SG3525 Frequency - 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 27th January 2009, 09:14 AM   #1
Account Disabled
 
Join Date: Oct 2008
Default SG3525 Frequency

What is the formula used to calculate the frequency for the SG3525?

That info was not provided in the Datasheet.



?
  Reply With Quote
Old 27th January 2009, 10:07 AM   #2
pjp is offline pjp  India
diyAudio Member
 
pjp's Avatar
 
Join Date: Nov 2006
Location: under the rainclouds
The formula is given in a footnote on page 4 of the ST SG3525 datasheet.
  Reply With Quote
Old 28th January 2009, 07:01 AM   #3
Account Disabled
 
Join Date: Oct 2008
Default Sheet

I had the wrong data sheet from www.alldatasheet.com

The one i have for the Motorola version!!

Thanks
  Reply With Quote
Old 28th January 2009, 08:48 PM   #4
diyAudio Member
 
N-Channel's Avatar
 
Join Date: Mar 2003
Location: Sol System
Send a message via AIM to N-Channel
Clock (oscillator) frequency is:

F = 1/{0.7 * 3[R(d)] * R(t) * C(t)}.

So if you have no deadtime resistor, R(d) drops out of the equation. Now, for a clock frequency of, say, 120kHz, if your R(t) = 3.6kW, then your C(t) would = 3300pF. F(osc) is actually 120.25kHz, but that's close enough.

Remember, the SG3525 is dual-ended, so your switching frequency is always one-half the clock frequency, so your F(sw) = 60kHz.

Hope this helps.

Regards,

Steve
__________________
-. ---.. -..- ---
  Reply With Quote
Old 9th April 2009, 03:43 PM   #5
rajudp is offline rajudp  India
diyAudio Member
 
Join Date: Mar 2005
Location: Kerala
the frequency is 1/{( 0.7RT+3RD) * CT}
  Reply With Quote
Old 9th April 2009, 07:05 PM   #6
diyAudio Member
 
N-Channel's Avatar
 
Join Date: Mar 2003
Location: Sol System
Send a message via AIM to N-Channel
Oops! I guess I had the paranthesis-bracket-symbology a bit mucked up. Yes, Rd is multiplied by 3, and Rt is multiplied by 0.7

Apologies for the confusion.

Steve
__________________
-. ---.. -..- ---
  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
SG3525 problem ifrythings Power Supplies 36 12th December 2013 06:30 AM
Synchronizing SG3525 Pierre Power Supplies 17 17th March 2009 08:32 AM
SG3525, SMPS need help jegandren Power Supplies 12 12th September 2008 03:10 PM
SG3525 problem lorenzo_cy Power Supplies 7 19th April 2007 06:42 AM
SG3525 - Getting started... Wynand Power Supplies 8 26th February 2007 02:25 PM


New To Site? Need Help?

All times are GMT. The time now is 10:58 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