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Home > PWM Controller
UC3875 Datasheet

LOW COST POWER-SAVING MODE PWM CONTROLLER
FOR FLYBACK CONVERTERS
 
 

DESCRIPTION
 
 
The UTC UC3875 is a high performance current mode PWM
controller ideally suited for low standby power. The PWM switching
frequency is programmable externally at normal operation. Low
VDD startup current make the power reliable on startup design and
a large value resistor could be used in the startup circuit to
minimize the standby power. 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 UTC UC3875 contains protection with automatic recovery
including OLP (over load protection), OTP (over temperature
protection), OVP (over voltage protection), UVLO (VDD over voltage clamp and under voltage lockout).To protect the
power MOSFET, Gate-drive output is fixed up to 15V max. The UTC UC3875 contains protection OCP
(cycle-by-cycle current limiting).
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. 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 UTC UC3875 has such applications as: battery charger, power adaptor, set-top box power supplies, ink jet
printers, open-frame SMPS.
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