UC3869

UNISONIC TECHNOLOGIES CO., LTD UC3869 Preliminary HIGH VOLTAGE GREEN MODE PWM CONTROLLER  DESCRIPTION The UTC UC3869 is a highly integrated current mode PWM control IC with high voltage start up, optimized for high performance, low standby power consumption and cost effective offline flyback converter applications. PWM switching frequency at normal operation is internally fixed and is trimmed to a tight range. At no load condition, the IC operates in power-saving mode for lower standby power, decreasing frequency for Higher conversion efficiency at light load condition. The internal slope compensation improves system stability at high PWM duty cycle output. Leading-edge blanking on current sense input removes the signal glitch, which offering minimal external component count in the design. The UTC UC3869 offers complete protection coverage including Cycle-by-Cycle current limiting (OCP), VDD under voltage lockout (UVLO), over load protection (OLP), over temperature protection (OTP), and over voltage protection (OVP). Excellent EMI performance is achieved with UTC proprietary frequency hopping technique (ZL201020615247.1) together with soft driver control. Audio noise is eliminated due to switch frequency more than 20kHz during operation. The tone energy at below 22KHZ is minimized to avoid audio noise during operation.  FEATURES * High voltage startup * Power on soft start reducing MOSFET Vds stress * Efficiency and minimum standby power * Frequency shuffling for EMI * ...