OB2019 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, increase output current capability and efficiency and simplify thermal design. It can support wide range of system output voltage 3V~15V.

It is suitable for multiple mode applications including discontinuous conduction mode (DCM), quasi-resonant mode (QR) and continuous conduction mode (CCM). Especially for CCM, to guarantee system reliability, super fast SR turn-off comparator and soft gate driver are used to reduce the whole propagation delay in SR turn-off control path.

To avoid the ring impact induced by parasitic elements, the innovative property ring detection is implemented on chip to prevent SR turn on falsely so that a reliable and noise free operation of the SR system is insured.

In addition, the Vds voltage is regulated to about -20mV through on-chip soft gate driver control regardless of Rdson of SR MOSFET to achieve more reliable operation

OB2019 is offered in SOT23-6 package.


   Secondary-side synchronous rectifier for 3V~15V output system

   Up to 85V VD pin high voltage tolerance

   Self-supplying for operation without auxiliary winding

   Suitable for DCM, QR and CCM operation

   Soft gate drive for fast turn-off

   Accurate secondary side MOSFET Vds sensing

   Innovative property ring detection to avoid the ring impact induced by parasitic elements

   2.5A/0.4A peak current sink/source driver capability

   VDD UVLO protection


   AC/DC 3V~15V chargers/adaptors

   Low voltage rectification circuits