OB2576ALx is a high performance offline PSR power switch  with CC/CV operation for medium level power AC/DC charger and adapter applications. The device integrates an internal power MOSFET and operates in primary-side sensing and regulation. It removes the need for secondary feedback circuitry to lower the total bill of material cost. Proprietary Constant Voltage (CV) and Constant Current (CC) control is integrated as shown in the figure below.

In CV control, the controller changes the mode of operation according to load condition. The primary side regulation power supplies up to high power without the efficiency limitation of DCM or audible noise.

In CC control, OB2576ALx samples the Vcs peak current and the demagnetization pulse to regulation the output current. The current and output power setting can be adjusted externally by the sense resistor Rs at CS pin.

OB2576ALx offers comprehensive protection coverage with auto-recovery feature including Cycle-by-Cycle current limiting, VDD OVP, OLP, SCP, OTP, programmable Line OVP and Brownout protection etc.

OB2576ALx consumes less than 75mW input power at no- load condition with high line voltage.

OB2576ALx is offered in SOP8 package.

Figure.1. Typical CC/CV Curve


n Primary-side sensing and regulation without TL431 and opto-coupler

n High precision constant voltage and current regulation at universal AC input

n Programmable CV and CC regulation

n Integrated power MOSFET

n Built-in line compensation for tight CC regulation

n Built-in fixed cable compensation

n Built-in primary winding inductance compensation

n Built-in control loop compensation

n Built-in leading edge blanking (LEB)

n Ultra low start-up current and low operating current

n Comprehensive protection coverage with auto-recovery

l VDD over voltage protection (VDD OVP)

l VDD under voltage lockout with hysteresis (UVLO)

l Cycle-by-cycle current limiting

l Feedback open loop protection (OLP)

l  Output short circuit protection (SCP)

l  Programmable Line OVP and Brownout protection



Medium level Power AC/DC offline SMPS for

n Cell phone charger

n Tablet PC

n AC/DC adapter

n Set-top box power supplies