UC3842BP-S08-R datasheet(7/11 Pages) UTC

Part #	UC3842BP-S08-R

Description	HIGH PERFORMANCE CURRENT MODE CONTROLLERS

PDF	11 Pages

Scroll/Zoom	100%

Manufacturer	UTC [Unisonic Technologies]

Direct Link	http://www.utc-ic.com

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7 / 11 page

UC3842B/3843B

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

7 of 11

www.unisonic.com.tw

QW-R103-012.D

APPLICATION INFORMATION(Cont.)

Current Sense Circuit

Peak current (IS) is equaled:

IS(MAX)=1.0V/RS

There should be a small RC filter to suppress switch transients.

Oscillator Waveforms and Maximum Duty Cycle

VREF

RT/RC

GND

INTERINAL CLOCK

LARGE RT

SMALL CT

LARGE RT

CT (Oscillator timing capacitor) can be charged by VREF through RT and discharged by an internal current source. At

discharge time, the internal clock signal blanks the output to the low. Both oscillator frequency and maximum duty

cycle can be determined by Selection of RT and CT. All charge and discharge times can be calculated by the next

formulas:

tC=0.55 RT CT

tD=RTCTIn

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

0.0063R

2.7

0.0063R

UC3842BP-S08-R Datasheet(PDF) 7 Page - Unisonic Technologies