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.