OB OB2538AP

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. 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 is a cost effective PWM power switch optimized for off-line low power AC/DC applications including battery chargers and adaptors. It operates in primary side sensing and regulation, thus opto-coupler and TL431 are not required. Proprietary built-in CV and CC control can achieve high precision CC/CV control meeting most adaptor and charger application requirements.

• 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 Setting
• Built-in Secondary Constant Current Control with Primary Side Feedback
• Built-in Adaptive Current Peak Regulation
• Built-in Primary winding inductance compensation
• Programmable Cable drop Compensation
• Power on Soft-start
• Built-in Leading Edge Blanking (LEB)
• Cycle-by-Cycle Current Limiting
• VDD Under Voltage Lockout with Hysteresis (UVLO)
• VDD OVP
• VDD Clamp

• Cell Phone Charger
• Digital Cameras Charger
• Small Power Adaptor
• Auxiliary Power for PC, TV etc.
• Linear Regulator/RCC Replacement