AAT4608 Current Limited Load Switch in SOT-23 Package General Description Features The AAT4608 SmartSwitch™ is a member of AnalogicTech's Application Specific Power MOSFET™ (ASPM™) product family. It is a 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 currents which may cause the supply to fall out of regulation. The AAT4608 is also protected from thermal overload which limits power dissipation and junction temperatures. It can be used to control loads that require up to 1 A. Current limit threshold is programmed with a resistor from SET to ground. The quiescent supply current is typically a low 15µA max. • • • • • The AAT4608 is available in a 5 pin SOT-23 specified over -40 to 85°C. Applications • • • • 2.7V to 5.5V Input voltage range Programmable over current threshold Fast transient response: <1µs response to short circuit Low quiescent current • 15µA typical • 1µA max with Switch off 160mΩ typical R DS(ON) Undervoltage Lockout Thermal shutdown Temp range -40 to 85°C 4kV ESD Rating 5 pin SOT-23 package Preliminary Information • • • • • • SmartSwitch™ Peripheral ports Notebook computers Personal communication devices Hot swap supplies Typical Application INPUT 5 IN AAT4608 OUTPUT 1 OUT SOT-23 3 SET GND 1µF GND 4608.2001.10.0.9 2 RSET 0.47µF GND 1 AAT4608 Current Limited Load Switch in SOT-23 Package Pin Configuration 5-Pin SOT-23 (Top View) OUT 1 GND 2 SET 3 5 IN 4 NC Pin Descriptions 2 Pin # Symbol Function 1 OUT P-channel MOSFET drain. Connect 0.47µF capacitor from OUT to GND. 2 GND Ground connection 3 SET Current-Limit Set Input. A resistor from SET to ground sets the current limit for the switch. 4 NC No internal connection. 5 IN P-channel MOSFET source. Connect 1µF capacitor from IN to GND. 4608.2001.10.0.9 AAT4608 Current Limited Load Switch in SOT-23 Package Absolute Maximum Ratings (TA=25°C unless otherwise noted) Symbol Description VIN VSET, VOUT IMAX TJ TLEAD VESD IN to GND SET, 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 VIN+0.3 2 -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 Value Units 150 667 °C/W mW 2 Thermal Resistance Power Dissipation2 Note 2: Mounted on a demo board. Electrical Characteristics (VIN = 5V, TA = -40 to 85°C unless otherwise noted. Typical values are at TA=25°C) Symbol VIN IQ VUVLO RDS(ON) ILIM ILIM(MIN) TRESP 4608.2001.10.0.9 Description Operation Voltage Quiescent Current Undervoltage Lockout On-Resistance Current Limit Minimum Current Limit Current Limit Response Time Conditions Min Typ 2.7 VIN = 5V, IOUT = 0 Rising edge, 1% hysteresis, VIN=5.0V VIN=4.5V VIN=3.0V RSET = 6.8kΩ VIN=5V 2.0 0.5 15 2.3 160 165 195 1 150 0.8 Max 5.5 30 2.7 180 230 2.0 Units V µA V mΩ mΩ mΩ A mA µs 3 AAT4608 Current Limited Load Switch in SOT-23 Package Typical Characteristics (Unless otherwise noted, VIN = 5V, TA = 25°C) Quiescent Current 25 40 20 30 Input ( µA ) Quiescent Current (µA) Quiescent Current vs. Temperature 15 10 5 20 10 0 -40 -20 0 20 40 60 80 100 120 0 2.5 Temperature (C) 3 3.5 4 4.5 5 5.5 Input ( V ) Output Current vs VOUT RDS(ON) vs. Temperature 250 200 RDS(ON) (mΩ) Output Current ( A) 0.6 0.4 RSET =16 kΩ 0.2 Input = 3 V 150 Input = 5V 100 50 0 0 -40 0 1 2 3 4 -20 0 20 40 60 80 100 5 Te mperature (C) Vout ( V ) Short Circuit through 0.3Ω Short Circuit through 0.6Ω Input Voltage 8 4 Output Current 4 2 0 Output Voltage 0 -4 0 1 2 Time (µs) 4 3 9 Input Voltage 6 4 6 3 Output Current 2 0 Output (A) 6 8 Input and Output (V) 12 Output (A) Input and Output (V) 8 Output Voltage 0 -3 0 1 2 3 Time (µs) 4608.2001.10.0.9 AAT4608 Current Limited Load Switch in SOT-23 Package (Unless otherwise noted, VIN = 5V, TA = 25°C) RSET vs ILIM RSET coefficent vs I LIM 10 R SET I LIM Product ( kV ) R SET (kΩ) 100 10 1 0.1 9 8 7 6 5 1 10 I LIM (A) 0 0.5 1 1.5 2 I LIM (A) Current Limit v. Temperature Current Limit (%) 6% RSET = 22.1k V IN -VOUT=0.5V 4% 2% 0% -2% -4% -6% -50 - 25 0 25 50 75 100 Temperature (C) 4608.2001.10.0.9 5 AAT4608 Current Limited Load Switch in SOT-23 Package Functional Block Diagram IN OUT Undervoltage Lockout Over-Temp Protection 1.2V Reference Current Limit SET RSET GND 6 4608.2001.10.0.9 AAT4608 Current Limited Load Switch in SOT-23 Package Applications Information Setting Current Limit In most applications, the variation in ILIM must be taken into account when determining RSET. The ILIM variation is due to processing variations from part to part, as well as variations in the voltages at IN (pin 5) and OUT (pin 3), plus the operating temperature. See charts "Current Limit vs. Temperature", and "Output Current vs. VOUT". Together these three factors add up to a ±25% tolerance (see ILIM specification in Electrical Characteristics section). In the figure below, a cold device with a statistically higher current limit, and a hot device with a statistically lower current limit, both with RSET equal to 10.5kΩ are shown. While the chart, "R SET vs. ILIM" indicates an ILIM of 0.7A with an RSET of 10.5kΩ , this figure shows that the actual current limit will be at least 0.525A, and no greater than 0.880A. Current Limit Using 10.5 kΩ 1.2 Device with high current limit at -40°C 0.88 A 1 I LIM (A) 0.8 0.6 0.525 A 0.4 Device with low current limit at 85°C 0.2 0 0 1 2 3 4 5 VOUT (V ) To determine RSET, start with the maximum current drawn by the load, and multiply it by 1.33. (typical_ILIM = minimum_ILIM / 0.75) This is the typical current limit value. Next, refer to "RSET vs. ILIM" and find the RSET that corresponds to the typical current limit value. Choose the largest resistor available 4608.2001.10.0.9 that is less than or equal to it. For greater precision, the value of RSET may also be calculated using the ILIM RSET product found in the chart "RSET coefficient vs. ILIM". The maximum current is derived by multiplying the typical current for the chosen RSET in the chart by 1.25. A few standard resistor values are listed in the table "Current Limit RSET Values". Current Limit RSET Values RSET (kΩ) Current Limit typ (mA) 40.2 30.9 24.9 22.1 19.6 17.8 16.2 14.7 13.0 10.5 8.87 7.50 6.81 6.04 5.49 4.99 4.64 200 250 300 350 400 450 500 550 600 700 800 900 1000 1100 1200 1300 1400 Device will not current limit below: (mA) 150 188 225 263 300 338 375 413 450 525 600 675 750 825 900 975 1050 Device always current limits below: (mA) 250 313 375 438 500 563 625 688 750 875 1000 1125 1250 1375 1500 1625 1750 Example: A USB port requires 0.5A. 0.5A multiplied by 1.33 is 0.665A. From the chart named "RSET vs. ILIM", RSET should be less than 11kΩ. 10.5 kΩ is a standard value that is a little less than 11kΩ but very close. The chart reads approximately 0.700A as a typical ILIM value for 10.5kΩ. Multiplying 0.700A by 0.75 and 1.25 shows that the AAT4608 will limit the load current to greater than 0.525A but less than 0.875A. 7 AAT4608 Current Limited Load Switch in SOT-23 Package Overload Operation 1 0.75 0.25 0 5 Output Current 4 3 1Ω load is turned on at time = 0 Output (A) Output ( V ) 0.5 Output Voltage 2 1 0 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 Tim e ( s ) Operation in Current Limit Reverse Voltage When a heavy load is applied to the output of the AAT4608, the load current is limited to the value of ILIM determined by RSET. See the figure "Overload Operation". Since the load is demanding more current than ILIM, the voltage at the output drops. This causes the AAT4608 to dissipate a larger than normal quantity of power, and its die temperature to increase. When the die temperature exceeds an over temperature limit, the AAT4608 will shut down until is has cooled sufficiently, at which point it will startup again. The AAT4608 will continue to cycle on and off until the load is removed or power is removed. The AAT4608 is designed to control current flowing from IN to OUT. If a voltage is applied to OUT which is greater than the voltage on IN, large currents may flow. This could cause damage to the AAT4608. 8 4608.2001.10.0.9 AAT4608 Current Limited Load Switch in SOT-23 Package Ordering Information Part Number Package Marking Bulk Tape and Reel SOT-23-5 N/A AAT4608IGV-T1 SOT-23-5 N/A AAT4608IGV-1-T1 Package Information SOT-23-5 e Dim S1 H E D A A1 S b c I L 4608.2001.10.0.9 A A1 A2 b c D E e H L S S1 Θ Millimeters Min Max 0.95 1.45 0.05 0.15 0.90 1.30 0.35 0.50 0.08 0.20 2.84 3.00 1.50 1.70 1.90 2.60 3.00 0.35 0.55 0.47 0.55 .95 0° 10° Inches Min Max 0.037 0.057 0.002 0.006 0.035 0.051 0.014 0.019 0.003 0.078 0.112 0.112 0.059 0.067 0.0748 0.102 0.118 .0137 .0216 0.019 .0216 0.037 0° 10° 9 AAT4608 Current Limited Load Switch in SOT-23 Package 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 4608.2001.10.0.9