top of page

High Performance QR mode Primary-Side Power Switch


  • OB2571x is an excellent primary side regulation controller with CC/CV operation for medium level power AC/DC charger and adapter applications. The device integrates an internal power MOSFET and operates in QR mode to provide high  efficiency along with several functions of builf-in protections. lt removes the need for secondary feedback circuitry to lower the total bill of material cost. Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below.
    ln CV control, the controller changes the mode of operation according to load condition, At full loading. the controller operates in  quasi-resonant (OR) mode in the universal line voltage, The primary side regulation power supplies up to high power without the efficiency limitation of DCM or audible noise.
    ln CC control, OB2571x samples the Vcs peak current and the demagnetization pulse to regulation the output current The current and output power setting can be adjusted externally by the sense resistor Rs at CS pin.
    OB2571x offers comprehensive protection coverage with auto-recovery feature including  Cycle-by-Cycle current limiting, VDD OVP , OLP , SCP , OTP , etc.
    OB2571x consumes less than 75mW input power at no-load condition with high line voltage,
    OB2571x is offered in SOP8 package.

bottom of page