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RT9741
100mΩ, 1.5A/0.7A High-Side Power Switches
General Description
The RT9741 is a cost-effective, low-voltage, single NMOSFET high-side Power Switch IC for USB application. Low switch-on resistance (typ. 100mΩ) and low supply current (typ. 50μA) are realized in this IC.
The RT9741 integrates an over-current protection circuit, a short fold back circuit, a thermal shutdown circuit and an under-voltage lockout circuit for overall protection. Furthermore, the chip also integrates an embedded delay function to prevent miss-operation from happening due to inrush-current. The RT9741 is an ideal solution for USB power supply and can support flexible applications since it is available in the SOT-23-3 package.
Ordering Information
RT9741 Package Type V : SOT-23-3 Lead Plating System G : Green (Halogen Free and Pb Free) Output Current A : 1.5A C : 0.7A
Note : Richtek products are :
RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
Features
100mΩ (typ.) N-MOSFET Switch Operating Range : 2.7V to 5.5V Reverse Blocking Current Under-Voltage Lockout Thermal Protection with Foldback Over-Current Protection Short-Circuit Protection RoHS Compliant and Halogen Free
Applications
USB Peripherals Notebook PCs
Marking Information
RT9741AGV 4F=DNN
4F= : Product Code DNN : Date Code
RT9741CGV 4D=DNN
4D= : Product Code DNN : Date Code
Simplified Application Circuit
Supply Voltage 2.7V to 5.5V
RT9741
VIN CIN
VOUT
GND
FB COUT
FB
+
VBUS D+ DGND
Copyright ©2015 Richtek Technology Corporation. All rights reserved. DS9741-01 March 2015
Data
is a registered trademark of Richtek Technology Corporation.
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RT9741
Pin Configurations
(TOP VIEW)
GND
3
2
VIN VOUT SOT-23-3
Function Block Diagram
Bias Oscillator
UVLO
Charge Pump
Thermal Protection
Functional Pin Description
Pin No. Pin Name
Pin Description
1 VIN
Power Input.
2 VOUT
Output Voltage.
3 GND
Ground.
Current Limiting
Gate Control
Output Voltage Detection
Auto Discharge
VIN
VOUT GND
Operation
Charge Pumps and Drivers An internal charge pump supplies power to the driver circuit and provides the necessary voltage to pull the gate of the MOSFET above the source. The driver controls the gate voltage of the power switch.
Current Limit The RT9741 continuously monitors the output current for over-current protection to protect the system power, the power switch, and the load from damage during output short circuit. When an overload or short circuit occurs, the current-sense circuitry sends a control signal to the driver. The driver reduces the gate voltage and drives the power MOSFET into its saturation region, which switches the output into a constant-current mode and holds the current constant until the thermal shutdown occurs or the fault is removed.
Under-Voltage Lockout A voltage-sense circuit monitors the input voltage. When the input voltage is below approximately 1.3V, UVLO turns off the MOSFET switch.
Thermal Shutdown The RT9741 continuously monitors the operating temperature of the power switch for over-temperature protection. The RT9741 turns off the power switch to prevent the device from damage if the junction temperature rises to approximately 120°C due to over-current or shortcircuit conditions.
The pass element turns on again after the junction temperature cools to 80°C. The
RT9741 lowers its OTP trip level from 120°C to 100°C when output short circuit occurs (VOUT < 1V).
Copyright ©2015 Richtek Technology Corporation. All rights reserved.
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is a registered trademark of Richtek Technology Corporation.
DS9741-01 March 2015
RT9741
Absolute Maximum Ratings (Note 1)
Supply Input Voltage, VIN ----------------------------------------------------------------------------------------------- 6V Power Dissipation, PD @ TA = 25°C
SOT-23-3 -------------------------------------------------------------------------------------------------------------------- 0.41W Package Thermal Resistance (Note 2)
SOT-23-3, θJA --------------------------------------------------------------------------------------------------------------- 243.3°C/W Junction Temperature ----------------------------------------------------------------------------------------------------- 150°C Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------------- 260°C Storage Temperature Range -------------------------------------------------------------------------------------------- −65°C to 150°C ESD Susceptibility (Note 3)
HBM (Human Body Model) ---------------------------------------------------------------------------------------------- 2kV
Recommended Operating Conditions (Note 4)
Supply Input Voltage, VIN ----------------------------------------------------------------------------------------------- 2.7V to 5.5V Junction Temperature Range -------------------------------.