OB2001xK is a high performance and tightly integrated secondary side synchronous rectifier for switch mode power supply system. It combines a much lower voltage drop N-channel MOSFET to emulate the traditional diode rectifier at the secondary side of Flyback converter, which can reduce heat dissipation, increases output current capability and efficiency and simplify thermal design. OB2001xK can support low system output voltage down to 2V at constant current mode.

It is suitable for multiple mode applications including discontinuous conduction mode and quasi-resonant mode. With its versatility and optimization, OB2001xK can be used in various switch mode power supply topologies including secondary-side control topology and primary-side control topology.

From the information on the secondary side of the isolation transformer, OB2001xK generates a driving signal with dead time with respect to the primary side PWM signal to turn the integrated N-channel SR switch on and off in proximity of the zero current transition. It is optimized for 5V output voltage.

The externally adjustable minimum on time and property off time control scheme effectively avoid the ring impact induced by parasitic elements so that a reliable and noise free operation of the SR system is insured.

OB2001xK is offered in SOP8 package.


   Secondary-side synchronous rectifier optimized for 5V output system

   Suitable for DCM, QR operation

   Accurate secondary side MOSFET Vds sensing

   Low cost small size CC/CV mode support

   Up to 200kHz operation frequency

   Output voltage overshoot control

   VDD UVLO protection



   AC/DC 5V adaptors

   Cell phone charger

   5V Bias supply

   Low voltage rectification circuits