UC3842B/3843B

LINEAR INTEGRATED CIRCUIT

UNISONICTECHNOLOGIESCO.,LTD

7 of 10

www.unisonic.com.tw

QW-R103-012.E

APPLICATION INFORMATION(Cont.)

Shutdown Techniques

8

3

SHUTDOWN

330Ω

500Ω

TO CURRENT

SENSE-RESISTOR

1KΩ

SHUTDOWN

1

COMP

The UTC UC3842B’s shutdown can be accomplished by two ways: raise Pin 3 above 1V; or pull Pin 1 below a

voltage two diode drops above ground. Either method can cause the PWM comparator’s output to be high. Because

the PWM latch is reset dominant, the output will remain low until the next clock cycle after the shutdown condition at

Pins 1 and/or 3 is removed.

Slope Compensation