OB2370T is a high performance offline PSR power switch for low power AC/DC charger and adapter applications. The device integrated an internal power MOSFET and 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, OB2370T samples the Vcs peak current and the demagnetization pulse to control the output current. 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. The chip consumes very low operation current. It achieves less than 30mW standby power to meet strict standby power standard.
The OB2370T offers comprehensive protection coverage with auto-recovery features including Cycle-by-Cycle current limiting, OVP, feedback loop open protection, short circuit protection, built-in leading edge blanking, VDD under voltage lockout (UVLO), on chip OTP etc.
OB2370T is offered in SOP8 package.
Figure 1 Typical I-V Curve
n Primary-side sensing and regulation in QR mode without TL431 and opto-coupler
n Multi-mode PWM/PFM operation for efficiency improving
n Less than 30mW standby power
n Integrated power MOSFET
n Built-in line voltage and primary winding inductance compensation
n Programmable CC Line compensation
n Audio noise free operation
n Built-in Leading Edge Blanking (LEB)
n Cycle-by-cycle current limiting
n Ultra low start-up current and low operating current
n Wide Vdd supply voltage range
n Comprehensive protection coverage with auto-recovery
l VDD over voltage protection
l VDD under voltage lockout with hysteresis (UVLO)
l Output over voltage protection (OVP)
l Output under voltage protection (UVP)
l Feedback loop open protection (OLP)
l On chip OTP
n Compact AC/DC adapter/chargers application