AAT4612 Current Limited Load Switch General Description Features The AAT4612 SmartSwitch is a current limited Pchannel MOSFET power switch designed for highside load switching applications operating with inputs ranging from 2.4V to 5.5V, making it ideal for both 3V and 5V systems. An integrated current limiting circuit protects the input supply from large currents which could potentially cause the supply to fall out of regulation. In addition, the AAT4612’s thermal overload protection limits power dissipation and junction temperatures associated with prolonged periods of operation in current limit. Due to its low RDS(ON), the AAT4612 can be used to control loads that require up to 1A even while operating at high ambient temperatures. The ultra-fast current limit response to a sudden short circuit is a mere 500ns which reduces the requirements of local supply bypassing. Quiescent current is a low 10µA and, in shutdown mode, the supply current decreases to less than 1µA. • • • The AAT4612 is available in a Pb-free 5-pin SOT23 package or a Pb-free 8-pin SC70JW package and is specified over the -40°C to +85°C temperature range. • • • • • • • SmartSwitch™ Input Voltage Range: 2.4V to 5.5V 1A Current Limit Trip Threshold Fast Transient Response: • <1µs Response to Short Circuit Low Quiescent Current: • 10µA Typ • 1µA Max with Switch Off 100mΩ Typical RDS(ON) Under-Voltage Lockout Thermal Shutdown 4kV ESD Rating 5-Pin SOT23 or 8-Pin SC70JW Package -40°C to +85°C Temperature Range Applications • • • • Hot Swap Supplies Notebook Computers Peripheral Ports Personal Communication Devices Typical Application INPUT IN VCC OUT AAT4612 CIN 1μF GND 4612.2006.09.1.3 ON ON GND C OUT 0.47μF GND 1 AAT4612 Current Limited Load Switch Pin Descriptions Pin # SOT23-5 SC70JW-8 Symbol 1 2 OUT P-channel MOSFET drain. 2 5, 6, 7, 8 GND Ground connection. N/C Not internally connected. 3 Function 4 1 ON Active low enable input. 5 3, 4 IN P-channel MOSFET source. Pin Configuration SOT23-5 (Top View) OUT GND N/C 2 1 SC70JW-8 (Top View) 5 IN 2 3 4 ON ON OUT IN IN 1 8 2 7 3 6 4 5 GND GND GND GND 4612.2006.09.1.3 AAT4612 Current Limited Load Switch Absolute Maximum Ratings1 TA = 25°C unless otherwise noted. Symbol VIN VON VOUT IOUT TJ VESD TLEAD Description IN to GND ON to GND OUT to GND Output Current Operating Junction Temperature Range ESD Rating2—HBM Maximum Soldering Temperature (at Leads) Value Units -0.3 to 6 -0.3 to 6 -0.3 to 6 Internally Limited -40 to 150 4000 300 V V V A °C V °C Thermal Characteristics3 Symbol ΘJA PD Description Maximum Thermal Resistance (SOT23-5, SC70JW-8) Maximum Power Dissipation (SOT23-5, SC70JW-8) Value Units 150 667 °C/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 a demo board. 4612.2006.09.1.3 3 AAT4612 Current Limited Load Switch Electrical Characteristics VIN = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C; bold values denote full temperature range. Symbol VIN IQ IQ(OFF) ISD(OFF) VUVLO VUVLO(hys) RDS(ON) Description Operation Voltage Quiescent Current Off Supply Current Off Switch Current Under-Voltage Lockout Under-Voltage Lockout Hysteresis On Resistance ILIM VON(L) Current Limit ON Input Low Voltage VON(H) ON Input High Voltage ION(SINK) tRESP TOFF TON OTMP ON Input leakage Current Loop Response Turn-Off Time Turn-On Time Over-Temperature Shutdown Conditions Min Typ 2.4 VIN = 5V, ON = Active, IOUT = 0 ON = Inactive, VIN = 5.5V ON = Inactive, VIN = 5.5V, VOUT = 0 VIN Falling VIN = 5.0V, TA = 25°C VIN = 3.0V, TA = 25°C VOUT = VIN to 0.5V VIN = 2.7V to 5.5V1 VIN = 2.7V ≤ 4.2V VIN = > 4.2V to 5.0V1 VON = 5.5V VIN = 5V VIN = 5V, RL = 10Ω VIN = 5V, RL = 10Ω 10 1 0.1 1.9 0.3 130 170 1.5 Max Units 5.5 20 1 1 V µA µA µA V V 175 225 2.0 0.8 2.0 2.4 mΩ A V V 0.01 500 2.5 1 125 1 µA ns µs µs °C 1. For VIN outside this range, consult typical ON threshold curve. 4 4612.2006.09.1.3 AAT4612 Current Limited Load Switch Typical Characteristics Quiescent Current vs. Temperature Quiescent Current vs. Input Voltage 20 Quiescent Current (µA) Quiescent Current (µA) 20 15 10 5 0 -40 -20 0 20 40 60 80 100 15 10 5 0 120 0 1 2 Temperature (°C) Current Limit vs. Output Voltage 5 6 250 1.4 VIN = 3V 200 1.0 RDS(ON) (mΩ Ω) Current Limit (A) 4 RDS(ON) vs. Temperature 1.2 0.8 0.6 0.4 150 VIN = 5V 100 50 0.2 0 0.0 0 1 2 3 4 -40 5 -20 0 20 40 60 80 100 120 Temperature (°°C) Output Voltage (V) Off-Supply Current vs. Temperature Off-Switch Current vs. Temperature 1.00 1.00 Off-Switch Current (µA) Off-Supply Current (µA) 3 Input Voltage (V) 0.10 0.01 0.00 0.10 0.01 0.00 -40 -20 0 20 40 60 Temperature (°C) 4612.2006.09.1.3 80 100 120 -40 -20 0 20 40 60 80 100 120 Temperature (°C) 5 AAT4612 Current Limited Load Switch Turn-On Turn-Off (RL = 10Ω; CL = 0.47µF) (RL = 10Ω; CL = 0.47µF) 6 6 5 5 4 ON 3 Voltage (V) Voltage (V) Typical Characteristics OUT 2 1 0 3 ON 2 OUT 1 0 -1 -0.5 -1 0.0 0.5 1.0 1.5 2.0 Time (µs) -5 0 5 10 15 20 Time (µs) Thermal Shutdown Response Short Circuit Through 0.3Ω 6.0 12 Input Voltage 5.0 10 4.0 8 3.0 6 Output Current 2.0 4 Output Voltage 1.0 2 0.0 Output Current (A) Input and Output Voltage (V) 4 Output Current (1A/div) 0 -1 0 1 2 3 4 Output Voltage (5V/div) 5 Time (50ms/div) Time (µs) ON Threshold vs. Input Voltage 2.4 ON Threshold (V) 2.2 2 1.8 VON(H) 1.6 1.4 VON(L) 1.2 1 0.8 0.6 0.4 2 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) 6 4612.2006.09.1.3 AAT4612 Current Limited Load Switch Functional Block Diagram IN OUT OverTemperature Protection Under-Voltage Lockout Current Limit ON GND Functional Description The AAT4612 is a single channel current limited load switch that protects against short circuits by current limiting to a preset level. A patented fast acting current limit loop limits the current in a fraction of a microsecond and instantly resets to low impedance once the short-circuit condition is removed. The AAT4612 is internally protected from thermal damage by an over-temperature detection circuit. If the die temperature reaches the internal thermal limit, the power device is switched off until the die temperature cools to a level below the ther- 4612.2006.09.1.3 mal limit threshold. The device will thermal cycle indefinitely until the over-current condition is removed. The AAT4612 operates with input voltages ranging from 2.4V to 5.5V which, along with its extremely low operating current, makes it ideal for battery-powered applications. In cases where the input voltage drops below 2.4V, the AAT4612 MOSFET is protected from entering the saturated region of operation by being automatically shut down by an under-voltage lockout circuit. The AAT4612 is ideally suited for protection of peripheral ports such as USB, RS232, and parallel ports. 7 AAT4612 Current Limited Load Switch Applications Information Input Capacitor The input capacitor, CIN, protects the power supply from current transients generated by the load attached to the AAT4612. When a short circuit is suddenly applied to the output of the AAT4612, a large current, limited only by the RDS(ON) of the MOSFET, will flow for less than 1µs before the current limit circuitry activates. (See characteristic curve "Short Circuit Through 0.3Ω.") In this event, a moderately sized CIN will dramatically reduce the voltage transient seen by the power supply and by other circuitry upstream from the AAT4612. The extremely fast short-circuit response time of the AAT4612 reduces the size requirement of CIN. CIN should be located as close to the device IN pin as practically possible. Ceramic, tantalum, or aluminum electrolytic capacitors are appropriate 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 In order to insure stability while current limit is active, a small capacitance of approximately 0.47µF is required. No matter how large the output capacitor, however, output current is limited to the value set by the AAT4612 current limiting circuitry, so very large output capacitors can be used. For example, USB ports are specified to have at least 120µF of capacitance downstream from their controlling power switch. The current limiting circuit will allow an output capacitance of 1000µF or more without disturbing the upstream power supply. that accommodate this condition. The threshold voltages are compatible with 5V TTL and 2.5V to 5V CMOS systems. When switching the AAT4612 on into a capacitive load, the AAT4612 will charge the output capacitive load at a rate no greater than the current limit setting. Attaching Loads Capacitive loads attached to an enabled AAT4612 will charge at a rate no greater than the current limit setting. Thermal Considerations Since the AAT4612 has internal current limit and over-temperature protection, junction temperature is rarely a concern. However, if the application requires large currents in a hot 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: 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 AAT4612 at high temperature. RθJA is the thermal resistance between the AAT4612 die and the board onto which it is mounted. TA(MAX) is the maximum temperature that the PCB under the AAT4612 would be if the AAT4612 were not dissipating power. Equation 1 can be rearranged to solve for IMAX: ON In many systems, power planes are controlled by integrated circuits which run at lower voltages than the power plane itself. The enable input (ON) of the AAT4612 has low and high threshold voltages 8 Eq. 2: IMAX = TSD(MIN) - TA(MAX) RDS(ON)(MAX) · RΘJA TSD(MIN) is the minimum temperature required to activate the AAT4612 over-temperature protection. 4612.2006.09.1.3 AAT4612 Current Limited Load Switch With typical specification of 125°C, 115°C is a safe minimum value to use. For example, if an application is specified to operate in 50°C environments, the PCB operates at temperatures as high as 85°C. The application is sealed and its PCB is small, causing RθJA to be approximately 150°C/W. Using Equation 2, Eq. 3: IMAX = TSD(MIN) - TA(MAX) RDS(ON)(MAX) · RΘJA The AAT4612 is safe to operate at the maximum current level of 0.93A at 85°C. 4612.2006.09.1.3 9 AAT4612 Current Limited Load Switch Ordering Information Package Marking1 Part Number (Tape and Reel)2 SOT23-5 ATXYY AAT4612IGV-T1 SC70JW-8 ATXYY AAT4612IJS-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 SOT23-5 2.85 ± 0.15 1.90 BSC 0.40 ± 0.10 0.075 ± 0.075 0.15 ± 0.07 4° ± 4° 10° ± 5° 1.10 ± 0.20 0.60 REF 1.20 ± 0.25 2.80 ± 0.20 1.575 ± 0.125 0.95 BSC 0.60 REF 0.45 ± 0.15 GAUGE PLANE 0.10 BSC All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on all part numbers listed in BOLD. 10 4612.2006.09.1.3 AAT4612 Current Limited Load Switch SC70JW-8 2.20 ± 0.20 1.75 ± 0.10 0.50 BSC 0.50 BSC 0.50 BSC 0.225 ± 0.075 2.00 ± 0.20 0.100 7° ± 3° 0.45 ± 0.10 4° ± 4° 0.05 ± 0.05 0.15 ± 0.05 1.10 MAX 0.85 ± 0.15 0.048REF 2.10 ± 0.30 All dimensions in millimeters. © 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 4612.2006.09.1.3 11