FEATURES
uLiiSemi Proprietary Cycle Turning Technology for
Improved EMI Performance.
uExtended Burst Mode Control For Improved
Efficiency and Minimum Standby Power Design
uAudio Noise Free Operation
uExternal Programmable PWM Switching Frequency
and Over Temperature Protection (OTP)
uInternal Synchronized Slope Compensation
uLow VDD Startup Current and Low Operating
Current
uLeading Edge Blanking on Current Sense Input
uVDD Over Voltage Clamp and Under Voltage
Lockout with Hysteresis (UVLO)
uGate Output Maximum Voltage Clamp (18V)
uLine Input Compensated Over Universal Input
Voltage Range.
uCycle-by-Cycle Over-current Threshold Setting For
Constant Output Power Limiting Over Universal
Input Voltage Range.
uOverload Protection (OLP)

APPLICATIONS
² Offline AC/DC flyback converter
² Battery Charger
² Power Adaptor
² NoteBook Power Supplies
² Open-frame SMPS

GENERAL DESCRIPTION
LN3C69 is is a highly integrated current mode PWM
control IC optimized for high performance, low standby
power and cost effective offline flyback converter
applications in less than 70W range. 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 LN3C69. 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 thus greatly reduces the
external component count and system cost in the
design. LN3C69 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 clamp 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 LiiSemi
proprietary Cycle Turning technique together with soft
switching control at the totem pole gate drive output.
Tone energy at below 22kHz is minimized in the
design and audio noise is eliminated during operation.
LN3C69 is offered in SOP8 and DIP8 packages.