UNISONIC TECHNOLOGIES CO., LTD

US4651S

LINEAR INTEGRATED CIRCUIT

www.unisonic.com.tw

1 of 9

Copyright © 2015 Unisonic Technologies Co., Ltd

QW-R129-003.B

LOW COST POWER-SAVING

MODE POWER-SWITCH FOR

FLYBACK CONVERTERS



DESCRIPTION

The UTC US4651S is a high performance current mode

power-switch ideally suited for low standby power. Drain start up

make the power reliable on startup design and lower 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 US4651S contains protection with automatic recovery

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

SOP-8

clamp and under voltage lockout).To protect the power MOSFET, Gate-drive output is fixed up to 16V max. The UTC

US4651S

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 US4651S has such applications as: battery charger, power adaptor, set-top box power supplies, ink jet

printers, open-frame SMPS.

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FEATURES

* UTC proprietary frequency hopping technology for Improved EMI

performance.

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

* Soft Start

* Dynamic peak current limiting for constant output power

* Built-in synchronized slope compensation

* Drain start up for lower standby power

* Fixed switch frequency 65kHz

* 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

US4651SG-S08-R

SOP-8

Tape Reel

US4651SG-S08-R

(1)Packing Type

(2)Package Type

(3)Green Package

(1) R: Tape Reel

(2) S08: SOP-8

(3) G: Halogen Free and Lead Free