a portable device is specified to operate in a 50°C environment. The printed circuit board assembly will operate at temperatures as high as 85°C. This portable device has a sealed case and the area of the printed board assembly is rellatively small causing RθJA to be approximately 120°C/W. Using Equation 2, IMAX= 115 - 85 = 1.4 A 130 × 120 If this system requires less than 1.4 A, the thermal limit will not activate during normal operation. Overload Operation 6 5 Input Voltage Voltage (V) 4 1 W is applied to output at t = 0 RSET is 2 kW 3 2 Output Voltage 1 0 -0.5 0 0.5 1 1.5 2 Time (s) 4601.2001.11.0.92 9 AAT4601 1.5A Current Limited P-Channel Switch Applications Information Input Capacitor The input capacitor serves two purposes. First, it protects the source power supply from transient current effects generated by the application load circuit. If a short circuit is suddenly applied to the output of an AAT4601, there is a microsecond long period during which a large can current flow before the current limit circuitry activates. Refer to the characteristic curve named "Short Circuit Through 0.3Ω." A properly sized input capacitor can dramatically reduce the load switch input transient response effects seen by the power supply and other circuitry upstream from the AAT4601. The second purpose of the input capacitor is to prevent transient events generated by the load circuit from affecting the operation of the AAT4601. For example, if an AAT4601 is used in a circuit that operates from a 3 volt power supply with poor step load response, it is possible that turning on the load switch could cause the input power supply to droop below the AAT4601's under voltage lockout threshold. This drop in voltage would cause the AAT4601 to turn off until the input power supply's voltage recovers. Since this cycle would be self-perpetuating, the entire circuit could be seen to be unstable. In the very rare case where capacitor cost is prohibitive, the output load circuit should be slew rate limited when turned on. Output Capacitor In order to insure stability while the device current limit is active, a small capacitance of approximately 1µF should be used. When the AAT4601 is activated using the ON function, there are no momentary current transients as in the case of when a short circuit suddenly applied to a device that is already on. Refer to the characteristic curve named "Switch Turn-On Time." No matter how big the output capacitor, output current is limited to the value allowed by the threshold determined by RSET and the internal current limiting circuitry. This permits very large output capacitors to be used. 10 For example, USB ports are specified to have at least 120µF of down stream capacitance from their controlling power switch. An output capacitance as large as 1000µF would not disturb the input power supply to the AAT4601 used to control the USB port. ON Input When the AAT4601 is in the off state, the output is an open circuit and the device quiecent current consumption is reduced to less than 1µA. The ON threshold voltage is set to allow the AAT4601 to be controlled by 5 volt TTL levels as well as CMOS power from 2.5 volts to 5 volts. The ON function control voltage level should not exceed the input supply level applied to the IN pin. FAULT Output A FAULT flag is provided to alert a system if the load switch is not receiving a sufficient voltage level to operate properly. If either the current limit or over temperature circuits in any combination are active for more than approximately two milliseconds continuously, the FAULT pin is pulled to ground internally through a 100Ω resistance. The 2 millisecond delay on the FAULT function is intended to prevent capacitive loads connected to the load switch output from activating FAULT when the device is turned on. The placement of a pull up resistor between the FAULT pin and the IN pin is recommended. Reasonable values for the pull up resistor should range from 10kΩ to 100kΩ. Since FAULT is an open drain terminal, it may be pulled up to any voltage that is not greater than the level present on the IN pin. This is done to allow the AAT4601 to signal ancillary circuitry that is powered by voltage level less than the level on the IN pin. Reverse Voltage The AAT4601 is designed to control current flowing from IN to OUT. If a voltage is applied to OUT which is greater than that on IN, a large resulting reverse current may flow, potentially damaging the AAT4601. 4601.2001.11.0.92 AAT4601 1.5A Current Limited P-Channel Switch Printed Circuit Board Layout Recommendations Evaluation Board Layout For proper thermal management, and to take advantage of the low RDS(ON) of the AAT4601, a few circuit board layout rules should be followed: VIN and VOUT should be routed using wider than normal traces, and GND should be connected to a ground plane. For best performance, CIN and COUT should be placed close to the package pins. Figure 1: AAT4601 Evaluation board top side silk screen assembly drawing 4601.2001.11.0.92 The AAT4601 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: AAT4601 Evaluation board component side layout Figure 3: AAT4601 Evaluation board solder side layout 11 AAT4601 1.5A Current Limited P-Channel Switch Ordering Information Package Marking Part Number Bulk Tape and Reel SOP-8 AAT4601IAS-B1 AAT4601IAS-T1 TSSOP-8 AAT4601IHS-B1 AAT4601IHS-T1 Package Information SOP-8 Dim E H 1 2 D 7 (4x) A c A2 Q b y 12 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. 4601.2001.11.0.92 AAT4601 1.5A Current Limited P-Channel Switch TSSOP-8 Dim E 1 DETAIL A E1 2 D E 0.20 e 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° R1 A2 A R 1 b 4601.2001.11.0.92 A1 L DETAIL A 2 L1 13 AAT4601 1.5A Current Limited P-Channel Switch This page intentionally left blank. Advanced Analogic Technologies, Inc. 1250 Oakmead Parkway, Suite 310, Sunnyvale, CA 94086 Phone (408) 524-9684 Fax (408) 524-9689 14 4601.2001.11.0.92