• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 62 subscribers
  • Views 217 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ucc28700 5v 1a output current

Giuseppe Giancola1
Intellectual 730 points

hi, i'm trying to make a 5V 1A flyback supply, usig a coilcraft transformer B0570-BL, http://www.coilcraft.com/ncp101x.cfm.

now, i'm using the standard circuit with Rs1=120k, Rs2= 30k, Rlc=4.7k

my problem is that the output at no load i've 5.5V but when i connect a load the output voltage falls to 0.5V, what can i do? maybe to use a sensing circuit on the output?

thanks

  • 0
    Intellectual 730 points

    hi, i think the problem is on the aux windings, on Vs pin i have a voltage of 0v, so the ic doesn't work, moreover the output rise is too slow, it take about one minute to raise to 5V and when I connect a load the output voltage goes down to 0.11V. I changed the previous transformer with this:

    http://www.coilcraft.com/pdfs/da2077.pdf


    during the power on state, i measured a voltage about 12/14 volts on vdd and the mosfet is an IRF830.

    any ideas?? 

    thanks