Adjustable Current Limited Load Switch with Fault Flag. Features OUT AAT4614 ON/ON. Fault Flag R SET

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1 General Description The SmartSwitch is a current limited P-channel MOSFET power switch designed for high side load switching applications. This switch operates with inputs ranging from.4v 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. Reverse current blocking is provided to protect the load switch from reverse current potentials while the device is shutdown. The is also protected from thermal overload which is limited by power dissipation and junction temperatures. Current limit threshold is programmed with a resistor from to ground and may be adjusted for levels up to.4a. The ultra-fast current limit response to a sudden short circuit is a mere s which reduces the requirements of local supply bypassing. An open drain FAULT flag signals an over-current or over-temperature condition after a 4ms blanking time to prevent false reporting. Quiescent current is a low A and the supply current decreases to less than A in shutdown mode. The is offered in the small Pb-free, 8-pin SC7JW, SOT3-6 and SOT3-5 packages, and is specified for operation over the -4 C to +85 C ambient temperature range. Features Input Voltage Range:.4V to 5.5V Programmable Over-Current Threshold Fast Transient Response: s Response to Short Circuit Low Quiescent Current A Typical while Enabled A Max with Switch Off (T A = 5 C) 3m Typical R DS(ON) Only.4V Needed for ON/OFF Control Under-Voltage Lockout Reverse Blocking During Disable 4ms Fault Blanking Fault Flag Open Drain Output (Not Available for SOT3-5 Package) Active Hi/Lo Enable Options Over-Temperature Protection 4kV ESD Rating 6-Pin SOT3, 5-Pin SOT3,or 8-Pin SC7JW Package Temperature Range: -4 C to +85 C Applications Hot Swap Supplies Notebook Computers Portable Products Proprietary Peripheral Ports USB Ports Typical Application Power Supply Input Output OUT µf EN/EN ON/ON FLT k.47µf Fault Flag R w w w. a n a l o g i c t e c h. c o m

2 Pin Description Pin # SOT3-6 SOT3-5 SC7JW-8 Symbol Description 5 OUT Current limiting load switch output (high side P-channel MOSFET Drain). Connect a.47 F capacitor from OUT to for best load transient response. 6,7,8 IC ground connection 3 n/a FLT Current limit fault fl ag pin, open-drain output, active low signal. Pull up with a k to k resistor. 4 4 ON/ON Load switch enable input. Active high and active low options are available Current limit set pin. Connect a resistor between this pin and ground to program the desired current limit set point Load switch power supply input pin (high side P-channel MOSFET source). Bypass with a F capacitor from to. Pin Configuration SOT3-6 (Top View) SOT3-5 (Top View) OUT 6 OUT 5 5 FLT 3 4 ON/ON 3 4 ON/ON FLT ON/ON 3 SC7JW-8 (Top View) OUT w w w. a n a l o g i c t e c h. c o m

3 Absolute Maximum Ratings Symbol Description Value Units V to -.3 to 6 V V ON,V FLT ON/ON, FLT to -.3 to V +.3 V V OUT, V OUT, to -.3 to V +.3 V I MAX Maximum DC Output Current ma V ESD ESD Rating, HBM 4 V T J Maximum Junction Operating temperature -4 to +5 C T LEAD Maximum Soldering Temperature (at leads, sec) 3 C Thermal Information Symbol Package Description Value Units P D JA SOT3-6(-5) 65 mw Maximum Power Dissipation SC7JW8,3 667 mw SOT3-6(-5) 5 C/W Maximum Thermal Resistance SC7JW8 3 6 C/W. 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.. Mounted on FR4 circuit board. 3. Derate 6.5mW/ C above 4 C ambient temperature w w w. a n a l o g i c t e c h. c o m 3

4 Electrical Characteristics V = 5V; T A = -4 C to 85 C unless otherwise noted. Typical values are at T A = 5 C. Symbol Description Conditions Min Typ Max Units V Input Voltage Range V I Q Operation Quiescent Current V = 5V, ON/ON = Active, I OUT = 5 I Q(OFF) Off Supply Current ON/ON = Inactive, V = 5.5V. A I SD(OFF) Off Switch Current ON/ON = Inactive, V = 5.5V, T A = 5 C. V UVLO Under-Voltage Lockout Rising edge.8.4 V UVLO_HYS Under-Voltage Lockout Hysteresis. V R DS(ON) On-Resistance V = 5.V, T A = 5 C 3 8 V = 3.V, T A = 5 C 5 3 m TC RDS On-Resistance Temperature Coeffi cient 8 ppm/ C I LIM Current Limit R = 6.8k ; V OUT = V -.5V.75.5 A V ON(L) ON/ON Input Low Voltage V =.7V to 5.5V.6 V ON(H) ON/ON Input High Voltage V =.7V to <4.V. V V 4.V to 5.5V.4 I ON(SK) Input Leakage Current V ON = 5.5V. A T RESP Current Limit Response Time V = 5V T ON Turn On Time V = 5V; R O = s T OFF Turn Off Time V = 5V; R O = 55 T SD Over-Temperature Shutdown Threshold V = 5V T J Increasing 5 T J Decreasing 5 C T BLANK Fault Flag Blanking Time 4 ms V FLT(LO) Fault Flag Logic Low Output I FLT(SK) = ma.4 V I FLT(SK) Fault Flag Logic High Leakage Current.5 A 4 w w w. a n a l o g i c t e c h. c o m

5 Typical Characteristics Unless otherwise noted, V = 5V, T A = 5 C, R = 6.8K. IQ (µa) 5 5 Quiescent Current vs. Temperature Temperature ( C) Normalized Current Limit (A) Output Current vs. Output Voltage (R = 6.8KΩ) Output Voltage (V) Quiescent Current vs. Input Voltage Off-Switch Current vs. Temperature IQ (µa) Input Voltage (V) Off-Switch Current (µa) Temperature ( C) R DS(ON) vs. Temperature R vs. I LIM RDS(ON) (mω) V = 3V V = 5V R (kω) Temperature ( C) I LIM (ma) w w w. a n a l o g i c t e c h. c o m 5

6 Typical Characteristics Unless otherwise noted, V = 5V, T A = 5 C, R = 6.8K. ON(ON) Threshold (V) ON(ON) Threshold vs. Input Voltage Input Voltage (V) VON(ON)-Hi V ON(ON)-Lo V OUT (V/div) ON (V/div) Turn-On (R L = Ω; C L =.47µF) Time (µs/div) Turn-Off (V = 5.V; R L = Ω; C L = µf) Short Circuit Through.3Ω Resistor V OUT (V/div) V OUT (V/div) ON (V/div) V (V/div) I OUT (4A/div) Time (µs/div) Time (µs/div) Thermal Shutdown Response (R L = Ω; C L =.47µF) Fault Delay from Short Circuit V OUT (V/div) V OUT (5V/div) I OUT (A/div) I OUT (A/div) FLT (5V/div) Time (5ms/div) Time (ms/div) 6 w w w. a n a l o g i c t e c h. c o m

7 Functional Block Diagram Reverse Blocking OUT Under- Voltage Lockout Over-Temp. Protection FLT 4ms Delay ON/ON.V Reference Current Limit Control Functional Description The is a single channel current limiting load switch that is intended to protect against short circuit and over current events by current limiting to a preset level. This device also provides a reverse current blocking feature, on / off enable control, and a fault flag to notify a system controller of an over current, short circuit or over temperature event. In the event of a load current exceeding a user programmed current limit level (I LIM ), a high speed current limit loop limits the current in a microsecond and will reset to low impedance once the short-circuit condition is removed. The 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. This device may operate in a thermal cycling state indefinitely or until the over-current condition is removed. The operates with input voltages ranging from.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.4v, the MOSFET is protected from entering the saturated region of operation by being automatically shutting down via an under-voltage lockout circuit. Current limit or over temperature conditions are reported by the open drain FAULT output. A 4ms blanking interval prevents false reporting during the charging of a capacitive load, which typically occurs during device turn-on, but may also occur during a port hot plug-in event. The is ideally suited for protection of peripheral ports such as USB, RS3, and parallel ports. Reverse Current Blocking The 's reverse current blocking feature prevents current to flow from OUT to when the device is disabled. When the device is enabled, the electrical characteristics between and OUT is still similar to an ideal switch; current can flow in either direction w w w. a n a l o g i c t e c h. c o m 7

8 Application Information Setting the Current Limit In most applications, the variation in I LIM must be taken into account when determining R. The I LIM variation is due to processing variations from part to part, as well as variations in the voltages at and OUT, plus the operating temperature. Together, these three factors add up to a ±5% tolerance (see I LIM specification in "Electrical Characteristics" section). Figure illustrates a cold device with a statistically higher current limit and a hot device with a statistically lower current limit, both with R equal to.5k. While the chart, "R vs. I LIM " indicates an I LIM of.7a with an R of.5k, this figure shows that the actual current limit will be at least.55a and no greater than.875a. Normalized Current Limit (A) A.53A -4 C V OUT (V) 85 C Figure : Current Limit at High and Low Temperature Using.5k To determine R, start with the application required current limit as the minimum current limit value and multiply it by.33 to derive the typical current limit value. Next, refer to Table to find the approximate R value. For greater precision, use the small current limit range linear approximation to calculate R value. For example, for 5mA current limit requirement, first calculate the typical current limit: 5.33 = 665mA. Then refer to Table ; the nearest small current limit range is 6mA to 7mA with ma current limit interval and.45kv R I LIM coefficient interval. Then adopt the method of linear approximation in small range to calculate the R I LIM coefficient. So, R I LIM = R (k ) R =.45 (665-6) 7.5kV 665mA I LIM Typ. (ma) =.3kΩ = 7.5kV R I LMT Coefficient (kv) Table : Current Limit Standard R Values. Input Capacitor The input capacitor C protects the power supply from current transients generated by the load attached to the. When a short circuit is suddenly applied to the output of the, a large current, limited only by the R DS(ON) of the MOSFET, will flow for less than s before the current limit circuitry activates. (See the curve Short Circuit Through.3 in the "Typical Characteristics" section of this datasheet.) In this event, a moderately sized C will dramatically reduce the voltage transient seen by the power supply and by other circuitry upstream from the. The extremely fast short-circuit response time of the reduces the size requirement for C. C should be located as close to the device V pin as practically possible. Ceramic, tantalum, or aluminum electrolytic capacitors are appropriate for C. There is no specific capacitor ESR requirement for C. However, for higher current operation, ceramic capacitors are recommended for C due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. 8 w w w. a n a l o g i c t e c h. c o m

9 Output Capacitor In order to insure stability while current limit is active, a low capacitance (approximately.47 F) is required. No matter how large the output capacitor, output current is limited to the value set by the current limiting circuitry, so very large output capacitors can be used. For example, USB ports are specified to have at least F of capacitance downstream from their controlling power switch. The current limiting circuit will allow an output capacitance of F or more without disturbing the upstream power supply. ON/ON(Enable Input) In many systems, power planes are controlled by integrated circuits which run at lower voltages than the power planes themselves. The enable input (ON) of the has low and high threshold voltages that accommodate this condition. The threshold voltages are compatible with 5V TTL and.5v to 5V CMOS systems. Both active high and active low options are available for all packages. Connecting to Capacitive Load When switching the onto a capacitive load, the will charge the output capacitive load at a rate no greater than the current limit setting. FAULT Output The FAULT Flag (FLT) is provided to alert the system if an load is not receiving sufficient voltage to operate properly. If current limit or over-temperature circuits in any combination are active for more than approximately 4ms, the FAULT Flag is pulled to ground through an approximately resistor. The filtering of voltage or current transients of less than 4ms prevents capacitive loads connected to the output from activating the FAULT Flag when they are initially attached. Pull-up resistances of k to k are recommended. Since FLT is an open drain terminal, it may be pulled up to any unrelated voltage less than the maximum operating voltage of 5.5V, allowing for level shifting between circuits. The FLT Pin is not available for the SOT3-5 package. Thermal Considerations Since the has internal current limit and overtemperature 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. Eq. : T J(MAX) = I MAX OUT-SW(MAX) R DS(ON)(MAX) R ΘJA + T A(MAX) In Equation, I MAX is the maximum current required by the load. R DS(ON)(MAX) is the maximum rated R DS(ON) of the at high temperature. R JA is the thermal resistance between the die and the board onto which it is mounted. T A(MAX) is the maximum temperature that the PCB under the would be if the were not dissipating power. Equation can be rearranged to solve for I MAX, as shown in Equation. Eq. : I MAX = T SD(M) - T A(MAX) R DS(ON)(MAX) R θja T SD(M) is the minimum temperature required to activate the 's over-temperature protection. With the typical specification of 5 C, 5 C is a safe minimum value to use. For example, if an application is specified to operate in 5 C environments, the PCB operates at temperatures as high as 85 C. The application is sealed and its PCB is small, causing R JA to be approximately 5 C/W. Using Equation, Eq. 3: I MAX = =.93(A) w w w. a n a l o g i c t e c h. c o m 9

10 Evaluation Board PCB Layout Figure : Evaluation Board Layout for SOT3-6 and SOT3-5 Package (Top View). Figure 3: Evaluation Board Layout for SOT3-6 and SOT3-5 Package (Bottom View). Figure 4: Evaluation Board Layout for SC7JW-8 Package (Top View). Figure 5: Evaluation Board Layout for SC7JW-8 Package (Bottom View). w w w. a n a l o g i c t e c h. c o m

11 Evaluation Board Schematic TP OUT TP C.47µF 3 U OUT FLT ON/ON C µf TP4 R 6.8K TP5 TP6 ON TP3 FAULT/ R3 6.8K R K Note: Do Not Solder R3 for SOT3-6 Device; Do Not Solder R,R for SOT3-5 Device 3 JP Figure 6: Evaluation Board Schematic for SOT3-6 and SOT3-5 Package. R TP6 ON TP5 TP3 FAULT K TP4 R 6.8K C µf 3 4 U FLT ON/ON OUT C.47µF TP TP OUT JP 3 Figure 7: Evaluation Board for SC7JW-8 Package w w w. a n a l o g i c t e c h. c o m

12 Component Part Number Description Manufacturer C GRM9R6A475KE9 CAP Ceramic F V X5R % 63 Murata C GRM9R6A475KE9 CAP Ceramic.47 FV X5R % 85 Murata JP Device Enable/Disable Selector R Chip Resistor 6.8K, /6W % 63 SMD Vishay R Chip Resistor K, /6W % 63 SMD Vishay R3 Chip Resistor 6.8K, /6W % 63 SMD, for SOT3-5 package device only Vishay TP 5K-ND OUT Keystone TP 5K-ND Keystone TP3 5K-ND FAULT (SOT3-6) / (SOT3-5) Keystone TP4 5K-ND Keystone TP5 5K-ND (for SOT3-6 only) Keystone TP6 5K-ND ON/ON Keystone U AI(GU/GV/JS)-(/)-T Load Switch AnalogicTech Table : Evaluation Board Bill of Materials (BOM). w w w. a n a l o g i c t e c h. c o m

13 Ordering Information Enable Input Package Marking Part Number (Tape and Reel) Active High SOT3-6 5BXYY IGU--T Active High SOT3-5 5CXYY IGV--T Active Low SOT3-6 8YXYY IGU--T Active Low SOT3-5 9GXYY IGV--T Active Low SC7JW-8 IJS--T Active High SC7JW-8 5DXYY IJS--T 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.% by weight in homogeneous materials. For more information, please visit our website at Package Information SOT ±.5.95 BSC.9 BSC.75 ± ±.5.4 ±. 6. ±.. ±.5.8 ±. ± 5 4 ± 4.6 REF.5 ±.7.45 ±.5. BSC GAUGE PLANE All dimensions in millimeters.. XYY = assembly and date code.. Sample stock is generally held on part numbers listed in BOLD w w w. a n a l o g i c t e c h. c o m 3

14 SOT ±.5.9 BSC.95 BSC.575 ±.5.8 ±..6 REF. ±.. ±.5.5 ±.7 GAUGE PLANE ± 5.4 ±..75 ±.75 4 ± 4.6 REF.45 ±.5. BSC SC7JW-8.5 BSC.5 BSC.5 BSC.75 ±.. ±..5 ±.75. ±..85 ±.5. MAX.5 ± ±. 7 ± 3 4 ± 4.48REF.5 ±.5. ±.3 All dimensions in millimeters. 4 w w w. a n a l o g i c t e c h. c o m

15 Revision History Date Revision Edits 5/6/ New version of the added for release; ordering information updated to include the part marking 9GXYY and the part number has been bolded Advanced Analogic Technologies, Inc. 33 Scott Boulevard, Santa Clara, CA 9554 Phone (48) Fax (48) 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 specifi cations or to discontinue any product or service without notice. Except as provided in AnalogicTech s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fi tness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specifi c 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 w w w. a n a l o g i c t e c h. c o m 5