UNISONIC TECHNOLOGIES CO., LTD

UC3875L

CMOS IC

www.unisonic.com.tw

1 of 11

Copyright © 2016 Unisonic Technologies Co., Ltd

QW-R103-125 .A

LOW COST POWER-SAVING

MODE PWM CONTROLLER

FOR FLYBACK CONVERTERS



DESCRIPTION

The UTC UC3875L 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

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 UC3875L contains protection with automatic recovery

including OLP (over load protection), OCP (cycle-by-cycle current

lockout). It also provides the protections including OTP (over

temperature protection), OVP (over voltage protection) in UC3875L

with latch up. To protect the power MOSFET, Gate-drive output is

fixed up to 16V max.

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 UC3875L has such applications as: battery charger,

power adaptor, set-top box power supplies, ink jet printers,

open-frame SMPS.



FEATURES

* UTC proprietary frequency hopping technology for Improved EMI

performance.

* Lower than 30mW Standby Power Design

* Dynamic peak current limiting for constant output power

* Built-in synchronized slope compensation

* OLP with automatic recovery

* OTP and OVP with latch up

* Programmable frequency

* Gate output voltage clamped at 16V

* Low start-up current

* Cycle-by-cycle Current Limiting

* Under voltage lockout (UVLO)

* Few external components required

SOP-8