OB2506x is a highly integrated current mode PFM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications.

Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below. In CC control, the current and output power setting can be adjusted externally by the sense resistor Rs at CS pin. In CV control, multi-mode operations are utilized to achieve high performance and high efficiency. Device operates in PFM in CC mode at heavy load condition and it operates in PWM with frequency reduction at medium load. When the load is very small, the IC operates in ‘Extended Burst Mode’ to minimize the standby power loss. As a result, high conversion efficiency can be achieved in the whole loading range.  

OB2506x offers comprehensive protection coverage with auto-recovery feature including Cycle-by-Cycle current limiting, VCC over voltage protection, built-in leading edge blanking, VCC under voltage lockout (UVLO), OTP etc.

OB2506x is offered in SOP8 and DIP8 packages.

Figure.1. Typical CC/CV Curve


   Extended burst mode control for improved efficiency and low standby power design

   High precision constant voltage and current regulation at universal AC input

   Multi-mode PWM/PFM operation for efficiency improving

   Integrated 1A/2A MOSFET

   Programmable CV and CC regulation

   Built-in primary winding inductance compensation

   Built-in leading edge blanking (LEB)

   Ultra low start-up current and low operating current.

   Comprehensive protection coverage with auto-recovery

o    On-chip OTP

o    VCC over voltage protection

o    VCC under voltage lockout with hysteresis (UVLO)

o    Cycle-by-Cycle current limiting

o    Output over voltage protection



Offline AC/DC flyback converter for

   General power supply

   Power Adapter