OB2268/9 is a highly integrated current mode PWM
control IC optimized for high performance, low
standby power and cost effective offline flyback
converter applications in above 20W power level.
PWM switching frequency at normal operation is
externally programmable and trimmed to tight range.
At no load or light load condition, the IC operates in
extended ‘burst mode’ to minimize switching loss.
Lower standby power and higher conversion
efficiency is thus achieved.
www.DataSheVet4DUD.colmow startup current and low operating current
contribute to a reliable power on startup design with
OB2268/9. A large value resistor could thus be used
in the startup circuit to minimize the standby power.
The internal slope compensation improves system
large signal stability and reduces the possible sub-
harmonic oscillation at high PWM duty cycle output.
Leading-edge blanking on current sense input
removes the signal glitch due to snubber circuit diode
reverse recovery. and greatly reduces the external
component count and system cost in the design.
OB2268/9 offers complete protection coverage with
automatic self-recovery feature including Cycle-by-
Cycle current limiting (OCP), over load protection
(OLP), over temperature protection (OTP), VDD
over voltage protection (OVP) and under voltage
lockout (UVLO). The Gate-drive output is clamped
to maximum 18V to protect the power MOSFET.
Excellent EMI performance is achieved with On-
Bright proprietary frequency shuffling technique
(OB2269 only) together with soft switching control at
the totem pole gate drive output.
The tone energy at below 20KHZ is minimized in
operation. Consequently, audio noise performance is
Current Mode PWM Controller
OB2268/9 is offered in SOP-8 and DIP-8 packages.
■ Extended Burst Mode Control For Improved
Efficiency and Minimum Standby Power Design
■ Audio Noise Free Operation
■ External Programmable PWM Switching
■ Internal Synchronized Slope Compensation
■ Low VIN/VDD Startup Current(4uA) and Low
Operating Current (2.3mA)
■ Leading Edge Blanking on Current Sense Input
■ Complete Protection Coverage With Auto Self-
o External Programmable Over Temperature
o With or Without On-chip VDD OVP for
Output Over Voltage Protection.
o Under Voltage Lockout with Hysteresis
o Gate Output Maximum Voltage Clamp (18V)
o Line Compensated Cycle-by-Cycle Over-
current Threshold Setting For Constant Output
Current Limiting Over Universal Input Voltage
o Over Load Protection. (OLP)
■ On-Bright Proprietary Frequency Shuffling
Technology for Improved EMI Performance
Offline AC/DC flyback converter for
■ Laptop Power Adaptor
■ PC/TV/Set-Top Box Power Supplies
■ Open-frame SMPS
■ Battery Charger
A Liteon Semiconductor Company