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| AAT4612 Current Limited Load Switch General Description The AAT4612 SmartSwitchTM is a member of AnalogicTech's Application Specific Power MOSFETTM (ASPMTM) product family. It is a Current Limited P-channel MOSFET power switch designed for high-side load-switching applications operating with inputs ranging from 2.4V to 5.5V which makes it ideal for both 3V and 5V systems. An integrated current-limiting circuit protects the input supply from large currents which potentially cause the supply to fall out of regulation. In addition, the AAT4612 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 10A and in shutdown mode, the supply current decreases to less than 1A. The AAT4612 is available in a 5-pin SOT23, and an 8-pin SC70JW specified over a -40 to 85C temperature range. The AAT4600 Series is a family of adjustable and fixed SmartSwitchTM products with a range of current handling capabilities. Available are single versions with adjustable current limit (AAT4610, AAT4601) as well as fixed current limit (AAT4625), and dual versions with fixed current limit (AAT4626, AAT4670). Features * * * * SmartSwitchTM * * * * * * * 2.4V to 5.5V Input voltage range 1A current limit trip threshold Fast transient response: * <1s response to short circuit Low quiescent current * 10A typ * 1A max with Switch off 100m typical R DS(ON) Undervoltage Lockout Thermal Shutdown Temp range -40 to 85C 4kV ESD Rating 5-pin SOT23 package 8-pin SC70JW package Preliminary Information Applications * * * * Peripheral ports Notebook computers Personal communication devices Hot swap supplies Typical Application INPUT 5 IN OUT 1 VCC AAT4612 SOT23 CIN 1F ON 4 ON GND 2 COUT 0.47F GND GND 4612.2002.1.0.9 1 AAT4612 Current Limited Load Switch Pin Descriptions Pin # SOT23-5 SC70JW Symbol OUT GND NC Function P-channel MOSFET drain Ground connection Not internally connected Active low enable Input P-channel MOSFET source 1 2 3 4 5 2 5, 6, 7, 8 1 3, 4 ON IN Pin Configuration SOT23-5 SC70JW-8 OUT GND NC 15 2 34 IN ON ON OUT IN IN 1 2 8 7 3 4 6 5 GND GND GND GND 1 2 2 4612.2002.1.0.9 AAT4612 Current Limited Load Switch Absolute Maximum Ratings Symbol VIN VON VOUT Iout TJ VESD TLEAD (TA=25C unless otherwise noted) Description IN to GND ON to GND OUT to GND Output Current Operating Junction Temperature Range ESD Rating1--HBM Maximum Soldering Temperature (at Leads) Value -0.3 to 6 -0.3 to 6 -0.3 to 6 Internally Limited -40 to 150 4000 300 Units V V V A C V C 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 1.5k resistor into each pin. Thermal Characteristics Symbol JA PD Description Maximum Thermal Resistance 2 (SOT23-5, SC70JW-8) Maximum Power Dissipation (SOT23-5, SC70JW-8) 2 Value 150 667 Units C/W mW Note 2: Mounted on a demo board. Electrical Characteristics Symbol VIN IQ IQ(OFF) ISD(OFF) VUVLO VUVLO(hys) RDS(ON) ILIM VON(L) VON(H) ION(SINK) tRESP TOFF TON OTMP (VIN = 5V, TA = -40 to 85C unless otherwise noted. Typical values are at TA=25C; bold values denote full temperature range) Description Operation Voltage Quiescent Current Off Supply Current Off Switch Current Undervoltage Lockout Undervoltage Lockout Hysteresis On-Resistance Current Limit ON Input Low Voltage ON Input High Voltage ON Input leakage Current Loop Response Turn-Off Time Turn-On Time Over Temperature Shutdown Conditions VIN = 5V, ON = active, IOUT = 0 ON = inactive, VIN = 5.5V ON = inactive, VIN = 5.5V, VOUT = 0 VIN falling VIN=5.0V, TA = 25C VIN=3.0V, TA = 25C VOUT = VIN - 0.5V VIN = 2.7V to 5.5V 3 VIN = 2.7V 4.2V VIN = > 4.2V to 5.0V 3 VON = 5.5V VIN = 5V VIN = 5V, RL = 10 VIN = 5V, RL = 10 Min 2.4 Typ 10 0.1 1.9 0.3 100 140 1.5 Max 5.5 20 1 1 Units V A A A V V m A V V 1 2.0 2.4 150 180 2.0 0.8 0.01 500 2.5 1 125 1 A ns s s C Note 3: For VIN outside this range consult typical ON threshold curve. 4612.2002.1.0.9 3 AAT4612 Current Limited Load Switch Typical Characteristics Quiescent Current vs. Temperature 20 20 Quiescent Current vs. Input Voltage Quiescent Current (A) 15 Quiescent Current (A) -40 -20 0 20 40 60 80 100 120 15 10 10 5 5 0 0 0 1 2 3 4 5 6 Temperature (C) IN (V) Current Limit vs. V OUT 1.4 1.2 180 160 140 RDS(ON) vs. Temperature Current Limit (A) VIN=3V RDS(ON) (m) 1.0 0.8 0.6 0.4 0.2 0.0 0 1 2 3 4 5 120 100 80 60 40 20 0 -40 -20 0 20 40 60 80 100 120 VIN=5V V OUT (V) Temperature (C) Off-Supply Current vs. Temperature Off-Supply Current (A) 1.00 1.00 Off-Switch Current vs. Temperature 0.10 Off-Switch Current (A) -40 -20 0 20 40 60 80 100 120 0.10 0.01 0.01 0.00 0.00 -40 -20 0 20 40 60 80 100 120 Temperature (C) Temperature (C) 4 4612.2002.1.0.9 AAT4612 Current Limited Load Switch Typical Characteristics Turn-On RL=10, CL=0.47F 6 5 6 5 Turn-Off RL=10, CL=0.47F Voltage (V) 3 2 1 0 -1 -0.5 ON OUT Voltage (V) 4 4 3 2 1 0 -1 ON OUT 0.0 0.5 1.0 1.5 2.0 -5 0 5 10 15 20 Time (s) Time (s) Short Circuit through 0.3 6.0 12 Thermal Shutdown Response Input and Output (V) Input Voltage 5.0 4.0 3.0 2.0 1.0 0.0 -1 0 1 2 3 4 5 10 Output Voltage (5V/div) 6 Output Current Output Voltage 4 2 0 Output (A) 8 Output Current (1A/div) Time (50ms/div) Time (s) ON Threshold vs. VIN 2.4 2.2 ON Threshold (V) 2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 2 2.5 3 VON(H) VON(L) 3.5 4 4.5 5 5.5 VIN (V) 4612.2002.1.0.9 5 AAT4612 Current Limited Load Switch Functional Block Diagram IN Over-Temp Protection OUT 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 micro second 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 thermal 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. 6 4612.2002.1.0.9 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 1s before the current limit circuitry activates. (See characteristic curve "Short Circuit Through 0.3.") 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 VIN 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. 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. TJ(MAX) = IMAX2 x R DS(ON)(MAX) x RJA + 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. RJA 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; Equation 2. IMAX= (TSD(MIN) - TA(MAX)) (RDS(ON)(MAX) x RJA) Output Capacitor In order to insure stability while current limit is active, a small capacitance of approximately 0.47F 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 120F of capacitance down stream from their controlling power switch. The current limiting circuit will allow an output capacitance of 1000F or more without disturbing the upstream power supply. TSD(MIN) is the minimum temperature required to activate the AAT4612 over temperature protection. With typical specification of 125C, 115C is a safe minimum value to use. For example, if an application is specified to operate in 50C environments, the PCB operates at temperatures as high as 85C. The application is sealed and its PCB is small, causing RJA to be approximately 150 C/W. Using Equation 2, IMAX = ((115 - 85) =1A (188m x 150)) 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 that accommodate this condition. The threshold voltages are compatible with 5 volt TTL, and 2.5 volt to 5 volt CMOS systems. The AAT4612 is safe to operate at the maximum current level of 1A at 85C. 4612.2002.1.0.9 7 AAT4612 Current Limited Load Switch Ordering Information Package SOT23-5 SC70JW-8 Marking Part Number Bulk N/A N/A Tape and Reel AAT4612IGV-T1 AAT4612IJS-T1 Package Information SOT23-5 e Dim S1 E H D A2 A1 S b A c L A A1 A2 b c D E e H L S S1 Millimeters Min Max 1.00 1.30 0.00 0.10 0.70 0.90 0.35 0.50 0.10 0.25 2.70 3.10 1.40 1.80 1.90 2.60 3.00 0.37 0.45 0.55 0.85 1.05 1 9 Inches Min Max 0.039 0.051 0.000 0.004 0.028 0.035 0.014 0.020 0.004 0.010 0.106 0.122 0.055 0.071 0.075 0.102 0.118 0.015 0.018 0.022 0.033 0.041 1 9 I 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. 8 4612.2002.1.0.9 AAT4612 Current Limited Load Switch SC70JW-8 e e e Dim E E1 L A A1 A2 D e b c 1 E b D 0.048REF c A2 A Millimeters Min Max 2.10 BSC 1.75 2.00 0.23 0.40 1.10 0 0.10 0.70 1.00 2.00 BSC 0.50 BSC 0.15 0.30 0.10 0.20 0 8 4 10 Inches Min Max 0.083 BSC 0.069 0.079 0.009 0.016 0.043 0.004 0.028 0.039 0.079 BSC 0.020 BSC 0.006 0.012 0.004 0.008 0 8 4 10 A1 1 L E1 4612.2002.1.0.9 9 AAT4612 Current Limited Load 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 10 4612.2002.1.0.9 |
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