OB2736 is a highly integrated high frequency Quasi-Resonant(QR) controller with adaptive multi-mode regulation, optimized for high performance, low EMI, low standby power consumption and wide output voltage range GaN FETs PD adapter solutions, together with PD secondary controller, such as OB2613. The controller is as well compatible with cost effective offline flyback converter applications covering a wide output range.

With On-Bright proprietary technology, OB2736 operates in QR Valley lockout operation in high line input voltage at normal load condition. To minimize switching loss, the maximum average switching frequency in QR mode is internally limited to 225KHz. As the load decreases, at light load, it operates in Fast frequency decreasing mode with lower frequency for high power conversion efficiency. When the load is very small, the IC operates in ‘Extended Burst Mode’ to minimize the standby power loss. Additionally, in the low line input voltage, the IC operates in fixed frequency (100KHz) CCM mode at the heavy loading. As a result, high conversion efficiency can be achieved in the whole loading range.

High voltage startup is implemented in OB2736, which features with short startup time and low standby power loss.

OB2736 offers complete protection including brownout protection, cycle-by-cycle current limiting (OCP), over load protection (OLP), over temperature protection (OTP), output short protection (SCP), output and VDD over voltage protection.  Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique.

The tone energy at below 22KHz is minimized to avoid audio noise during operation.

OB2736 is offered in SOP8 package.


   Multi-Mode Operation

225KHz max. average frequency  in QR mode @ high line

100KHz min. average frequency in CCM mode @ low line

Valley lockout operation @ Green Mode

Fast frequency decreasing(FFD) @Light load

Burst Mode @ Deep Light Load & No Load

   Precise low voltage gate clamping to drive GaN Power FETs

   Adaptive loop gain compensation with load detection

   Extended burst mode control for improved efficiency and low standby power

   Power on soft start reducing MOSFET Vds stress

   Adaptive frequency shuffling for EMI

   Low operating current at no/light load

   Audio noise free operation

   High voltage startup integrating intelligent brownout detection, AC off detection with X-CAP discharge function

   Comprehensive auto-recovery protection

o    VDD under voltage lockout with hysteresis (UVLO)       

o    Cycle-by-cycle over current protection (OCP)

o    Overload protection (OLP)

o    Over temperature protection (OTP)

o    VDD over voltage protection

o    Output over voltage protection

o    Output short protection (SCP)

o    Brownout protection

o    Output diode short protection


Offline AC/DC flyback converter for

   High power density GaN FETs  PD adapters