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OB2371 is an excellent primary side regulation controller with CC/CV operation for medium level power AC/DC charger and adapter applications. The device directly drives a power MOSFET and operates in QR mode to provide high efficiency along with several functions of built-in protections. 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 line voltage and load condition. At full loading, the controller operates in quasi-resonant (QR) mode in the universal line voltage. The primary side regulation power supplies up to high power without the efficiency limitation of DCM or audible noise.
In CC control, OB2371 samples the Vcs peak current and the demagnetization pulse to regulation the output constant current. The current and output power setting can be adjusted externally by the sense resistor Rs at CS pin.
OB2371 offers comprehensive protection coverage with auto-recovery feature including Cycle-by-Cycle current limiting, VDD OVP, OLP, SCP, OTP etc.
OB2371 consumes less than 75mW input power at no- load condition with high line voltage.
OB2371 is offered in SOP8 and SOT23-6 package.
Figure.1. Typical CC/CV Curve
nPrimary-side sensing and regulation operates in QR mode without TL431 and opto-coupler
nHigh precision constant voltage and current regulation at universal AC input
noperation with low line voltage at full load
nGood dynamic response
nProgrammable CV and CC regulation
nBuilt-in primary winding inductance compensation
nProgrammable cable drop compensation
nBuilt-in control loop compensation
nExternal over temperature protection with latch shutdown (OTP)(sop-8 package)
nAudio noise free operation
nBuilt-in leading edge blanking (LEB)
nUltra low start-up current and low operating current
nComprehensive protection coverage with auto-recovery
lVDD over voltage protection (OVP)
lVDD under voltage lockout with hysteresis (UVLO)
lCycle-by-cycle current limiting
lFeedback open loop protection (OLP)
lOutput short circuit protection (SCP)
Medium level Power AC/DC offline SMPS for
nCell phone charger
nTablet PC
nAC/DC adapter
nSet-top box power supplies
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