OB3398 is a primary side regulation off-line LED lighting controller which can achieve accurate LED current. It significantly simplifies LED lighting system design by eliminating the secondary side feedback circuitry. Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below.

The LED current (CC control) can be adjusted externally by the resistor Rs at CS pin.

OB3398 offers comprehensive protection coverage with auto-recovery features including Cycle-by-Cycle current limiting, VDD clamp and UVLO. Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique.

OB3398 is offered in SOT23-5 package.

Fig.1. Typical CC/CV Curve



n High Precise Constant Current Regulation at Universal AC input

n Primary-side Sensing and Regulation Without TL431 and Opto-coupler

n Floating PSR control scheme with two transformer windings

n Adjustable Constant Current and Output Power Setting

n Built-in Primary winding inductance compensation

n Built-in Leading Edge Blanking (LEB)

n Cycle-by-Cycle Current Limiting

n VDD Under Voltage Lockout with Hysteresis (UVLO)

n Over temperature protection (OTP)

n VDD Clamp



Low Power AC/DC offline SMPS for

n LED applications



Application Schematic 1


Application Schematic 2