TNY266 flyback switcher - 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 12th November 2010, 11:04 AM   #1
Khron is offline Khron  Romania
diyAudio Member
 
Join Date: Jul 2005
Location: Finland
Send a message via AIM to Khron Send a message via MSN to Khron Send a message via Yahoo to Khron
Default TNY266 flyback switcher

Hello again,

I'm in the process of putting together a "UV exposer" with a MAX1698A led driver, and i've decided to supply it from a 5vsb section "grafted" from an HP power supply, based on a TNY266 chip.

The schematic i'm using is attached below. Now, the switcher is definitely working (scoped it out), and on the 220u filter cap, from the aux primary winding, i'm getting 14-17v. Trouble is, for some reason, the chip is on minimum duty cycle, and on the secondary, i'm getting some tiny blips (which i'm not even sure are enough to open the rectifier schottky). I also changed the optocoupler, same thing.

I wonder if the coil i'm using is a bit too big (180uH), but... Should / could that affect things quite like that? Secondary caps are two 1500uH/6.3v Nichicon HD. I also tacked on a 51ohm resistor as a ~100mA minimum load. Nothing else is mounted on the board (so just supply-related components).

Could the TL431 be bad?
Attached Images
File Type: jpg sch.jpg (93.9 KB, 75 views)
  Reply With Quote
Old 12th November 2010, 05:40 PM   #2
diyAudio Member
 
Sch3mat1c's Avatar
 
Join Date: Jan 2003
Location: Milwaukee, WI
Send a message via ICQ to Sch3mat1c Send a message via AIM to Sch3mat1c
Is the secondary phased correctly?

Current mode PWM drivers generate narrow spikes when you try driving rectifiers instead of inductors...

Tim
__________________
Seven Transistor Labs
Projects and Resources
  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
LM2575 for flyback? lumanauw Power Supplies 6 9th October 2010 07:02 PM
1000w out offline flyback zerohead_ak47 Power Supplies 47 17th January 2009 12:32 PM
110W Flyback chimi Power Supplies 6 27th October 2008 12:38 PM
Lossless Snubbered Flyback ChocoHolic Power Supplies 8 19th August 2007 09:30 AM
Flyback design for preamp TomSSS Power Supplies 0 12th November 2006 12:53 AM


New To Site? Need Help?

All times are GMT. The time now is 03:35 PM.


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