GENERAL DESCRIPTION
OB2268C is a highly integrated current mode PWM
control IC optimized for high performance, low
standby power and cost effective offline flyback
converter applications.
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.
VDD low startup current and low operating current
contribute to a reliable power on startup design with
OB2268C. 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 subharmonic
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. This greatly helps to reduce the
external component count and system cost in
application.
OB2268C 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
at 18V to protect the power MOSFET.
In OB2268C, OCP threshold slope is internally
optimized to reach constant output power limit over
universal AC input range.
Excellent EMI performance is achieved with soft
switching control at the totem pole gate drive output.