OB2211/OB2212
Primary-Side Regulation PWM Power Switch
FEATURES
Primary-side Sensing and Regulation With No
TL431 and Opto-coupler
Multi-mode Operation for High Efficiency
Programmable CV and CC Regulation
Adjustable Constant Current and Output Power
setting
Frequency Shuffling and Adjustable Gate Drive
Greatly Improving EMI
Power on Soft-start Time (4ms)
“Extended Burst Mode Control” for Improved
Efficiency and Minimum Standby Design
Built-in Leading Edge Blanking (LEB)
Cycle-by-Cycle Current Limiting
VDD Under Voltage Lockout with Hysteresis
(UVLO)
VDD Over Voltage Shutdown and Clamp
Auto-restart in Over Voltage condition
Fail-safe protection for open loop fault condition
GENERAL DESCRIPTION
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.
APPLICATIONS
Low Power AC/DC offline SMPS for
Cell Phone Charger
Digital Cameras Charger
Small Power Adaptor
Auxiliary Power for PC, TV etc.
Linear Regulator/RCC Replacement
OB2211 is offered in SOP8 package.
OB2212 is offered in DIP8 package
Fig 1. Typical CC/CV Curve
TYPICAL APPLICATION
©On-Bright Electronics
Confidential
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