Dear All,
In the following App Note...
http://www.st.com/stonline/products/literature/an/5656.htm
....a schematic is given for an electronic lamp ballast using switch mode PFC and PWM stages.
I am wondering why the PWM stage (which supplies the lamp) has no output voltage feedback sensing...
i believe you can mitigate flux walking with a series cap. Or use current mode control. I think in days gone by comparators weren't quick enough to do current mode control.
Flux walking can also be a problem with half and full bridges. I tested a push pull once and one fet had been connected...
carnage1.. I hear that a sub-miniature mains (50Hz) transformer can be a good idea for an auxiliary supply within an SMPS.....especially in large SMPS's.
If it was only for a few Watts then i suppose the fact that it probably uses a diode bridge followed by a smoothing cap probably doesn't make...
Comcokid i checked out those products in your post. They look like the cheapest, simplest, lowest component count SMPS for eg a few Watts to eg switch out the inrush resistor relay in a Power factor corrected Switch Mode Power Supply.
Hope any reader can tell me if this is wrong.
And i didn't...
Good luck with the book situation, come to think of it, i havn't seen too much on push-pulls either.
I agree that differential mode filters provides some common mode rejection.
This is interesting though, on page 5 of this application note (half way down on the left)....it says that...
I notice in the book "power supply cookbook" by Marty Brown that he concludes every smps design example with the design of a second order common mode EMC filter.
He states that if this isnt sufficient a differential filter stage should be added to make it 3rd order.
I would have thought that...
