120mΩ, 1.3A Power Switch with Programmable Current Limit


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The RT9728A is a cost effective, low voltage, single P-MOSFET high-side power switch IC for USB application with a programmable current limit feature. Low switch-on resistance (typ.120mΩ) and low supply current (typ. 120μA) are realized in this IC. The RT9728A offers a programmable current limit threshold between 75mA and 1.3A (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 from happening due to high inrush current. The RT9728A is an ideal solution for USB power supply and can support flexible applications since it is functional for various current limit requirements. It is available in 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
  • Networked Communication
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) 1.3
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 1.3A (typ.)
  • Meet USB Current Limiting Requirements
  • Operating Voltage Range : 2.5V to 5.5V
  • Reverse Input-Output Voltage Protection
  • Built-in Soft-Start
  • 120mΩ High-Side MOSFET
  • 120μA Supply Current
  • RoHS Compliant and Halogen Free
TitleLast UpdateShareDownload
120mΩ, 1.3A Power Switch with Programmable Current Limit2011/01/25
Technical Documents
TitleLast UpdateShareDownload
Richtek Selection Guide [Oct., 2020]2020/12/30
Part NumberPackage TypePackage Qty.Free SampleBuy From Authorized Distributor
RT9728AHGESOT-263000 Not available Buy from Distributor
RT9728AHGQWWDFN2x2-62500 Not available Buy from Distributor
RT9728AHZQWWDFN2x2-62500 Not available Buy from Distributor
RT9728ALGESOT-263000 Not available Buy from Distributor
RT9728ALZQWWDFN2x2-62500 Not available Buy from Distributor