OB3655 is an offline LED lighting controller with 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. It significantly simplifies the LED lighting system design by eliminating the secondary side feedback components and the opto-coupler.


The system uses the 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 and load compensation are built in OB3655 for high precisely constant output current control.


OB3655 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.


OB3655 is offered in SOT23-6 package.


n High precision constant current regulation at universal AC input

n Fast start-up (<0.5s)

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

n Low system cost and high efficiency

n Quasi-resonant operation

n Programmable CC regulation

n Built-in primary winding inductance compensation

n Built-in line compensation

n Built-in load 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 Thermal fold-back control




n LED lighting