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AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 1 - DESCRIPTION FEATURES The A4788 is intended for applications where heavy capacitive loads and short circuits are likely to be encountered. The A 4788 is an integrated 80mΩ (TYP) power switch for self-powered and bus powered universal series bus (USB) applications. The A4788 is internally current limited and has thermal shutdown function to protect device and load from over-current damage. Thermal shutdown shuts off the output MOSFET and asserts the flag pin output if the die temperature exceeds 150°C until the die temperature drops to 130°C. The soft-start circuit can minimize inrush current in applications where highly capacitive loads are employed. The flag pin asserts low when during over-current and thermal conditions after a 13ms blanking time to prevent false reporting. The A4788 is available in SOT-25 packages.
ORDERING INFORMATION
SPQ:3,000/Reel E5 A4788E5R-X A4788E5VR-X Note X=Maximum Current A:1.1A B:2.1A C:2.6A V: Halogen free Package R: Tape & Reel AiT provides all RoHS products 80mΩ (TYP) High-side P-Channel MOSFET Low Quiescent Current Input Voltage from 2.5V to5.5V Three Current Limit Levels 1.1A, 2.1A, 2.6A Maximum Shutdown Current ≤1uA Soft-Start Function Under-Voltage Lockout Protection for VIN No Reversed Leakage Current Thermal Shutdown Protection Fast turn on response Operation temperature from -40°C to 85°C APPLICATION Smart Phone & LCD TV Set-Top-Box VOIP USB Bus/Self Powered Hubs/Peripherals Portable Consumer or Medical Products TYPICAL APPLICATION
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 2 - PIN DESCRIPTION SOT-25, E5 Top View Pin# Symbol Function SOT-25
1 V OUT
Switch Output. The P-Channel Drain of Switch, Which Typically Connects to Load.
2 GND Ground
3 FLAG
Flag pin. Active low, open-drain output. Indicates over-current or thermal shutdown conditions. Over-current condition must last longer than tD in order to assert Flag. 4 EN Enable Input. Logic Level Enable Input, Active high available.
5 V IN
Power Supply Input. The P-Channel Source of Switch, Which also supplies IC’s internal circuitry. Connect to Positive Supply.
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 3 - ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range, (unless otherwise noted)* VIN, Supply Input Voltage -0.3V ~ 6.0V VOUT, Output Voltage -0.3V ~ 6.0V VEN, EN Input Voltage -0.3V ~ 6.0V VFLAG, FLAG Output Voltage -0.3V ~ 6.0V TJ, Operating Junction Temperature -40℃ ~ 150℃ TSTG, Storage Temperature -65℃ ~ 150℃ TL, Lead Temperature Soldering, 10secs 260℃ ESD Ratings V(ESD), Electrostatic Discharge Human-body model (HBM) ±3000V Charge device model (CDM) ±1500V *Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. *Voltages are with respect to the GND pin. RECOMMENDED OPERATING CONDITIONS Over operating free-air temperature range (unless otherwise noted) Parameter Symbol Min. Max. Unit Input Voltage V IN 2.5 5.5 V EN Voltage range V EN 0 5 . 5 V All other pins 0 5.5 V Operating temperature T A -40 +85 ℃ Operating Junction Temperature Range T J -40 +125 ℃
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 4 -
ELECTRICAL CHARACTERISTICS
VIN=2.5V~5.5V，typical values are at VIN=5V, TA = 25°C, unless otherwise noted. Parameter Conditions Min Typ Max Unit VIN Input Voltage 2.5 - 5.5 V IQ Quiescent supply current Switch on, V OUT = open - 30 - μA ISD Shutdown supply current Switch off, V OUT = open - 0.1 - μA ILKG(VIN) Leakage current of VIN & FLAG Switch off, V OUT = 0V - 0.1 10 μA VOC-L FLAG Output Low Voltage C IN=10uF, ISINK =2mA - - 0.4 V VIL Enable input threshold VIN =2.5V to 5.5V - - 0.4 V VIH V IN =2.5V to 5.5V 16 - - V IEN EN input current VEN=0V to 5.5V - 10 - μA RDS(ON) Switch resistance I OUT = 500mA - 80 - mΩ tON Output turn-on delay time R L =10Ω, CL = 1 μ F - 2 - m s tOFF Output turn-off delay time R L =10Ω, CL =1μF - 20 - μs A4788-A Current limit threshold Ramped load - 1.1 - A A4788-B - 2.1 - A A4788-C - 2.6 - A tD Over-current FLAG response delay time Apply VOUT= 0 until FLAG is low - 13 - ms RFLAG FLAG output resistance FLAG is low and I SINK =10mA - 20 - Ω RDIS VOUT shutdown discharge resistance Switch off - 300 - Ω TSD Thermal shutdown temperature T J Increasing - 150 - ℃ TSD_HY Thermal shutdown hy steresis Apply V OUT= 0 until FLAG is low - 30 - ℃
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 5 - TYPICAL PERFORMANCE CHARACTERISTICS Fig1 Turn-On Rise Time vs Temperature Fig2 Turn-On Rise Time vs Input Voltage Fig3 Turn-Off Fall Time vs Temperature Fig4 Turn-Off Fall Time vs Input Voltage Fig5 UVLO Threshold vs Temperature Fig6 Output Leakage Current vs Te mperature
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 6 - Fig7 Shutdown Supply Current vs Temperature Fig8 Shutdown Supply Current vs Input Voltage Fig9 Quiescent Supply Current vs Temperature Fig10 Quiescent Supply Current vs Input Voltage Fig11 Enable Threshold vs Temperature Fig12 Enable Threshold vs Input Voltage
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 7 - Fig13 On Resistance vs Temperature Fig14 On Resistance vs Input Voltage Fig15 FLAG Response Delay Time vs Temperature Fig16 FLAG Respons e Delay Time vs input Voltage Fig17 Short-Circuit Current Limit vs Temperature Fig18 Short-Ci rcuit Current Limit vs Input Voltage
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 8 - Fig19 Current Limit Threshold vs Temperature Fig20 Current Limit Threshold vs Temperature Fig21 Turn-On Response Fig22 Tu rn-Off Response Fig23 UVLO at VIN Rising Fig24 UVLO at V IN Falling
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 9 - Fig25 NO Loaf into Short-Circuit Fig26 Device Enabled into Shor t-Circuit Fig27 Short-Circuit Response Time
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 10 - BLOCK DIAGRAM
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 11 - PARAMETER MEASUREMENT INFORMATION Fig1 Switch Turn-On and Turn-Off Delay Times Fig2 Fault Timing: Output Reset by Toggling EN Fig3 Fault Timing: Output Reset by Removing Load
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 12 - DETAILED INFORMATION Input and output VIN is the power supply connection to the logic circuitry and the source of the P-channel MOSFET. VOUT is the drain of the P-channel MOSFET. In a typical circuit, current flows from VIN to VOUT toward the load. The output P-channel MOSFET and driver circuit are also designed to allow the MOSFET drain to be externally forced to a higher voltage than the source (VOUT > VIN) when the switch is disabled. Thermal Shutdown Thermal shutdown is employed to protect device and load from damage. It shuts off the output MOSFET and asserts the FLAG output, if the die temperature exceeds 150°C until the die temperature drops to 130°C. Soft-Start In order to eliminate the upstream voltage sag caused by the la rge inrush current during hot-plug events, the soft-start feature effectively isolates power supplies from such highly capacitive loads. Current limiting and short protection The current limit circuit is designed to limit the output current to protect the upstream power supply. The typical current limit threshold is set by internally to approximately 1 .1A, 2.1A and 2.6A. Under output short-circuit condition, the typical current limit folded back 75%. If the chip keeps at over-current condition for a long time. the junction temperature may exceed 150°C, and over-temperature protection will shut down the output until Supply Filtering temperature dops below 130°C or limit (short) condition is removed. Reverse-voltage protection The reverse-voltage protection f eature turns off the P-MOSFT sw itch whenever the output voltage exceeds the input voltage by 40mV. FLAG output The FLAG signal is an open-drain output pin. FLAG is asserted w hen an over-current or thermal shutdown condition occurs, and active low output. In the case of an over -current condition, FLAG will be asserted only after the response delay time (t D) has elapsed. This ensures that FLAG is asserted only upon valid over-current conditions and that erroneous error reporting is eliminated. Fo r example, false over-current conditions can occur during hot-plug events when a highly capacitive load is c onnected and causes a high transient inrush current that exceeds the current limit threshold for up to 1ms, The FLAG response delay time tD is about 13ms. Power dissipation. The device’s junction temperature depends on several factors su ch as the load, PCB layout, ambient temperature, and package type. Equations that can be used to ca lculate power dissipation and junction temperature are found below: PD=RDS(ON) x IOUT2 To relate this to junction temperature, the following equation can be used: TJ = PD x θJA + TA Where: T J = junction temperature TA = ambient temperature θJA = the thermal resistance of the package
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 13 -
APPLICATION INFORMATION
In order to prevent the input voltage drooping during hot-plug events, connect a ceramic capacitor CIN from VIN to GND. The C IN is positioned close to V IN and GND of the device. However, higher capacitor values could reduce the voltage sag on the input further. Furthermore, an output short will cause ringing on the input without the input capacitor. It could destroy the internal circuitry when the input transient exceeds 6V which is the absolute maximum supply voltage even for a short duration. If the upstream supply cable is long or the V IN transient exceeds 6V during the VOUT short, recommend adding a second filter capacitor (not less than 47μF) at the upstream supply output terminal Output filter capacitor Between V OUT and GND, connect a low-ESR 10μF ceramic capacitor to meet the 330mV maximum drop requirement. Standard bypass methods should be used to minimize inductance and resistance between the bypass capacitor and the down-stream connector. This will reduce EMI and improve the transient performance. If long cables are connected to the output terminals, an anti-p arallel schottky diode such as BAT54 is suggested to be placed in parallel with the output terminals to absorb the negative ringing due to the cable inductance. PCB layout guide For best performance of the A4788, the following guidelines must be strictly followed: (1) Keep all power line as short and wide as possible and use at least 2-ounce copper for all power line. (2) Dual low-ESR 10μF ceramic capacitors between V OUT and GND, VIN and GND. (3) Locate the output capacitor as close to the connectors as p ossible to lower impedance between the port and the capacitor and improve transient performance. (4) Input and output capacitors should be placed closed to the chip and connected to ground plane to reduce noise coupling. (5) Locate the ceramic bypass capacitors as close as possible to the V IN pin and VOUT pin.
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 14 -
PACKAGE INFORMATION
Dimension in SOT-25 (Unit: mm) Symbol Millimeters Min Max A 1.050 1.250 A1 0.000 0.100 A2 1.050 1.150 b 0.300 0.500 c 0.100 0.200 D 2.820 3.020 E 1.500 1.700 E1 2.650 2.950 e 0.950 BSC E1 1.800 2.000 L 0.300 0.600 θ 0 8
AiT Semiconductor Inc. A4788 www.ait-ic.com POWER SWITCH 1.1A_2.1A_2.6A CURRENT LIMITED W/FLAG POWER SWITCH REV1.0 - MAR 2022 RELEASED - - 15 - IMPORTANT NOTICE AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, to discontinue any integrated circu it product or service without n otice, and advises its customers to obtain the latest version of relevant information to verify, before placin g orders, that the information being relied on is current. AiT Semiconductor Inc.'s integrat ed circuit products are not de signed, intended, authorized, or warranted to be suitable for use in life support applications, devices or sy stems or other critical applications. Use of AiT products in such applications is understood to be fully at the risk of the customer. As used herein may involve potential risks of death, personal injury, or servere property, or environmental damage. In order to minimize risks associated with the customer's applications, the customer should provide adequate design and operating safeguards. AiT Semiconductor Inc. assumes to no liability to customer product design or application support. AiT warrants the performance of its products of the specifications applicable at the time of sale.