GENERAL DESCRIPTION

OB3639A is an 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. It significantly simplifies the LED lighting system design by eliminating the secondary side feedback components and the opto-coupler.

The proprietary CC control is used and the system can achieve high power factor with constant on-time control. Quasi-resonant (QR) operation and clamping frequency greatly improve 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 OB3639A for high precisely constant output current control.

OB3639A offers comprehensive protection coverage with auto-recovery features including programmable VIN foldback, programmable VIN OVP, programmable thermal foldback, LED open loop protection, LED short circuit protection, cycle-by-cycle current limiting, built-in leading edge blanking, VDD under voltage lockout (UVLO), etc.

OB3639A is offered in SOP-8 package.

FEATURES

High PF (>0.9)

Low THD (<10%)

Programmable VIN foldback

Programmable VIN OVP

Programmable thermal foldback

High precision constant current

Fast start-up (<0.5s)

Low system cost and high efficiency

Quasi-resonant operation

Programmable CC regulation

Built-in line/load compensation

LED short circuit protection

LED open loop protection

Cycle-by-cycle current limiting

VDD over voltage protection

Up to 80W application

APPLICATIONS

n LED lighting

TYPICAL APPLICATION

Application Schematic 1:  Vin_ovr_min/Vin_bro≤3.4

Application Schematic 2:  Vin_ovr_min/Vin_bro≥3.4