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Home > PWM Controller
UC3869 Datasheet


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), V
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.

* High voltage startup  
* Power on soft start reducing MOSFET Vds stress  
* Efficiency and minimum standby power
* Frequency shuffling for EMI  
* Audio noise free operation
* Fixed 65KHZ switching frequency
* Comprehensive protection coverage
 V DD  Under Voltage Lockout with Hysteresis (UVLO)  
Cycle-by-cycle over current protection (OCP)
 Overload Protection (OLP) 
 External programmable Over Temperature Protection (OTP)
 V DD  Over voltage Protection(OVP) 
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