UNISONIC TECHNOLOGIES CO., LTD

UC2843B

Preliminary

LINEAR INTEGRATED CIRCUIT

www.unisonic.com.tw

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Copyright © 2009 Unisonic Technologies Co., Ltd

QW-R103-048.a

HIGH-PERFORMANCE

CURRENT-MODE PWM

CONTROLLERS

DESCRIPTION

The UTC UC2843B provides off-line or DC-DC fixed-frequency

current-mode control design with minimum external components.

Internally-implemented circuits include an under-voltage lockout

(UVLO) and a precision reference with accuracy at the error amplifier

input. The UTC UC2843B also contain internal circuits which include

a pulse width modulation (PWM) comparator providing current-limit

control, logic ensuring latched operation, and a totem-pole output

stage designed to source or sink high-peak current. The output

stage is low when it is in off-state condition and suitable for

N-channel MOSFETs driving.

The UTC UC2843B also has following advantages: the start-up

current lower than 0.5mA while the oscillator discharge current is

specified to 8.3mA (Typ.). In UVLO conditions, the output has a

The typical UVLO threshold of the UTC UC2843B is 8.4V (on)

and 7.6V (off) and can operate to duty cycles approximately 100%.

FEATURES

* Current mode operation:500 kHz

* Low start-up current value<0.5mA

* Latching PWM for cycle-by-cycle current limiting

* Trimmed oscillator discharge current

* Automatic feed-forward compensation

* Internally trimmed reference with UVLO

* High-current totem-pole output UVLO with hysteresis

* Double-pulse suppression

* Halogen free

ORDERING INFORMATION

Ordering Number

Package

Packing

UC2843BG-S08-R

SOP-8

Tape Reel