GENERAL DESCRIPTION
OB2305C is a high performance offline PSR controller for low power AC/DC charger and adapter 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 at large load condition and it operates in PWM with frequency reduction at light/medium load. The chip consumes very low operation current. It achieves less than 30mW standby power to meet strict standby power standard.
OB2305C offers comprehensive protection coverage with auto-recovery feature including Cycle-by-Cycle current limiting, VDD over voltage protection, feedback loop open protection, short circuit protection, built-in leading edge blanking, VDD under voltage lockout (UVLO), OTP etc.
OB2305C is offered in SOT23-6 package (for up to 10W application) and SOP8 package (for up to 15W application).
Figure.1. Typical CC/CV Curve
FEATURES
Primary-side sensing and regulation without TL431 and opto-coupler
High precision constant voltage and current regulation at universal AC input
Multi-mode PWM/PFM operation for efficiency improving
Less than 30mW standby power consumption at 230V with typical application circuit
Programmable CV and CC regulation
Built-in dynamic signal detection from 2nd-side synchronous rectification
Built-in line voltage and primary winding inductance compensation
Programmable cable drop compensation
No need for control loop compensation
Precise internal over temperature protection
Audio noise free operation
Built-in leading edge blanking (LEB)
Ultra low start-up current and low operating current
Comprehensive protection coverage with auto-recovery
VDD over voltage protection
VDD under voltage lockout with hysteresis (UVLO)
Cycle-by-cycle current limiting
Feedback loop open protection
Output short circuit protection
Over temperature protection (OTP)
APPLICATIONS
Low Power AC/DC offline SMPS for
Cell Phone Charger
Digital Cameras Charger
Small Power Adapter
Auxiliary Power for PC, TV etc.
Linear Regulator/RCC Replacement