OB2538

On-Bright Confidential to ACT OB2538 High Precision CC/CV Primary-Side PWM Controller Product Specification GENERAL DESCRIPTION OB2538 is a high performance offline PWM Power switch for low power AC/DC charger and adaptor applications. It operates in primary-side sensing and regulation. Consequently, opto-coupler and TL431 could be eliminated. Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below. In CC control, the current and output power setting can be adjusted externally by the sense resistor Rs at CS pin. In CV control, multi-mode operations are utilized to achieve high performance and high efficiency. In addition, good load regulation is achieved by the built-in cable drop compensation. Device operates in PFM in CC mode as well at large load condition and it operates in PWM with frequency reduction at light/medium load. OB2538 offers power on soft start control and protection coverage with auto-recovery features including Cycle-by-Cycle current limiting, VDD OVP, VDD clamp and UVLO. Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique. High precision constant voltage (CV) and constant current (CC) can be achieved by OB2538. . FEATURES „ 5% Constant Voltage Regulation, 5% Constant Current Regulation at Universal AC input „ Primary-side Sensing and Regulation Without TL431 and Opto-coupler „ Programmable CV and CC Regulation „ Adjustable Constant Current and Output Power ...