OB3636Ax is a flyback power switch with high power factor, low THD and high constant voltage (CV) precision. It can achieve low system cost for an isolated application by primary side control in a single stage converter. It significantly simplifies the CV system design by eliminating the secondary side feedback components and the opto-coupler.

The proprietary CV 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 fast start-up time requirement.

OB3636Ax offers comprehensive protection including open circuit protection, short circuit protection, over load protection, cycle-by-cycle current limiting, built-in leading edge blanking, VDD under voltage lockout (UVLO), etc.


OB3636Ax is offered in SOP7 and CDFN8-6 package.


n High precision constant voltage regulation

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

n High PF (>0.9)

n Low THD (<10%)

n Fast start-up

n Low system cost and high efficiency

n Quasi-resonant operation

n Short circuit protection

n Open circuit protection

n Cycle-by-cycle current limiting

n Built-in leading edge blanking (LEB)

n VDD under voltage lockout with hysteresis (UVLO)

n VDD over voltage protection

n Over temperature protection (OTP)

n Over load protection (OLP)

n Audio Noise Free



n LED lighting


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