SMPS design

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#1 21660807 21 Jan 2012 01:44

Charith Mendis Charith Mendis

Anonymous

Post #1
21660807 21 Jan 2012 01:44

I have been given to design a SMPS for the following specifications.

Vin = 230V ac 50 Hz
Vout = 221V DC
Iload = 20mA DC
output ripple = 1% of the output voltage

N-channel High Side MOSFET, and should work in DCM. I think this specification is little awkward and I am unable to design a specific circuit.

Can anyone help me on this?
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#2 21660808 21 Jan 2012 01:45

Charith Mendis Charith Mendis

Anonymous

Post #2
21660808 21 Jan 2012 01:45

I forgot, they wanted this done by a buck converter. It's become even harder.
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#3 21660809 21 Jan 2012 12:37

Todd Hayden Todd Hayden

Anonymous

Post #3
21660809 21 Jan 2012 12:37

At what point are you stuck? Wouldn't you normally use a buck converter to regulate to a lower voltage, why is that harder?
#4 21660810 21 Jan 2012 15:35

Cody Miller Cody Miller

Anonymous

Post #4
21660810 21 Jan 2012 15:35

The design then should be broken up into two parts.

* The 230 VAC to an intermediate DC voltage.
* The intermediate DC voltage to Vout.

What kind of budget are you looking at for this project. Can you buy modules like these "AC to DC modules":http://www.vicorpower.com/cms/home/product-selector?productCategory_filter=AC-DC%20Power%20Systems
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#5 21660811 21 Jan 2012 19:24

Steve Lawson Steve Lawson

Anonymous

Post #5
21660811 21 Jan 2012 19:24

Silly question, but, for that small amount of current and slight voltage drop, isn't SMPS overkill? How about a simple linear regulator? We're talking a mere 5th of a watt, here!
#6 21660812 21 Jan 2012 22:13

Charith Mendis Charith Mendis

Anonymous

Post #6
21660812 21 Jan 2012 22:13

Yes, but the absurdly high voltage at the output makes it hard to make 5-15V needed for the controller Vcc. I can't use an external power. With an isolated topology I could have achieved this.
#7 21660813 21 Jan 2012 22:14

Charith Mendis Charith Mendis

Anonymous

Post #7
21660813 21 Jan 2012 22:14

I am stuck at finding a good MOSFET driver and a controller. I have done the design for the buck and it works in PSPICE.
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#8 21660814 21 Jan 2012 22:17

Charith Mendis Charith Mendis

Anonymous

Post #8
21660814 21 Jan 2012 22:17

It can't be a isolated supply. The budget is
#9 21660815 21 Jan 2012 22:21

Charith Mendis Charith Mendis

Anonymous

Post #9
21660815 21 Jan 2012 22:21

Yes, you are right. But, I need to design according to their specification.

Can you specify good MOSFET drivers and a controller IC for this? Also I need their PSpice models. I need to do a simulation myself to get sure. Also, method to drive the Vcc of ICs is a problem. I can't use external power.
#10 21660816 21 Jan 2012 22:24

Charith Mendis Charith Mendis

Anonymous

Post #10
21660816 21 Jan 2012 22:24

Hello, by intermediate voltage do you mean 325V(the peak) got from a smoothed bridge rectifier?
I am using it currently.
#11 21660817 21 Jan 2012 22:31

Steve Lawson Steve Lawson

Anonymous

Post #11
21660817 21 Jan 2012 22:31

How much regulation is needed?
#12 21660818 22 Jan 2012 02:35

Charith Mendis Charith Mendis

Anonymous

Post #12
21660818 22 Jan 2012 02:35

1% of the Vout as the output ripple.
#13 21660819 22 Jan 2012 11:45

Todd Hayden Todd Hayden

Anonymous

Post #13
21660819 22 Jan 2012 11:45

Why are they mandating an N channel high side switch (why do they care)? Is this homework, paid work, or hobby?
#14 21660820 22 Jan 2012 13:06

Charith Mendis Charith Mendis

Anonymous

Post #14
21660820 22 Jan 2012 13:06

Actually this is a favour asked from a member in our faculty, eventhough it seems absurd.
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