OB3338B is a dimmable offline LED lighting controller with high power factor, low THD and high constant current (CC) precision. It can achieve low system cost for an isolated lighting application by primary side control in a single stage converter.


The proprietary CC control scheme is used and the system can achieve high power factor with constant on-time control scheme. Quasi-resonant (QR) operation and clamping frequency greatly improves the system efficiency. The advanced start-up technology is used to meet the start-up time requirement (<0.5s). The constant output current is compensated for tolerance of transformer inductance variation. And the line compensation is built in OB3338B for high precisely constant output current control.

OB3338B offers a dimmable function, the LED current can be controlled by setting the duty cycle of PWM waveform into the DIM pin.

OB3338B offers comprehensive protection coverage with auto-recovery features including LED open loop protection, LED short circuit protection, cycle-by-cycle current limiting, built-in leading edge blanking, VDD under voltage lockout (UVLO), etc.


OB3338B is offered in SOP8 package.


n Dimmable LED current control

n Primary-side sensing and regulation without TL431 and opto-coupler

n High precision constant current regulation at universal AC input

n High PF

n Low THD

n Fast start-up

n Quasi-resonant operation

n Built-in line compensation

n LED short circuit protection

n LED open loop protection

n Cycle-by-cycle current limiting

n Built-in leading edge blanking (LEB)

n VDD under voltage lockout with hysteresis

n VDD over voltage protection

n Over temperature protection (OTP)



n LED lighting