UNISONIC TECHNOLOGIES CO., LTD

UC3875C

Preliminary

LINEAR INTEGRATED CIRCUIT

www.unisonic.com.tw

1 of 9

Copyright © 2015 Unisonic Technologies Co., Ltd

QW-R103-075.b

LOW COST POWER-SAVING

MODE PWM CONTROLLER

FOR FLYBACK CONVERTERS



DESCRIPTION

The UTC UC3875C 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 UC3875C contains protection with automatic recovery

including OLP (over load protection), OTP (over temperature

power MOSFET, Gate-drive output is fixed up to 15V max. The UTC UC3875C 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 UC3875C 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.

* Power-saving mode for high light-load and standby efficiency

* Dynamic peak current limiting for constant output power

* Built-in synchronized slope compensation

* Programmable PWM Frequency

* Gate output voltage clamped at 15V

* Low start-up current

* Cycle-by-cycle Current Limiting

* Under voltage lockout (UVLO)

* Few external components required

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ORDERING INFORMATION

Ordering Number

Package

Packing

UC3875CG-S08-R

SOP-8

Tape Reel

UC3875CG-S08-R

(1)Packing Type

(2)Package Type

(1) R: Tape Reel

(2) S08: SOP-8

(3) G: Halogen Free and Lead Free

(3)Green Package