Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

LT1083/84/85 linear regulator family: what's the output voltage range?
LT1083/84/85 linear regulator family: what's the output voltage range?
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 25th July 2007, 03:57 AM   #1
jarthel is offline jarthel  Australia
diyAudio Member
 
Join Date: Jan 2002
Location: somewhere in Australia
Default LT1083/84/85 linear regulator family: what's the output voltage range?

I have the datasheet in front of me. BUT I cannot find the output voltage range for these chips. All I see is input-output voltage differential which is 30V.

I look at the net and no luck there.

Thank you.
  Reply With Quote
Old 25th July 2007, 04:11 AM   #2
gootee is offline gootee  United States
diyAudio Member
 
Join Date: Nov 2006
Location: Indiana
So, as long as the i/o differential is <= 30v, and the i/o differential is > the max dropout voltage, which is around 1.5V IIRC, then they'll work.

As it is with all three-terminal regulators that I am familiar with, strictly speaking, there is no other limitation of the absolute output voltage range. For example, if you wanted to float the whole circuit at around 2000 volts, then the input and output voltages could be at around 2000 volts, as long as V_in - V_out <= 30V, always.

- Tom Gootee

http://www.fullnet.com/~tomg/index.html
  Reply With Quote
Old 25th July 2007, 10:39 AM   #3
jarthel is offline jarthel  Australia
diyAudio Member
 
Join Date: Jan 2002
Location: somewhere in Australia
I somewhat believe that is wrong (i.e. no limit on output voltage).

I have looked at the datasheet of lm317 and lt1086. LT1086 (also from linear) has a max input voltage of 30V. so output voltage range is definitely 30V - dropout voltage.

LM317 is around 30+ V and the HV version I think goes up to 40+ (fairchild's equivalent is 50+ V)
  Reply With Quote
Old 25th July 2007, 12:02 PM   #4
jan.didden is offline jan.didden  Europe
diyAudio Member
 
jan.didden's Avatar
 
Join Date: May 2002
Location: The great city of Turnhout, BE
Tom is right. If you put in 100V and set it for output of 80V you're OK. But that means you either need an adjustable reg like the 317 series, or use a non-adjustable and then put the ref voltage on the "ground" pin (which then is no longer at ground, of course).

Check the data sheet for the LM317 for applications examples for floating regs.

If you use a non-adjustable with the ref pin grounded, yes then you are stuck within Vin max.

Jan Didden
__________________
Cable: a potential source of trouble interconnecting two other potential sources of trouble - Erik Margan
Linear Audio pubs and articles . The SilentSwitcher now at diyaudio store SilentSwitcher. Keeping in touch with SY.
  Reply With Quote
Old 25th July 2007, 11:27 PM   #5
jarthel is offline jarthel  Australia
diyAudio Member
 
Join Date: Jan 2002
Location: somewhere in Australia
Quote:
Originally posted by janneman
Tom is right. If you put in 100V and set it for output of 80V you're OK. But that means you either need an adjustable reg like the 317 series, or use a non-adjustable and then put the ref voltage on the "ground" pin (which then is no longer at ground, of course).

Check the data sheet for the LM317 for applications examples for floating regs.

If you use a non-adjustable with the ref pin grounded, yes then you are stuck within Vin max.

Jan Didden
I'm just confused that the datasheet would specify an output voltage range and you're saying there's really no limit?

in this datasheet (http://cache.national.com/ds/LM/LM117.pdf - 1st sentence), it is clearly said the max output voltage is 37V.

sorry to be a pain but I'm really confused.

thank you.
  Reply With Quote
Old 25th July 2007, 11:48 PM   #6
BWRX is offline BWRX  United States
diyAudio Moderator Emeritus
 
BWRX's Avatar
 
Join Date: Jan 2005
Location: Pennsylvania
It says "The LM117 series of adjustable 3-terminal positive voltage regulators is capable of supplying in excess of 1.5A over a 1.2V to 37V output range."

That does not imply that the maximum output voltage is 37V. You can float the regulator at a much higher voltage as long as the input to output differential is under 40V and it can handle the power dissipation.
__________________
Brian
  Reply With Quote
Old 26th July 2007, 02:53 PM   #7
jarthel is offline jarthel  Australia
diyAudio Member
 
Join Date: Jan 2002
Location: somewhere in Australia
thank you all for the help
  Reply With Quote

Reply


LT1083/84/85 linear regulator family: what's the output voltage range?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Looking for the ideal linear SMD voltage regulator, any suggestions? rhysh Power Supplies 2 12th March 2009 02:07 AM
LT1083/LT1084 Regulator uhcmos Swap Meet 18 6th August 2008 05:46 PM
LT1083/LT1084 Regulator uhcmos Solid State 2 9th June 2008 06:51 PM
has anyone used a CLC + voltage regulator (like LT1083) in their project? jarthel Chip Amps 3 22nd June 2007 04:26 AM
IC Voltage regulator (LT1083) problem trombone Power Supplies 5 10th March 2006 02:28 PM


New To Site? Need Help?

All times are GMT. The time now is 01:58 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 16.67%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki