How to find DCM or CCm

[whatty]

Hi
I am using PWM controller uc3843 DOES THIS IC UC3843 WORKS IN DCM OR CCM HOW TO FIND IT OR HOW TO MAKE IT WORK IN DCM MODE.
i didnt find anything the Texas instrument datasheet saying setting of DCM or CCM  using the pins. i had attached the datasheet and even in application notes i couldn't find anything saying how make the ic to work in CCM or DCM mode.

[Zipdox]

Whether it runs in DCM or CCM is not a function of the PWM controller but of the inductor, switching frequency and load.

[whatty]

yeah ok as you said i will design the ferrite core transformer according to the dcm calculations and procedures how would i set the frequency in uc3843 so that the circuit operates in dcm mode ....? in uc3843 we could change the frequency by adjusting R and C values across R/T pin how could this determine the DCM mode please can you explain in detail....? 

[BadeBhaiya]

DCM and CCM are terms which are not very useful when you're talking about converters in a non-academic setting. Imagine this, if the load is extremely light, a single switching cycle of the UC3843 (or whatever the SMPS IC) would be adequate to uphold the output voltage rail and as a result, the feedback would be higher than the threshold for a long enough time that the inductor current would fall to 0A (viola! DCM). In contrast with a heavy load, the feedback will never be high enough to ever stop the switcher (CCM!!).

As for setting the switching frequency, just have a read of the datasheet. It should give you everything you need