High Performance Quasi-Resonant PWM Controller
OB2201 is a high performance flyback Quasi-
Resonant (QR) controller optimized to achieve
high efficiency in the universal input range and full
loading range with effective system cost.
At full loading, the IC operates in fix frequency
(52KHz) CCM mode in the low line input range
and operates in QR mode in high line input range.
In this way, high efficiency in the universal input
range at full loading can be achieved.
At normal load condition, it operates in QR mode.
To minimize switching loss, the maximum
switching frequency in QR mode is internally
limited to 90 KHz. When the loading goes low, it
operates in PFM mode for high power conversion
efficiency. When the load is very small, the IC
operates in ‘Extended Burst Mode’ to minimize the
standby power loss. As a result, high conversion
efficiency can be achieved in the whole loading
OB2201 offers comprehensive protection
coverage including Cycle-by-Cycle Current
Limiting (OCP), VCC Under Voltage Lockout
(UVLO), Output Over Voltage Protection (OVP),
Over Temperature Protection (OTP), Over Load
Protection (OLP), VCC Over Voltage Protection
(VCC OVP), VCC Clamp, and Gate Clamp.
OB2201 also features protections against pin
open and short conditions on selected pins.
OB2201 is offered in SOP-8 and DIP-8 packages.
■ Multi-Mode Operation:
• At Full Loading, Fix Frequency (52KHz)
CCM Operation @ Low Line and QR Mode
Operation @ High Line Input
• Quasi-Resonant Operation at Normal
• Pulse Frequency Modulation (PFM)
Operation at Light Load
• Burst Mode at No Load
■ Adaptive Frequency Shuffling and Slope
Compensation @ Fix Frequency CCM Mode
■ Programmable OTP with latch Shutdown
■ Fixed 4ms Soft-start
■ 2.5us Minimum Off Time
■ 12.5us Maximum On Time Limit
■ 55us Maximum Off Time Limit
■ 90KHz Maximum Frequency Limit
■ Internal Leading Edge Blanking
■ Output Over Voltage Protection
■ 800mA Peak Current Sink/Source Capability
Offline AC/DC flyback converter for
■ Power Adaptor and Open-frame SMPS
■ Set-Top Box Power Supplies