*Glances back at the OP*, oh yeah, a couple amps will be needed, won't it. Well, most of these are families, should be able to find something bigger SRF or LPD or whatever. Or that inverter transformer is looking quite good, despite its size and cost.
Gotcha,
Thanks.
It's of significant orders of magnitude larger in L... 1.2mH @ 65kHz ....
Would that make much of a difference generally speaking ?
The original design runs the minimum recommended by TI, 50kHz.
Oh.. by the way ... what does SRF or LPD mean ? not Self Resonant Frequency surely ?
your mosfet you say is switching unevenly.
You can often correct this by judicious adjustment of the current sense filter and the fet gate series resistor.
But there is no gate series resistor in your schem. I think you need one.
Sometimes of course, uneven fet switching can be caused by insufficient slope compensation in current mode designs.
Sometimes it can be caused by insufiicient delta current in the current signal, ie you have used too big inductance and the on state current ramp is so shallow that it easily hits the sense threshold through noise instead of in the normal way.
Also, here is my pcb layout doc attached
Oh by the way, a lot of the spikes i saw are just "pickup"...induced into the scope probes impedance by all the noise that an smps chucks out.
There is a test to see if it is pickup....connect your scope ground clip to the probe tip and see if you see the spikes still, with the probe tip touching whichever node on the circuit.
I think I mentioned that
The original one is there C11 and R7.
Of course.
Please read back a few pages.
It has been mentioned
Indeed it has even been drawn !
Edit: this is the droid you are looking for master skywalker
https://www.eevblog.com/forum/projects/design-of-smps-not-sure-what-these-spikes-are-being-caused-by/msg1550420/#msg1550420
P.S. do you have any clues as to why a center tap would reduce the amps out ?
No probs "brah"
Thanks for the clue !
Cheers,
Phill from W.A.
Output current: probably lower because primary inductance is lower? A 50% tap gives Lp ~= 25% of total inductance. Maximum peak current remains the same, so you get less energy per cycle = less average power. Ideally what you'd have done: wind the same (or more) number of turns on top.
Tim
You are right. Many great articles on it.
Trouble is you can't ask an article a question.
Hence why this forum is what it is.
A great way for people to help each other out about the things they don't understand just by reading them.
No need for teachers if we could all just read it in a book right ?
The "just google it" seems to be a catchall these days. It's good but not always the best way to get the exact knowledge you seek.
I am sure you agree. I have seen some of your posts
Indeed ,and if you had followed the thread from the start, you would see that someone has already provided what I think is one of the best ones out there in this very thread !