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Old 11th February 2011, 01:45 AM   #1
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Default Please !!!Help me:( about SMSP

Hi all!
I'm newbie.I don't know much about SMSP,I have a exercise a bout it." Design SMSP with Vout=15V". I hope U'll teach me.
And i want to ask a Question:
LM2577 's a kind of SPSM??
Tks everybody
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Old 11th February 2011, 09:00 AM   #2
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Switched-mode power supply - Wikipedia, the free encyclopedia
Do My Assignment | Do My Homework | Assignment Expert
LM2577 is a DC-DC converter that relies on similar concepts as a SMPS. I guarantee you that if you propose a solution based on an LM2577, you won't pass for that assignment. If you do, the course and/or tutor sucks balls.

This one might actually help: http://focus.ti.com/lit/an/slva001d/slva001d.pdf
Good luck!

Last edited by mastodon; 11th February 2011 at 09:05 AM.
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Old 11th February 2011, 09:40 AM   #3
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Quote:
Originally Posted by mastodon View Post
Switched-mode power supply - Wikipedia, the free encyclopedia
Do My Assignment | Do My Homework | Assignment Expert
LM2577 is a DC-DC converter that relies on similar concepts as a SMPS. I guarantee you that if you propose a solution based on an LM2577, you won't pass for that assignment. If you do, the course and/or tutor sucks balls.

This one might actually help: http://focus.ti.com/lit/an/slva001d/slva001d.pdf
Good luck!
Tks very much,U can share document about" Boost mode Calculator",can't U?
I want to know more about Boost mode,tks
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Old 11th February 2011, 09:53 AM   #4
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Google offline in your parts of the world, is it?

Switching-Mode Power Supply Design Tutorial Table of Contents

As for me, from here, you're on your own.
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Old 11th February 2011, 11:06 AM   #5
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Originally Posted by mastodon View Post
Google offline in your parts of the world, is it?

Switching-Mode Power Supply Design Tutorial Table of Contents

As for me, from here, you're on your own.
tks
I have private message for U,
I hope U'll help me
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Old 11th February 2011, 11:18 AM   #6
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What level are you at ?

SMPS design can be VERY complicated or VERY simple, depending on whether you are studying at grad level or high school level.

At high school level your tutor may be satisfied with a simple "Buck Regulator".

At grad level he may be expecting something more elaborate.

+15V

What is your starting voltage ?

What current output do you require ?


Your opening comment is as vague as walking into a car dealership and saying that you want a car that sits four people.
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Old 11th February 2011, 11:23 AM   #7
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Originally Posted by Andy5112405 View Post
What level are you at ?

SMPS design can be VERY complicated or VERY simple, depending on whether you are studying at grad level or high school level.

At high school level your tutor may be satisfied with a simple "Buck Regulator".

At grad level he may be expecting something more elaborate.

+15V

What is your starting voltage ?

What current output do you require ?


Your opening comment is as vague as walking into a car dealership and saying that you want a car that sits four people.
tks
i'm 19 yearsold.
At high school level your tutor may be satisfied with a simple "Buck Regulator"
I think so
Vin=5V and Vout=15V,I want to know how to calculate R,C,L,D.That's enough
Tks for help me
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Old 11th February 2011, 11:23 AM   #8
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A "Buck Regulator" generates a voltage across an inductor (coil) that can either be added to or subtracted from the source voltage.

More complex designs use high frequency switching to generate AC across a transformer.

Mains, self exciting SMPS designs are difficult to design and are very prone to exploding during initial testing.
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Old 11th February 2011, 11:30 AM   #9
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Have a search for the TL497 datasheet. This is a very simple Buck Regulator.
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Old 11th February 2011, 11:41 AM   #10
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Click the image to open in full size.

Basically Pin 1 is compared with the internal reference 1.2V. If pin 1 is less than 1.2V then the regulator will try to output more power to the inductor L1 to increase the output voltage.

If Pin 1 is greater than 1.2V then the regulator will reduce the power into L1.

L1 is usually an RM6, RM8 or RM10 pot core and needs to be about 25 Turns of 20swg wire.

To understand how this works you need to look up Pulse Width Modulation on Wikipedia.

SMPSs run on power. The more POWER you put into the inductor, the more power you can use.

PWM uses a constant frequency, I can't remember the frequency for the circuit above, but the Duty Cycle is variable. ie the ON time is different to the OFF time so the square wave drive to TR1 varies from pulses that are ON for most of time and OFF for short periods, to On for short periods and OFF for long periods. If TR1 is ON for most of its duty cycle then more power will be imparted into L1.

The more POWER that is imparted into L1, the greater the voltage that you will see across it. As this is IN PHASE with the output, this is added to the input voltage.

This type of circuit is only really practical for low power use unless stupidly large inductors are employed.

The circuit illustrated will be good for about 1A output.

The 1N4002 shown in the diagram is woefully inadequate, you really need an ultrafast diode here.

The values of VR1, R4 and R5 simply set Pin 1 to 1.2V with the required output voltage. Increasing R4 will increase the output voltage. You may need to add a few more turns to L1. L1, within limits, can never be too big. Increasing the number of turns to 30 or 40 will just mean that TR1 has to impart less power into it. Too many turns and the inrush current and back emf may exceed the rating of TR1.

Last edited by Andy5112405; 11th February 2011 at 12:09 PM.
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