OB2211/OB2212 is an 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 from design. 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. Device operates in fixed frequency mode
at large load conditions, frequency reduction mode at
light/medium load and ‘Extended burst mode’ at
No/light load conditions.
OB2211/OB2212 offers power on soft start control
and complete protection coverage with auto-recovery
features including Cycle-by-Cycle current limiting,
VDD over-voltage clamp and UVLO, fail-safe
protection for open loop fault condition. Excellent
EMI performance is achieved with On-Bright
proprietary frequency shuffling technique together
with soft switching control at the totem pole gate
drive output with No-Y cap design.