120mΩ, 1.8A Power Switch with Adjustable Current Limit


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The RT9728B is a cost effective, low voltage, single P-MOSFET power switch IC for USB application with a adjustable current limit feature. Low switch-on resistance (typ. 120mΩ) and low supply current (typ. 120μA) are realized in this IC. The RT9728B offers a adjustable current limit threshold between 75mA and 1.8A (typ.) via an external resistor. The ±10% current limit accuracy can be realized for all current limit settings. In addition, a flag output is available to indicate fault conditions to the local USB controller. Furthermore, the chip also integrates an embedded delay function to prevent mis-operation due to high inrush current. The RT9728B is an ideal solution for USB power supplies and can support flexible applications since it is suitable for various current limit requirements. It is available in the SOT-23-6 and WDFN-6L 2x2 packages.


  • USB Bus/Self Powered Hubs
  • USB Peripheral Ports
  • ACPI Power Distribution
  • Battery Power Equipment
  • 3G/3.5G Data Card, Set-Top Boxes
Key Spec.
Status Active
Number of Outputs 1
Vin (min) (V) 2.5
Vin (max) (V) 5.5
Ron (typ) (mOhm) 120
Iq (typ) (mA) 0.12
Current Limit (typ) (A) 1.8
FLAG Indicator Yes
Iocp Adjustable Yes
Switch Type Power Switch
Features Adjustable Current Limit;Cycle-by-Cycle Current Limit;Enable Input;SCP
Package Type SOT-26;WDFN2x2-6
  • ±10% Current Limit Accuracy @ 1.3A
  • Adjustable Current Limit : 75mA to 1.8A (typ.)
  • Meet USB Current Limiting Requirements
  • Operating Voltage Range : 2.5V to 5.5V
  • Reverse Input-Output Voltage Protection
  • Built-in Soft-Start
  • 120mΩ P-MOSFET
  • 120μA Supply Current
  • RoHS Compliant and Halogen Free
TitleLast UpdateShareDownload
120mΩ, 1.8A Power Switch with Adjustable Current Limit2013/06/19
Technical Documents
TitleLast UpdateShareDownload
Richtek Selection Guide [Oct., 2020]2020/12/30
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT9728BHGQWWDFN2x2-62500 Not available Buy from Distributor
RT9728BLGESOT-263000 Not available Buy from Distributor
RT9728BLGQWWDFN2x2-62500 Not available Buy from Distributor