Offline SMPS 16W: Post mains rectifier capacitor voltage fluctuation?

Status
Not open for further replies.
T

treez

Guest
Hello ,
I am doing a offline flyback (Pin=16W), (Vin=230VAC) (Post mains rectifier capacitor = 330nF.)

Page 7 (equn 2) of the following gives the voltage variation on the post mains rectifier capacitor.
https://www.mouser.com/pdfdocs/2-9.pdf

However, how do I calculate the "dch" value.
Since I only use 330nF, "DCH" will be large, but I don't know how to calculate it.
 

I assume that the voltage almost follows the fullwave rectified sine and drops to zero at zerocrossings, DCH = Vpeak. In detail, you need to know how the switcher reacts on input voltage variations.
 
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
We would use such a low DC bus capacitor value if we implement a flyback switcher with PFC features. In this case, the secondary filter capacitor must store energy between the input voltage peaks to get a smooth output.
 
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
We would use such a low DC bus capacitor value if we implement a flyback switcher with PFC features. In this case, the secondary filter capacitor must store energy between the input voltage peaks to get a smooth output
Click to expand...
..Yes indeed that's why we are doing it...its for a high volume light bulb, so we need a good degree of PFC
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…