Primary-Side PWM Power Switch with CC/CV
OB2211H 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. 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.
OB2211H offers power on soft start control and
protection coverage with auto-recovery features
including Cycle-by-Cycle current limiting, VDD
clamp and UVLO. Excellent EMI performance is
achieved with On-Bright proprietary frequency
shuffling technique together with soft switching
control at the totem pole gate drive output.
OB2211H achieves better CC control accuracy and
higher system efficiency through PWM control than
its sibling part OB2211.
Primary-side Sensing and Regulation Without
TL431 and Opto-coupler
Multi-mode Operation for High Efficiency
Programmable CV and CC Regulation
Adjustable Constant Current and Output Power
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
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
OB2211H is offered in SOP8 package.
Fig 1. Typical CC/CV Curve