help needed on attached circuit - diyAudio
Go Back   Home > Forums > Amplifiers > Power Supplies

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 17th July 2008, 04:47 PM   #1
diyAudio Member
 
Join Date: Feb 2008
Send a message via Yahoo to jegandren
Default help needed on attached circuit

Hi all,

Attached is a AC - DC circuit with a power factor corrector IC. From the attachment when a pulse is given to the gate of the MOSFET, so current would flow from drain to source. My question is wouldn't it short the circuit and lead to fatal circuit blow.
Attached Images
File Type: gif untitled.gif (12.5 KB, 165 views)
  Reply With Quote
Old 17th July 2008, 10:07 PM   #2
TechGuy is offline TechGuy  United States
diyAudio Member
 
Join Date: Apr 2006
Location: Connecticut
Not unless the controller causes the inductor to saturate. When the Mosfet is switched on, the inductor resists the flow of current, limiting that amount of power drawn. The inductor will restrict current flow until it reaches saturation. So as long as the mosfet is switched off before the inductor saturates, it will operate without a problem.
  Reply With Quote
Old 21st July 2008, 11:11 AM   #3
jtkraj is offline jtkraj  India
diyAudio Member
 
Join Date: Jun 2008
If you go through the Buck-Boost topology. you will understand and have basic idea about how these kind of circuit operates.

you will find a hell lot of articles in Web to learn about the PFC operation.
  Reply With Quote
Old 21st July 2008, 02:57 PM   #4
golam is offline golam  Bangladesh
diyAudio Member
 
Join Date: Jun 2008
Hi Jegandren,

No, the circuit will not be shorted. The schematic you have given is the schematic of a Non-isolated flyback circuit. The non-isolated flyback turns on the MOSFET for a fraction D of the switching period, which, since it produces a voltage across the inductor, causes current to ramp up, storing energy in the inductance. When the MOSFET turns off, the inductor current goes through the diode and into the output capacitor and load. The non-isolated flyback should have a single output (there is no way to make more than one). The output is not isolated from the input and the output cannot be made less than the input voltage - even if you turn the MOSFET completely off, the output will equal the input (minus a diode drop).

Frequently people call the non-isolated flyback a 'boost' converter, which is not appropriate.

Thanks.
__________________
Microcontroller is the future in Electronics.
মাইক্রোকন্ট্রলারই ইলেক্ট্রনিক্সের ভবিষ্যৎ।
  Reply With Quote
Old 22nd July 2008, 05:59 PM   #5
mflorin is offline mflorin  Romania
diyAudio Member
 
Join Date: Jun 2005
Location: IASI
If you're going to use L4981A, then check controller's datasheet and all available application notes (www.st.com). You'll find all the information you need (including basic stuff).
See also the PFC free software that will help you design a PFC stage based on L4981A.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Sub amp circuit needed space2000 Solid State 9 4th November 2011 11:23 AM
Advice needed about Lexsen power - photo attached Brit01 Solid State 2 28th July 2008 09:05 AM
Help needed for H-Bridge circuit xyz9915 Solid State 5 5th May 2008 11:30 AM
Active BSC and RC circuit - help needed HiFiNutNut Multi-Way 2 21st March 2005 10:30 PM
transistor subz question..circuit attached tone Digital Source 0 18th April 2003 12:45 PM


New To Site? Need Help?

All times are GMT. The time now is 01:04 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2